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oracle exadata oracle exadata database machine exadata computing platform specialized optimized running oracle database goal exadata achieve higher performance availability lower cost moving database algorithms intelligence storage networking bypassing traditional processing layers exadata combined hardware software platform includes scale-out compute servers scale-out intelligent storage servers ultra-fast infiniband networking ultra fast nvme flash specialized exadata software wide range shapes price points exadata storage uses high-performance servers store data run exadata software run data-intensive database processing directly shared storage tier exadata debuted 2008 first oracle corporation family engineered systems use corporate data centers deployed private clouds october 2015 exadata became available oracle cloud subscription service known exadata cloud service early 2017 third exadata deployment choice became available exadata cloud customer exadata cloud service technology deployed on-premises behind corporate firewall managed oracle cloud experts like exadata cloud service exadata cloud customer owned managed oracle licensed pay-as-you-go subscription oracle cloud customer program intended bring benefits oracle public cloud still satisfying security regulatory constraints exadata designed optimally run oracle database workload combination workloads oltp application running simultaneously analytics processing platform frequently used consolidate many databases previously running dedicated database servers exadata scale-out architecture naturally suited running oracle cloud computing requirements dynamically grow sometimes shrink historically specialized database computing platforms designed particular workload data warehousing poor unusable workloads oltp exadata optimizations database workloads implemented mixed workloads share system resources fairly resource management features also allow prioritized allocation system resources always favoring workloads servicing interactive users reporting batch even accessing data long running requests characterized data warehouses reports batch jobs analytics reputed run many times faster compared conventional non-exadata database server customer references often cite performance gains 10x greater analytics workloads also use oracle database in-memory option exadata additional acceleration in-memory databases exadata extended take advantage flash memory capacity many times larger capacity dram exadata ’ hybrid columnar compression feature intended reduce storage consumption data warehouses archival data well increase performance reducing amount io transactional oltp workloads exadata benefit incorporation flash memory exadata ’ storage hierarchy automatic tiering data memory flash disk storage special flash algorithms optimize flash response time sensitive database operations log writes demanding oltp all-flash storage eliminates latency disk media completely hardware components make typical database computing platform compute server connected network storage array database software runs compute server sends receives database information storage array network hardware components use standard software protocols talk separation via standard interfaces allows computing platform run wide variety software hardware different vendors application logic processing data performed compute server data must sent approach computing platform used wide range software applications though optimized particular application goal exadata create complete stack software hardware focused oracle database allowed processing moved optimal location exadata processing oracle database requests take advantage software layers hardware design include elements advantageous oracle database applications fast infiniband networking flash memory given importance data storage databases oracle particularly focused optimizing aspect exadata platform oracle wanted storage layer exadata could easily scale parallelize oracle database requests also recognized opportunity storage cooperate processing database requests beyond storing shipping data example rather send entire database table across network compute server find small number records data filtering could done storage resulting records sent across network addition flash memory exadata storage servers also opened range possibilities optimizing performance storage layer time performance capacity flash storage increased rapid rate network became performance bottleneck traditional database platforms exadata offloading database processing exadata storage servers avoided problem foundation exadata exadata storage server invented oracle replace traditional storage array also important oracle ownership main software hardware components exadata enabling changes deeply integrated released coordinated fashion benefit customers ability support entire exadata platform one vendor software enhancements specific exadata achieved better performance areas due integration hardware software example oltp application commits transaction database software request viewed exadata critical operation prioritized accordingly within network storage servers commit request move front less important messages network io queue another example use flash memory caching data accessed analytics applications columnar data format effective analytics workloads exadata moves data row disk flash automatically reformats data columnar format examples require oracle database understand intent application cascade understanding network storage software behave accordingly since exadata debut 2008 least two significant exadata software releases per year delivering dozens smart software enhancements enhancements based smaller number technical foundations explained detailed listing software enhancements grouped value analytics oltp workloads impact availability similar enhancements duplicated platforms require software api modifications integration across database software operating systems networking storage refer exadata documentation data sheet descriptions features exadata compute servers run oracle linux 7.6 operating system oracle database 11g release 2 enterprise edition oracle database 19c enterprise edition exadata system resources optionally virtualized using xen-based oracle vm oracle database options real application clusters multitenant database in-memory advanced compression advanced security partitioning active data guard others optionally available exadata applications certified supported version oracle database automatically compatible exadata additional modifications certifications required database software runs exadata on-premises run exadata cloud service exadata cloud customer addition on-premises software licenses eligible byol bring license transfer oracle cloud cloud customer exadata provides high-speed networks internal external connectivity 40 gigabits per second 40 gbit/s infiniband network used internal connectivity compute storage servers 25 10 1 gbit/s ethernet ports included data center connectivity infiniband network also used cluster interconnect compute servers exadata uses custom-designed database-oriented protocol infiniband network achieve higher performance makes extensive use remote direct memory access rdma improve efficiency avoiding data copies moving data servers exadata also direct-to-wire protocol allows database talk directly infiniband hardware bypassing operating system exadata also takes advantage infiniband lanes network resource management feature prioritize important traffic across network feature oracle database software tags network messages require low latency transaction commits lock messages io operations issued interactive users enabling bypass messages issued less critical high-throughput workloads reporting batch result analogous emergency vehicle siren able move quickly heavy traffic high-priority network messages moved front server network switch storage queues bypassing lower-priority messages resulting shorter predictable response times oracle enterprise manager cloud control em manages oracle software hardware including exadata database machine em integrates built-in exadata management tooling well customers existing systems management helpdesk tools exadata plug-in em provides integrated view compute servers storage servers switches topology also provides discovery monitoring alerting capability exadata systems management exadata cloud service exadata cloud customer platforms managed oracle customers control manage software databases running compute servers exadata cloud platforms include web-based provisioning wizard customers quickly provision chosen exadata system subsequently database instances customers also perform familiar database administration os administration tasks aided cloud automation backup patching upgrades exadata available two models one based two-socket compute servers based eight-socket compute servers two models differ hardware used compute servers networking storage servers software models recent oracle exadata database machine x8 generation introduced april 2019 x8-2 compute servers feature small form factor 1 ru rack unit height employ 2-socket intel xeon processors socket 24 compute cores 48 total cores per compute server memory starts 384 gigabytes gb expanded 1.5 terabytes tb exadata database machine base configuration 2 compute servers 3 storage servers referred quarter rack hardware also available eighth rack configuration half processing half storage capacity database workload and/or data size increases additional compute storage servers may added increase volume work performed parallel using exadata elastic configuration x8-8 compute server uses eight-socket compute servers consume 5 ru height greater memory capacity x8-2 whereas x8-2 compute server contains 48 compute cores x8-8 server contains 192 compute cores allows large database workloads easily scale-up within compute server still supporting exadata ’ scale-out expandability across multiple servers larger memory capacity x8-8 also favors in-memory databases large oltp consolidation data warehouse workloads like x8-2 exadata x8-8 base configuration 2 compute servers 3 storage servers consumes half rack space additional compute storage servers may added rack full three choices exadata storage servers extreme flash ef high capacity hc extended xt extreme flash storage server all-flash storage containing 8 pcie flash drives total 51.2 tb raw storage capacity current x8-2 configuration high capacity storage server current x8-2 configuration contains 12 disks 14 tb total 168 tb raw storage capacity improve io response times high-capacity storage server also employs 25.6 tb pcie flash cache active data blocks exadata ’ smart flash cache smart flash log columnar flash cache write back flash cache features determine use flash addition adding storage servers exadata database machine base configuration storage servers may also acquired added exadata storage expansion racks storage performance specifications full rack exadata configuration follows introduction exadata x8 oracle added exadata storage server extended xt low-cost storage infrequently accessed data xt storage server contains disk capacity x8-2 high capacity storage server contain flash storage require exadata storage server software license architects traditional computing platforms always cope technology change affecting design systems goal eliminate bottlenecks output storage moves network processed compute servers without slowdown solving imbalance generally involves adding faster network connections compute servers advent ultra-fast pcie flash memory nvme flash interface flash memory started became mainstream corporate computing around 2010 cache front hard disks replacement disks entirely every year thereafter flash capacity performance increased significantly 2017 leading-edge flash performance crossed threshold advanced networks unable match performance flash became substantial bottleneck example popular all-flash storage system 480 flash cards rated 75 gb/s data throughput whereas without network bottleneck many flash cards produce 2,600 gb/s data throughput plugging flash directly compute server removes network bottleneck also removes ability share storage multiple compute servers offloading storage exadata way bypass network bottleneck filtering unneeded data storage sending remaining data across network nowiki /nowiki per 1 full rack 8 compute servers 14 storage servers nowiki ** /nowiki per 1 full rack 2 compute servers 14 storage servers prior x5-2 generation exadata systems available fixed-size configurations eighth quarter half full rack sizes x5-2 exadata release january 2015 elastic configurations introduced elastic configuration customer-specified combination database servers storage servers elastic configurations allow individual storage compute servers added base configuration physical rack full example exadata system optimized in-memory database processing could created adding many compute servers maximum memory conversely exadata system optimized large data warehouse could configured adding many high-capacity storage servers ratio compute storage servers vary depending characteristics intended workload elastic configurations may also used scale earlier generation exadata systems using x8-2 servers addition exadata database machines always able span multiple racks using built-in infiniband network connections thus exadata ’ scale-out extends beyond single physical rack oracle corporation releases new generation exadata every twelve eighteen months release oracle refreshes hardware components latest intel xeon processors memory disk flash networking hardware refreshes result performance increases every release exadata software also refreshed generation periodically enhancing combination performance availability security management workload consolidation october 2015 features support oracle cloud introduced emphasis exadata generation described exadata v1 released 2008 focused accelerating data warehousing delivering full throughput storage database per oracle exadata achieved moving database filtering operations storage instead sending data compute servers filtering oracle refers capability exadata smart scan exadata v1 also supported consolidation feature allocating io bandwidth databases workloads called iorm io resource manager exadata v1 available full rack half rack sizes choice high performance high capacity storage servers exadata v2 released 2009 added quarter rack configuration support oltp workloads via flash storage database-aware flash caching exadata v2 also introduced hybrid columnar compression reduce amount storage consumed large data warehousing tables storage indexes exadata v2 increased performance eliminating need read entire regions storage based knowledge data contained region exadata x2-2 third generation released 2010 second model exadata exadata x2-8 introduced x2-8 subsequent “ 8 socket ” exadata models feature intel processors targeted large memory scale-up workloads use flash storage beyond caching began release smart flash logging feature support 10 gigabit per second gb/sec ethernet connectivity also added data security encryption encouraged incorporation hardware decryption exadata x2-2 largely eliminating performance overhead compared software decryption storage expansion rack based exadata x2-2 added 2011 accommodate large fast-growing data warehouses archival databases subsequent 2-socket exadata generations included new storage expansion rack exadata x3-2 x3-8 released 2012 including new eighth rack x3-2 entry-level configuration flash storage capacity quadrupled oltp write throughput reportedly increased 20x via write-back flash cache feature number availability enhancements added bypassing slow failed storage media reducing duration storage server brownouts simplifying replacement failed disks exadata x4-2 released 2013 flash capacity doubled flash compression added effectively doubling capacity network resource management introduced automatically prioritizing critical messages infiniband bandwidth doubled support active/active connections exadata x4-8 released 2014 plus capacity demand licensing io latency capping timeout thresholds exadata x5-2 x5-8 released 2015 major set enhancements flash disk capacity doubled elastic configurations introduced enable expansion one server time virtualization added option exadata along trusted partitions flexible licensing within virtual machine database snapshots exadata storage enabled efficient development testing oracle database in-memory exadata included fault tolerant redundancy high performance exadata storage servers replaced all-flash extreme performance storage servers exadata became first major vendor adopt nvme flash interface columnar flash cache introduced automatically reformat analytics data row format flash ipv6 support completed exadata cloud service launched oracle cloud exadata x6-2 x6-8 released 2016 flash capacity doubled e xafusion direct-to-wire protocol reduced messaging overhead cluster smart fusion block transfer eliminated log write delays oltp applications cluster exadata cloud customer debuted enabling oracle cloud benefits within corporate data centers exadata x7-2 x7-8 released 2017 flash capacity doubled flash cards became hot pluggable online replacement 10 terabyte tb disk drives debuted along 25 gb/sec ethernet connectivity oracle database in-memory processing extended flash storage storage server dram utilized faster oltp exadata x8-2 x8-8 released 2019 exadata storage server extended xt introduced low-cost storage infrequently accessed data 14 terabyte tb disk drives debuted along 60 compute cores exadata storage servers machine learning algorithms added automatically monitor cpu network memory detect anomalies stuck processes memory leaks flaky networks automatically create auto index rebuild drop indexes optimizer statistics also gathered real-time dml executes enhanced security advanced intrusion detection environment aide added detect alert unknown changes system software made
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Databases
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ken coar ken coar software developer known participation creation apache software foundation coar active open software projects lectures internationally open development methodologies distributed collaboration
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Operating systems
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nec nec world fourth largest pc manufacturer 1990 nec semiconductors business unit worldwide semiconductor sales leader 1985 1990 second largest 1995 one top three 2000 one top 10 2006 remained one top 20 semiconductor sales leaders merging renesas electronics nec member sumitomo group nec 463 2017 fortune 500 list kunihiko iwadare takeshiro maeda established nippon electric limited partnership august 31 1898 using facilities bought miyoshi electrical manufacturing company iwadare acted representative partner maeda handled company sales western electric interest japanese phone market represented walter tenney carleton carleton also responsible renovation miyoshi facilities agreed partnership would reorganized joint-stock company treaty would allow july 17 1899 revised treaty japan united states went effect nippon electric company limited organized day western electric company become first japanese joint-venture foreign capital iwadare named managing director ernest clement carleton named directors maeda mototeru fujii assigned auditors iwadare maeda carleton handled overall management company started production sales maintenance telephones switches nec modernized production facilities construction mita plant 1901 mita shikokumachi completed december 1902 japanese ministry communications adopted new technology 1903 common battery switchboard supplied nec common battery switchboards powered subscriber phone eliminating need permanent magnet generator subscriber phone switchboards initially imported manufactured locally 1909 nec started exporting telephone sets china 1904 1905 iwadare visited western electric u.s. see management production control return japan discontinued oyakata system sub-contracting replaced new system managers employees direct employees company inefficiency also removed production process company paid higher salaries incentives efficiency new accounting cost controls put place time clocks installed 1899 1907 number telephone subscribers japan rose 35,000 95,000 nec entered china market 1908 implementation telegraph treaty japan china also entered korean market setting office seoul january 1908 period 1907 1912 sales rose 1.6 million yen 2 million yen expansion japanese phone service key part nec success period expansion take pause ministry communications delayed third expansion plan phone service march 1913 despite 120,000 potential telephone-subscribers waiting phone installations nec sales fell sixty percent 1912 1915 interim iwadare started importing appliances including electric fans kitchen appliances washing machines vacuum cleaners electric fans never seen japan imports intended prop company sales 1916 government resumed delayed telephone-expansion plan adding 75,000 subscribers 326,000 kilometers new toll lines thanks third expansion plan nec expanded time much rest japanese industry contracted 1919 nec started first association sumitomo engaging sumitomo densen seizosho manufacture cables part venture nec provided cable manufacturing equipment sumitomo densen rights western electrics duplex cable patents also transferred sumitomo densen great kantō earthquake struck japan 1923 140,000 people killed 3.4 million left homeless four nec factories destroyed killing 105 nec engineers workers thirteen tokyo telephone offices destroyed fire telephone telegraph service interrupted damage telephone cables response ministry communications accelerated major programs install automatic telephone switching systems enter radio broadcasting first automatic switching systems strowger-type model made automatic telephone manufacturing co. atm united kingdom nec participated installation automatic switching systems ultimately becoming general sales agent atm nec developed strowger-type automatic switching system 1924 first japan one plants almost leveled kanto earthquake mita plant chosen support expanding production new three-story steel-reinforced concrete building built starting 1925 modeled western electric hawthorne works nec started radio communications business 1924 japan first radio broadcaster radio tokyo founded 1924 started broadcasting 1925 nec imported broadcasting equipment western electric expansion radio broadcasting osaka nagoya marked emergence radio industry nec established radio research unit 1924 nec started developing electron tubes 1925 1930 manufacturing first 500 w radio transmitter provided chinese xinjing station 100 kw radio broadcasting system 1934 photo-telegraphic equipment developed nec transmitted photos accession ceremony emperor hirohito ceremony held kyoto 1928 newspapers asahi shimbun mainichi shimbun competing cover ceremony asahi shimbun using siemens device mainichi planning use french photo-telegraphic equipment end papers acquired used nec product due faster transmission rate higher picture quality 1929 nippon electric provided japan ministry communications a-type switching system first systems developed japan nippon supplied japan ministry communications nonloaded line carrier equipment long distance telephone channels 1937 world war ii described company blackest days history 1938 mita tamagawa plants placed military control direct supervision military officers 1939 nippon electric established research laboratory tamagawa plant became first japanese company successfully test microwave multiplex communications december 22 1941 enemy property control law passed nec shares owned international standard electric corporation ise itt subsidiary western electric affiliate seized capital technical relations abruptly severed munitions company law passed october 1943 placing overall control nec plants military jurisdiction ueno plant leveled military attack march 1945 fire bombings april may heavily damaged tamagawa plant reducing capacity forty percent okayama plant totally destroyed bombing attack june year end war nec production substantially reduced damage facilities material personnel shortages war production slowly returned civilian use nec re-opened major plants end january 1946 nec began transistor research development 1950 started exporting radio-broadcast equipment korea first major postwar contract 1951 nec received deming prize excellence quality control 1952 computer research development began 1954 nec produced first crossbar switching system japan installed nippon telegraph telephone public corporation currently nippon telegraph telephone corporation ntt 1956 nec began joint research development ntt electronic switching systems year nec established taiwan telecommunication company first postwar overseas joint venture 1958 completed neac-1101 neac-1102 computers year 1959 nec demonstrated first transistorized computer neac-2201 demonstrated unesco automath show paris company began integrated circuit research development 1960 1963 nec started trading american depositary receipts ten million shares sold united states nippon electric new york nec america inc. incorporated year nec supplied kdd submarine cable systems laying pacific ocean 1964 supplied short-haul 24 channel pcm carrier transmission equipment ntt 1965 nec de mexico s. a. de c. v. nec brasil s. a. nec australia pty ltd. established 1968 1969 nec supplied comsat corporation spade satellite communications system 1971 1972 switzerland ordered nec satellite communications earth station year small transportable satellite communications earth station set china shares nec common stock listed amsterdam stock exchange 1973 nec also designed automated broadcasting system japan broadcasting corporation year nec electronics europe gmbh also established 1974 acos series computer introduced new central research laboratories completed 1975 1977 japan national space development agency launched nec geostationary meteorological satellite named himawari period nec introduced concept c c integration computers communications nec america inc. opened plant dallas texas manufacture pabx telephone systems 1978 also acquired electronic arrays inc. california year start semiconductor chip production united states 1980 nec created first digital signal processor nec µpd7710 nec semiconductors uk ltd. established 1981 producing vlsis lsis nec introduced 8-bit pc-8800 series personal computer 1981 followed 16-bit pc-9800 series 1982 1983 nec stock listed basel geneva zurich switzerland exchanges nec quickly became dominant leader japanese pc industry holding 80 market share nec changed english company name nec corporation year nec information systems inc. started manufacturing computers related products united states 1984 nec also released v-series processor year 1986 nec delivered sx-2 super computer houston advanced research center woodlands texas year neax61 digital switching system went service 1987 nec technologies uk ltd. established united kingdom manufacture vcrs printers computer monitors mobile telephones europe also year nec licensed technology hudson soft video game manufacturer create video game console called pc-engine later released 1989 turbografx-16 north american market successor pc-fx released japan 1994 pc-engine achieved considerable following said nec held much stronger influence video game industry role leading semiconductor manufacturer direct video game products nec usa inc. established 1989 holding company north american operations 1983 nec brasil brazilian subsidiary nec forced nationalise corporate stock orders brazilian military government whereby shareholder control nec brasil ceded private equity group brasilinvest brazilian investment banker mário garnero since nec brasil foundation 1968 become major supplier telecommunications equipment brazilian government 1986 minister communications antônio carlos magalhães put nec brasil financial difficulties suspending government contract payments company whose main client federal government subsidiary crisis nec corporation japan sold nec brasil organizações globo onemillion us dollars us 1,000,000 shortly thereafter magalhães resumed government contracts corresponding payments nec brazil became valued 350million us dollars us 350,000,000 suspicions regarding nec-globo deal included among things unilateral breach contract globo founder roberto marinho regarding management regional television station brazilian state bahia took national stage 1992 first corruption charges impeached brazilian president fernando collor de mello organizações globo subsequently sold shares nec brazil hit all-time high state monopoly years back nec corporation 1999 following break-up privatisation brazilian state-owned telephone monopoly telebrás 1990 new head office building known super tower completed shiba tokyo additionally joint-venture agreements established manufacture market digital electronic switching systems lsis china 1993 nec asynchronous transfer mode atm switching system neax61 nippon electronic automatic exchange atm service node went service united states nec europe ltd. established holding company european operations year nec c c research laboratories nec europe ltd. opened germany 1994 nec china co ltd. established holding company chinese operations 1996 1997 nec developed 4gbit dram semiconductor group honored one first japan quality awards 1998 nec opened world advanced semiconductor r facility nec 1 personal computer vendor japan 1980s faced increasing competition fujitsu seiko epson ibm japan nevertheless early 1990s nec still largest well 50 market share japanese market competition heated later rival fujitsu started aggressively market computers industry standard x86 instead nec 1997 nec share reduced 35 nec celebrated 100th anniversary 1999 nec electronics corporation separated nec 2002 new semiconductor company nec laboratories america inc. nec labs started november 2002 merger nec research institute neci nec usa computer communications research laboratory ccrl nec built earth simulator computer esc fastest supercomputer world 2002 2004 since produced nec n343i 2006 2003 nec 20.8 market share personal computer market japan slightly ahead fujitsu 2007 nec nissan co. corp. started evaluating joint venture produce lithium ion batteries hybrid electric cars april 23 2009 renesas technology corp nec electronics corp struck basic agreement merge around april 2010 april 1 2010 nec electronics renesas technology merged forming renesas electronics set fourth largest semiconductor company according isuppli published data q3 2010 nec held 19.8 market share pc market japan january 27 2011 nec formed pc joint venture chinese pc maker lenovo fourth largest pc maker world part deal companies said statement establish new company called lenovo nec holdings b.v. registered netherlands nec receive us 175 million lenovo issuance lenovo shares lenovo unit 51 stake joint venture nec hold 49 stake february 2011 bloomberg news said joint venture would allow lenovo expand field servers nec masato yamamoto said nec would able grow china january 26 2012 nec corporation announced would cut 10,000 jobs globally due big loss nec consolidated financial statement line economic crisis europe lagged development smartphones domestic market compare apple samsung previously january 2009 nec cut 20,000 jobs mainly sluggish semiconductor liquid crystal display related businesses 2013 nec biggest pc server manufacturer japan 23.6 share august 2014 nec corporation commissioned build super-fast undersea data transmission cable linking united states japan consortium international companies consisting china mobile international china telecom global global transit google kddi singtel pipeline went online june 30 2016 april 2017 kemet corporation purchase 61 controlling interest nec tokin nec making nec tokin wholly owned subsidiary purchase complete company change name tokin corporation nec structured organization around three principal segments solutions network solutions electronic devices solutions business delivers computing solutions business enterprises government individual customers—in form software hardware related services network solutions business designs provides broadband network systems mobile wireless communications network systems mobile handsets broadcast systems nec electronic devices business includes semiconductors displays electronic components nec produces versa notebooks international market lavie series japanese markets principal subsidiaries nec include defense products include achievements nec include nec ranked consistently top four companies previous five years number u.s. patents issued averaging 1764 year nec main title sponsor davis cup competition 2002 bnp paribas took sponsorship nec 1982 2012 sponsored nec cup go tournament japan nec 1986 2003 sponsored nec shun-ei go tournament young players japan nec sponsored english football club everton 1985 1995 1995 fa cup final triumph everton final game decade-long nec sponsorship danka took sponsors nec signed deal sponsor sauber f1 team 2011 season 2014 season nec signed new deal sponsor sahara force india f1 team 2015 season april 2013 nec became umbrella sponsor pga tour latinoamérica third-tier men professional golf tour nec one sponsored v.league volleyball started works teams years came include professional players nec also used montedio yamagata football soccer j league sponsors along local companies
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Computer security
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thomas a. drake thomas andrews drake born 1957 former senior executive u.s. national security agency nsa decorated united states air force united states navy veteran whistleblower 2010 government alleged drake mishandled documents one espionage act cases u.s. history drake defenders claim instead persecuted challenging trailblazer project 2011 recipient ridenhour prize truth-telling co-recipient sam adams associates integrity intelligence saaii award june 9 2011 10 original charges dropped drake rejected several deals refused plea bargain truth eventually pleaded one misdemeanor count exceeding authorized use computer jesselyn radack government accountability project helped represent called act civil disobedience drake father world war ii veteran mother secretary pearl s. buck entered u.s. air force 1979 becoming airborne voice processing specialist fluency german went elint electronic intelligence missions capacity encountered surveillance state east germany stasi informed worldview compares developments united states since september 11 attacks drake left air force 1989 also u.s. navy analyzed intelligence national military joint intelligence center according washington post also one time worked cia 1989 drake began work nsa contractor evaluating software contractor worked projects like jackpot librarian becoming expert quality-testing software working system measuring quality computer code nsa drake also continued academic studies 2000 hired software systems quality specialist management information technology consultant columbia maryland-based costal research technology inc. crti wholly owned subsidiary alexandria virginia-based computer systems management inc. csmi late 2001 went work nsa full-time employee signals intelligence directorate fort meade maryland actual first day job nsa employee september 11 2001 2002 became technical director software engineering implementation within cryptologic systems professional health office 2003 drake became process portfolio manager within nsa newly formed directorate engineering held top secret security clearance congressional investigations 9/11 testified nsa failures 2006 reassigned national defense university became nsa chair assistant professor behavioral sciences within industrial college armed forces icaf drake forced leave ndu 2007 security clearance suspended resigned nsa next year drake went work strayer university forced job indictment april 2010 found work apple store founded knowpari systems consulting firm 2011 drake awarded ridenhour prize truth telling co-recipient sam adams associates integrity intelligence saaii award accepting saaii award said references 1857 speech frederick douglass late 1990s early 2000s nsa desired new tools collect intelligence growing flood information pouring new digital networks like internet drake became involved internal nsa debate two tools trailblazer project thinthread project became part minority favored thinthread several reasons including theoretical ability protect privacy us individuals gathering intelligence trailblazer required billions dollars dwarfing cost thinthread drake eventually became disillusioned indignant regarding problems saw agency around 2000 nsa head michael hayden chose trailblazer thinthread thinthread cancelled trailblazer ramped eventually employing ibm saic boeing csc others drake worked way legal processes prescribed government employees believe questionable activities taking place departments accordance whistleblower protection laws intelligence community whistleblower protection act drake complained internally designated authorities bosses nsa inspector general defense department inspector general house senate congressional intelligence committees also kept contact diane roark staffer republicans house intelligence committee u.s. congress house committee responsible oversight executive branch intelligence activities roark staff expert nsa budget two met 2000 september 2002 roark three former nsa officials william binney j. kirk wiebe ed loomis filed dod inspector general report regarding problems nsa including trailblazer drake major source report gave information dod investigation matter roark tried notify superior then-chairman house permanent select committee intelligence porter goss also attempted contact william rehnquist chief justice united states supreme court time addition roark made effort inform vice president dick cheney legal counsel david addington republican staff colleague committee 1980s addington later revealed washington post report author controlling legal technical documents bush administration warrantless surveillance program typing documents tempest-shielded computer across desk room 268 eisenhower executive office building storing vault office roark got response three men 2003 nsa inspector general ig declared trailblazer expensive failure cost 1 billion dollars 2004 dod ig produced final report investigation prompted roark others 2002 report basically agreed assertions found serious flaws nsa time nsa even banned starting projects certain size fear would waste money however plans release dod ig report public time 2011 new yorker article journalist jane mayer wrote drake felt nsa committing serious crimes american people level worse president nixon done 1970s drake reviewed laws regarding disclosure information decided revealed unclassified information reporter worst thing would happen probably would fired november 2005 drake contacted siobhan gorman baltimore sun newspaper sending emails hushmail discussing various topics claims careful give sensitive classified information one basic ground rules set beginning communication communication occurred around 2006 gorman wrote several articles waste fraud abuse nsa including articles trailblazer received award society professional journalists series exposing government wrongdoing judge richard bennett later ruled evidence reporter relied upon allegedly classified information found mr. drake house articles july 2007 armed fbi agents raided homes roark binney wiebe people filed complaint dod inspector general 2002 binney claims pointed guns wife wiebe said reminded soviet union none people charged crimes november 2007 raid drake residence computers documents books confiscated never charged giving sensitive information anyone charge actually brought 'retaining information fbi tried get roark testify drake refused reporter gorman contacted fbi drake initially cooperated investigation telling fbi alleged illegality nsa activities government created 'draft indictment drake prepared prosecutor steven tyrrell listed charges disclosing classified information newspaper reporter conspiracy diane roark binney wiebe loomis complainants dod ig 2002 also allegedly listed unindicted co-conspirators 2009 new prosecutor came case william welch ii changed indictment charges removed naming 'co-conspirators new case contained charges drake prosecutors wanted drake plead guilty refused believed innocent charges government wanted help prosecute whistleblowers refused well later explained motivations ridenhour prizes organization april 2010 drake indicted baltimore maryland grand jury following charges indictment contained many allegations relate actual charges specifically charged unauthorized disclosure classified information charged sigint statute indictment gave details communications roark gorman charged crime directly relating communications indictment also list names gorman roark confirmed reporters e.g mark hosenball newsweek roark lawyer claimed indictment contains mischaracterization facts relationship client drake roark later spoke support drake whistleblowers trailblazer project willful retention charges regarded five documents allegedly related national defense found drake residence five documents question referred success regular meetings volume friend trial testing collections sites success declassified months drake indicted never classified first place according official complaint filed j. william leonard former director information security oversight office regular meetings marked unclassified posted nsanet prosecution argues defendant known really classified drake team also argued latter three five named documents part collection thousands unclassified papers related dod inspector general report mentioned drake defense attorneys argued meant defendant brought home material accidentally willfully obstruction charge related drake allegedly deleting documents purportedly aware fbi investigating leaks media fbi contemplating investigating leaks siobhan gorman baltimore sun false statements charge filed relation fbi questioning drake without lawyer present initial stages investigation cooperating one count alleged statements made regarding whether willfully taken certain documents home another count allegedly lying purported transmission classified information gorman drake defenders point government expert found destroyed evidence also point drake careful give classified information gorman many documents question 'retroactively classified seized home fbi federal offices involved filing indictment included doj public integrity section doj criminal division doj national security division fbi nsa office security counterintelligence drake represented james wyda deborah boardman federal public defenders drake also client government accountability project whistleblower non-profit jesselyn radack director homeland security human rights gap worked drake author nsa authority james bamford consultant drake defense well government prosecutor william m. welch ii previously charged contempt removed ted stevens case served government initial senior litigation counsel john p. pearson doj public integrity section government trial attorney lanny a. breuer charge overseeing prosecution federal judge richard d. bennett responsible hearing handling case initially set trial june 2011 drake case written washington post new york times agence france-press newsweek wired washingtonian.com federation american scientists secrecy news politico elsewhere jesselyn radack government accountability project also discussed case u.s. government publicly stated prosecution thomas drake intended deter government employees reporting problems whistle-blowers key many many department investigations—we n't retaliate encourage matthew a. miller spokesman justice department said indictment brought merits nothing else spring 2011 prosecution made several moves restrict normally open proceedings jury trial united states courtroom reported gerstein politico others done legal auspices classified information procedures act cipa attempts theory prevent release classified information open trials prosecution also moved use controversial silent witness rule exhibits hidden public use code words court government attempted use rule handful times previously legality challenged fifth sixth amendments government also moved restrict cross-examination witnesses restrict jurors reading siobhan gorman baltimore sun articles problems nsa trailblazer prevent defense making arguments introducing evidence courtroom whistleblowing overclassification addition prosecution also court seal two exhibits defense already published one public court filings listed various documents prosecution would try use trial prosecution argued cipa also applied non-classified information attempted unclassified information presented trial redacted form referring siobhan gorman baltimore sun news stories government legally pleaded newspaper articles unduly prejudicial purpose admission newspaper articles put nsa trial prosecution also contended legal obligation prove drake intent harm national security saying prove defendant intended harm country specific part espionage act drake charged 'overclassification defense government argued defense claim would 'confusing jury thus irrelevant charges government also argued discussion trial legal concept whistle-blowing would likewise irrelevant charges early june shortly may 22 2011 broadcast 60 minutes episode drake case government dropped charges drake agreed seek jail time return drake agreement plead guilty single misdemeanor misusing agency computer system july sentencing hearing presiding judge richard d. bennett maryland federal district court issued harsh words government saying unconscionable charge defendant two years home searched list serious crimes could resulted 35 years prison drop 10 counts indictment eve trial expressing irritation prosecution bennett also completely rejected government request 50,000 fine despite sentencing guidelines recommending fine 500- 5,000 noted drake financially devastated spending 82,000 defense losing 154,600 job nsa pension fired university teaching position sentenced drake one year probation 240 hours community service drake appeared daily show august 6 2012 talk history case september sent audio message support cryptoparty march 15 2013 drake spoke national press club luncheon national intelligence community attitude towards whistle-blowing drake inspired edward snowden leak information nsa spying program prism june 2013 snowden went public rather reporting within system due reprisals drake whistleblowers led assistant defense dept inspector general dod ig charge whistleblower unit john crane become whistleblower became apparent drake identity leaked dod ig justice dept drake become activist surveillance state frequently giving interviews speaking events restore fourth one themes speeches interviews privacy exercise follows put entire life box documents bank accounts passwords everything—and give complete stranger—a fellow american safekeeping would states yet encounter yes september 2013 interview drake reaffirmed belief problems nsa chronic systemic solution would completely dismantle subsequently rebuild entire organization july 3 2014 drake along former technical director nsa william binney gave testimony german parliamentary committee investigating nsa spying scandal described close cooperation nsa german secret service bnd november 10 2015 drake appeared pen american center panel newseum secret sources whistleblowers national security free expression drake one four individuals history united states charged specifically willful retention national defense information prosecutions delivery classified information third party—something drake charged particular portion espionage act created 1950 second red scare part mccarran internal security act anthony russo daniel ellsberg first prosecuted retention came known pentagon papers ellsberg gave new york times eventually resulting another landmark espionage act case 1971 new york times co. v. united states prosecution russo ellsberg dismissed 1972 government misconduct second prosecution samuel loring morison 1985 navy analyst sold satellite photographs jane defence weekly later pardoned president bill clinton third american israel public affairs committee case 2005 united states v. franklin rosen weissman drake founding member veteran intelligence professionals sanity september 2015 drake 27 members vips steering group wrote letter president challenging recently published book claimed rebut report united states senate intelligence committee central intelligence agency use torture 2014 documentary called silenced drake featured released nominated emmy award 2016 analogous theme oscar-winning documentary citizenfour portrays similar treatment edward snowden silenced official selection recipient several awards multiple film festivals even release major cable networks march 2015 also 2014 drake involvement thinthread subsequent indictment etc. along others associated activities roark binney wiebe loomis snowden featured pbs documentary united states secrets drake featured throughout 2016 documentary nothing hide regarding government surveillance internet privacy
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Computer security
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great seal great seal seal used head state someone authorised behalf confirm formal documents laws treaties appointments letters dispatch used guarantee authenticity important solemn records documents middle ages great seal played far greater political role much real power associated control seal addition great seal prince usually also privy seal used correspondence private nature seal usually formally entrusted upon office-holder act keeper seal keeper may separate office also usually combined chancellor nowadays great seal usually entrusted upon minister particularly minister justice great seals republics usually show nation coat arms e.g great seal united states allegorical image e.g france reason design used usually remains unchanged seals may however replaced wear depending often seal used monarchies contrast great seal often changed time accession new monarch seal often depicts reigning monarch full form
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Computer security
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ocsp stapling online certificate status protocol ocsp stapling formally known tls certificate status request extension standard checking revocation status x.509 digital certificates allows presenter certificate bear resource cost involved providing online certificate status protocol ocsp responses appending stapling time-stamped ocsp response signed ca initial tls handshake eliminating need clients contact ca aim improving security performance original ocsp implementation number issues firstly introduce significant cost certificate authorities ca requires provide responses every client given certificate real time example certificate issued high traffic website servers cas likely hit enormous volumes ocsp requests querying validity certificate also ocsp checking potentially impairs users privacy slows browsing since requires client contact third party ca confirm validity certificate encounters moreover client fails connect ca ocsp response forced decide continuing connection anyway defeating purpose ocsp b terminating connection based assumption attack could result excessive false warnings blocks ocsp stapling aimed addressing issues original ocsp implementation ocsp stapling resolves problems fashion reminiscent kerberos ticket stapling scenario certificate holder queries ocsp server regular intervals obtaining signed time-stamped ocsp response site visitors attempt connect site response included stapled tls/ssl handshake via certificate status request extension response note tls client must explicitly include certificate status request extension clienthello tls/ssl handshake message may appear allowing site operator control verification responses would allow fraudulent site issue false verification revoked certificate stapled responses ca n't forged need directly signed certificate authority server client receive stapled response contact ocsp server however client receives invalid stapled response abort connection increased risk ocsp stapling notification revocation certificate may delayed last-signed ocsp response expires result clients continue verifiable assurance certificate authority certificate presently valid quite recently longer need individually contact ocsp server means brunt resource burden placed back certificate holder also means client software longer needs disclose users browsing habits third party overall performance also improved client fetches ocsp response directly ca usually involves lookup domain name ca ocsp server dns well establishing connection ocsp server ocsp stapling used certificate status information delivered client already established channel reducing overhead improving performance tls certificate status request extension specified rfc 6066 section 8 rfc 6961 defines multiple certificate status request extension allows server send multiple ocsp responses tls handshake draft proposal x509v3 extension field expired april 2013 specified compliant server presenting certificate carrying extension must return valid ocsp token response status_request extension specified tls client hello current version proposal extended support additional tls extensions tls developer adam langley discussed extension april 2014 article following repair heartbleed openssl bug ocsp stapling support progressively implemented openssl project included support 0.9.8g release assistance grant mozilla foundation apache http server supports ocsp stapling since version 2.3.3 nginx web server since version 1.3.7 litespeed web server since version 4.2.4 microsoft iis since windows server 2008 haproxy since version 1.5.0 f5 networks big-ip since version 11.6.0 kemp loadmasters since version 7.2.37.1 many web servers advertise support ocsp stapling implementations always reliable example apache queries ocsp server event temporary failure discard cached good response previous request start serving bad response nginx lazy loading ocsp responses means first web requests unable add ocsp response browser side ocsp stapling implemented firefox 26 internet explorer since windows vista google chrome linux chrome os windows since vista smtp exim message transfer agent supports ocsp stapling client server modes ocsp stapling designed reduce cost ocsp validation client ocsp responder especially large sites serving many simultaneous users however ocsp stapling supports one ocsp response time insufficient certificate chains intermediate ca certs limitation addressed multiple certificate status request extension specified rfc 6961 adds support sending multiple ocsp responses
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Internet protocols
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police central e-crime unit police central e-crime unit pceu part specialist crime directorate metropolitan police service london dedicated combating e-crime england wales northern ireland unit national remit created april 2008 centralise efforts police forces uk excluding scotland fight forms e-crime unit responsibilities quite specific included activities carried bodies excluding activities currently done others unit stated mission improve police response victims e-crime developing capability police service across england wales northern ireland co-ordinating law enforcement approach types e-crime providing national investigative capability serious e-crime incidents pceu created 1 october 2008 responsible improving uk national policing response cyber crime unit housed within specialist crime directorate scd6 part metropolitan police service based central london jurisdiction within england wales northern ireland however unit worked closely scdea scotland international law enforcement pceu seat table europol interpol cyber workstreams since february 2012 pceu presence outside london creation 3 regional hubs hubs located england north west north east midlands areas hubs launched acpo cyber conference sheffield pceu one strands work within acpo e-crime programme led dac janet williams pceu merged national cyber crime unit part new national crime agency
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Computer security
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line printer daemon protocol line printer daemon protocol/line printer remote protocol lpd lpr network printing protocol submitting print jobs remote printer original implementation lpd berkeley printing system bsd unix operating system lprng project also supports protocol common unix printing system cups common modern linux distributions also found mac os x supports lpd well internet printing protocol ipp commercial solutions available also use berkeley printing protocol components robust functionality performance necessary available lpr/lpd cups alone might required large corporate environments lpd protocol specification documented rfc 1179 server lpd protocol listens requests tcp port 515 request begins byte containing request code followed arguments request terminated ascii lf character lpd printer identified ip address server machine queue name machine many different queue names may exist one lpd server queue unique settings note lpd queue name case sensitive modern implementations lpd network printers might ignore case queue name altogether send jobs printer others option automatically create new queue print job new queue name received helps simplify setup lpd server companies e.g d-link model dp-301p+ tradition calling queue name “ lpt1 ” “ lpt1 ” printer supports lpd/lpr sometimes referred tcp/ip printer tcp/ip used establish connections printers clients network although term would equally applicable printer supports internet printing protocol
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Operating systems
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world games video game world games sports video game developed epyx commodore 64 1986 versions apple iigs amstrad cpc zx spectrum sega master system contemporary systems also released nes version released milton bradley ported rare virtual console version released europe april 25 2008 game continuation epyx sports line previously released extremely successful titles summer games winter games events available vary slightly depending platform may include game allowed player compete events sequentially choose events choose one event practice event info gave commodore 64 version world games three-plus stars five describing least favorite series stating slalom skiing best event magazine concluded epyx nice consistent job execution tho hard take many points even boring material computer gaming world rick teverbaugh criticized slalom skiing log rolling events difficulty concluded world games still must avid sports games charles ardai called game adequate sequel epyx previous games praised graphics criticized mechanics bizarre little joystick patterns little events still recommended game log rolling event jame trunzo praised game use advanced graphics sound including humorous effects also noted variety included games preventing game getting repetitive game reviewed 1988 dragon 132 hartley patricia kirk lesser role computers column reviewers gave game 5 5 stars
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Computer architecture
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human security gateway human security gateway database research information related human security additions database made daily contains 27,000 english french-language resources related conflict human security run human security report project gateway focuses attention threats stemming violence individuals societies risk uses approach gathering categorizing information complementary broad conception human security definition human security united nations development programme undp used 1994 human development report gateway offers users catalogued resources including reports journal articles fact sheets coverage ranges global national sub-national levels information available english french via presentation formats gateway searched keyword geographic region subject heading abstract viewed downloading full-text article report subscribers notified additions database filtered topic region language format feeds provided email rss news feed topics include child soldiers climate change conflict prevention criminal violence gender governance health human rights humanitarian intervention international law landmines natural resources peacekeeping post-conflict peacebuilding small arms refugees terrorism
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Databases
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data center security data center security set policies precautions practices adopted avoid unauthorized access manipulation data center resources data center houses enterprise applications data hence providing proper security system critical denial service dos theft confidential information data alteration data loss common security problems afflicting data center environments according cost data breach survey 49 u.s. companies 14 different industry sectors participated noticed physical security needed protect value hardware therein cost breach security severe consequences company managing data center customers whose data copied 2012 breach global payments processing vendor visa 1.5 million credit card numbers stolen highlights risks storing managing valuable confidential data result global payments partnership visa terminated estimated lost 100 million defenses exploitable software vulnerabilities often built assumption insiders trusted studies show internal attacks tend damaging variety amount information available inside organizations quantity data stored data centers increased partly due concentrations created cloud-computing common threats data centers common vulnerabilities include many worm attacks data centers exploited well-known vulnerabilities many systems shipped default accounts passwords exploited unauthorized access theft information common attacks include network security infrastructure includes security tools used data center enforce security policies tools include packet-filtering technologies acls firewalls intrusion detection systems idss network-based host-based acls filtering mechanisms explicitly defined based packet header information permit deny traffic specific interfaces acls used multiple locations within data center internet edge intranet server farm following describes standard extended access lists standard acls simplest type acl filtering traffic solely based source ip addresses standard acls typically deployed control access network devices network management remote access example configure standard acl router specify systems allowed telnet standard acls n't recommended option traffic filtering due lack granularity standard aclss configured number 1 99 cisco routers extended acls extended acl filtering decisions based source destination ip addresses layer 4 protocols layer 4 ports icmp message type code type service precedence cisco routers define extended acls name number 100 199 range firewall sophisticated filtering device separates lan segments giving segment different security level establishing security perimeter controls traffic flow segments.firewalls commonly deployed internet edge act boundary internal networks.they expected following characteristics performance main goal firewall separate secured unsecured areas network firewalls post primary traffic path potentially exposed large volumes data hence performance becomes natural design factor ensure firewall meets particular requirements application support another important aspect ability firewall control protect particular application protocol telnet ftp http firewall expected understand application-level packet exchanges determine whether packets follow application behavior deny traffic different types firewalls based packet-processing capabilities awareness application-level information idss real-time systems detect intruders suspicious activities report monitoring system configured block mitigate intrusions progress eventually immunize systems future attacks two fundamental components cisco layer 2 switches provide tools prevent common layer 2 attacks scanning probing dos ddos etc. following security features covered layer 2 security process securing data center requires comprehensive system-analysis approach ongoing process improves security levels data center evolves data center constantly evolving new applications services become available attacks becoming sophisticated frequent trends require steady evaluation security readiness key component security-readiness evaluation policies govern application security network including data center application includes design best practices implementation details result security often considered key component main infrastructure requirement since key responsibility data centers make sure availability services data center management systems often consider security affects traffic flows failures scalability due fact security measures may vary depending data center design use unique features compliance requirements company business goals n't set specific measures cover possible scenarios exist general two types data center security physical security virtual security physical security data center set protocol built-in within data center facilities order prevent physical damage machines storing data protocols able handle everything ranging natural disasters corporate espionage terrorist attacks prevent physical attacks data centers use techniques virtual security security measures put place data centers prevent remote unauthorized access affect integrity availability confidentiality data stored servers virtual network security hard task handle exist many ways could attacked worst part evolving years years instance attacker could decide use malware similar exploits order bypass various firewalls access data old systems may well put security risk contain modern methods data security virtual attacks prevented techniques
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Computer security
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robert love robert m. love born c. 1981 american author speaker google engineer open source software developer love best known contributions linux kernel notable work including preemptive kernel process scheduler kernel event layer virtual memory subsystem inotify google member android team helped launch first version platform love also active gnome community working networkmanager gnome volume manager project utopia beagle love born 1981 south florida attended graduated charles w. flanagan high school undergraduate studies attended university florida graduated bachelor arts mathematics bachelor science computer science still college love employed kernel hacker montavista software montavista worked procps several kernel-related projects including one notable preemptive kernel love began work ximian december 15 2003 first served senior engineer linux desktop group ximian spearheaded effort named project utopia better integrate hardware management linux desktop ximian acquisition novell love rose position chief architect suse linux enterprise desktop novell worked various kernel gnome projects including inotify beagle love resigned novell may 4 2007 work google mobile device platform android joining project announced engineered several kernel system-level solutions android including novel shared memory subsystem ashmem love continues work google director engineering search infrastructure love lives boston massachusetts love author linux kernel development third edition book understanding developing code linux kernel book widely regarded approachable well written translated several languages three editions published imprints pearson education also wrote linux system programming second edition subtitled talking directly kernel c library published o'reilly media work documents linux system call c library api love also coauthor linux nutshell comprehensive linux command reference also published o'reilly media linux nutshell awarded favorite linux book time linux journal love contributing editor linux journal author articles magazine love invited speak around world including linux.conf.au australia fosdem belgium guadec england keynote speaker love written co-written several books linux operating system
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Operating systems
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socialflow socialflow social media optimization platform leading brands publishers company uses twitter firehose click data derived proprietary link proxy along proprietary algorithms optimize delivery messages social networks company believes understanding utilizing key metrics engagement clicks per tweet clicks per follower central growing large active social media following analysis data visualization way news filtered around death osama bin laden via twitter received international news coverage led questions role twitter journalism socialflow founded early 2009 frank speiser mike perrone sought apply scientific approach task building sustaining engaged social media audiences scale socialflow announced april 7 2011 raised 7 million series funding series round led softbank softbank ny rre ventures betaworks highline venture partners aol venture partners sv angel group high profile angel investors participating april 16 2013 socialflow announced raised 10 million round series b funding fairhaven capital led round joined existing investors softbank capital rre ventures aol ventures betaworks well new investors kbs+ ventures rand capital corporation company announced june 7 2011 peter hershberg joined company president socialflow gained considerable media attention published breaking bin laden visualizing power single tweet study demonstrated twitter evolved primary news source death osama bin laden broke twitter next study engaging news-hungry audiences tweet tweet looked twitter audiences al-jazeera english bbc news cnn economist fox news new york times revealed similarities differences respective organization audience simultaneously demonstrating true value audience engagement another notable study created socialflow looked launch kony 2012 video social media noted forbes writer anthony kosner study socialflow research group showed rather emerging big liberal enclaves american coasts initial wave social media traffic launched kony 2012 video originated mid-sized relatively conservative cities middle america
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Web technology
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delayed binding delayed binding also called tcp connection splicing postponement connection client server order obtain sufficient information make routing decision application switches routers delay binding client session server proper handshakes complete prevent denial-of-service attacks
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Internet protocols
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bell law computer classes bell law computer classes formulated gordon bell 1972 describes types computing systems referred computer classes form evolve may eventually die new classes computers create new applications resulting new markets new industries bell considers law partially corollary moore law states number transistors per chip double every 24 months unlike moore law new computer class usually based lower cost components fewer transistors less bits magnetic surface etc new class forms every decade also takes decade understand class formed evolved likely continue formed lower priced class may evolve performance take disrupt existing class evolution caused clusters scalable personal computers 1 thousands computers span price performance range use pc mainframes become largest supercomputers day scalable clusters became universal class beginning mid-1990s 2010 clusters least one million independent computers constitute world largest cluster established market class computers aka platforms introduced continue evolve roughly constant price subject learning curve cost reduction increasing functionality performance based moore law gives transistors per chip bits per unit area increased functionality per system roughly every decade technology advances semiconductors storage networks interfaces enable new lower cost computer class aka platform form serve new need enabled smaller devices e.g less transistors per chip less expensive storage displays i/o network unique interface people information processing sink source new lower priced class established maintained quasi independent industry market class likely evolve substitute existing class classes described computer clusters beginning 1990s single class scalable computers mega-servers built clusters tens thousands commodity microcomputer-storage-networked bricks began cover replace mainframes minis workstations become largest computers day applied scientific calculation commonly called supercomputer bell law computer classes class formation first mentioned 1970 introduction digital equipment pdp-11 mini differentiate mainframes potentially emerging micros law described 1972 gordon bell emergence observation new lower-priced microcomputer class based microprocessor stimulated creation law bell described articles bell books see also several laws e.g moore law metcalfe law describe computer industry
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Computer architecture
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securityfocus securityfocus online computer security news portal purveyor information security services home well-known bugtraq mailing list securityfocus columnists writers included former department justice cybercrime prosecutor mark rasch hacker-turned-journalist kevin poulsen securityfocus acquired symantec august 2002
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Computer security
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amigados amigados disk operating system amigaos includes file systems file directory manipulation command-line interface file redirection amigaos 1.x amigados based tripos port metacomco written bcpl bcpl use native pointers advanced functionality operating system difficult use error-prone third-party amigados resource project arp formerly amigados replacement project project begun amiga developer charlie heath replaced many bcpl utilities smaller sophisticated equivalents written c assembler provided wrapper library codice_1 eliminated interfacing problems applications automatically performing conversions native pointers used c assembler bcpl equivalents vice versa amigados functions amigaos 2.x onwards amigados rewritten c retaining 1.x compatibility possible starting amigaos 4 amigados abandoned legacy bcpl starting amigaos 4.1 amigados extended 64-bit file-access support amiga console standard amiga virtual device normally assigned con driven console.handler developed primitive interface amigaos 1.1 became stable versions 1.2 1.3 started known amigashell original handler replaced newconsole.handler newcon console various features considered date created 1985 like command template help redirection null nil ansi color terminal new console handler – implemented release 1.2 – allows many features command history pipelines automatic creation files output redirected tcp/ip stacks like amitcp released early 1990s console could also receive redirection internet-enabled amiga device handlers e.g. tcp copy file tcp site/port unlike systems originally launched mid-1980s amigados implement proprietary character set developers chose use ansi–iso standard iso-8859-1 latin 1 includes ascii character set unix systems amiga console accepts linefeed lf end-of-line eol character amiga console support accented characters well characters created combinations 'dead keys keyboard example typical amigados command syntax amigados redirect output command files pipes printer null device amiga devices amigados commands expected provide standard template describes arguments accept used basic help feature commands although third-party replacement console handlers shells bash zshell ported unix kingcon often provide verbose help built-in commands requesting template command copy following output obtained reading template user know following syntax acceptable command user terminate program invoking key combination pressing printing character keyboard suspends console output output may resumed pressing key delete input pressing cause input processed command soon current command stops running like operating systems amigados also provides wildcard characters substitutes character sequence random characters string example wildcard characters amigados commands parsing follows wildcard indicates character prefixing indicates number repetitions viewed analogous regular expression .* amigados also feature dealing batch programming calls script programming number commands echo endif val skip deal structured script programming scripts text-based files created amigados internal text editor program called ed unrelated unix ed third-party text editor invoke script program amigados uses command execute method executing scripts keeps console window busy script finished scheduled job users interact console window script ends interrupt protection bits flags files links directories filesystem change one either use command protect use information entry icons menu workbench selected files amigados supports following set protection bits abbreviated hsparwed h-bit often misunderstood mean hide smart file system sfs files directories h-bit set hidden system still possible access hidden files n't appear directory listings demonstration h-bit action dos amiga deals environment variables used batch programming global local variables referred dollar sign front variable name example myvar global variables available system-wide local variables valid current shell case name collision local variables precedence global variables global variables set using command setenv local variables set using command set also commands getenv get used print global local variables examples demonstrate simple usage global variables kept files env optionally saved disk envarc survive reboot power cycling env default assign ram env envarc assign sys prefs/env-archive sys refers boot device bootup content envarc copied env accessibility programming amigados scripts one must keep mind global variables system-wide script-internal variables shall set using local variables one risks conflicts global variables scripts also global variables require filesystem access typically makes slower access local variables since envarc also used store system settings string variables system settings default icons tends grow large time copying everything env located ram disk becomes expensive led alternative ways set env using dedicated ramdisk handlers copy files envarc files requested examples handlers example demonstrating creative abuse global variables well lab skip amigados variant infamous goto amigados general case-insensitive indicating device dh0 dh0 dh0 always refers partition however file directory names filesystem-dependent filesystems allow case sensitivity flag upon formatting example file system smart file system convenient dealing software ported mostly case-sensitive un*x world causes much confusion native amiga applications assume case insensitivity advanced users hence typically use case sensitivity flag file systems used software originating un*x note also re-casing file directory volume names allowed using ordinary methods commands rename foo foo relabel bar bar valid exactly expected contrast example linux mv foo foo results error message mv foo foo file case-insensitive filesystems like vfat partitions physical drives typically referred df0 floppy drive 0 dh0 hard drive 0 etc however unlike many operating systems outside built-in physical hardware devices like df0 hd0 names single disks volumes partitions totally arbitrary example hard disk partition could named work system anything else time creation volume names used place corresponding device names disk partition device dh0 called workbench could accessed either name dh0 workbench users must indicate system workbench volume workbench always typing colon entering information requester form amigashell accessed volume name found operating system prompt user insert disk given volume name allow user cancel operation addition logical device names set assign command directory device programs often assigned virtual volume name installation directory instance fictional wordprocessor called writer might assign writer dh0 productivity/writer allows easy relocation installed programs default name sys used refer volume system booted various default names provided refer important system locations e.g startup scripts c amigados commands fonts installed fonts etc assignment volume labels also set multiple directories treated union contents example fonts might assigned sys fonts extended include example work userfonts using add option amigados assign command system would permit use fonts installed either directory listing fonts would show files locations physical device df0 shares floppy drive mechanics pc0 crossdos virtual device capable reading pc formatted floppy disks pc formatted floppy disk inserted floppy drive df0 floppy amiga icon change indicate disk unknown normal amiga device show four question marks standard unknown volume name pc0 icon appear revealing name pc formatted disk disk change amiga formatted disks invert behaviour amigados supports various filesystems variants first filesystem simply called amiga filesystem suitable mainly floppy disks support automatic booting hard disks floppy booting done using code bootblock soon replaced fastfilesystem ffs hence original filesystem known name old filesystem ofs ffs efficient space quite measurably faster ofs hence name amigaos 2.x ffs became official part os soon expanded recognise cached partitions international partitions allowing accented characters file partition names finally morphos amigaos 4 long filenames 108 characters 31 amigaos 4.x morphos featured new version ffs called fastfilesystem 2 ffs2 incorporated features original ffs including author put minor changes order preserve backwards compatibility major structural changes however ff2 amigaos 4.1 differs expand features capabilities aid plug-ins ffs2 amigaos 4 morphos version smart filesystem fork original sfs 100 compatible filesystems like fat12 fat16 fat32 windows ext2 linux available easily installable drag drop system libraries third party modules fat95 features read/write support found aminet software repository morphos 2 built-in support fat filesystems amigaos 4.1 adopted new filesystem called jxfs capable support partitions terabyte size alternate filesystems third-party manufacturers include professional filesystem filesystem easy structure based metadata allowing high internal coherence capable defragmenting fly require unmounted mounted smart filesystem journaling filesystem performs journaled activities system inactivities chosen morphos standard filesystem old file system/fast file system fast file system 2 amigaos4.x/morphos dos6 dos7 feature international filenames featured dos2 do3 directory caching abandoned due bugs original implementation dos4 dos5 recommended use reason dostypes backwards compatible forward compatible dos7 formatted disk read original amiga ffs dos3 disk read ks1.3 amiga however disk formatted dos0 using ffs ffs2 read version amiga operating system reason dos0 tended format choice software developers distributing floppy except custom filesystem bootblock used common practice amiga games software needed amigaos 2 anyway dos3 generally used july 2007 update amigaos 4.0 2007 first two plug-ins ffs2 released amigados single mandated filename extension .info must appended filename icon file called myprog exists icon file must called myprog.info addition image data icon file also records program metadata options keywords position desktop amigaos snapshot icons places defined user information file directory window size position information stored .info file associated directory disk icon information stored disk.info root volume exception icons amiga system identify file types using extensions instead examine either icon associated file binary header file determine file type
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Operating systems
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guse grid cloud user support environment guse also known ws-pgrade web service – parallel grid run-time application development environment /guse open source science gateway framework enables users access grid cloud infrastructures guse developed laboratory parallel distributed systems lpds institute computer science control sztaki hungarian academy sciences relevant requirement development guse enable simultaneous handling large number jobs even range millions without compromising response time user interface order achieve level concurrency workflow management back-end guse implemented based web service concept service oriented architecture soa many user communities would like access several dcis transparent way ’ want learn peculiar features used dcis want concentrate scientific application using science gateway sg solution sg provides interface scientist community distributed computing infrastructures dcis sg framework like guse provides specific set enabling technologies well frontend backend services together build generic gateway sg frameworks specialized certain scientific area hence scientists many different areas use enabling technology guse provides required software stack develop sg frameworks sg instances provide simplified user interface highly tailored needs given scientific community typical examples enabling technologies web application containers tomcat glassfish etc portal web application frameworks liferay spring etc database management systems mysql etc workflow management systems guse moteur etc sgs varying goals general researchers use gateways focus scientific goals less assembling e-infrastructure required important goal make easier scientists use national computing storage resources creating using collaborative tools sharing data sg framework used national grid initiatives ngis support small user communities afford develop customized sg guse sg framework also provides two application programming interfaces apis namely application-specific module api remote api create application-specific sgs according needs different user communities guse provides ws-pgrade graphical user interface create execute workflows various distributed computing infrastructures dcis among many features main five capabilities guse follows 1 guse general-purpose sg framework users access twenty different dcis via dci bridge service six different data storage types http https gsiftp s3 sftp srm via data avenue service dci bridge data avenue developed part ws-pgrade/guse service stack also used independent services enabling use types gateways workflow systems 2 ws-pgrade/guse workflow-oriented system extends directed acyclic graph dag -based workflow concept advanced parameter sweep ps features special workflow nodes condition-dependent workflow execution workflow embedding support moreover guse extends concrete workflow concept concepts abstract workflow workflow instance template 3 ws-pgrade/guse supports development execution workflow-based applications users guse define applications workflows share applications among ex-porting internal application repository users import applications execute modify user space 4 guse supports fast development sg instances customization technology guse serve different needs according community requirements computational power complexity applications specificity user interface fit community needs meet terminology 5 important design aspect guse flexibility flexibility guse expressed main goal designing multitier architecture ws-pgrade/guse enable versatile access many different kinds dcis data storage different kinds user interfaces access technically performed dci bridge job submission service bottom within guse architectural layers via data avenue blacktop service independent service provided sztaki dci bridge web service-based application providing standard access various dcis connects dci plug-ins external dci resources user submits workflow job components submitted transparently various dci systems via dci bridge service using standard ogsa basic execution service 1.0 bes interface result access protocol technical details various dci systems totally hidden behind bes interface job description language bes standardized job submission description language jsdl dcis supported dci bridge following middle tier guse architecture contains high-level guse services workflow storage stores every piece information needed define workflow graph structure description input files pointers output files pointers executable code target dci workflow nodes except input files workflow local input files local output files created workflow execution stored file storage workflow interpreter responsible execution workflows stored workflow storage information system holds information users workflows running job status users ws-pgrade gateways work isolated workspace i.e. see workflows order enable collaboration among isolated users application repository stores ws-pgrade workflows one five possible stages physically five categories stored zip files five categories stored workflows follows collaboration among gateway users possible via categories top three-tier structure presentation tier provides ws-pgrade graphical user interface generic sg framework functionalities underlying services exposed users portlets residing liferay portlet container part ws-pgrade layer easily customized extended according needs sg instances derived guse next section introduces essential user-level elements ws-pgrade guse provides framework european sgs guse gives one underlying workflow development infrastructures great number research activities numerous eu fp7 projects ongoing eu- national projects guse
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Distributed computing architecture
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castlequest castlequest known japan adventure/puzzle-hybrid video game developed published ascii corporation 1985 fm-7 pc-88 sharp x1 additional versions followed 1986 famicom msx subsequently released 1989 nes united states nexoft corporation sequel castle released 1985 msx sg-1000 systems though nes like game early example metroidvania genre object game navigate groken castle rescue princess margarita player push certain objects throughout game accomplish progress rooms prince advance next room aligning cement blocks honey jars candle cakes elevator controlling block rooms quite time consuming since prince open particular door stand door meaning open door jumping mid-air prince must also carry key matches color door intends open player navigate castle help map obtained first room he/she begins map provide player matrix 10x10 rooms highlight room princess located player must also avoid touching enemies like knights bishops wizards fire spirits attack cats phantom flowers family computer nes versions room wider screen display scrolls horizontally player moves different room sizes many adjustments room layouts made comparison msx version family computer version player starts 4 lives game supports famicom data recorder ascii turbo file peripherals saving loading game progress game reworked us nes release save/load feature removed nes 15-pin expansion port turbo file connects however player 50 instead 4 lives initially two magical fairies help another obvious difference msx nes/family computer versions player attack enemies sword dagger nes/family computer versions attack limited enemy must close player kill take place puts player risk killed enemy timing crucial prince dash retrieve weapon timely basis attacking wrong time prevent player launching another attack enemy right location attacked leading certain loss one life player scenario however relevant msx version since way eliminate enemy throw object force enemy climb escalator remain crushed ceiling
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Computer architecture
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base mérimée base mérimée french database monuments listed national significance history architecture art created 1978 placed online 1995 french ministry culture division architectural heritage database periodically updated database contains information derived first survey historic monuments made mérimée 1840 cultural heritage inventory specifically religious domestic agricultural educational military industrial architecture name refers writer prosper mérimée also second inspector-general historic monuments
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Databases
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paul vixie paul vixie american computer scientist whose technical contributions include domain name system dns protocol design procedure mechanisms achieve operational robustness dns implementations significant contributions open source software principles methodology also created launched first successful commercial anti-spam service authored standard unix system programs sends proxynet rtty vixie cron one point ran consulting business vixie enterprises vixie software engineer digital equipment corporation dec 1988 1993 left dec 1994 founded internet software consortium isc together rick adams carl malamud support bind software internet activities isc assumed new company internet systems consortium 2004 although isc operates f root name server vixie one point joined open root server network orsn project operated l root server 1995 cofounded palo alto internet exchange paix metromedia fiber network mfn bought 1999 served chief technology officer mfn abovenet later president paix 1998 cofounded mail abuse prevention system maps california non-profit company goal stopping email abuse vixie author several request comments rfc including best current practice document classless in-addr.arpa delegation bcp 20 unix software stated 2002 hold record 'most cert advisories due single author 2008 vixie served judge mozilla foundation download day attempt set guinness world record downloads single day new piece software vixie served board trustees american registry internet numbers arin 2005 2013 served chairman 2009 2010 vixie also serves security stability advisory committee icann vixie attended george washington high school san francisco california received ph.d. computer science keio university 2011 2013 nearly 20 years isc founded new company farsight security inc. spinning security business unit isc 2014 vixie inducted internet hall fame innovator
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Operating systems
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ebrima ebrima opentype font designed support african writing systems created microsoft part windows 7 operating system supports advanced opentype features combining diacritics positioning latin alphabet based segoe font
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Operating systems
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australasian language technology association australasian language technology association alta promotes language technology research development australia new zealand alta organises regular events exchange research results academic industrial training co-ordinates activities professional societies alta founding regional organization asian federation natural language processing afnlp every year early december alta organises research workshop commonly known altw gathering together growing language technology community australia new zealand academic industrial world workshop welcomes original work aspect natural language processing including speech text accepted papers published alta proceedings also included part acl anthology since 2008 alta involved organising australian computational linguistics olympiad ozclo contest high school students area linguistics computational linguistics
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Computational linguistics
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acronis secure zone acronis secure zone hard disk partition type created used acronis true image ati backup storage target backup applications typically use network storage storing backup archives problematic resources available acronis designed solution problem carving part local disk proprietary partition refer acronis secure zone asz since partition accessibly true image backup recovery functions backup target safe malware user files uses corruption ati manage single asz per computer restore data aszs present e.g portable hard drive connected although acronis secure zone partition type actually rebadged fat32 partition labeled acronis sz partition type code set 0xbc knowing requirements one manually create and/or manage existing acronis secure zone using partition manager since asz actually modified fat32 partition type possible gain direct access partition changing partition type code 0x0b fat32 lba ati designed self-manage backup archives stored asz backup files stored autogenerated names root folder enough freespace next backup file ati automatically delete oldest image set base+incremental/differential files order create space new files oem versions true image designed use special oem secure zone technically regular asz uses partition type 0xbb typically contains single image file factory default os application configuration set forth manufacturer
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Computer file systems
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spam bully spam bully anti-spam software made axaware llc spambully uses bayesian filtering separate good emails spam emails also uses allow/block lists determine emails go user inbox popular features include ability report spammers providers ftc option converting spambully toolbar variety languages including spanish german italian russian
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Computer security
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bcfg2 bcfg2 pronounced bee-config configuration management tool developed mathematics computer science division argonne national laboratory bcfg2 aids infrastructure management lifecycle – configuration analysis service deployment configuration auditing includes tools visualizing configuration information well reporting tools help administrators understand configuration patterns environments bcfg2 differs similar configuration management tools due auditing capability one stated design goals bcfg2 determine interactive direct changes made machine report extra changes client optionally remove additional configuration bcfg2 written python enables system administrator manage configuration large number computers using central configuration model bcfg2 operates using simple model system configuration modeling intuitive items like packages services configuration files well dependencies model system configuration used verification validation allowing robust auditing deployed systems bcfg2 configuration specification written using declarative xml model entire specification validated using widely available xml schema validators along custom schemas included bcfg2 built cross-platform bcfg2 works unix-like operating systems bcfg2 based client-server architecture client responsible interpreting processing configuration served server configuration literal client-side processing configuration required completion configuration process client uploads set statistics server bcfg2 client performs client configuration reconfiguration operations renders declarative configuration specification provided bcfg2 server set configuration operations attempt change client state described configuration specification operation bcfg2 client intended simple possible conceptually sole purpose client reconcile differences current client state state described specification received bcfg2 server bcfg2 server responsible taking network description turning series configuration specifications particular clients also manages probed data tracks statistics clients bcfg2 server takes information two sources generating client configuration specifications first pool metadata describes clients members aspect-based classing system clients defined terms aspects abstract behavior file system repository contains mappings metadata literal configuration combined form literal configuration specifications clients example abstract configuration entries example literal configuration entries
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Operating systems
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page cache computing page cache sometimes also called disk cache transparent cache pages originating secondary storage device hard disk drive hdd solid-state drive ssd operating system keeps page cache otherwise unused portions main memory ram resulting quicker access contents cached pages overall performance improvements page cache implemented kernels paging memory management mostly transparent applications usually physical memory directly allocated applications used operating system page cache since memory would otherwise idle easily reclaimed applications request generally associated performance penalty operating system might even report memory free available compared main memory hard disk drive read/writes slow random accesses require expensive disk seeks result larger amounts main memory bring performance improvements data cached memory separate disk caching provided hardware side dedicated ram nvram chips located either disk controller case cache integrated hard disk drive usually called disk buffer disk array controller memory confused page cache pages page cache modified brought called dirty pages since non-dirty pages page cache identical copies secondary storage e.g hard disk drive solid-state drive discarding reusing space much quicker paging application memory often preferred flushing dirty pages secondary storage reusing space executable binaries applications libraries also typically accessed page cache mapped individual process spaces using virtual memory done mmap system call unix-like operating systems means binary files shared separate processes also unused parts binaries flushed main memory eventually leading memory conservation since cached pages easily evicted re-used operating systems notably windows nt even report page cache usage available memory memory actually allocated disk pages led confusion utilization page cache windows page cache also aids writing disk pages main memory modified writing data disk marked dirty flushed disk freed file write occurs cached page particular block looked already found page cache write done page main memory found page cache write perfectly falls page size boundaries page even read disk allocated immediately marked dirty otherwise page fetched disk requested modifications done file created opened page cache written might result zero byte file later read however cached pages written program code often mapped read-only copy-on-write latter case modifications code visible process written disk 2019 security researchers demonstrated side-channel attacks page cache possible bypass privilege separation exfiltrate data processes systematically monitoring whether file pages example executable library files present cache
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Operating systems
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non-volatile file system non-volatile file system nvfs flash memory file system introduced release palm personal digital assistant handheld models tungsten t5 tungsten e2 palm tx z22 treo 650/700/680/755p palm centro nvfs claimed palmone file system designed keep information safe battery run power previous non-flash memory designs would lose stored data event power loss nvfs derivative flash memory continually stores data even power applied palmone invented nvfs response complaints handheld data destroyed battery power ran past necessary keep handheld continuously charged avoid losing data since information stored volatile memory similar feature adopted pdas running windows mobile 5.0 operating system named persistent storage nvfs uses nand flash memory technology retain handheld data event battery swap battery runs power palmone claims flash memory plus majority consumers since many want charge handheld often consumes less overall power nvfs uses brand-new data architecture might render incompatible applications ran well non-nvfs handhelds nvfs file system designed use clusters 512 byte blocks power users complained files take approximately 33 space volatile file systems fact volatile file system uses block size 14 bytes compared nvfs file system minimum block size 512 bytes palmone responded complaint offering free 128 megabyte sd card request selected customers nvfs early release palm time palmone would commit work rom flash update reduce overhead nvfs architecture currently palm-branded products using nvfs shipped nvfs fix already installed tungsten e2 uses 4kb blocks recommended earlier versions palm treo 650 tungsten t5 install nvfs fix earliest possible convenience controversy gave tungsten t5 treo 650 unfavorable remarks power users palmone released first sprint treo 650 updater designed ensure block size overhead reduced 512 bytes 16-32 bytes usually 32 bytes low 16 bytes depending file demand resulting drastic memory management efficiency improvements nvfs file system second update sprint treo 650 released june 16 2005 unlocked gsm firmware upgrade also released day second sprint treo 650 firmware update also improves efficiency nvfs file system addition addressing known problems prior release firmware update rogers wireless treo 650 firmware update quietly posted rogers wireless treo 650 support site shares bug fixes nvfs memory efficiency updates unlocked gsm version initial release palmone tungsten e2 verizon wireless treo 650 earthlink wireless treo 650 already nvfs memory system problems assessed according palm info center june 22 2005 palmone tungsten t5 version 1.1 update fixes nvfs file system inefficiency problem since release november 2004 version 1.1 update also updates tungsten t5 version number garnet 5.4.8 july 25 2005 cingular treo 650 fix officially released one fixes addressing inefficiency problems associated nvfs file system cingular treo 650 holders encouraged deploy flash rom update earliest time possible
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Computer file systems
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mark weatherford mark weatherford american cybersecurity professional held variety executive level positions public private sectors appointed first deputy secretary cybersecurity us department homeland security 2011 2013 currently global information security strategist booking holdings weatherford graduate university arizona tucson arizona received master degree naval postgraduate school monterey california holds certified information systems security professional cissp certification former us navy cryptologic officer led navy ’ computer network defense operations naval computer incident response team navcirt joining dhs served 2010–11 vice president chief security officer north american electric reliability corporation nerc directed organization ’ critical infrastructure cybersecurity program electric utilities across north america also appointed governor arnold schwarzenegger state california first chief information security officer office information security 2008–09 also first chief information security officer ciso state colorado 2004–07 appointed governor bill owens governor bill ritter notably helped establish state ’ first cybersecurity program spearheaded nation first cybersecurity legislation aimed protect citizens leaving dhs principal chertoff group washington dc senior vice president chief cybersecurity strategist varmour weatherford one information security magazine ’ security 7 award winners 2008 awarded sc magazine cso year award 2010 2012 2013 named one 10 influential people government information security govinfosecurity member marysville high school marysville california hall fame inducted information systems security association issa international hall fame october 2018
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Computer security
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assignment operator c++ c++ programming language assignment operator codice_1 operator used assignment like operators c++ overloaded copy assignment operator often called assignment operator special case assignment operator source right-hand side destination left-hand side class type one special member functions means default version generated automatically compiler programmer declare one default version performs memberwise copy member copied copy assignment operator may also programmer-declared compiler-generated copy assignment operator differs copy constructor must clean data members assignment target correctly handle self-assignment whereas copy constructor assigns values uninitialized data members example language permits overloaded assignment operator arbitrary return type including codice_2 however operator usually defined return reference assignee consistent behavior assignment operator built-in types returning assigned value allows using operator invocation expression instance control statements chained assignment also c++ standard library requires behavior user-supplied types deep copies objects made exception safety taken consideration one way achieve resource deallocation never fails however no-fail no-throw swap function available member subobjects class provides copy constructor destructor according rule three straightforward way implement copy assignment follows c++ supports assignment different classes via implicit copy constructor assignment operator destination instance class ancestor source instance class copying ancestor descendant objects could leave descendant fields uninitialized permitted
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Programming language topics
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list devices using mediatek tablet processors page contains list every major device using mediatek tablet processor organized chip devices uses section begin=header symtab25
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Computer architecture
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highcharts highcharts software library charting written pure javascript first released 2009 created highsoft vik norway regularly featured national media finansavisen dagsrevyen torstein hønsi main creator product product first demonstrated thought 2006 interview finansavisen spoke need program creating graphs charts allowing users publish charts directly website unlike many software products n't developed well known tech location silicon valley company based small norwegian town vik company based norway product used globally stated interview 2014 customer base primarily abroad 97 company revenue generated clients outside norway highchart products featured norwegian tv late 2012 parent company featured national tv show segment middle 30-minute show dagsrevyen highcharts free non-commercial use licenses needed use commercial applications source code highcharts downloaded modified license
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Programming language topics
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augmented assignment augmented assignment compound assignment name given certain assignment operators certain programming languages especially derived c augmented assignment generally used replace statement operator takes variable one arguments assigns result back variable simple example codice_1 expanded codice_2 similar constructions often available various binary operators general languages offering feature operators take variable one arguments return result type augmented assignment equivalent assigns result back variable place including arithmetic operators bitshift operators bitwise operators example following statement variation found many programs means find number stored variable x add 1 store result addition variable x simple seems may inefficiency location variable x looked twice compiler recognize two parts expression identical x might reference array element complexity comparison augmented assignment version version excuse compiler failing generate code looks location variable x modifies place course machine code supports sequence instance x simple variable machine code sequence might something like code would generated forms special op code might meaning modify memory adding 1 x decent compiler would generate code forms machine codes offer inc dec operations add subtract one others might allow constants one generally form stands operator always may special op codes help still possibility x complicated entity compiler encouraged avoid duplication accessing x course x lengthy name less typing required last basis similar feature algol compilers offered via burroughs b6700 systems using tilde symbol stand variable assigned would become forth general x =~ 1 producing optimum code would remain province compiler expression-oriented programming languages c assignment augmented assignment expressions value allows use complex expressions however produce sequences symbols difficult read understand worse mistype easily produce different sequence gibberish although accepted compiler produce desired results languages python assignment augmented assignment statements expressions thus used complex expressions example following valid c valid python assignment languages augmented assignment form right-associative assignment languages c c++ python augmented assignment assignment location includes function calls mandated call functions i.e statement function codice_3 mandated called language implements augmented assignment macro expansion codice_3 called twice c c++ c assignment operator augmented follows called compound assignment operator said languages following list though complete all-inclusive lists major programming languages support augmented assignment operators
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Programming language topics
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port computer networking computer networking port communication endpoint physical well wireless connections terminated ports hardware devices software level within operating system port logical construct identifies specific process type network service ports identified protocol address combination 16-bit unsigned numbers commonly known port number common protocols use port numbers transmission control protocol tcp user datagram protocol udp port number always associated ip address host protocol type communication completes destination origination network address message specific port numbers commonly reserved identify specific services arriving packet easily forwarded running application purpose lowest numbered 1024 port numbers identify historically commonly used services called well-known port numbers higher-numbered ports available general use applications known ephemeral ports used service enumeration ports provide multiplexing service multiple services multiple communication sessions one network address client–server model application architecture multiple simultaneous communication sessions may initiated service port number 16-bit unsigned integer thus ranging 0 65535 tcp port number 0 reserved used udp source port optional value zero means port process associates input output channels via internet socket type file descriptor transport protocol ip address port number known binding enables process send receive data via network operating system networking software task transmitting outgoing data application ports onto network forwarding arriving network packets processes matching packet ip address port number tcp one process may bind specific ip address port combination common application failures sometimes called port conflicts occur multiple programs attempt use port number ip address protocol applications implementing common services often use specifically reserved well-known port numbers receiving service requests clients process known listening involves receipt request well-known port establishing one-to-one server-client dialog using local port number clients may continue connect listening port works tcp connection identified tuple consisting local address local port remote address remote port well-known ports defined convention overseen internet assigned numbers authority iana core network services world-wide web typically use well-known port numbers many operating systems special privileges required applications bind ports often deemed critical operation ip networks conversely client end connection typically uses high port number allocated short term use therefore called ephemeral port internet assigned numbers authority iana responsible global coordination dns root ip addressing internet protocol resources includes registration commonly used port numbers well-known internet services port numbers divided three ranges well-known ports registered ports dynamic private ports well-known ports also known system ports 0 1023 requirements new assignments range stricter registrations examples include registered ports 1024 49151 iana maintains official list well-known registered ranges dynamic private ports 49152 65535 one common use range ephemeral ports transport layer protocols transmission control protocol tcp user datagram protocol udp transfer data using protocol data units pdus tcp pdu segment datagram udp protocols use header field recording source destination port number port numbers encoded transport protocol packet header readily interpreted sending receiving computers also components networking infrastructure particular firewalls commonly configured differentiate packets based source destination port numbers port forwarding example application practice attempting connect range ports sequence single computer commonly known port scanning usually associated either malicious cracking attempts network administrators looking possible vulnerabilities help prevent attacks port connection attempts frequently monitored logged computers technique port knocking uses series port connections knocks client computer enable server connection example use ports internet mail system server used sending receiving email generally needs two services first service used transport email servers accomplished simple mail transfer protocol smtp smtp service application usually listens tcp port 25 incoming requests second service usually either post office protocol pop internet message access protocol imap used e-mail client applications users personal computers fetch email messages server pop service listens tcp port number 110 services may running host computer case port number distinguishes service requested remote computer user computer another mail server listening port number server well defined iana calls well-known ports client port number often chosen dynamic port range see applications clients server use specific port numbers assigned iana good example dhcp client always uses udp port 68 server always uses udp port 67 port numbers sometimes seen web uniform resource locators urls default http uses port 80 https uses port 443 url like nowiki http //www.example.com:8080/path/ /nowiki specifies web browser connects instead port 8080 http server concept port numbers established early developers arpanet informal co-operation software authors system administrators term port number yet used time preceded use term socket number early development stages network socket number remote host 40-bit quantity first 32 bits similar today ipv4 address time most-significant 8 bits host number least-significant portion socket number bits 33 40 entity called another eightbit number abbreviated aen today network socket refers related distinct concept namely internal address endpoint used within node march 26 1972 vint cerf jon postel called documenting then-current usages establishing socket number catalog rfc 322 network administrators asked submit note place phone call describing function socket numbers network service programs host catalog subsequently published rfc 433 december 1972 included list hosts port numbers corresponding function used host network first registry function served primarily documentation usage indicated port number usage conflicting hosts useful public services document promised resolution conflicts based standard postel published may 1972 rfc 349 first proposed official assignments port numbers network services suggested dedicated administrative function called czar maintain registry 256 values aen divided following ranges telnet service received first official assignment value 1 detail first set assignments early arpanet aen also called socket name used initial connection protocol icp component network control program ncp ncp forerunner modern internet protocols today terminology service name still closely connected port numbers former text strings used network functions represent numerical port number
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Internet protocols
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torrentlocker torrentlocker ransomware trojan targeting microsoft windows first observed february 2014 least five major releases made available december 2014 malware encrypts victim files similar manner cryptolocker implementing symmetric block cipher aes key encrypted asymmetric cipher torrentlocker scans system programs files conceals contents aes encryption leaving ransom instructions victim done pay decryption ransom operator demands victim amount usually starts around within 3 days victim told pay amount bitcoins sent unique bitcoin address differs infected user
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Computer security
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orvyl wylbur orvyl timesharing monitor developed stanford university ibm system/360 system/370 computers 1967–68 orvyl one first time-sharing systems made available ibm computers wylbur text editor word processor program designed work either without orvyl conjunction orvyl names orvyl wylbur often used interchangeably wylbur full standalone operating system mold dartmouth time sharing system dtss unix instead runs top ibm batch operating system os/360 svs mvs takes form editor remote job entry system thus much relationship ibm operating systems emacs unix reasons wylbur often thought text editor rather time-sharing system however whereas unix need emacs provide text editing services ibm operating systems originally needed wylbur later innovations ibm time sharing option tso made wylbur less relevant ibm users gradually replaced article use full upper case spelling commands keywords references characters string assume ebcdic code page orvyl wylbur used stanford linear accelerator center slac european organization nuclear research cern u.s. national institutes health nih many sites retired sites late 1990s owing concerns y2k issues remained use nih december 2009 orvyl wylbur still available open source stanford also proprietary versions superwylbur orvyl wylbur much admired shown excerpt 2004 article titled computing cern mainframe era orvyl wylbur first became available 1967-68 tss/360 tso official time-sharing solution ibm roughly time third-party time-sharing systems mts became available radar development effort cp-67 ibm cambridge scientific center took place wylbur additional advantage could used conjunction ibm mainstream operating system os/360 wylbur single-address-space system unlike tso conserved memory days memory precious even tso available organizations seeking minimize memory use would often keep even majority users wylbur rather letting use tso interactive environment wylbur provides compressed partitioned data sets pdss aka libraries save disk space mvs source code typically stored sequence card images 80 character lines line contained one characters 80 characters still used store line even data e.g. source code stored variable blocked vb space could wasted strings embedded blanks wylbur implements stream-oriented storage text pdss sequential data sets one character line might take 16 characters line length offset chunk length character rather 80 store wylbur external program run via jcl used convert files wylbur edit format although tso allows user locked-down wylbur system possible write wylbur exec scripts execute batch jobs perform functions ordinarily would required tso account filling batch job skeleton parameters submitting batch job retrieving output displaying screen wylbur security advantages tso disadvantages advantages include disadvantages related security included wylbur special edit format wylbur data sets compressed line number revision flag line addition wylbur supports standard fb vb datasets wylbur user normally specifies default volume may special word catlg requesting search catalogue existing dataset requesting new dataset cataloged wylbur ability convert line numbers edit ibm data sets either scaled integers explicit decimal point wylbur provides line editor works temporary data sets similar buffers editors point time one temporary data sets designated default wylbur maintains current line pointer temporary data set user may specify explicit working data set command omits default temporary data set used working data set unit operation set lines associative range individual lines identified line number range 0.0 99999.999 leading zeros integer part trailing zeros fractional part may omitted user specify line number following ways wylbur libraries nonstandard format however allows user export native os files integer sequence numbers import native os files integer sequence rescale line number factor 1000 range specified combination pattern similar regular expression syntax closer snobol unix perl backtracking nih wylbur capture subpatterns pattern may sample commands change 73/80 x10+10 every 3rd line 'abc 1/3 1.5-2/3.7+2 copy 'bal 10/15 emd change 73/80 every 3rd line start 2 'bal 10/15 change digits*3 substring 2/4 specification base+increment means replacement text first line base incremented subsequent lines x10+10 replaces matched text first line x10 second line x20 third line x30 specification substring 2/4 means columns 2-4 matched string note less flexible captures various organizations developed enhanced versions wylbur included superwylbur several enhancements original wylbur important macro processor adds commands constants functions expressions wylbur even command syntax include parameters defined expressions user use forms expression expression force evaluation expression function argument variable parentheses may omitted e.g. .time instead .time doubled requests valued quoted superwylbur two types constants superwylbur operators whose names contain special characters need separated spaces operators whose names contain period letters must separated spaces superwylbur following types operators name macro function begins period arguments colon separates name semicolon separates successive arguments superwylbur provides following types macro functions arithmetic functions accounting functions date time conversion parameters default current date time environmental queries return values set commands full screen functions jes functions macro functions string functions working file functions arguments default current default working data set complete list macro functions pseudofunctions like functions except appear left hand side assignment e.g. let foo bar baz
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Operating systems
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mailxaminer mailxaminer digital forensic program built allow examination email messages web application based email clients application developed systools inc slogan ‘ simplifying email forensics ’ mailxaminer first loads messages chosen email storage source arranges hierarchically purpose evidence analysis extraction product name derived combination ‘ mail ’ ‘ examiner ’ denoting platform examine emails programming application provides carving deleted evidence evidence damaged sources cases evidence spoliation post analysis software serves output generation court admissible digital formats e.g concordance adobe pdf systools official developer mailxaminer launched first release december 1 2013 subsequent allotment official product licensing constant screening mailxaminer given systools inc. present stable release product version 4.9 launched year 2014 added capabilities serving skin tone analysis link analysis timeline analysis program helped achieve level refurbishment act improvement process email examination procedure since launch support forensic disk image optical character recognition format skype database analysis also added application since one upgrades support limited email storage formats imaged within file owing email examination theme application currently application serving legal departments law enforcement agencies government sectors sectors requirement investigation email messages
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Computer security
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vaxmate vaxmate ibm pc/at compatible personal computer introduced digital equipment corporation september 1986 replacement rainbow 100 standard form first commercial diskless personal computer operating system files could served vax/vms server running company vax/vms services ms-dos software went several name changes finally becoming pathworks alternatively optional expansion box containing either 20 mb 40 mb hard disk could purchased allowed operate conventional stand-alone pc basic system contained 8 mhz intel 80286 cpu 1 mbyte ram 1.2 mb rx33 5¼-inch floppy disk drive 14-inch diagonal amber green monochrome crt thinwire ethernet interface contained system unit also provided parallel printer port serial communications port separate mouse lk250 keyboard used device well expansion box 80287 numeric coprocessor could ordered option memory could expanded 2 mb another option 3 mb north america internal modem also available superseded decstation 200 300 january 1989
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Computer architecture
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windows vista networking technologies computing microsoft windows vista windows server 2008 introduced 2007/2008 new networking stack named next generation tcp/ip stack improve previous stack several ways stack includes native implementation ipv6 well complete overhaul ipv4 new tcp/ip stack uses new method store configuration settings enables dynamic control require computer restart change settings new stack implemented dual-stack model depends strong host-model features infrastructure enable modular components one dynamically insert remove next generation tcp/ip stack connects nics via network driver interface specification ndis driver network stack implemented codice_1 implements transport network data link layers tcp/ip model transport layer includes implementations tcp udp unformatted raw protocols network layer ipv4 ipv6 protocols implemented dual-stack architecture data link layer also called framing layer implements 802.3 802.1 ppp loopback tunnelling protocols layer accommodate windows filtering platform wfp shims allows packets layer introspected also host wfp callout api networking api exposed via three components user interface configuring troubleshooting working network connections changed significantly prior versions windows well users make use new network sharing center see status network connections access every aspect configuration single icon notification area system tray represents connectivity network adapters whether wired wireless network browsed using network explorer replaces windows xp network places network explorer items shared device scanner file share network location awareness nla service uniquely identifies network exposes network attributes connectivity type applications determine optimal network configuration however applications use nla apis explicitly aware network connectivity changes adapt accordingly windows vista uses link layer topology discovery lltd protocol graphically present different devices connected network network map addition network map uses lltd determine connectivity information media type wired wireless map topologically accurate ability know network topology important diagnosing solving networking problems streaming content network connection device implement lltd appear network map icon representing device allowing users one-click access device user interface lltd invoked provides metadata device contains static state information mac address ipv4/ipv6 address signal strength etc windows vista classifies networks connects either public private domain uses network location awareness switch network types different network types different firewall policies open network public wireless network classified public restrictive network settings mode computers network trusted external access computer including sharing files printers disabled home network classified private enables file sharing computers computer joined domain network classified domain network network policies set domain controller network first connected windows vista prompts choose correct network type subsequent connections network service used gain information network connected automatically switch network configuration connected network windows vista introduces concept network profiles network system stores ip address dns server proxy server network features specific network network profile network subsequently connected settings need reconfigured ones saved profile used case mobile machines network profiles chosen automatically based networks available profile part either public private domain network windows vista networking stack supports dual internet protocol ip layer architecture ipv4 ipv6 implementations share common transport framing layers windows vista provides gui configuration ipv4 ipv6 properties ipv6 supported networking components services windows vista dns client use ipv6 transport internet explorer windows vista applications use wininet windows mail file sharing support literal ipv6 addresses windows firewall ipsec policies snap-in support ipv6 addresses permissible character strings ipv6 mode windows vista use link local multicast name resolution llmnr protocol described resolve names local hosts network dns server running service useful networks without central managing server ad hoc wireless networks ipv6 also used ppp-based dial-up pppoe connections windows vista also act client/server file sharing dcom ipv6 support dhcpv6 used ipv6 also included ipv6 even used full native ipv6 connectivity available using teredo tunneling even traverse ipv4 symmetric network address translations nats well full support multicast also included via mldv2 ssm protocols ipv6 interface id randomly generated permanent autoconfigured ipv6 addresses prevent determining mac address based known company ids nic manufacturers support wireless networks built network stack new set apis called native wifi emulate wired connections case previous versions windows allows implementation wireless-specific features larger frame sizes optimized error recovery procedures native wifi exposed auto configuration module acm replaces windows xp wireless zero configuration acm extensible developers incorporate additional wireless functionality automatic wireless roaming override automatic configuration connection logic without affecting built-in framework easier find wireless networks range tell networks open closed hidden wireless networks advertise name ssid better supported security wireless networks improved improved support newer wireless standards like 802.11i eap-tls default authentication mode connections made secure connection level supported wireless access point wpa2 used even ad-hoc mode windows vista also provides fast roaming service allow users move one access point another without loss connectivity preauthentication new wireless access point used retain connectivity wireless networks managed either connect network dialog box within gui netsh wlan command shell settings wireless networks also configured using group policy windows vista enhances security joining domain wireless network use single sign use credentials join wireless network well domain housed within network case radius server used peap authentication joining network ms-chap v2 authentication log domain bootstrap wireless profile also created wireless client first authenticates computer wireless network joins network stage machine still access domain resources machine run script stored either system usb thumb drive authenticates domain authentication done either using username password combination security certificates public key infrastructure pki vendor verisign windows vista features windows connect supports setting wireless network using several methods supported wi-fi protected setup standard implements native code api web services devices wsdapi support devices profile web services dpws also managed code implementation wcf dpws enables simpler device discoverability like upnp describes available services clients function discovery new technology serves abstraction layer applications devices allowing applications discover devices referencing device function rather bus type nature connection plug play extensions pnp-x allow network-connected devices appear local devices inside windows connected physically upnp support also enhanced include integration pnp-x function discovery windows vista networking stack also uses several performance optimizations allow higher throughput allowing faster recovery packet losses using high packet loss environment wireless networks windows vista uses newreno algorithm allows sender send data retrying case receives partial acknowledgement acknowledgement receiver part data received also uses selective acknowledgements sack reduce amount data retransmitted case portion data sent received correctly forward rto-recovery f-rto prevent unnecessary retransmission tcp segments round trip time increases also includes neighbour unreachability detection capability ipv4 ipv6 tracks accessibility neighboring nodes allows faster error recovery case neighboring node fails ndis 6.0 introduced windows vista supports offloading ipv6 traffic checksum calculations ipv6 improved manageability scalability performance reduced complexity ndis miniports simpler models writing lightweight filter drivers lwf lwf drivers combination ndis intermediate drivers miniport driver eliminate need write separate protocol miniport bypass mode examine selected control data paths tcp/ip stack also provides fail-back support default gateway changes periodically attempting send tcp traffic previously detected unavailable gateway provide faster throughput sending traffic primary default gateway subnet another significant change aims improve network throughput automatic resizing tcp receive window receive window rwin specifies much data host prepared receive limited among things available buffer space words measure much data remote transmitter send requiring acknowledgement outstanding data receive window small remote transmitter frequently find hit limit much outstanding data transmit even though enough bandwidth available transmit data leads incomplete link utilization using larger rwin size boosts throughput situations auto-adjusting rwin tries keep throughput rate high permissible bandwidth link receive window auto tuning functionality continually monitors bandwidth latency tcp connections individually optimize receive window connection window size increased high-bandwidth ~5 mbit/s+ high-latency 10ms situations traditional tcp implementations uses tcp slow start algorithm detect fast transmit without choking receiver intermediate nodes nutshell specifies transmission start slow rate transmitting packets number controlled congestion window – specifies number outstanding packets transmitted acknowledgement receipt receiver yet received acknowledgements received congestion window expanded one tcp segment time till acknowledgement fails arrive sender assumes congestion window size instant network gets congested however high bandwidth network sustain quite large congestion window without choking slow start algorithm take quite time reach threshold – leaving network under-utilized significant time new tcp/ip stack also supports explicit congestion notification ecn keep throughput hit due network congestion low possible without ecn tcp message segment dropped router buffer full hosts get notice building congestion packets start dropped sender detects segment reach destination due lack feedback congested router information extent reduction transmission rate needs make standard tcp implementations detect drop time waiting acknowledgement receiver sender reduces size congestion window limit amount data flight time multiple packet drops even result reset congestion window tcp maximum segment size tcp slow start exponential backoff additive increase produce stable network behaviour letting routers recover congestion however dropping packets noticeable impacts time-sensitive streams like streaming media takes time drop noticed retransmitted ecn support enabled router sets two bits data packets indicate receiver experiencing congestion yet fully choked receiver turn lets sender know router facing congestion sender lowers transmission rate amount router still congested set bits eventually sender slow even advantage approach router get full enough drop packets thus sender lower transmission rate significantly cause serious delays time-sensitive streams risk severe under-utilization bandwidth without ecn way routers tell hosts anything dropping packets ecn like random early drop except packets marked instead dropped caveat sender receiver well intermediate routers ecn-friendly router along way prevent use ecn considers ecn-marked packets invalid drops typically whole connection setup fails piece network equipment drops connection setup packets ecn flags set routers n't know ecn still drop packets normally ecn-hostile network equipment internet reason ecn disabled default enabled via codice_2 command previous versions windows processing needed receive transfer data one network interface done single processor even multi processor system supported network interface adapters windows vista distribute job traffic processing network communication among multiple processors feature called receive side scaling windows vista also supports network cards tcp offload engine certain hardware-accelerated tcp/ip-related functionality windows vista uses tcp chimney offload system offload cards framing routing error-correction acknowledgement retransmission jobs required tcp however application compatibility tcp data transfer functionality offloaded nic tcp connection setup remove load cpu traffic processing ipv4 ipv6 offloaded windows vista also supports netdma uses dma engine allow processors freed hassles moving data network card data buffers application buffers requires specific hardware dma architectures intel i/o acceleration enabled compound tcp modified tcp congestion avoidance algorithm meant improve networking performance applications enabled default pre-service pack 1 version windows vista enabled sp1 windows server 2008 uses different algorithm modify congestion window – borrowing tcp vegas tcp new reno every acknowledgement received increases congestion window aggressively thus reaching peak throughput much faster increasing overall throughput windows vista networking stack includes integrated policy-based quality service qos functionality prioritize network traffic quality service used manage network usage specific applications users throttling bandwidth available used limit bandwidth usage applications high priority applications real time conferencing applications run ensure get bandwidth need traffic throttling also used prevent large data transfer operations using available bandwidth qos policies confined application executable name folder path source destination ipv4 ipv6 addresses source destination tcp udp ports range ports windows vista qos policies applied application network layer thus eliminating need rewrite applications using qos apis qos-aware qos policies either set per-machine basis set active directory group policy objects ensures windows vista clients connected active directory container domain site organizational unit enforce policy settings windows vista supports wireless multimedia wmm profile classes qos wireless networks certified wi-fi alliance bg background data best effort non real time data vi real time videos vo real time voice data wireless access point well wireless nic supports wmm profiles windows vista provide preferential treatment data sent windows vista includes specialized qos api called qwave quality windows audio/video experience pre-configured quality service module time dependent multimedia data audio video streams qwave uses different packet priority schemes real-time flows multimedia packets best-effort flows file downloads e-mails ensure real-time data gets little delays possible providing high quality channel data packets qwave intended ensure real-time transport multimedia networks within wireless network qwave supports multiple simultaneous multimedia well data streams qwave depend solely bandwidth reservation schemes provided rsvp providing qos guarantees bandwidth wireless network fluctuates constantly result also uses continuous bandwidth monitoring implement service guarantees applications explicitly use qwave apis use service multimedia application requests qwave initiate new media stream qwave tries reserve bandwidth using rsvp time uses qos probes make sure network enough bandwidth support stream conditions met stream allowed prioritized applications eat share bandwidth however environmental factors affect reception wireless signals reduce bandwidth even stream allowed access reserved bandwidth due qwave continuously monitors available bandwidth decreases application informed creating feedback loop adapt stream fit lower bandwidth range bandwidth available qwave automatically reserves informs application improvement probing quality network probe packets sent source statistics round trip time loss latency jitter etc path analyzed results cached probe repeated specific time intervals update cache whenever stream requested cache looked qwave also serializes creation multiple simultaneous streams even across devices probes sent one stream interfered others qwave uses client side buffers keep transmission rate within range slowest part network access point buffers overwhelmed thus reducing packet loss qwave works best source sink client multimedia stream qwave aware also wireless access point ap needs qos-enabled supporting bandwidth reservation also work without qos-aware aps however since qwave reserve bandwidth case depend application adapt stream based available bandwidth affected network conditions data network well qwave also available devices part windows rally technologies order provide better security transferring data network windows vista provides enhancements cryptographic algorithms used obfuscate data support 256-bit 384-bit 512-bit elliptic curve diffie–hellman ecdh algorithms well 128-bit 192-bit 256-bit advanced encryption standard aes included network stack direct support ssl connections new winsock api allows socket applications directly control security traffic network providing security policy requirements traffic querying security settings rather add extra code support secure connection computers running windows vista part logically isolated networks within active directory domain computers logical network partition able access resources domain even though systems may physically network unless logical partition wo n't able access partitioned resources system may part multiple network partitions windows vista also includes extensible authentication protocol host eaphost framework provides extensibility authentication methods commonly used protected network access technologies 802.1x ppp allows networking vendors develop easily install new authentication methods known eap methods planned feature new tcp/ip suite known routing compartments utilized per-user routing table thus compartmentalizing network according user needs data one segment would go another feature however removed release windows vista slated included possibly future release windows windows vista also introduces network access protection nap makes sure computers connecting network conform required level system health set administrator network nap enabled network windows vista computer attempts join network verified computer up-to-date security updates virus signatures factors including configuration ipsec 802.1x authentication settings specified network administrator granted full access network criteria met failing may either denied access network granted limited access certain resources may optionally granted access servers provide latest updates updates installed computer granted access network however windows vista nap client i.e. client computer connects nap enabled network health policy verification servers running windows server 2008 ipsec configuration fully integrated windows firewall advanced security snap-in netsh advfirewall command-line tool prevent contradictory rules offer simplified configuration along authenticating firewall advanced firewall filtering rules exceptions ipsec policies set domain public private profiles source destination ip addresses ip address range source destination tcp udp ports multiple ports specific types interfaces icmp icmpv6 traffic type code services edge traversal ipsec protection state specified users computers based active directory accounts prior windows vista setting maintaining ipsec policy configuration many scenarios required setting set rules protection another set rules traffic exemptions ipsec nodes windows vista communicate simultaneously negotiating protected communications response received negotiation completes subsequent communications protected eliminates need set ipsec filters exemptions set hosts support ipsec allows setting required incoming protected initiated communication optional outgoing communication ipsec also allows securing traffic domain controllers member computers still allowing clear text domain joins communication types ipsec protected domain joins allowed using ntlm v2 domain controllers member computers running windows server 2008 windows vista respectively ipsec fully supports ipv6 authip allows second authentication integration nap authenticating health certificate network diagnostics framework support failed ipsec negotiation new ipsec performance counters improved detection cluster node failure faster renegotiation security associations support stronger algorithms main mode negotiation stronger dh algorithms suite b data integrity encryption aes cbc aes-gmac sha-256 aes-gcm ability assist user diagnosing network problem expected major new networking feature extensive support runtime diagnostics wired wireless networks including support tcp management information base mib -ii better system event logging tracing vista tcp/ip stack also supports estats defines extended performance statistics tcp help determining cause network performance bottlenecks windows vista inform user causes network transmission failure incorrect ip address incorrect dns default gateway settings gateway failure port use blocked receiver ready dhcp service running netbios tcp/ip name resolution failure etc transmission errors also exhaustively logged analyzed better find cause error windows vista greater awareness network topology host computer using technologies universal plug play new network awareness technology windows vista provide help user fixing network issues simply provide graphical view perceived network configuration windows vista network stack includes windows filtering platform allows external applications access hook packet processing pipeline networking subsystem wfp allows incoming outgoing packets filtered analyzed modified several layers tcp/ip protocol stack wfp inbuilt filtering engine applications need write custom engine need provide custom logic engine use wfp includes base filtering engine implements filter requests packets processed using generic filtering engine also includes callout module applications providing custom processing logic hooked wfp put uses inspecting packets malware selective packet restriction firewalls providing custom encryption systems among others upon initial release wfp plagued bugs including memory leaks race conditions windows firewall windows vista implemented wfp windows vista includes significant peer-to-peer support introduction new apis protocols new version peer name resolution protocol pnrp v2 well set peer distributed routing table peer graphing peer grouping peer naming peer identity management apis introduced contacts created administered new peer-to-peer subsystem—serverless presence allows users manage real-time presence information track presence registered users across subnet internet new people near service allows discovery management contacts subnet uses windows contacts manage store contact information new capabilities allows peers send application invitations peers ad-hoc collaboration also supported without centralized server windows meeting space example application pnrp also allows creating overlay network called graph peer overlay network corresponds node graph nodes graph share book-keeping information responsible functioning network whole example distributed resource management network node resource needs shared information shared records flooded peers graph peer stores record local database record consists header body body contains data specific application using api header contains metadata describe data body name-value pairs serialized using xml addition author version information also contain index body data fast searching node connect nodes directly well communication need shared entire graph api also allows creation secure overlay network called group consisting subset nodes graph group shared multiple applications unlike graph peers group must identifiable unique named registered using pnrp digital signature certificate termed group member certificate gmc records exchanged digitally signed peers must invited group invitation contains gmc enables join group new windows internet computer names wicn peer networking feature allows ipv6-connected machine obtain custom unique domain name computer connected internet users specify secured unsecured host name computer console command without requiring register domain name configuring dynamic dns wicn used application accepts ip address dns name pnrp performs domain name resolution peer-to-peer level another planned feature windows vista would provided new domain-like networking setup known castle make release castle would made possible identification service provides user authentication members network without centralized server would allowed user credentials propagate across peer-to-peer network making suitable home network people near formerly people nearby peer-to-peer service designed simplify communication collaboration among users connected subnet people near used windows meeting space collaboration contact discovery people near listed part microsoft mobile platform strategy revealed windows hardware engineering conference 2004 people near uses windows contacts manage contact information default user may receive invitations users connected subnet user designate another user trusted contact enable collaboration across internet increase security determine presence contacts new background intelligent transfer service bits 3.0 new feature called neighbor casting supports peer-to-peer file transfers within domain facilitates peer caching allows users download serve content wsus updates peers subnet receive notification file downloaded access temporary file download progress control http redirects saves bandwidth network reduces performance load server bits 3.0 also uses internet gateway device protocol counters accurately calculate available bandwidth http kernel mode driver windows vista http.sys enhanced support server-side authentication logging idn hostnames event tracing better manageability netsh http new performance counters wininet protocol handler http ftp handles ipv6 literal addresses includes support gzip deflate decompression improve content encoding performance internationalized domain names support event tracing winhttp client api server-based applications services supports ipv6 autoproxy http/1.1 chunked transfer encoding larger data uploads ssl client certificates server proxy authentication automatic handling redirects keep-alive connections http/1.0 protocol including support keep-alive persistent connections session cookies winsock updated new apis support event tracing winsock layered service provider support enhanced logged installations removals new api reliably installing lsps command reliably remove lsps facilities categorize lsps remove lsps processing path system critical services support network diagnostics framework winsock kernel wsk new transport-independent kernel-mode network programming interface npi provides tdi client developers sockets-like programming model similar supported user-mode winsock sockets programming concepts exist user-mode winsock socket creation bind connect accept send receive winsock kernel completely new programming interface unique characteristics asynchronous i/o uses irps event callbacks enhance performance tdi supported windows vista backward compatibility new version server message block smb protocol introduced windows vista number changes improve performance add additional capabilities windows vista later operating systems use smb 2.0 communicating machines running windows vista later smb 1.0 continues use connections previous version windows samba samba 3.6 also includes support smb 2.0 remote differential compression rdc client-server synchronization protocol allows data synchronized remote source using compression techniques minimize amount data sent across network synchronizes files calculating transferring differences on-the-fly therefore rdc suitable efficient synchronization files updated independently network bandwidth small scenarios files large differences small windows vista bluetooth stack improved support hardware ids edr performance improvements adaptive frequency hopping wi-fi co-existence synchronous connection oriented sco protocol support needed audio profiles windows vista bluetooth stack supports kernel mode device driver interface besides user-mode programming interface enables third parties add support additional bluetooth profiles sco sdp l2cap lacking windows xp service pack 2 built-in bluetooth stack entirely replaced third-party stack additional profile support also provides rfcomm support using sockets besides virtual com ports kb942567 called windows vista feature pack wireless adds bluetooth 2.1+edr support remote wake s3 s4 support self-powered bluetooth modules feature pack initially available oems eventually included windows vista service pack 2
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Operating systems
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url subscription architecture url subscription architecture urlsa open system subscribing frequently updated digital content web blogs news stories private conversations designed alternative rss supports social subscribing private subscriptions rich content urlsa users subscribe users url content subscribed notified content url updated users typically maintain list subscriptions everything news stories conversations architecture allows users generate private content conversation photo album fly subscribe users fact urlsa content-less architecture users subscribe url content rather content means virtually type content addressable url made subscribable urlsa specifies strict protocol behavior followed creating updating cancelling subscriptions contrast rss data format architecturally urlsa activity happens two types independent applications subscription managers host user accounts content providers provide subscribable urls interact mainly via set well-defined web service calls user subscribes url subscription manager contacts url content provider establishes subscription urlsa user also subscribe another user url assuming subscribing user given permission user subscribes someone else url subscription manager contacts user subscription manager initiates subscribing mechanism behalf user user subscribed url content provider notify updates content url update happens content provider immediately pushes notification users subscribed url time user may unsubscribe url time updates cease interprocess communication urlsa conducted via web services exception updates transmitted udp datagrams reasons efficiency
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Web technology
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isam isam acronym indexed sequential access method method creating maintaining manipulating indexes key-fields extracted random data file records achieve fast retrieval required file records ibm developed isam mainframe computers today term used several related concepts isam system data organized records composed fixed length fields records stored sequentially originally speed access tape system secondary set hash tables known indexes contain pointers tables allowing individual records retrieved without search entire data set departure contemporaneous navigational databases pointers data stored inside records key improvement isam indexes small searched quickly thereby allowing database access records needs additional modifications data require changes data table indexes question isam file created index nodes fixed pointers change inserts deletes occur later content leaf nodes change afterwards consequence inserts leaf node exceed node capacity new records stored overflow chains many inserts deletions table overflow chains gradually become large affects time required retrieval record relational databases easily built isam framework addition logic maintain validity links tables typically field used link foreign key indexed quick lookup slower simply storing pointer related data directly records also means changes physical layout data require updating pointers—the entry still valid isam simple understand implement primarily consists direct sequential access database file also inexpensive tradeoff client machine must manage connection file accesses turn leads possibility conflicting inserts files leading inconsistent database state typically solved addition client-server framework marshals client requests maintains ordering basic concept behind database management system dbms client layer underlying data store isam replaced ibm methodology called vsam virtual storage access method still later ibm developed db2 2004 ibm promotes primary database management system vsam physical access method used db2 openvms operating system uses files-11 file system conjunction rms record management services rms provides additional layer application files disk provides consistent method data organization access across multiple 3gl 4gl languages rms provides four different methods accessing data sequential relative record number access record file address access indexed access indexed access method reading writing data provides desired outcome fact file organized isam file appropriate previously defined keys access data via previously defined key extremely fast multiple keys overlapping keys key compression within hash tables supported utility define/redefine keys existing files provided records deleted although garbage collection done via separate utility isam developed time core memory scarce resource accordingly ibm designed system use minimum amount memory tradeoff channel control unit disk kept busier isam file consists collection data records two three levels index track index contains highest key disk track cylinder indexes cylinder index stores highest key cylinder disk address corresponding track index optional master index usually used large files contains highest key cylinder index track disk address cylinder index file loaded data records moved inserted records placed separate overflow area locate record key indexes disk searched complex self-modifying channel program increased busy time channel control unit disk increased physical virtual memory sizes later systems seen inefficient vsam developed alter tradeoff memory usage disk activity isam use self-modifying channel programs later caused difficulties cp-67 support os/360 since cp-67 copied entire channel program fixed memory i/o operation started translated virtual addresses real
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Computer file systems
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lga 1155 lga 1155 also called socket h2 socket used intel microprocessors based sandy bridge 2nd-gen 32nm 2k-series ivy bridge 3rd-gen 22nm 3k-series microarchitectures successor lga 1156 known socket h succeeded lga 1150 2013 lga 1155 1155 protruding pins make contact pads processor pins arranged 40×40 array 24×16 central void additional 61 omitted pins two adjoining central void six four corners 35 groups around perimeter yielding 1600 − 384 − 61 1155 pin count processors lga 1155 lga 1156 sockets compatible since different socket notches lga 1155 also marked beginning secure boot support later boards 4 holes fastening heatsink motherboard placed square lateral length 75 mm intel sockets lga 1156 lga 1155 lga 1150 lga 1151 cooling solutions therefore interchangeable cooling systems compatible lga 1155 lga 1156 sockets processors dimensions profile construction similar levels heat production sandy bridge chipsets except b65 q65 q67 support sandy bridge ivy bridge cpus bios upgrade sandy bridge based processors officially support ddr3-1333 memory however practice speeds ddr3-2133 tested work successfully h61 chipset supports one double-sided dimm memory module ram module per memory-channel therefore limited 16 gb instead 32 gb like others support h61-based motherboards four dimm slots four single-sided dimms installed ivy bridge chipsets motherboards support sandy bridge ivy bridge cpus ivy bridge based processors officially support ddr3-1600 ddr3-1333 sandy bridge consumer ivy bridge chipsets also allow overclocking k-series processors pcghx user wrote article website describing take uefi modules z97 motherboards use z77-motherboard make later support booting ssd using nvm express protocol instead ahci protocol article claims z97 motherboards first officially fully support nvme protocol als erstes gilt es die fraglichen module aus einem möglichst ähnlichen bios der z97-generation zu extrahieren dies ist die erste generation von mainboards die nvme-laufwerke nativ unterstützt mods described also work b75 chipset motherboards
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Computer architecture
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marshall kirk mckusick marshall kirk mckusick born january 19 1954 computer scientist known extensive work bsd unix 1980s freebsd present day president usenix association 1990 1992 2002 2004 still serves board editorial board acm queue magazine known friends colleagues kirk mckusick received b.s electrical engineering cornell university 2 m.s degrees 1979 1980 respectively ph.d. computer science university california berkeley 1984 mckusick openly gay lives california eric allman domestic partner since graduate school married october 2013 mckusick started bsd virtue fact shared office berkeley bill joy spearheaded beginnings bsd system largest contributions bsd file system helped design original berkeley fast file system ffs recently implemented soft updates alternative approach maintaining disk integrity crash power outage ffs revised version unix file system ufs known ufs2 magic number used ufs2 super block structure reflects mckusick birth date define fs_ufs2_magic 0x19540119 found /usr/include/ufs/ffs/fs.h freebsd systems included easter egg also primarily responsible creating complementary features filesystem snapshots background fsck file system check repair integrate closely soft updates filesystem snapshot filesystem brought immediately power outage fsck run background process design implementation series books regarded high-quality works computer science influential development bsd descendants bsd daemon often used identify bsd copyrighted marshall kirk mckusick
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Operating systems
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portable object computing distributed programming portable object object accessed normal method call possibly residing memory another computer portable sense moves machine machine irrespective operating system computer architecture mobility end goal many remote procedure call systems advantage portable objects easy use expressive allowing programmers completely unaware objects reside locations detractors cite fault naïve programmers expect network-related errors unbounded nondeterminism associated large networks
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Distributed computing architecture
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comparison programming languages functional programming page provides comparison tables functional programming instructions programming languages comparison basic instructions imperative paradigm provided comparison basic instructions
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Programming language topics
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norton insight norton insight whitelists files based reputation norton-branded antivirus software leverages data skip known files virus scans symantec claims quicker scans accurate detection use technology insight codenamed mr. clean initial aim help users determine programs internet safe install mr. clean would provide risk assessment discern safe malicious files however goal later changed making virus scans efficient instead scanning every file known files skipped cutting scanning times norton community watch voluntary anonymous service allows user norton product forward information symantec servers among data collected processes running sha256 values reappearing hash value corresponding file whitelisted norton insight checks processes user computer whitelist matching processes excluded scanning process trusted deemed safe excluded risk scanning two trust levels standard high third option disable norton insight standard trust processes appearing majority participants computers deemed safe high trust addition excludes digitally signed files scanning norton analyzes ntfs file system upon startup unaccounted changes found trust values processes system revoked case mistake revocation mechanism implemented clients receive list revoked sha256 values via liveupdate client file matching sha256 currently trusting file trust revoked file scanned norton file insight feature released norton 2010 products norton download insight feature provides insight files download install computer file insight give reputation information locates file computer well feature copies information users clipboard supports norton download insight feature assizes reputation file file insight window provides following information upon release download insight program would erroneously flags downloaded file digital signature version number therefore potential threat tech herald tested norton internet security 2009 found insight affected system performance whitelisting files scans publication also noted total number files scanned number trusted skipped files varied scan average amount time insight took scan 561 megabyte folder 21,816 clean files 0:00:24:41 despite oddities editor observed norton internet security 2009 faster subsequent products
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Computer security
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tiger security software tiger security software unix-like computer operating systems used security audit tool host-based intrusion detection system supports multiple unix platforms tiger free gpl license unlike tools needs posix tools written entirely shell language tiger based set modular scripts run either together independently check different aspects unix system including review tiger originally developed douglas lee schales dave k. hess khalid warraich dave r. safford 1992 texas university three different forks evolved tiger tara developed advanced research computing tiger analytical research assistant one internally developed hp corporation bryan gartner last one developed debian gnu/linux distribution javier fernández-sanguino current upstream maintainer forks aimed making tiger work newer versions different unix operating systems forks merged may 2002 june 2002 new source code labeled 3.0 release published download section newly created savannah site following merge following releases published tiger interesting features including modular design easy expand used audit tool host-based intrusion detection system tool described program manpage tiger complements intrusion detection system ids network ids snort kernel log-based intrusion detection system lids snare linux systrace openbsd example integrity checkers many aide integrit samhain tripwire ... logcheckers providing framework work together checking system configuration status
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Computer security
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cyber information domain service germany cyber information domain service german cyber- und informationsraum cir youngest branch germany military bundeswehr decision form new military branch presented defense minister ursula von der leyen 26 april 2016 becoming operational 1 april 2017 headquarter cyber information domain service bonn november 2015 german ministry defense activated staff group within ministry tasked developing plans reorganization cyber military intelligence geo-information operative communication units bundeswehr 26 april 2016 defense minister ursula von der leyen presented plans new military branch public 5 october 2016 command staff became operational department within ministry defense 1 april 2017 cyber information domain service activated 6th branch bundeswehr cyber information domain service headquarters take command existing cyber military intelligence geo-information operative communication units command planned fully operational 2021 cids commanded chief cyber information domain service german inspekteur des cyber- und informationsraum inspcir three-star general position based bonn
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Computer security
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transparency human–computer interaction change computing system new feature new component transparent system change adheres previous external interface much possible changing internal behaviour purpose shield change systems human users end interface confusingly term refers overall invisibility component refer visibility component internals white box open system term transparent widely used computing marketing substitution term invisible since term invisible bad connotation usually seen something user ca n't see control term transparent good connotation usually associated hiding anything vast majority times term transparent used misleading way refer actual invisibility computing process misleading counter-intuitive definition modern computer literature tends prefer use agnostic transparent term used particularly often regard abstraction layer invisible either upper lower neighbouring layer also temporarily used later around 1969 ibm honeywell programming manuals term referred certain computer programming technique application code transparent clear low-level detail device-specific management contained logic solving main problem achieved encapsulation – putting code modules hid internal details making invisible main application example network file system transparent introduces access files stored remotely network way uniform previous local access file system user might even notice using folder hierarchy early file transfer protocol ftp considerably less transparent requires user learn access files ftp client similarly file systems allow transparent compression decompression data enabling users store files medium without special knowledge file systems encrypt files transparently approach require running compression encryption utility manually software engineering also considered good practice develop use abstraction layers database access application work different databases abstraction layer allows parts program access database transparently see data access object example object-oriented programming transparency facilitated use interfaces hide actual implementations done different underlying classes transparency means form distributed system hide distributed nature users appearing functioning normal centralized system many types transparency formal definitions concepts found rm-odp open distributed processing reference model iso 10746 degree properties achieved may vary widely every system hide everything users instance due existence fixed finite speed light always latency accessing resources distant user one expects real-time interaction distributed system may noticeable
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Distributed computing architecture
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files-11 files-11 also known on-disk structure file system used digital equipment corporation openvms operating system also simpler form older rsx-11 hierarchical file system support access control lists record-oriented i/o remote network access file versioning files-11 similar significantly advanced file systems used previous digital equipment corporation operating systems tops-20 rsts/e native openvms file system descended older dec operating systems similar many ways designed dave cutler major difference layout directories file systems provided form rudimentary non-hierarchical directory structure typically based assigning one directory per user account rsts/e user account represented two numbers project programmer pair one associated directory special system files program executables os stored directory reserved system account suitable pdp-11 systems possessed limited permanent storage capacity vax systems much larger hard drives required flexible method file storage hierarchical directory layout particular notable improvement ods-2 files-11 general term five separate file systems known on-disk structure ods levels 1 5 ods-1 flat file system used rsx-11 os supported older vms systems rsx compatibility never used support vms largely superseded ods-2 ods-5 ods-2 standard vms file system remains common file system system disks disk operating system installed although seldom referred ods level designations ods-3 ods-4 files-11 support cd-rom iso 9660 high sierra format file systems respectively ods-5 extended version ods-2 available alpha ia-64 platforms adds support case-preserving filenames non-ascii characters improvements hierarchical directory support originally intended file serving microsoft windows non-vms systems part nt affinity project also used user disks internet servers files directories files-11 file system contained inside one parent directories eventually root directory master file directory see file system therefore organised directed acyclic graph dag structure example see right file 2 directory entry dir 2 dir 3 directories simultaneously even removed one would still exist directory removed also similar concept hard links unix although care must taken file actually deleted disks set hard links available ods-5 disks disk hard links enabled operational vms system access one online disks contains complete independent file system either local storage case cluster storage shared remote systems openvms cluster configuration non-private disks shared nodes cluster see figure 1 configuration two system disks accessible nodes via network private disk shared mounted use particular user process machine access files across cluster managed openvms distributed lock manager integral part file system multiple disks combined form single large logical disk volume set disks also automatically replicated shadow sets data security faster read performance disk identified either physical name often user-defined logical name example boot device system disk may physical name 3 dka100 generally referred logical name sys sysdevice file systems disk exception ods-1 hierarchical fully specified filename consists nodename username password device name directory filename file type version number format example dir1.dir2.dir3 file.ext refers latest version file.ext current default disk directory dir1.dir2.dir3 dir1 subdirectory master file directory mfd root directory dir2 subdirectory dir1 disk mfd identified 000000 parts filename omitted case taken current default file specification default file specification replaces concept current directory operating systems providing set defaults node device name directory processes default file specification includes disk name directory vms file system routines accept default file specification also include file type type command example defaults .lis file type command type f extension attempts open file f.lis every file version number defaults 1 versions filename present otherwise one higher greatest version every time file saved rather overwriting existing version new file name incremented version number created old versions deleted explicitly delete purge command optionally older versions file deleted automatically file version limit reached set set file/version_limit old versions thus overwritten kept disk may retrieved time architectural limit version numbers 32767 versioning behavior easily overridden unwanted particular files directly updated databases create new versions unless explicitly programmed ods-2 limited eight levels subdirectories uppercase alphanumeric names plus underscore dash dollar sign 39.39 characters 39 filename another 39 extension ods-5 expands character set lowercase letters printable ascii characters well iso latin-1 unicode characters increases maximum filename length allows unlimited levels subdirectories constructing pathname ods-5 file uses characters allowed ods-2 special syntax used preserve backwards compatibility file file.tar.gz 1 ods-5 disk example would referred file^.tar.gz —the file name file.tar extension .gz vms file security defined two mechanisms uic-based access control acl-based access control uic access control based owner file uic user accessing file access determined four groups permissions four permission bits system access applies user whose uic group code less equal sysgen parameter maxsysgroup typically 8 10 octal example system user owner group apply owner file user user group world applies user also fifth permission bit control used determine access change file metadata protection group set explicitly always set system owner never group world uic-based access control also affected four system privileges allow users holding override access controls acls allow additional privileges assigned user– group–specific basis example web server uic could granted read access files particular directory acls marked inherited directory file acl applies files underneath acls modified using edit/acl command take form identifier/access pairs example acl entry would allow user http server read execute file logical name system variable may reference disk directory file contain program-specific information example logical sys sysdevice contains system boot device logical name normally refers single directory disk e.g sys login user login home directory directories logicals used true disk names—sys login dir file valid file specification however concealed logical names defined define/translation=concealed used way rooted directories defined trailing directory specification hence would allow home dir file used common simple logicals point specific directories associated application software may located disk directory hence logical abc_exe may point directory executable programs application abc abc_temp may point directory temporary files application directory may disk directory tree abc_exe could somewhere another disk different directory tree logical names close equivalent posix operating systems resemble unix environment variables except expanded file system instead command shell application program must defined use common many logical names defined system startup command file well user login command files vms logical names may reference logical names predefined nesting limit 10 may contain lists names search existing filename frequently referenced logical names closest non-dec operating system support concept logical names amigaos assign command amigaos disk operating system amigados port tripos bears resemblance dec operating systems example physical device names follow pattern like df0 first floppy disk cdrom2 3rd cd-rom drive etc however since system boot attached drive operating system creates sys assignment automatically reference boot device used assignments libs prefs c et al also made referenced sys users course allowed create destroy assignments record management services structured i/o layer vms operating system rms provides comprehensive program support managing structured files record-based indexed database files vms file system conjunction rms extends files access past simple byte-streams allows os-level support variety rich files types file vms file system may thought database containing series records one individual fields text file example list records lines separated newline character rms example record-oriented filesystem four record formats defined rms four record access methods methods retrieve extant records files disk level ods represents file system array blocks block 512 contiguous bytes one physical disk volume disk blocks assigned clusters originally 3 contiguous blocks later increased larger disk sizes file disk ideally entirely contiguous i.e blocks contain file sequential disk fragmentation sometimes require file located discontiguous clusters case fragments called 'extents disks may combined disks form volume set files stored anywhere across set disks larger disk sizes reduced use volume sets management single physical disk simpler every file files-11 disk volume set unique file identification fid composed three numbers file number num file sequence number seq relative volume number rvn num indicates indexf.sys file see metadata file located seq generation number incremented file deleted another file created reusing indexf.sys entry dangling references old file accidentally point new one rvn indicates volume number file stored using volume set structural support ods volume provided directory file —a special file containing list file names file version numbers associated fids similar vsam catalogs mvs root directory structure master file directory mfd root directory contains directly indirectly every file volume top level ods file system master file directory mfd contains top-level directory files including several system files used store file system information ods-1 volumes two-level directory structure used user identification code uic associated user file directory ufd form group.user ods-2 later volumes layout directories mfd free-form subject limit nesting directories 8 levels ods-2 unlimited ods-5 multi-volume sets mfd always stored first volume contains subdirectories volumes following system files present ods mfd note file system implementation refer files name file ids always values thus indexf.sys always file num 1 seq 1 index file contains basic information files-11 volume set two organizations indexf.sys traditional organization organization used disks gpt.sys guid partition table gpt structures traditional organization block 1 boot block contains location primary bootstrap image used load vms operating system always located logical block 0 disk hardware firmware read block always present even non-system non-bootable volumes boot block primary home block contains volume name location extents comprising remainder index file volume owner uic volume protection information normally several additional copies home block known secondary home blocks allow recovery volume lost damaged disks gpt.sys gpt.sys contains equivalent boot block known master boot record mbr primary home block home blocks present gpt-based disk alternate home blocks structures included indexf.sys blocks indexf.sys file unused rest index file composed file headers describe extents allocated files residing volume file metadata owner uic acls protection information file described one file headers—more one required file large number extents file header fixed-length block contains fixed– variable–length sections possible map acl sections header contained completely primary header however acl long file contains many extents enough space primary header store case extension header allocated store overflow information file header begins 4 offsets idoffset mpoffset acoffset roffset since size areas fixed-length header may vary map acl areas offsets required locate additional areas offset number 16-bit words beginning file header beginning area file requires multiple headers extension segment number segnum contains sequence number header beginning 0 first entry indexf.sys struclev contains current structure level high byte version low byte file system ods-2 structure level 2 increase version number indicates backwards-compatible change older software may ignore changes structure level incompatible w_fid containing three values fid_num fid_seq fid_rvn corresponding file sequence relative volume number contains id file ext_fid composed three values holds location next extension header values rvn specified 0 represent current volume 0 normally valid rvn filechar contains several flags affect file handled organised accmode describes privilege level process must running order access file vms defines four privilege levels user supervisor exec kernel type access read write execute delete encoded 2-bit integer fileprot contains discretionary access control information file divided 4 groups 4 bits system owner group world bit 0 corresponds read access 1 write 2 execute 3 delete setting bit denies particular access group clearing allows file header extension header backlink contains file id primary header otherwise contains file id directory file containing primary entry file
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Computer file systems
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hacker bible hacker bible publication german hacker organization chaos computer club ccc published two editions date 1985 1988 edited wau holland published grüne kraft press hacker bible compendium documents stories hacker scene example instruction guide acoustic coupler named “ data-loo ” germ. datenklo furthermore offers manuals technical explanations first edition appeared 1985 subtitle “ cable salad good kabelsalat ist gesund ” sold 25,000 copies mid-1988 second edition 1988 given additional name “ new testament ” comic images cover sleeve creation german comic artists mali beinhorn werner büsch comic workshop büsch-beinhorn production distribution hacker bible discontinued 1990 since 1999 ccc offered scanned full-text version online german materials texts peter glaser documentation karl koch works tron chaos-cd
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Computer security
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apple filing protocol apple filing protocol afp formerly appletalk filing protocol proprietary network protocol part apple file service afs offers file services macos classic mac os macos afp one several file services supported others including server message block smb network file system nfs file transfer protocol ftp webdav afp currently supports unicode file names posix access control list permissions resource forks named extended attributes advanced file locking mac os 9 earlier afp primary protocol file services afp versions 3.0 greater rely exclusively tcp/ip port 548 427 establishing communication supporting appletalk service discovery protocol afp 2.x family supports tcp/ip using data stream interface appletalk communication service discovery many third-party afp implementations use afp 2.x thereby supporting appletalk connection method still earlier versions rely exclusively appletalk reason older literature refers afp appletalk filing protocol literature may refer afp appleshare name mac os 9 earlier afp client notable current compatibility topics early implementations afp server software available mac os starting system 6 appleshare appleshare ip early 1.x releases mac os x server client operating systems afp called personal file sharing supported ten simultaneous connections afp implementations relied version 1.x 2.x protocol appleshare ip 5.x 6.x 1.x releases mac os x server introduced afp version 2.2 first version offer transport connections using tcp/ip well appletalk also increased maximum share point size four gibibytes two tebibytes although maximum file size could stored remained two gibibytes due limitations original mac os changes made afp since version 3.0 represent major advances protocol introducing features designed specifically mac os x clients however like appleshare client original mac os afp client mac os x continues support type creator codes along filename extensions afp 3.0 introduced mac os x server 10.0.3 used mac os x server 10.1.5 first version use unix-style posix permissions model unicode utf-8 file name encodings version 3.0 supported maximum share point file size two tebibytes maximum file size volume size mac os x version 10.2 note maximum file size changed version 2.2 described afp 3.0 31 bytes maximum length filename sent afp afp 3.1 introduced mac os x server version 10.2. notable changes included support kerberos authentication automatic client reconnect nfs resharing secure afp connections via secure shell ssh maximum share point file size increased 8 tebibytes mac os x server 10.2 16 tebibytes mac os x server 10.3 afp 3.2 adds support access control lists extended attributes mac os x server 10.4 maximum share point size least 16 tebibytes although apple published limits document mac os x server 10.4 afp 3.2+ introduced mac os x leopard adds case sensitivity support improves support time machine synchronization lock stealing sleep notifications afp 3.3 mandates support replay cache functionality required time machine afp 3.4 introduced os x mountain lion includes minor change mapping posix errors afp errors see apple developer documentation afp version differences mac os x tiger users connect afp servers browsing network globe entering afp uniform resource locator url connect server dialog mac os x leopard later releases afp shares displayed finder side-bar afp urls take form afp // server share server server ip address domain name system dns name bonjour name share name share point snow leopard later url form afp // server share path used mount subdirectory underneath share point macos also offers personal file sharing light implementation current version afp mac os x 10.4 users share contents public folders checking personal file sharing sharing section system preferences afp urls appletalk servers took form afp //at/ appletalk name appletalk zone networks without appletalk zones asterisk would substituted zone name third party server implementations afp available number companies
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Computer file systems
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digital curation digital curation selection preservation maintenance collection archiving digital assets digital curation establishes maintains adds value repositories digital data present future use often accomplished archivists librarians scientists historians scholars enterprises starting use digital curation improve quality information data within operational strategic processes successful digital curation mitigate digital obsolescence keeping information accessible users indefinitely progressively digital curation acts umbrella concept includes many subsets appearing related terms digital asset management data curation digital preservation electronic records management term curation past commonly referred museum library professionals since applied interaction social media including compiling digital images web links movie files term “ digital curation ” first used e-science biological science fields means differentiating additional suite activities ordinarily employed library museum curators add value collections enable reuse smaller subtask simply preserving data significantly concise archival task additionally historical understanding term “ curator ” demands simple care collection curator expected command academic mastery subject matter requisite part appraisal selection assets subsequent adding value collection application metadata five commonly accepted principles govern occupation digital curation digital curation center offers following step-by-step life cycle procedures putting principles practice sequential actions occasional actions term digital curation sometimes used interchangeably terms digital preservation digital archiving digital preservation focus significant degree energy optimizing reusability preservation remains subtask concept digital archiving turn subtask digital curation example archiving part curation subsequent tasks themed collection-building considered archival task similarly preservation part archiving tasks selection appraisal necessarily part preservation data curation another term often used interchangeably digital curation however common usage two terms differs “ data ” all-encompassing term used generally indicate anything recorded binary form term “ data curation ” common scientific parlance usually refers accumulating managing information relative process research data-driven research education request role information professional gradually develop tradition digital service data curation particularly management digital research data documents discrete digital assets technically subset broader concept data context scientific vernacular digital curation represents broader purview responsibilities data curation due interest preserving adding value digital assets kind ever lowering cost increasing prevalence entirely new categories technology led quickly growing flow new data sets come well established sources business government trend also driven new styles sensors becoming embedded areas modern life particularly true consumers whose production digital assets longer relegated strictly work consumers create wider ranges digital assets including videos photos location data purchases fitness tracking data name share wider ranges social platforms additionally advance technology introduced new ways working data examples international partnerships leverage astronomical data create “ virtual observatories ” similar partnerships also leveraged data resulting research large hadron collider cern database protein structures protein data bank comparison archiving analog assets notably passive nature often limited simply ensuring suitable storage environment digital preservation requires proactive approach today ’ artifacts cultural significance notably transient nature prone obsolescence social trends dependent technologies change rapid progression technology occasionally makes necessary migrate digital asset holdings one file format another order mitigate dangers hardware software obsolescence would render asset unusable modern tools program planning often underestimate amount human labor costs required adequate digital curation large collections result cost-benefit assessments often paint inaccurate picture amount work involved true cost institution successful outcomes failures concept cost business field would obvious varieties business systems running daily operations example human resources systems deal recruitment payroll communication systems manage internal external email administration systems handle finance marketing aspects however business systems institutions designed long-term information preservation initially instances business systems revised become digital curation systems preserving transaction information due cost consideration example business systems enterprise content management ecm applications used designated group people business executives customers information management support key processes organizationally long run transfer digital content ecm applications digital curation dc applications would trend large organizations domestically internationally improvement maturity models ecm dc may add value information request cost deduction extensive use modification absence coordination across different sectors society industry areas standardization semantic ontological definitions forming partnerships proper stewardship assets resulted lack interoperability institutions partial breakdown digital curation practice standpoint ordinary user example coordination open archival information system oais oais reference model allows professionals many organizations individuals contribute efforts oais open forums developing international standards archival information long-term access curation digital objects limited strictly born-digital assets many institutions engaged monumental efforts digitize analog holdings effort increase access collections examples materials books photographs maps audio recordings process converting printed resources digital collections epitomized degree librarians related specialists example digital curation centre claimed world leading centre expertise digital information curation assists higher education research institutions conversions topics knowledge embodied forms conducive print choreography dance motion skilled workers artisans difficult encode new digital approaches 3d holograms computer-programmed expressions developing mathematics seems possible new common language developed would express mathematical ideas ways digitally stored linked made accessible global digital mathematics library project define develop language ability intended user community access repository ’ holdings equal importance preceding curatorial tasks must take account user community ’ format communication preferences also consideration communities access various legal privacy reasons three elements essential needs institutions dealing issues digital curation leadership resources collaboration three elements related role advance-guards librarians archivists working open approaches technology standardized process scholarly communication archivist leadership needs dynamic active role embrace technology standardized process scholarly communication addition archivist leader might adopt business concept methods deal workflow raise funds invest technology system comply industry standards order obtain resources collaboration archives digital curation community could provide share training technologies standards tools help institutions challengeable issues digital curation.digital preservation coalition dpc open preservation foundation novel partnerships offer collaboration opportunity institutions facing similar challenges digital curation issues information field especially libraries archives museums significantly need bring knowledge new technologies traditional graduate school education enough meet demand training program current staffs cultural repository would efficient supplement request professional workshops moocs massively open online courses data curation management international digital curation conference idcc established annual event since 2005 aiming collaborate individuals organizations institutions facing challenges supporting development exchanging ideas field international journal digital curation ijdc administered ijdc editorial board including editor-in-chief digital curation center dcc following members ijdc dedicate provide scholarly platform sharing discussing improving knowledge information digital curation within worldwide community ijdc two types submission editorial guidelines peer-reviewed papers general articles base original research field information relevant events digital curation ijdc published university edinburgh digital curation centre electronic form rolling basis two times year open access public supports knowledge exchangeable digital curation worldwide many approaches digital curation exist evolved time response changing technological landscape two examples sheer curation channelization sheer curation approach digital curation curation activities quietly integrated normal work flow creating managing data digital assets word sheer used emphasize lightweight virtually transparent nature curation activities term sheer curation coined alistair miles imagestore project uk digital curation centre scarp project approach depends curators close contact 'immersion data creators working practices example case study neuroimaging research group whyte et al. explored ways building digital curation capacity around apprenticeship style learning neuroimaging researchers share access datasets re-use experimental procedures sheer curation depends hypothesis good data digital asset management point creation primary use also good practice preparation sharing publication and/or long-term preservation assets therefore sheer curation attempts identify promote tools good practices local data digital asset management specific domains tools practices add immediate value creators primary users assets curation best supported identifying existing practices sharing stewardship re-use add value augmenting ways short-term benefits longer term reduce risks digital assets provide new opportunities sustain long-term accessibility re-use value aim sheer curation establish solid foundation curation activities may directly benefit creators primary users digital assets especially required ensure long-term preservation providing foundation curation activities may carried specialists appropriate institutional organisation levels whilst causing minimum interference others similar idea curation source used context laboratory information management systems lims refers specifically automatic recording metadata information data point capture developed apply semantic web techniques integrate laboratory instrumentation documentation systems sheer curation curation-at-source contrasted post hoc digital preservation project initiated preserve collection digital assets already created beyond period primary use channelization curation digital assets web often brands media companies continuous flows content turning user experience lean-forward interactive medium lean-back passive medium curation content done independent third party selects media number on-demand outlets across globe adds playlist offer digital channel dedicated certain subjects themes interests end user would see and/or hear continuous stream content
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Databases
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autonomous decentralized system autonomous decentralized system ads decentralized system composed modules components designed operate independently capable interacting meet overall goal system design paradigm enables system continue function event component failures also enables maintenance repair carried system remains operational autonomous decentralized systems number applications including industrial production lines railway signalling robotics ads recently expanded control applications service application embedded systems thus autonomous decentralized service systems autonomous decentralized device systems autonomous decentralized systems first proposed 1977 ads received significant attention systems deployed japanese railway systems many years safely 7 billion trips proving value concept japan railway ads considered smart train also learns recognizing outstanding contribution dr. kinji mori received numerous awards including 2013 ieee life fellow 2012 distinguished service award tokyo metropolitan government 2012 distinguished specialist among 1000 world chinese government 2008 ieice fellow 1995 ieee fellow 1994 research development award excellence achievers science technology agency 1994 ichimura industrial prize 1992 technology achievement award society instrument control engineers 1988 national patent award science technology agency 1988 mainichi technology prize excellence dr. mori donated cash ichimura industrial price ieee fund ieee kanai award since 1977 ads subject research many researchers world including us japan eu particularly germany china ads decoupled architecture component subsystem communicates message passing using shared data fields unique feature ads central operating system coordinator instead subsystem manages functionality coordination subsystems subsystem needs interact subsystems broadcasts shared data fields containing request subsystems broadcast include identification address subsystem rather subsystems depending purpose function receive broadcast message make determination action take ads moves service-oriented architecture soa adss autonomous decentralized service system data transmission carried esb enterprise service bus agent service receives data esb acts according service specification results transmitted esb autonomous agents ads also similar blackboard system used ai collection agents act upon seeing data change common blackboard ads may include human loop human autonomous agents co-learn time perform system functionality cloud computing also uses autonomous computing architecture framework different ads one application ads software testing particularly combinatorial testing framework proposed based ads concurrent combinatorial testing using ar ta ieee international symposium autonomous decentralized systems isads major conference topic symposium biannual event first symposium held 1993 isads 1993 march 30 april 1 1993 kawasaki japan isads 1995： april 25–27 1995 phoenix arizona usa isads 1997：april 9–11 1997 berlin germany isads 1999：march 20–23 1999 tokyo japan isads 2001：march 26–28 2001 dallas texas usa isads 2003： april 9–11 2003 pisa italy isads 2005：april 4–8 2005 chengdu china isads 2007： march 21–23 2007 sedona arizona usa isads 2009： march 23–25 2009 athens greece isads 2011：june 29 july 1 2011 kobe japan isads 2013：march 6–8 2013 mexico city mexico isads 2015：march 25–27 2015 taichung taiwan
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Computer architecture
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laser squad laser squad turn-based tactics video game originally released zx spectrum later commodore 64 amstrad cpc msx amiga atari st pc computers 1988 1992 designed julian gollop team target games later mythos games codo technologies published blade software expanding ideas applied previous rebelstar series games laser squad originally came five mission scenarios expansion pack released 8-bit versions containing two scenarios reaction gaming magazines positive gaining high review rating several accolades legacy game seen titles like x-com series especially acclaimed also created julian gollop initially conceived sequel laser squad laser squad turn-based tactics war game player completes objectives rescue retrieval operations simply eliminating enemy taking advantage cover squad level military tactics careful use weaponry squad team members maneuvering around map one time taking actions move turn shoot pick use unit action points heavily laden units may tire easily may rest avoid running action points quickly subsequent turns morale also plays factor unit witnessing deaths teammates panic run player control original target games 8-bit release came first three missions expansion pack offered via mail order next two subsequent blade software 8-bit release included standard mail order expansion pack offered missions six seven instead offers covered cassette floppy disk versions well featuring new scenarios expansion packs included additional weapons part scenarios including expansion pack seven scenarios total one difficulty settings squad allocation computer video games reviewing original zx spectrum version awarded near-perfect 97 score c+vg hit stating laser squad one hottest games 've ever played spectrum reviews included 89 sinclair user sinclair gave game 9/10 calling sophisticated strategy wargame ... par elite thinking warmongers game voted number 16 sinclair readers top 100 games time commodore 64 version also fared well cu amiga-64 giving 'cu screen star award 92 rating zzap 64 gave game score 83 stating game absorbing fresh approach man-to-man combat amstrad action awarded cpc version 91 'aa mastergame accolade expansion pack 2 received even higher rating 93 became available review two excellent additions game already excellent amiga version also received positive reviews amiga format awarded 'gold award 93 rating explaining terrific game superbly playable definitely recommended amiga reviews given zero cu amiga-64 gave game scores 88 87 respectively ranked 25th best amiga game ever amiga power 1991 2004 readers retro gamer voted laser squad 63rd top classic game rebelstar laser squad among earliest examples turn-based unit-level wargame video games 1990 mythos games released fantasy game lords chaos many similarities laser squad follow-up gollop earlier zx spectrum game laser squad franchise revived gollop codo technologies 2002 play-by-email game laser squad nemesis although departs turn-based action point system customizable weaponry many laser squad mechanics re-used later x-com series games created also gollop mythos games published microprose notably first x-com game began development laser squad ii name choices characters organizations games mythos codo thread connecting laser squad rebelstar games cover art firaxis games 2k games remake ufo enemy unknown pays homage laser squad
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Computer architecture
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apache solr solr pronounced solar open-source enterprise-search platform written java apache lucene project major features include full-text search hit highlighting faceted search real-time indexing dynamic clustering database integration nosql features rich document e.g. word pdf handling providing distributed search index replication solr designed scalability fault tolerance solr widely used enterprise search analytics use cases active development community regular releases solr runs standalone full-text search server uses lucene java search library core full-text indexing search rest-like http/xml json apis make usable popular programming languages solr external configuration allows tailored many types application without java coding plugin architecture support advanced customization apache lucene apache solr produced apache software foundation development team 2004 solr created yonik seeley cnet networks in-house project add search capability company website january 2006 cnet networks decided openly publish source code donating apache software foundation like new apache project entered incubation period helped solve organizational legal financial issues january 2007 solr graduated incubation status standalone top-level project tlp grew steadily accumulated features thereby attracting users contributors committers although quite new public project powered several high-traffic websites september 2008 solr 1.3 released including distributed search capabilities performance enhancements among many others january 2009 solr enterprise search yonik seeley along grant ingersoll erik hatcher joined lucidworks formerly lucid imagination first company providing commercial support training apache solr search technologies since support offerings around solr abundant november 2009 saw release solr 1.4 version introduced enhancements indexing searching faceting along many improvements rich document processing pdf word html search results clustering based carrot2 also improved database integration release also features many additional plug-ins march 2010 lucene solr projects merged solr became lucene sub project separate downloads continued products jointly developed single set committers 2011 solr version number scheme changed order match lucene solr 1.4 next release solr labeled 3.1 order keep solr lucene version number october 2012 solr version 4.0 released including new solrcloud feature 2013 2014 saw number solr releases 4.x line steadily growing feature set improving reliability february 2015 solr 5.0 released first release solr packaged standalone application ending official support deploying solr war solr 5.3 featured built-in pluggable authentication authorization framework april 2016 solr 6.0 released added support executing parallel sql queries across solrcloud collections includes streamexpression support new jdbc driver sql interface september 2017 solr 7.0 released release among things added support multiple replica types auto-scaling math engine march 2019 solr 8.0 released including many bugfixes component updates solr nodes listen serve http/2 requests aware default internal requests also sent using http/2 furthermore admin ui login added support basicauth kerberos plotting math expressions apache zeppelin possible order search document apache solr performs following operations sequence solr individuals companies contribute new features bug fixes solr bundled built-in search many applications content management systems enterprise content management systems hadoop distributions cloudera hortonworks mapr bundle solr search engine products marketed big data datastax dse integrates solr search engine cassandra solr supported end point various data processing frameworks enterprise integration frameworks solr exposes industry standard http rest-like apis xml json support integrate system programming language supporting standards ease use also client libraries available java c php python ruby popular programming languages
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Databases
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roccat browser roccat browser web browser designed os x ios currently developed runecats utilises webkit rendering engine roccat browser includes features roccat draw allows user annotate webpages within browser resource saver disables re-enables web plugins adobe flash player reducing processing power increasing battery life roccat flick allows user share websites network macs iphones ipads roccat browser also runs cloud system called rclouds lets backup tabs bookmarks settings things related browser roccat also provides unique tab system displays preview website within tab tab bar move top bottom either side placed drawer roccat also available ios devices ipad iphone mobile version features many features desktop counterpart
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Internet protocols
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virtual file system virtual file system vfs virtual filesystem switch abstract layer top concrete file system purpose vfs allow client applications access different types concrete file systems uniform way vfs example used access local network storage devices transparently without client application noticing difference used bridge differences windows classic mac os/macos unix filesystems applications access files local file systems types without know type file system accessing vfs specifies interface contract kernel concrete file system therefore easy add support new file system types kernel simply fulfilling contract terms contract might change incompatibly release release would require concrete file system support recompiled possibly modified recompilation allow work new release operating system supplier operating system might make backward-compatible changes contract concrete file system support built given release operating system would work future versions operating system one first virtual file system mechanisms unix-like systems introduced sun microsystems sunos 2.0 1985 allowed unix system calls access local ufs file systems remote nfs file systems transparently reason unix vendors licensed nfs code sun often copied design sun vfs file systems could plugged also implementation ms-dos fat file system developed sun plugged sunos vfs although n't shipped product sunos 4.1 sunos implementation basis vfs mechanism system v release 4 john heidemann developed stacking vfs sunos 4.0 experimental ficus file system design provided code reuse among file system types differing similar semantics e.g encrypting file system could reuse naming storage-management code non-encrypting file system heidemann adapted work use 4.4bsd part thesis research descendants code underpin file system implementations modern bsd derivatives including macos unix virtual file systems include file system switch system v release 3 generic file system ultrix vfs linux os/2 microsoft windows virtual file system mechanism called installable file system filesystem userspace fuse mechanism allows userland code plug virtual file system mechanism linux netbsd freebsd opensolaris macos microsoft windows virtual filesystems also implemented userland shell namespace extensions however support lowest-level file system access application programming interfaces windows applications able access file systems implemented namespace extensions kio gvfs/gio provide similar mechanisms kde gnome desktop environments respectively similar limitations although made use fuse techniques therefore integrate smoothly system sometimes virtual file system refers file group files necessarily inside concrete file system acts manageable container provide functionality concrete file system usage software examples containers cbfs storage single-file virtual file system emulator like pctask so-called winuae oracle virtualbox microsoft virtual pc vmware primary benefit type file system centralized easy remove single-file virtual file system may include basic features expected file system virtual otherwise access internal structure file systems often limited programs specifically written make use single-file virtual file system instead implementation driver allowing universal access another major drawback performance relatively low compared virtual file systems low performance mostly due cost shuffling virtual files data written deleted virtual file system direct examples single-file virtual file systems include emulators pctask winuae encapsulate filesystem data also emulated disk layout makes easy treat os installation like piece software—transferring removable media network amiga emulator pctask emulated intel pc 8088 based machine clocked 4.77mhz later 80486sx clocked 25 mhz users pctask could create file large size amiga filesystem file would virtually accessed emulator real pc hard disk file could formatted fat16 filesystem store normal ms-dos windows files uae windows winuae allows large single files windows treated amiga file systems winuae file called hardfile uae could also treat directory host filesystem windows linux macos amigaos amiga filesystem
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Computer file systems
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ibm informix-4gl informix-4gl 4gl programming language developed informix mid-1980s includes embedded sql report writer language form language limited set imperative capabilities functions statements supports arrays etc. language particularly close natural language easy learn use two versions compiler either produce 1 intermediate byte code interpreter known rapid development system 2 c programming language code compilation c compiler machine-code executes faster compiles slower executables bigger specifically designed run client network connected ibm informix database engine service mechanism calling c programming language functions conversely called executing c programs rds version also features interactive debugger dumb terminals particular feature comprehensive error checking built final executable extremely helpful error messages produced compilers executables also features embedded modal statements changing compiler executable behaviour e.g causing compiler include memory structures matching database schema structures elements continue executing spite error conditions trapped later informix-4gl project started 1985 chris maloney chief architect roy harrington charge related informix turbo later renamed online engine bypassed cooked file system favour raw disk rapid application development tool called fourgen case tools bundled informix-4gl 1989 1996 another flavor informix programming-tool produced called newera supported object-oriented programming level code-compatibility informix-4gl informix acquired ibm april 2001 despite age informix-4gl still widely used develop business applications sizable market exists around due popularity accounting inherently text based activity often chosen purely text-based interface optimize data entry efficiency new accounting applications still developed informix-4gl reason stansoft released 2010 eppix telecommunication accounting system uses ibm tuxedo services written c programming language call pre-compiled 4gl object modules dynamically run-time
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Programming language topics
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orbitera orbitera american cloud services provider subsidiary google company develops sells e-commerce platform automates billing ordering processes cloud marketplaces orbitera founded 2012 brian singer found challenges associated selling software tech companies previously worked company initially raised 2 million seed funding resolute ventures investors 2016 company platform used adobe systems red hat avnet among others year company acquired google result deal company became part google cloud platform 2018 orbitera partnered mobile device management provider mobileiron develop store cloud-based software since inception orbitera e-commerce platform supports multi-cloud commerce platform handles billing processes buying selling cloud-based services automates building online marketplaces bundled cloud services enables product trials test drives company 2018 partnership mobileiron enable clients sell groups services customer segment allow customized branding offer streamlined billing support data voice third-party cloud services
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Distributed computing architecture
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google play google play previously android market digital distribution service operated developed google llc serves official app store android operating system allowing users browse download applications developed android software development kit sdk published google google play also serves digital media store offering music books movies television programs previously offered google hardware devices purchase introduction separate online hardware retailer google store march 11 2015 also offered news publications magazines revamp google news may 15 2018 applications available google play either free charge cost downloaded directly android device play store mobile app deploying application device google play website applications exploiting hardware capabilities device targeted users devices specific hardware components motion sensor motion-dependent games front-facing camera online video calling google play store 82 billion app downloads 2016 reached 3.5 million apps published 2017 subject multiple issues concerning security malicious software approved uploaded store downloaded users varying degrees severity google play launched march 6 2012 bringing together android market google music google ebookstore one brand marking shift google digital distribution strategy services included google play google play books google play games google play movies tv google play music following re-branding google gradually expanded geographical support services google play features 3.5 million android applications users 145 countries purchase apps although google notes support pages paid content may available provinces territories even governing country listed developers 150 locations distribute apps google play though every location supports merchant registration distribute apps developers pay one-time 25 registration fee google play developer console account app developers control countries app distributed well pricing app in-app purchases country developers receive 70 application price remaining 30 goes distribution partner operating fees developers set sales original price struck banner underneath informing users sale ends google play allows developers release early versions apps select group users alpha beta tests developers also release apps staged rollouts update reaches percentage users increase time users pre-order select apps well movies music books games items delivered soon available network carriers offer billing google play purchases allowing users opt charges monthly phone bill rather credit cards users request refunds within 48 hours purchase something bought n't working n't expected bought accident changed mind purchase apps meeting specific usability requirements qualify wear os app google play games online gaming service android features real-time multiplayer gaming capabilities cloud saves social public leaderboards achievements service introduced google i/o 2013 developer conference standalone mobile app launched july 24 2013 google play music music podcast streaming service online music locker features 40 million songs gives users free cloud storage 50,000 songs google play music available 64 countries google play books ebook digital distribution service google play offers five million ebooks available purchase users also upload 1,000 ebooks form pdf epub file formats google play books available 75 countries google play books often found mirror archive.org website freely available readers download google play movies tv video demand service offering movies television shows available purchase rental depending availability movies available 110 countries tv shows available australia austria canada france germany japan switzerland united states united kingdom google play newsstand news aggregator digital newsstand service offering subscriptions digital magazines topical news feeds basic newsstand service topical news feeds available worldwide paid newsstand content available 35 countries may 15 2018 mobile app merged google news weather form google news newsstand section continued appear google play website november 5 2018 google play march 2015 devices section users purchase google nexus devices chromebooks chromecasts google-branded hardware accessories separate online hardware retailer called google store introduced march 11 2015 replacing devices section google play google play previously styled google play originated three distinct products android market google music google ebookstore android market announced google august 28 2008 made available users october 22 december 2010 content filtering added android market app details page started showing promotional graphic top maximum size app raised 25 megabytes 50 megabytes google ebookstore launched december 6 2010 debuting three million ebooks making largest ebooks collection world november 2011 google announced google music section play store offering music purchases march 2012 google increased maximum allowed size app allowing developers attach two expansion files app basic download expansion file maximum size 2 gigabytes giving app developers total 4 gigabytes also march 2012 android market re-branded google play may 2016 announced google play store including android apps would coming chrome os september 2016 apart searching content name apps also searched keywords provided developer searching apps users press suggested search filters helping find apps matching determined filters discoverability apps play store consists lists featuring top apps category including top free list popular free apps time top paid list popular paid apps time top grossing list apps generating highest amounts revenue trending apps list apps recent installation growth top new free list popular new free apps top new paid list popular new paid apps featured list new apps selected google play team staff picks frequently-updated list apps selected google play team editors choice list apps considered best time top developer list apps made developers considered best march 2017 google added free app week section offering one normally-paid app free july 2017 google expanded editors choice section feature curated lists apps deemed provide good android experiences within overall themes fitness video calling puzzle games google play enables users know popularity apps displaying number times app downloaded download count color-coded badge special color designations surpassing certain app download milestones including grey 100 500 1,000 5,000 downloads blue 10,000 50,000 downloads green 100,000 500,000 downloads red/orange 1 million 5 million 10 million 1 billion downloads users submit reviews ratings apps digital content distributed google play displayed publicly ratings based 5-point scale app developers respond reviews using google play developer console google redesigned google play interface several occasions february 2011 google introduced website interface then-named android market provides access computer applications purchased downloaded installed android device remotely market account section letting users give devices nickname easy recognition may 2011 google added new application lists android market including top paid top free editor choice top grossing top developers trending july google introduced interface focus featured content search filters us book sales movie rentals may 2013 redesign website interface matched then-recently redesigned android app july 2014 play store android app added new headers books/movies sections new additional information screen offering list featuring latest available app version installed size content rating simplified app permissions prompt overview categories days later got redesign consistent then-new material design design language app updated october 2015 feature new animations divide content apps games entertainment sections well added support languages read right-to-left april 2016 google announced redesign icons used suite play apps adding similar style consistent look may 2017 google removed shopping bag google play icon triangle associated colors remaining march 2018 google experimented changing format screenshots used app pages webp format png reverted change caused images load slower update also saw small ui tweaks google play store site reviews section opening dedicated page larger images light box viewer google states developer policy center google play supports variety monetization strategies benefit developers users including paid distribution in-app products subscriptions ad-based models requires developers comply policies order ensure best user experience requires developers charging apps downloads google play must use google play payment system in-app purchases unlocking additional app functionality must also use google play payment system except cases purchase solely physical products digital content may consumed outside app e.g songs played music players support paid applications introduced february 13 2009 developers united states united kingdom support expanded additional 29 countries september 30 2010 in-app billing system originally introduced march 2011 developers google play required feature physical address app page google play requirement established september 2014 february 2017 google announced would let developers set sales apps original price struck banner underneath informing users sale ends google also announced made changes algorithms promote games based user engagement downloads finally announced new editorial pages considers optimal gaming experiences android promoting curating games google allows users purchase content credit debit cards carrier billing gift cards paypal google began rolling carrier billing purchases may 2012 followed support paypal may 2014 rumor google play gift cards started circulating online august 2012 references discovered android police 3.8.15 version update play store android app soon images gift cards started leak august 21 2012 made official google rolled next weeks google play gift cards currently available australia austria belgium brazil canada denmark finland france germany greece hong kong india indonesia ireland italy japan malaysia mexico netherlands new zealand norway poland portugal saudi arabia singapore south africa south korea spain sweden switzerland thailand turkey united kingdom united states google introduced in-app subscriptions google play may 2012 june 2016 sources reported google announced subscriptions charged google play would split revenue 85/15 developers receive 85 revenue google takes 15 change traditional 70/30 split years prior move followed apple then-recently announced change model although commentators quick point apple grants 85/15 revenue share one year active subscriptions google subscription change takes effect immediately january 1 2018 transaction fee subscription products decreased 15 subscribers developers retain 12 paid months unlike sources reporting google using model apple in-app subscriptions app store play store google official pre-installed app store android-certified devices provides access content google play store including apps books magazines music movies television programs play store filters list apps compatible user device developers target specific hardware components compass software components widget android versions 7.0 nougat carriers also ban certain apps installed users devices example tethering applications requirement android applications must acquired using play store users may download android applications developer website third-party app store alternative play store applications self-contained android package files apk similar .exe files install programs microsoft windows computers android devices unknown sources feature settings allows users bypass play store install apks sources depending developer preferences apps installed phone external storage card android users complained google play store access blocked constant data exchange google cloud also valuable cpu ressources used slowing android system play store app features history installed apps users remove apps list changes also synchronizing google play website interface option remove apps history exist google publishes source code android android open source project allowing enthusiasts developers program distribute modified versions operating system however modified versions compatible apps developed google official android versions android compatibility program serves define baseline implementation android compatible third-party apps written developers android devices comply google compatibility requirements may install access google play store application stated help page android open source project devices android compatible may participate android ecosystem including android market devices n't meet compatibility requirements exist outside ecosystem words android compatibility program separate android compatible devices devices merely run derivatives source code welcome uses android source code android compatible devices—as defined tested android compatibility program—may participate android ecosystem device manufacturers choose use app store instead of—or addition to—the play store examples include amazon opting amazon appstore instead google play kindle fire tablet computers samsung adding galaxy apps line samsung galaxy smartphones tablets 2012 google began decoupling certain aspects android operating system particularly core applications could updated google play store independently os one components google play services closed-source system-level process providing apis google services installed automatically nearly devices running android 2.2 froyo higher changes google add new system functionality play services update apps without distribute upgrade operating system result android 4.2 4.3 jelly bean contained relatively fewer user-facing changes focusing minor changes platform improvements april 2016 google announced google play awards described way recognize incredible developer community highlight best apps games awards showcase five nominees across ten award categories apps featured dedicated section google play google stated nominees selected panel experts google play team based criteria emphasizing app quality innovation launch major update last 12 months winners announced may google also previously released yearly lists apps deemed best google play march 6 2017 five years google play launch google released lists best-selling apps games movies music books past five years june 2017 google introduced android excellence new editorial program highlight apps deemed highest quality google play editors google places restrictions types apps published particular allowing sexually explicit content child endangerment violence bullying harassment hate speech gambling illegal activities requiring precautions user-generated content march 2015 google disclosed past months begun using combination automated tools human reviewers check apps malware terms service violations published play store time began rolling new age-based ratings system apps games based given region official ratings authority example esrb us october 2016 google announced new detection filtering system designed provide additional enhancements protect integrity store new system aimed detect filter cases developers attempting manipulate placement apps illegitimate means like fraudulent installs fake reviews incentivized ratings mobile carriers block users installing certain apps march 2009 reports surfaced several tethering apps banned store however apps later restored new ban preventing t-mobile subscribers downloading apps google released statement april 2011 google removed grooveshark app store due unspecified policy violations cnet noted removal came top music labels accused service violating copyright law techcrunch wrote approximately two weeks later grooveshark returned android albeit official app market rather playing android ability install third-party applications browser grooveshark taken responsibility distributing application may 2011 google banned account developer several video game emulators neither google developer publicly revealed reason ban march 2013 google began pull ad blocking apps play store per section 4.4 developers agreement prohibits apps interfere servers services apps exempt power management policies introduced android marshmallow without adversely affected banned july 2018 google banned additional categories apps including perform cryptocurrency mining on-device apps facilitate sale explosives firearms ammunition certain firearms accessories used present ads contain adult content aimed towards children multiple apps highly similar content user experience apps created automated tool wizard service based templates submitted google play operator service behalf persons february 2012 google introduced new automated antivirus system called google bouncer scan new existing apps malware e. g. spyware trojan horses 2017 bouncer feature safety measures within android platform rebranded umbrella name google play protect system regularly scans apps threats android apps ask require certain permissions device including access body sensors calendar camera contacts location microphone phone sms storage july 2017 google described new security effort called peer grouping apps performing similar functionalities calculator apps grouped together attributes compared one app stands requesting device permissions others group google systems automatically flag app security engineers take closer inspection peer grouping based app descriptions metadata statistics download count early march 2011 droiddream trojan rootkit exploit released then-named android market form several free applications many cases pirated versions existing priced apps exploit allowed hackers steal information imei imsi numbers phone model user id service provider exploit also installed backdoor allowed hackers download code infected device exploit affected devices running android versions earlier 2.3 gingerbread google removed apps market immediately alerted apps already downloaded 50,000 times according android police estimate android police wrote method removing exploit infected device reset factory state although community-developed solutions blocking aspects exploit created days later google confirmed 58 malicious apps uploaded android market downloaded 260,000 devices removed store google emailed affected users information far determine information obtained device-specific imei/imsi unique codes used identify mobile devices version android running device opposed personal data account information also announced new remote kill functionality alongside security update lets google remotely remove malicious apps users devices however days later malicious version security update found internet though contain specific droiddream malware new apps featuring malware renamed droiddream light surfaced following june also removed store black hat security conference 2012 security firm trustwave demonstrated ability upload app would circumvent bouncer blocker system application used javascript exploit steal contacts sms messages photos also capable making phone open arbitrary web pages launch denial-of-service attacks nicholas percoco senior vice president trustwave spiderlabs advanced security team stated wanted test bounds capable app stayed google play two weeks repeatedly scanned bouncer system without detection percoco saying attack malware attacker get google play bypass bouncer trustwave reached google share findings noted manual testing apps might necessary detect apps using malware-masking techniques according 2014 research study released riskiq security services company malicious apps introduced google play increased 388 2011 2013 number apps removed google dropped 60 2011 23 2013 study revealed apps personalizing android phones led categories likely malicious according pc world google said would need information riskiq analysis comment findings october 2016 engadget reported blog post named password storage sensitive apps freelance android hacker jon sawyer decided test top privacy apps google play testing two applications one named hide pictures keep safe vault named private photo vault sawyer found significant errors password handling commented companies selling products claim securely store intimate pieces data yet snake oil would near equal protection changing file extension renaming photos april 2017 security firm check point announced malware named falseguide hidden inside approximately 40 game guide apps google play malware capable gaining administrator access infected devices receives additional modules let show popup ads malware type botnet also capable launching ddos attacks alerted malware google removed instances store time approximately two million android users already downloaded apps oldest around since november 2016 june 2017 researchers sophos security company announced finding 47 apps using third-party development library shows intrusive advertisements users phones even apps force-closed user advertisements remain google removed apps receiving reports sophos apps remained asked comment google n't respond august 2017 500 apps removed google play security firm lookout discovered apps contained sdk allowed malicious advertising apps collectively downloaded 100 million times consisted wide variety use cases including health weather photo-editing internet radio emoji 2017 700,000 apps banned google play due abusive contents 70 increase number apps banned 2016 developers publishing google play sued patent infringement patent trolls people broad vaguely worded patents use target small developers developer manages successfully challenge initial assertion patent troll changes claim violation order accuse developer violated different assertion patent situation continues case goes legal system substantial economic costs prompting developers settle february 2013 austin meyer flight simulator game developer sued used copy-protection system app system said google gave us course google provides everyone else making game android meyer claimed google would assist lawsuit stated would settle case battle troll continued several years uploading video june 2016 discussing sued uploading app google play patent troll apparently owns google play store android authority wrote scenario played many app developers many years prompted discussions larger issue stake developers stop making apps fear patent problems users outside countries/regions listed access free apps games google play
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Operating systems
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standard streams computer programming standard streams preconnected input output communication channels computer program environment begins execution three input/output i/o connections called standard input stdin standard output stdout standard error stderr originally i/o happened via physically connected system console input via keyboard output via monitor standard streams abstract command executed via interactive shell streams typically connected text terminal shell running changed redirection pipeline generally child process inherits standard streams parent process users generally know standard streams input output channels handle data coming input device write data application data may text encoding binary data many modern systems standard error stream program redirected log file typically error analysis purposes streams may used chain applications meaning output stream one program redirected input stream another application many operating systems expressed listing application names separated vertical bar character reason often called pipeline character well-known example use pagination application providing user control display output stream display operating systems predating unix programs explicitly connect appropriate input output devices os-specific intricacies caused tedious programming task many systems necessary obtain control environment settings access local file table determine intended data set handle hardware correctly case punch card reader magnetic tape drive disk drive line printer card punch interactive terminal one unix several groundbreaking advances abstract devices removed need program know care kind devices communicating older operating systems forced upon programmer record structure frequently non-orthogonal data semantics device control unix eliminated complexity concept data stream ordered sequence data bytes read end file program may also write bytes desired need easily declare count grouping another unix breakthrough automatically associate input output terminal keyboard terminal display respectively default — program programmer absolutely nothing establish input output typical input-process-output program unless chose different paradigm contrast previous operating systems usually required some—often complex—job control language establish connections equivalent burden orchestrated program since unix provided standard streams unix c runtime environment obliged support well result c runtime environments c descendants regardless operating system provide equivalent functionality standard input stream data often text going program program requests data transfers use read operation programs require stream input example dir ls programs display file names contained directory may take command-line arguments perform operations without stream data input unless redirected standard input inherited parent process case interactive shell usually associated keyboard file descriptor standard input 0 zero posix unistd.h definition codice_1 corresponding c stdio.h variable codice_2 similarly c++ iostream variable codice_3 standard output stream program writes output data program requests data transfer write operation programs generate output example file rename command variously called mv move ren silent success unless redirected standard output inherited parent process case interactive shell usually text terminal initiated program file descriptor standard output 1 one posix unistd.h definition codice_4 corresponding c stdio.h variable codice_5 similarly c++ iostream variable codice_6 standard error another output stream typically used programs output error messages diagnostics stream independent standard output redirected separately solves semipredicate problem allowing output errors distinguished analogous function returning pair values – see semipredicate problem multivalued return usual destination text terminal started program provide best chance seen even standard output redirected readily observed example output program pipeline redirected input next program errors program still go directly text terminal acceptable normal direct standard output standard error destination text terminal messages appear order program writes unless buffering involved example common situations standard error stream unbuffered standard output stream line-buffered case text written standard error later may appear terminal earlier standard output stream buffer yet full file descriptor standard error defined posix 2 two unistd.h header file provides symbol codice_7 corresponding c stdio.h variable codice_8 c++ iostream standard header provides two variables associated stream codice_9 codice_10 former unbuffered latter using buffering mechanism c++ streams bourne-style shells allow standard error redirected destination standard output directed using csh-style shells allow standard error redirected destination standard output directed using standard error added unix several wasted phototypesetting runs ended error messages typeset instead displayed user terminal fortran equivalent unix file descriptors convention many fortran implementations use unit numbers codice_11 stdin codice_12 stdout codice_13 stderr fortran-2003 intrinsic codice_14 module standardized include named constants codice_15 codice_16 codice_17 portably specify unit numbers fortran 77 example fortran 2003 example program main end program algol 60 criticized standard file access algol 68 input output facilities collectively referred transput koster coordinated definition transput standard model included three standard channels codice_18 codice_19 codice_20 c programming language standard input output error streams attached existing unix file descriptors 0 1 2 respectively posix environment unistd.h definitions stdin_fileno stdout_fileno stderr_fileno used instead rather magic numbers file pointers stdin stdout stderr also provided ken thompson designer implementer original unix operating system modified sort version 5 unix accept representing standard input spread utilities became part operating system special file version 8 diagnostics part standard output version 6 dennis m. ritchie created concept standard error java standard streams referred stdin stdout stderr public static void main string args c .net languages standard streams referred codice_21 stdin codice_22 stdout codice_23 stderr basic read write capabilities stdin stdout streams also accessible directly class codice_24 e.g codice_25 used instead codice_26 codice_21 codice_22 codice_23 codice_30 stdin codice_31 stdout stderr objects allow access underlying standard streams text basis full binary access standard streams must performed codice_32 objects returned codice_33 codice_34 codice_35 respectively // c example public static int main string args visual basic .net example public function main integer end function applying codice_36 class one use instance properties codice_37 codice_38 codice_39 class access standard streams process graphical user interfaces guis rarely make use standard streams consequently redirecting gui programs constructing gui pipeline neither practical useful nearest analogy probably cutting copying one application pasting another since manual user operations required moving large numbers pastes especially efficient services menu implemented nextstep mac os x also analogous standard streams operating systems graphical applications provide functionality systemwide menu operates current selection gui matter application gui programs primarily unix still write debug information standard error others many unix media players may read files standard input popular windows programs open separate console window addition gui windows emulators psx dosbox gtk-server use stdin communication interface interpreted program realize gui common lisp interface manager paradigm presents gui elements sent extended output stream
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Operating systems
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jet set willy ii jet set willy ii final frontier platform game released 1985 software projects variety 8-bit home computers official sequel jet set willy one successful home computer games ever released officially jet set willy ii final frontier last miner willy series although numerous unofficial sequels remakes homages updates released even day jet set willy ii expansion original jsw rather new game unto map primarily expanded version original mansion new elements predecessor several based rumoured events jsw fact never programmed able launch titular ship screen called yacht explore island zx spectrum amstrad cpc msx versions willy blasted rocket room space 33 rooms dons spacesuit due proliferation hacking cheating original game jet set willy ii pays homage includes screen called cheat accessed cheating control willy also differs original jet set willy ii written original programmer matthew smith instead developed derrick p. rowson jet set willy ii came form enhanced copy protection called padlock ii prevent felt tip copying seven pages rather single page used jet set willy ending jsw ii also different willy collected 150 175 available items goes bed game takes control willy guides bathroom falls toilet lands room named oh central cavern laid identically deriving name opening level manic miner screen playable amstrad cpc version escape save player intentionally killing remaining lives jsw ii originally created amstrad version jet set willy derrick p. rowson steve wetherill expansions exploit 64k ram amstrad cpc range compared 48k zx spectrum game home platform version subsequently ported back spectrum porting across amstrad porting back spectrum may also explain number small differences including loss coloured backgrounds certain screens cpc version ran 4-colour display mode game subsequently ported platforms including commodore 64 commodore 16 bbc micro acorn electron msx bbc micro cassette version 2 rooms zx spectrum version omits 60 rooms rather subset cpc zx spectrum versions unofficial ports acorn archimedes windows/dos unix/x environments also exist c64 screen different format amstrad developers unable take data used amstrad instead lay re-implement screens sprites however rowson able use much data directly amstrad hence game released sooner in-depth article game code spectrum stated room compressed took differing amounts memory room editor would impossible code november 2016 rowson released jsw2+ re-write jsw2 well technical improvements code allowing complicated rooms built-in ‘ cheat ’ devices allowing infinite lives teleportation rowson also added new rooms made many rooms easier fewer slower sprites
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Computer architecture
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lotuslive ibm smartcloud social business suite business networking collaboration cloud-based services hosted ibm collaboration solutions division ibm integrated services include social networking businesses online meetings file sharing instant message data visualization e-mail several ibm smartcloud social business offerings ibm smartcloud social business also provides mechanisms third-party applications integrate lotuslive ibm announced integration skype linkedin salesforce.com ups silanis lotusphere 2012 ibm announced rebranded lotuslive product line ibm smartcloud social business
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Distributed computing architecture
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login spoofing login spoofings techniques used steal user password user presented ordinary looking login prompt username password actually malicious program usually called trojan horse control attacker username password entered information logged way passed along attacker breaching security prevent operating systems require special key combination called secure attention key entered login screen presented example control-alt-delete users instructed report login prompts appear without pressed secure attention sequence kernel part operating system interacts directly hardware detect whether secure attention key pressed intercepted third party programs unless kernel compromised whereas concept phishing usually involves scam victims respond unsolicited e-mails either identical similar appearance familiar site may prior affiliation login spoofing usually indicative much heinous form vandalism attack case attacker already gained access victim computer least degree internet-based login spoofing spoofing caused
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Computer security
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secure attention key secure attention key sak secure attention sequence sas special key key combination pressed computer keyboard login screen must user completely trustworthy operating system kernel interacts directly hardware able detect whether secure attention key pressed event detected kernel starts trusted login processing secure attention key designed make login spoofing impossible kernel suspend program including masquerading computer login process starting trustable login operation systems configured use sak users must always suspicious login prompts displayed without pressed key combination microsoft windows handled winlogon component use secure attention key also required windows user account control uac prompt examples similar combination often used pc system bios force reboot boot sequence
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Computer security
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wampserver wampserver refers software stack microsoft windows operating system created romain bourdon consisting apache web server openssl ssl support mysql database php programming language
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Web technology
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péter kacsuk péter kacsuk hungarian computer scientist mta-sztaki budapest hungary péter kacsuk received msc university doctorate degrees technical university budapest hungary 1976 1984 respectively received kandidat degree equivalent phd hungarian academy 1989 habilitated university vienna 1997 received professor title hungarian president 1999 doctor academy degree dsc hungarian academy sciences 2001 currently head laboratory parallel distributed systems lpds computer automation research institute hungarian academy sciences péter kacsuk part-time full professor cavendish school computer science university westminster eötvös lóránd university science since 2001 served visiting scientist professor several times various universities australia austria canada england germany spain japan usa published two books two lecture notes 200 scientific papers parallel computer architectures parallel software engineering grid computing chair joint egee see-grid summer school grid application support 2006 2007 chair coregrid summer school 2007 involved many eu grid projects edg gridlab egee seegrid coregrid gridcoord iceage cancergrid etc. coordinator eu fp7 edges enabling desktop grids e-science project co-editor-in-chief journal grid computing published springer received following awards selected media appearances hungary links audio/video material
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Distributed computing architecture
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prolog prolog logic programming language associated artificial intelligence computational linguistics prolog roots first-order logic formal logic unlike many programming languages prolog intended primarily declarative programming language program logic expressed terms relations represented facts rules computation initiated running query relations language first conceived alain colmerauer group marseille france early 1970s first prolog system developed 1972 colmerauer philippe roussel prolog one first logic programming languages remains popular among languages today several free commercial implementations available language used theorem proving expert systems term rewriting type systems automated planning well original intended field use natural language processing modern prolog environments support creation graphical user interfaces well administrative networked applications prolog well-suited specific tasks benefit rule-based logical queries searching databases voice control systems filling templates prolog program logic expressed terms relations computation initiated running query relations relations queries constructed using prolog single data type term relations defined clauses given query prolog engine attempts find resolution refutation negated query negated query refuted i.e. instantiation free variables found makes union clauses singleton set consisting negated query false follows original query found instantiation applied logical consequence program makes prolog logic programming languages particularly useful database symbolic mathematics language parsing applications prolog allows impure predicates checking truth value certain special predicates may deliberate side effect printing value screen programmer permitted use amount conventional imperative programming logical paradigm inconvenient purely logical subset called pure prolog well number extralogical features prolog single data type term terms either atoms numbers variables compound terms special cases compound terms iso prolog provides codice_11 codice_12 codice_13 codice_14 predicates type-checking prolog programs describe relations defined means clauses pure prolog restricted horn clauses two types clauses facts rules rule form head body read head true body true rule body consists calls predicates called rule goals built-in predicate codice_15 meaning 2-arity operator name codice_16 denotes conjunction goals codice_17 denotes disjunction conjunctions disjunctions appear body head rule clauses empty bodies called facts example fact cat tom equivalent rule cat tom true built-in predicate codice_18 always true given fact one ask tom cat things cats clauses bodies called rules example rule animal x cat x add rule ask things animals due relational nature many built-in predicates typically used several directions example codice_19 used determine length list codice_20 given list codice_21 well generate list skeleton given length codice_22 also generate list skeletons lengths together codice_23 similarly codice_24 used append two lists codice_25 given lists codice_26 codice_27 well split given list parts codice_28 given list codice_21 reason comparatively small set library predicates suffices many prolog programs general purpose language prolog also provides various built-in predicates perform routine activities like input/output using graphics otherwise communicating operating system predicates given relational meaning useful side-effects exhibit system example predicate codice_30 displays term screen execution prolog program initiated user posting single goal called query logically prolog engine tries find resolution refutation negated query resolution method used prolog called sld resolution negated query refuted follows query appropriate variable bindings place logical consequence program case generated variable bindings reported user query said succeeded operationally prolog execution strategy thought generalization function calls languages one difference multiple clause heads match given call case system creates choice-point unifies goal clause head first alternative continues goals first alternative goal fails course executing program variable bindings made since recent choice-point created undone execution continues next alternative choice-point execution strategy called chronological backtracking example results following query evaluated true obtained follows initially matching clause-head query codice_31 first one proving query equivalent proving body clause appropriate variable bindings place i.e. conjunction codice_32 next goal proved leftmost one conjunction i.e. codice_33 two clause heads match goal system creates choice-point tries first alternative whose body codice_34 goal proved using fact codice_35 binding codice_36 generated next goal proved second part conjunction codice_37 proved corresponding fact since goals could proved query succeeds since query contained variables bindings reported user query variables like father_child father child enumerates valid answers backtracking notice code stated query codice_38 also succeeds one would insert additional goals describe relevant restrictions desired iterative algorithms implemented means recursive predicates built-in prolog predicate codice_39 provides negation failure allows non-monotonic reasoning goal codice_40 rule legal x \+ illegal x evaluated follows prolog attempts prove codice_41 proof goal found original goal i.e. codice_40 fails proof found original goal succeeds therefore codice_39 prefix operator called provable operator since query codice_44 succeeds goal provable kind negation sound argument ground i.e contains variables soundness lost argument contains variables proof procedure complete particular query codice_45 used enumerate things legal prolog loading code referred consulting prolog used interactively entering queries prolog prompt codice_46 solution prolog writes codice_47 solution exists printed multiple solutions query requested entering semi-colon codice_48 guidelines good programming practice improve code efficiency readability maintainability follow example programs written prolog example query computation expressed declaratively sequence state transitions example optimizing compiler three optimization passes could implemented relation initial program optimized form equivalently using dcg notation quicksort sorting algorithm relating list sorted version design pattern general reusable solution commonly occurring problem software design prolog design patterns go various names skeletons techniques cliches program schemata logic description schemata alternative design patterns higher order programming higher-order predicate predicate takes one predicates arguments although support higher-order programming takes prolog outside domain first-order logic allow quantification predicates iso prolog built-in higher-order predicates codice_49 codice_50 codice_51 codice_52 codice_53 codice_54 furthermore since arbitrary prolog goals constructed evaluated run-time easy write higher-order predicates like codice_55 applies arbitrary predicate member given list codice_56 filters elements satisfy given predicate also allowing currying convert solutions temporal representation answer substitutions backtracking spatial representation terms prolog various all-solutions predicates collect answer substitutions given query list used list comprehension example perfect numbers equal sum proper divisors used enumerate perfect numbers also check whether number perfect another example predicate codice_57 applies predicate codice_58 corresponding positions pair lists codice_58 predicate codice_60 codice_61 unifies codice_62 single unique value codice_63 equivalent applying map function functional programming codice_64 higher-order programming style prolog pioneered hilog λprolog programming large prolog provides module system module system standardised iso however prolog compilers support modules compatibility problems module systems major prolog compilers consequently modules written one prolog compiler necessarily work others special notation called definite clause grammars dcgs rule defined via codice_65 instead codice_66 expanded preprocessor codice_67 facility analogous macros languages according straightforward rewriting rules resulting ordinary prolog clauses notably rewriting equips predicate two additional arguments used implicitly thread state around analogous monads languages dcgs often used write parsers list generators also provide convenient interface difference lists prolog homoiconic language provides many facilities reflection implicit execution strategy makes possible write concise meta-circular evaluator also called meta-interpreter pure prolog code solve true solve subgoal1 subgoal2 solve head codice_68 represents empty conjunction codice_69 unifies clauses database form codice_70 since prolog programs sequences prolog terms codice_66 infix operator easily read inspected using built-in mechanisms like codice_72 possible write customized interpreters augment prolog domain-specific features example sterling shapiro present meta-interpreter performs reasoning uncertainty reproduced slight modifications solve true 1 solve subgoal1 subgoal2 certainty solve goal 1 solve head certainty interpreter uses table built-in prolog predicates form builtin b builtin read x etc clauses represented codice_73 given called codice_74 execute codice_75 obtain measure certainty result pure prolog based subset first-order predicate logic horn clauses turing-complete turing completeness prolog shown using simulate turing machine simple example turing machine specified facts machine performs incrementation one number unary encoding loops number 1 cells appends additional 1 end example query result illustrates computation expressed declaratively sequence state transitions implemented prolog relation successive states interest iso prolog standard consists two parts iso/iec 13211-1 published 1995 aims standardize existing practices many implementations core elements prolog clarified aspects language previously ambiguous leads portable programs three corrigenda cor.1:2007 cor.2:2012 cor.3:2017 iso/iec 13211-2 published 2000 adds support modules standard standard maintained iso/iec jtc1/sc22/wg17 working group ansi x3j17 us technical advisory group standard efficiency prolog code typically compiled abstract machine code often influenced register-based warren abstract machine wam instruction set implementations employ abstract interpretation derive type mode information predicates compile time compile real machine code high performance devising efficient implementation methods prolog code field active research logic programming community various execution methods employed implementations include clause binarization stack-based virtual machines prolog systems typically implement well-known optimization method called tail call optimization tco deterministic predicates exhibiting tail recursion generally tail calls clause stack frame discarded performing call tail position therefore deterministic tail-recursive predicates executed constant stack space like loops languages finding clauses unifiable term query linear number clauses term indexing uses data structure enables sub-linear-time lookups indexing affects program performance affect semantics prologs use indexing first term indexing terms expensive techniques based field-encoded words superimposed codewords provide fast indexing across full query head prolog systems win-prolog swi-prolog implement hashing help handle large datasets efficiently tends yield large performance gains working large corpora wordnet prolog systems b-prolog xsb swi-prolog yap ciao implement memoization method called tabling frees user manually storing intermediate results subgoals encountered query evaluation maintained table along answers subgoals subgoal re-encountered evaluation reuses information table rather re-performing resolution program clauses tabling space–time tradeoff execution time reduced using memory store intermediate results fifth generation computer systems project attempts implement prolog hardware aim achieving faster execution dedicated architectures furthermore prolog number properties may allow speed-up parallel execution recent approach compile restricted prolog programs field programmable gate array however rapid progress general-purpose hardware consistently overtaken specialised architectures although prolog widely used research education prolog logic programming languages significant impact computer industry general applications small industrial standards exceeding 100,000 lines code programming large considered complicated prolog compilers support modules compatibility problems module systems major prolog compilers portability prolog code across implementations also problem developments since 2007 meant portability within family edinburgh/quintus derived prolog implementations good enough allow maintaining portable real-world applications software developed prolog criticised high performance penalty compared conventional programming languages particular prolog non-deterministic evaluation strategy problematic programming deterministic computations even using n't care non-determinism single choice made instead backtracking possibilities cuts language constructs may used achieve desirable performance destroying one prolog main attractions ability run programs backwards forwards prolog purely declarative constructs like cut operator procedural reading prolog program needed understand order clauses prolog program significant execution strategy language depends logic programming languages datalog truly declarative restrict language result many practical prolog programs written conform prolog depth-first search order rather purely declarative logic programs various implementations developed prolog extend logic programming capabilities numerous directions include types modes constraint logic programming clp object-oriented logic programming oolp concurrency linear logic llp functional higher-order logic programming capabilities plus interoperability knowledge bases prolog untyped language attempts introduce types date back 1980s 2008 still attempts extend prolog types type information useful type safety also reasoning prolog programs. ref name= cite doi|10.1007/bf01213601 /ref syntax prolog specify arguments predicate inputs outputs however information significant recommended included comments modes provide valuable information reasoning prolog programs also used accelerate execution constraint logic programming extends prolog include concepts constraint satisfaction constraint logic program allows constraints body clauses codice_76 suited large-scale combinatorial optimisation problems thus useful applications industrial settings automated time-tabling production scheduling prolog systems ship least one constraint solver finite domains often also solvers domains like rational numbers flora-2 object-oriented knowledge representation reasoning system based f-logic incorporates hilog transaction logic defeasible reasoning logtalk object-oriented logic programming language use prolog implementations back-end compiler multi-paradigm language includes support prototypes classes oblog small portable object-oriented extension prolog margaret mcdougall edcaad university edinburgh objlog frame-based language combining objects prolog ii cnrs marseille france prolog++ developed logic programming associates first released 1989 ms-dos pcs support platforms added second version released 1995 book prolog++ chris moss published addison-wesley 1994 prolog systems provide graphics library swi-prolog visual prolog win-prolog b-prolog prolog-mpi open-source swi-prolog extension distributed computing message passing interface also various concurrent prolog programming languages prolog implementations notably swi-prolog ciao support server-side web programming support web protocols html xml also extensions support semantic web formats rdf owl prolog also suggested client-side language cedar free basic prolog interpreter version 4 cedar fca flash cedar app support provides new platform programming prolog actionscript frameworks exist bridge prolog languages name prolog chosen philippe roussel abbreviation french programming logic created around 1972 alain colmerauer philippe roussel based robert kowalski procedural interpretation horn clauses motivated part desire reconcile use logic declarative knowledge representation language procedural representation knowledge popular north america late 1960s early 1970s according robert kowalski first prolog system developed 1972 colmerauer phillipe roussel first implementation prolog interpreter written fortran gerard battani henri meloni david h. d. warren took interpreter edinburgh implemented alternative front-end came define “ edinburgh prolog ” syntax used modern implementations warren also implemented first compiler prolog creating influential dec-10 prolog collaboration fernando pereira warren later generalised ideas behind dec-10 prolog create warren abstract machine european ai researchers favored prolog americans favored lisp reportedly causing many nationalistic debates merits languages much modern development prolog came impetus fifth generation computer systems project fgcs developed variant prolog named kernel language first operating system pure prolog originally restricted use resolution theorem prover horn clauses form application theorem-prover treats clauses procedures pure prolog soon extended however include negation failure negative conditions form b shown trying failing solve corresponding positive conditions b subsequent extensions prolog original team introduced constraint logic programming abilities implementations prolog used watson watson uses ibm deepqa software apache uima unstructured information management architecture framework system written various languages including java c++ prolog runs suse linux enterprise server 11 operating system using apache hadoop framework provide distributed computing prolog used pattern matching natural language parse trees developers stated required language could conveniently express pattern matching rules parse trees annotations named entity recognition results technology could execute rules efficiently found prolog ideal choice language due simplicity expressiveness
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Programming language topics
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nyala typeface nyala font based sylfaen designed support latin alphabet ge'ez script used ethiopic languages created john hudson geraldine wade part windows vista windows server 2008 windows 7 font named mountain nyala species great african antelope native highlands ethiopia
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Operating systems
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series 30 series 30 often shortened s30 software platform application user interface created nokia entry level mobile phones lower series 40 s30 phones capable running java apps 2014 microsoft acquired nokia mobile phones business later discontinued s30 favor series 30+ first series 30 device nokia 1100 2003 originally s30 supposed one menu key second one added release nokia 1110 s30 devices also n't 5-way d-pad 4-way d-pad except nokia 1100 2-way d-pad following list series 30 devices released nokia
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Operating systems
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cifsd cifsd open-source in-kernel cifs/smb server created namjae jeon linux kernel initially goal provide improved file i/o performance bigger goal new features much easier develop maintain inside kernel expose layers fully directions attributed sections samba moving modules inside kernel features like remote direct memory access rdma work actual performance gain subset performance related operations belong kernelspace subset belong operations really related performance userspace dce/rpc management historically resulted number buffer overflow issues dangerous security bugs winreg user account management implemented user space cifsd file operations related performance open/read/write/close etc kernel space kcifsd also allows easier integration vfs interface file operations server daemon started starts forker thread kcifsd/0 initialization time open dedicated port 445 listening smb requests whenever new clients make request forker thread accept client connection fork new thread dedicated communication channel client server allows parallel processing smb requests commands clients well allowing new clients make new connections instance named kcifsd/1~n indicate connected clients depending smb request types new thread decide pass commands user space cifsd currently dce/rpc commands identified handled user space utilize linux kernel chosen process commands default workitems executed handlers default kworker threads allows multiplexing handlers kernel take care initiating extra worker threads load increased vice versa load decreased destroys extra worker threads connection established client dedicated kcifsd/1..n takes complete ownership receiving/parsing smb commands command received worked parallel i.e. multiple clients commands worked parallel receiving command separated kernel workitem prepared command queued handled default kworker'threads inside kernel smb workitem queued kworkers allows benefit load sharing managed optimally default kernel optimizing client performance handling client commands parallel cifsd userspace process transfer user account password registered using cifsadmin part utils user space allows sharing information parameters parsed smb.conf smb export layer kernel execution part daemon continuously running connected kernel interface using netlink socket waits requests dcerpc winreg handles rpc calls minimum dozen important file server netshareenum netservergetinfo various dfs related calls server must implement complete dce/rpc response prepared user space passed associated kernel thread client
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Computer file systems
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apache cxf apache cxf open-source fully featured web services framework originated combination two open-source projects celtix developed iona technologies xfire developed team hosted codehaus two projects combined people working together apache software foundation new name cxf derived combining celtix xfire cxf key design considerations include cxf often used apache servicemix apache camel apache activemq service-oriented architecture soa infrastructure projects cxf includes broad feature set primarily focused following areas
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Web technology
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pdf/x pdf/x subset pdf iso standard purpose pdf/x facilitate graphics exchange therefore series printing related requirements apply standard pdf files example pdf/x-1a fonts need embedded images need cmyk spot colors pdf/x-3 accepts calibrated rgb cielab colors retaining restrictions pdf/x-1a pdf/x files must follow certain restrictions also must contain special file identification inside pdf says pdf/x version means file conform single specific pdf/x standard even requirements met printing conditions output intent need specified file specified form standard profiles using codes like cgats tr 001 swop pdf/x file color managed data color managed graphic gets color profile even though file whole cmyk individual graphics may rgb calibration information various boxes must defined mediabox defines size entire document either artbox trimbox define extent printable area file printed bleed bleedbox must larger trimbox/artbox smaller mediabox must defined active content allowed pdf/x file means standard pdf features like forms signatures comments embedded sounds movies allowed pdf/x features forbidden pdf/x standard sometimes used affect rendering file allows things like annotations outside bleedbox pdf/x-6 development new print production standard built upon pdf 2.0 pdf/x formalized iso standards 15929 15930 versions pdf/x contain file identifications indicate version pdf/x conform appears document info dictionary document metadata according standard used 2010 complete list file identifications following strings pdf/x-1:2001 pdf/x-1a:2001 pdf/x-1a:2003 pdf/x-3:2002 pdf/x-3:2003 pdf/x-4 pdf/x-4p pdf/x-5g pdf/x-5pg observe means various revisions pdf/x-1a pdf/x-3 distinct types revisions pdf/x-4 pdf/x-5 variations
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Programming language topics
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subvocal recognition subvocal recognition svr process taking subvocalization converting detected results digital output aural text-based set electrodes attached skin throat without opening mouth uttering sound words recognized computer subvocal speech recognition deals electromyograms different speaker therefore consistency thrown positioning electrode improve accuracy researchers field relying statistical models get better pattern-matching times subject speaks electrodes even lapses carnegie mellon university researchers found speaker accuracy rates 94 one day see rate drop 48 day later two different speakers drops even relevant applications technology audible speech impossible astronauts underwater navy seals fighter pilots emergency workers charging loud harsh environments worcester polytechnic institute massachusetts research underway use subvocal information control source computer music instruments grant u.s. army research synthetic telepathy using subvocalization taking place university california irvine lead scientist mike d'zmura nasa ames research laboratory mountain view california supervision charles jorgensen conducting subvocalization research brain computer interface r program wadsworth center new york state department health confirmed existing ability decipher consonants vowels imagined speech allows brain-based communication using imagined speech us patents silent communication technologies include us patent 6587729 apparatus audibly communicating speech using radio frequency hearing effect us patent 5159703 silent subliminal presentation system us patent 6011991 communication system method including brain wave analysis and/or use brain activity us patent 3951134 apparatus method remotely monitoring altering brain waves
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Computational linguistics
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slugos slugos common source base group firmware distributions linksys nslu2 slugos comprises slugos/be big endian version slugos alternative firmware linksys nslu2 slugos/le little endian version slugos alternative firmware linksys nslu2
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Operating systems
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bbc basic bbc basic programming language developed 1981 native programming language mos technology 6502 based acorn bbc micro home/personal computer version basic programming language adapted uk computer literacy project bbc written mainly sophie wilson bbc basic based older atom basic acorn atom extended traditional basic named codice_1/codice_2 procedures functions codice_3 loops codice_4 structures inspired comal interpreter also included powerful statements controlling bbc micro four-channel sound output low-/high-resolution eight-mode graphics display due number optimizations bbc basic ran programs much faster microsoft basic running similar machines included using multiple linked lists variable lookup rather single long list pre-defining location integer variables separate integer maths routines speed improved bbc machine via use fast ram allowed mos 6502 processor motorola 6845 display driver share memory without pausing access result design features bbc basic ran david ahl benchmark 21 seconds besting even ibm pc far outpacing 8-bit platforms one unique features bbc basic inline assembler allowing users write assembly language programs 6502 later zilog z80 ns32016 arm assembler fully integrated basic interpreter shared variables could included characters saved via *save *load called via call usr commands allowed developers write assembly language code also basic code emit assembly language making possible use code-generation techniques even write simple compilers basic 1978 hermann hauser chris curry founded acorn computers much code developed cambridge university sophie wilson colleagues complete history available basic original version shipped early bbc micros basic ii used acorn electron bbc micros shipped 1982 including model b added codice_5 codice_6 keywords along offset assembly bug fixes basic iii produced uk version united states market version acorn abortive attempt enter cross-atlantic computer market apart bug fixes change basic ii codice_7 command could also spelled codice_8 regardless input uk version always listed codice_7 us version codice_8 main place basic iii found hi-basic version external second processor basic iv also known cmos basic available bbc master machines changed use new instructions available 65sc12 processor reducing size code therefore allowing inclusion codice_11 codice_12 statement codice_13 codice_14 codice_15 codice_16 statements faster floating point bug fixes included basic iv 1986 improvement basic iv included master compact machine version basic compact included re-coded mathematical routines said provide 30 speed increase version included rest master series hi-basic available two versions first based basic iii second based basic iv built run higher address b800 second processor rather usual 8000 address bbc b allowed program space available either external internal 6502 second processors version introduced support second zilog z80 processor another version bbc basic called bas128 supplied tape disc bbc master master compact loaded main ram used 64 kb sideways ram user programs provided support much larger programs cost lot slower normal rom-based version interpreter deal basic 6502 assembly language included characters contributed system popularity industrial research engineers bbc mos risc os usually supplied rom may assumed specific release operating system contained specific version basic simple way determine version basic actually running enquiring operating system identity thus making assumption see also beebwiki entry inkey bbc family possible run standard basic enhanced hibasic 6502 second processor one may determine program running second processor examining initial value page 800 using second processor distinguish basic hibasic one examine initial value himem 8000 basic running second processor b800 hibasic second processor similar situation exists risc os may normal basic basic64 offers higher precision maths normal basic identifies basic v basic64 identifies basic vi therefore following used error occurred distinguish one better ways see beebwiki almost cases n't need testing basic platform program running make call read whatever returned data returned deal move 32-bit arm cpu removal 16 kb limit basic code size many new features added basic v version 1.04 61 kb long current versions risc os still contain bbc basic v interpreter source code risc os 5 version bbc basic v released 'shared source risc os open 2011 tba software released test versions updated basic includes support vfp/neon assembler amongst new commands features supported graphics commands entirely backwards compatible sound less example codice_28 keyword basic v onwards command takes fourteen numeric parameters effectively nothing— older versions calls os_word 8 nothing risc os in-line 6502 assembler replaced arm assembler basic v said acorn certainly fastest interpreted basic world probably powerful basic found computer basic vi version basic v supports ieee 754 8-byte format real numbers opposed standard 5-byte format introduced basic i. bbc basic v vi delivered standard acorn archimedes riscpc version bbc basic v also available run arm second processor bbc micro compiler bbc basic v produced paul fellows team leader arthur os development called archimedes basic compiler published initially dabs press abc able implement almost language obvious exception eval function inevitably required run-time programmatic interpretation evidence completeness able support in-line assembler syntax compiler written bbc basic v. compiler running interpreter early development stages able compile versions distributed self-compiled object code many applications initially written run interpreter benefitted performance boost gave putting bbc basic v par languages serious application development bbc basic also ported many platforms ns32016 version bbc basic supplied acorn 32016 coprocessor acorn abc addition version bbc basic supplied bbc micro zilog z80 second processor z80-based version bbc basic also exists cp/m-based systems recently version existed sinclair zx spectrum however due efforts j. g. harston also responsible pdp-11 version bbc basic spectrum released january 2002 many improvements made subsequent releases zilog z80 version bbc basic also used tiki 100 desktop computer cambridge z88 portable amstrad nc100 notepad amstrad nc200 notebook computers version implemented ti-83 plus ti-84 plus series graphing calculators pc-based systems bbc basic also implemented dos bbcbasic 86 aimed maximum compatibility bbc micro bbasic concentrated basic language enhancements based basic ii version bbc basic integrated microsoft windows graphical user interface bbc basic windows created richard russell developer z80 x86 versions released 2001 version still active development seeing much industry use currently whilst supporting nearly completely original bbc basic specification basic iv windows version supports much basic v/vi syntax well advanced features features unique bbc basic windows include interpreter support record/structure types ability call windows api routines external dll recent versions included advanced features comparable languages like c external library recently added support objects sdl based version bbc basic available windows linux number mobile devices supporting sdl library gpl clone bbc basic named brandy written portable c also available emulator bbc micro commodore amiga produced ariadne software cbm uk extremely fast emulate 6502 full speed assembly code would run slower real bbc basic programs would run much faster due way optimised basic 6502 emulation interacted almost commercial games would run well behaved code educational software generally worked additionally used slightly less precise floating-point numeric format bundled special academic package amiga 500 hope schools would replace ageing bbc bs amiga 500s version bbc basic v z80 also made ti-83/84+ texas instruments calculator families benjamin ryves commodore 64 version shado produced small software house aztec software early 1980s
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Programming language topics
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homoiconicity computer programming homoiconicity greek words homo- meaning icon meaning representation property programming languages language homoiconic program written manipulated data using language thus program internal representation inferred reading program example lisp program written regular lisp list manipulated lisp code homoiconic languages code accessed transformed data using representation property often summarized saying language treats code data homoiconic language primary representation programs also data structure primitive type language makes metaprogramming easier language without property reflection language examining program entities runtime depends single homogeneous structure handle several different structures would appear complex syntax noted commonly cited example programming language lisp created easy lists manipulation structure given s-expressions take form nested lists lisp programs written form lists result program access functions procedures running programmatically alter fly homoiconic languages typically include full support syntactic macros allowing programmer express transformations programs concise way examples programming languages clojure contemporary dialect lisp rebol also successor red refal recently julia original source paper macro instruction extensions compiler languages according early influential paper trac text-handling language alan kay used possibly popularized term homoiconic use term 1969 phd thesis one advantage homoiconicity extending language new concepts typically becomes simpler data representing code passed meta base layer program abstract syntax tree function may composed manipulated data structure meta layer evaluated much easier understand manipulate code since easily understood simple data since format language data format typical demonstration homoiconicity meta-circular evaluator von neumann architecture systems includes vast majority general purpose computers today implicitly described homoiconic due way raw machine code executes memory data type bytes memory however feature also abstracted programming language level languages lisp dialects scheme clojure racket employ s-expressions achieve homoiconicity languages considered homoiconic include lisp uses s-expressions external representation data code s-expressions read primitive lisp function codice_1 codice_1 returns lisp data lists symbols numbers strings primitive lisp function codice_3 uses lisp code represented lisp data computes side-effects returns result result printed primitive function codice_4 creates external s-expression lisp data lisp data list using different data types sub lists symbols strings integer numbers lisp code example uses lists symbols numbers create expression primitive lisp function codice_5 set variable codice_6 result change codice_7 term codice_8 evaluate expression print expression string read expression string line 4 create new clause operator codice_9 separates head body clause codice_10 add existing clauses add database call later languages would call creating function runtime also remove clauses database codice_11 codice_12 nowiki /nowiki number clause name number arguments take also called arity also query database get body clause codice_13 analogous lisp codice_14 function concept treating code data manipulation evaluation thereof demonstrated neatly rebol rebol unlike lisp require parentheses separate expressions following example code rebol note codice_15 represents interpreter prompt spaces elements added readability codice_16 fact built-in function rebol language construct keyword enclosing code square brackets interpreter evaluate merely treats block containing words block type block furthermore assigned value word using appears syntax assignment actually understood interpreter special type codice_17 takes form word followed colon block still interpreted using codice_18 function provided rebol similar codice_14 lisp possible interrogate elements block change values thus altering behavior code evaluated
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Programming language topics
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u-dise u-dise unified district information system education database schools india database developed national university educational planning administration records information level dropouts condition school toilets
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Databases
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point-to-point protocol computer networking point-to-point protocol ppp data link layer layer 2 communications protocol used establish direct connection two nodes connects two routers directly without host networking device provide connection authentication transmission encryption compression ppp used many types physical networks including serial cable phone line trunk line cellular telephone specialized radio links fiber optic links sonet internet service providers isps used ppp customer dial-up access internet since ip packets transmitted modem line without data link protocol two derivatives ppp point-to-point protocol ethernet pppoe point-to-point protocol atm pppoa used commonly isps establish digital subscriber line dsl internet service connection customers ppp commonly used data link layer protocol connection synchronous asynchronous circuits largely superseded older serial line internet protocol slip telephone company mandated standards link access protocol balanced lapb x.25 protocol suite requirement ppp circuit provided duplex ppp designed work numerous network layer protocols including internet protocol ip trill novell internetwork packet exchange ipx nbf decnet appletalk like slip full internet connection telephone lines via modem reliable slip double checks make sure internet packets arrive intact resends damaged packets ppp designed somewhat original hdlc specifications designers ppp included many additional features seen proprietary data-link protocols time ppp specified rfc 1661 rfc 2516 describes point-to-point protocol ethernet pppoe method transmitting ppp ethernet sometimes used dsl rfc 2364 describes point-to-point protocol atm pppoa method transmitting ppp atm adaptation layer 5 aal5 also common alternative pppoe used dsl ppp layered protocol three components lcp initiates terminates connections gracefully allowing hosts negotiate connection options integral part ppp defined standard specification lcp provides automatic configuration interfaces end setting datagram size escaped characters magic numbers selecting optional authentication lcp protocol runs top ppp ppp protocol number 0xc021 therefore basic ppp connection established lcp able configure rfc 1994 describes challenge-handshake authentication protocol chap preferred establishing dial-up connections isps although deprecated password authentication protocol pap still sometimes used another option authentication ppp extensible authentication protocol eap described rfc 2284 link established additional network layer 3 configuration may take place commonly internet protocol control protocol ipcp used although internetwork packet exchange control protocol ipxcp appletalk control protocol atcp popular internet protocol version 6 control protocol ipv6cp see extended use future ipv6 replaces ipv4 dominant layer-3 protocol ppp permits multiple network layer protocols operate communication link every network layer protocol used separate network control protocol ncp provided order encapsulate negotiate options multiple network layer protocols negotiates network-layer information e.g network address compression options connection established example internet protocol ip uses ip control protocol ipcp internetwork packet exchange ipx uses novell ipx control protocol ipx/spx ncps include fields containing standardized codes indicate network layer protocol type ppp connection encapsulates following ncps may used ppp ppp detects looped links using feature involving magic numbers node sends ppp lcp messages messages may include magic number line looped node receives lcp message magic number instead getting message peer magic number previous section introduced use lcp options meet specific wan connection requirements ppp may include following lcp options ppp frames variants hdlc frames peers agree address field control field compression lcp fields omitted likewise peers agree protocol field compression 0x00 byte omitted protocol field indicates type payload packet 0xc021 lcp 0x80xy various ncps 0x0021 ip 0x0029 appletalk 0x002b ipx 0x003d multilink 0x003f netbios 0x00fd mppc mppe etc ppp limited contain general layer 3 data unlike ethertype information field contains ppp payload variable length negotiated maximum called maximum transmission unit default maximum 1500 octets might padded transmission information particular protocol padded protocol must allow information distinguished padding ppp frames encapsulated lower-layer protocol provides framing may provide functions checksum detect transmission errors ppp serial links usually encapsulated framing similar hdlc described ietf rfc 1662 flag field present ppp hdlc-like framing used address control fields always value hex ff stations hex 03 unnumbered information omitted whenever ppp lcp address-and-control-field-compression acfc negotiated frame check sequence fcs field used determining whether individual frame error contains checksum computed frame provide basic protection errors transmission crc code similar one used layer two protocol error protection schemes one used ethernet according rfc 1662 either 16 bits 2 bytes 32 bits 4 bytes size default 16 bits polynomial x x x 1 fcs calculated address control protocol information padding fields message encapsulated multilink ppp also referred mlppp mp mppp mlp multilink provides method spreading traffic across multiple distinct ppp connections defined rfc 1990 used example connect home computer internet service provider using two traditional 56k modems connect company two leased lines single ppp line frames arrive order possible frames divided among multiple ppp connections therefore multilink ppp must number fragments put right order arrive multilink ppp example link aggregation technology cisco ios release 11.1 later supports multilink ppp ppp one establish several simultaneous distinct ppp connections single link possible multilink ppp either multilink ppp uses contiguous numbers fragments packet consequence possible suspend sending sequence fragments one packet order send another packet prevents running multilink ppp multiple times links multiclass ppp kind multilink ppp class traffic uses separate sequence number space reassembly buffer multiclass ppp defined rfc 2686 pptp point-to-point tunneling protocol form ppp two hosts via gre using encryption mppe compression mppc many protocols used tunnel data ip networks like ssl ssh l2tp create virtual network interfaces give impression direct physical connections tunnel endpoints linux host example interfaces would called tun0 ppp0 two endpoints tunnel tunnel point-to-point connection ppp natural choice data link layer protocol virtual network interfaces ppp assign ip addresses virtual interfaces ip addresses used example route networks sides tunnel ipsec tunneling mode create virtual physical interfaces end tunnel since tunnel handled directly tcp/ip stack l2tp used provide interfaces technique called l2tp/ipsec case ppp provides ip addresses extremities tunnel ppp defined rfc 1661 point-to-point protocol july 1994 rfc 1547 requirements internet standard point-to-point protocol december 1993 provides historical information need ppp development series related rfcs written define variety network control protocols-including tcp/ip decnet appletalk ipx others-work ppp
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Internet protocols
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nokia n950 nokia n950 developers-only phone aimed toward linux-based meego os nokia n9 developers 5,000 units produced sent developers throughout july 2011 nokia exclusively distributed device developers offered sale public phone exists several variations final device issued developers black 1 gb main memory 16 gb emmc internal storage whilst prototypes known model number n9-00 confused n9-01 silver 512 mb main memory 64 gb emmc although marked sale sold ebay €2,000 device received unofficial android port nitdroid community also port nemomobile firefox os nokia n950 phone uses hardware components nokia n9 phone following exceptions nokia n950 developers use tools nokia including qt sdk harmattan python software development
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Operating systems
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oracle sql developer oracle sql developer integrated development environment ide working sql oracle databases oracle corporation provides product free uses java development kit oracle sql developer supports oracle products past variety third-party plugins supported users able deploy connect non-oracle databases oracle sql developer worked ibm db2 microsoft access microsoft sql server mysql sybase adaptive server amazon redshift teradata databases oracle sql developer supports automatic tabs code insight bracket matching syntax coloring pl/sql oracle sql developer product components include owa oracle web agent mod_plsql extension module apache web server helps setting dynamic web-pages pl/sql within oracle sql developer addition extensions provided oracle third parties written extensions add new features sql developer integrate products
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Databases
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programming language programming language dialect language scheme developed early 1980s jonathan a. rees kent m. pitman norman i. adams yale university experiment language design implementation purpose test thesis developed guy l. steele jr. gerald jay sussman series papers scheme scheme may used basis practical programming language exceptional expressive power implementations scheme could perform better lisp systems competitively implementations programming languages c bliss usually considered inherently efficient lisp conventional machine architectures much occurs via optimizing compiler named orbit contains features modern scheme lacks example object-oriented first-class environments called locales modified non-locally used module system several extra special forms lazy evaluation flow control equivalent common lisp setf like scheme supports call-with-current-continuation call/cc also limited form called codice_1 manual hypothetical implementation codice_2 could example shows objects intimately related closures message-passing primitive called codice_3 puts two objects together allowing something resembling inheritance ported many hardware platforms operating systems including
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Programming language topics
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eben moglen eben moglen professor law legal history columbia university founder director-counsel chairman software freedom law center moglen started computer programming language designer received bachelor degree swarthmore college 1980 1985 received master philosophy history jd yale university held visiting appointments harvard university tel aviv university university virginia since 1987 law clerk justice thurgood marshall 1986–87 term joined faculty columbia law school 1987 admitted new york bar 1988 received ph.d. history yale university 1993 moglen serves director public patent foundation moglen part philip zimmermann defense team zimmermann investigated export pretty good privacy public key encryption system us export laws 2003 received eff pioneer award february 2005 founded software freedom law center moglen closely involved free software foundation serving general counsel 1994-2016 board member 2000 2007 counsel moglen charged enforcing gnu general public license gpl behalf fsf later became heavily involved drafting version 3 gpl april 23 2007 announced blog post would stepping board directors free software foundation moglen stated gplv3 discussion draft 3 released wanted devote time writing teaching software freedom law center february 2011 moglen created freedom box foundation design software small server called freedombox freedombox aims affordable personal server runs free software focus anonymous secure communication freedombox launched version 0.1 2012 moglen says free software fundamental requirement democratic free society surrounded dependent upon technical devices controlling devices open via free software balance power equally moglen metaphorical corollary faraday law idea information appearance flow human minds connected via internet works like electromagnetic induction hence moglen phrase resist resistance i.e remove anything inhibits flow information moglen believes idea proprietary software ludicrous proprietary mathematics proprietary geometry would convert subjects something learn something must buy argued points software among things copied infinitely without costs moglen criticized calls reification selfishness said world full computers ca n't understand ca n't fix ca n't use controlled inaccessible proprietary software world controlled machines called lawyers help free software movement saying want share code make products share work without additional legal risks urged legal colleagues worth giving little order produce sounder ecology think kindly idea sharing moglen criticized trends result excluding people knowledge issue free software versus proprietary software argued much said stand lose moglen calls sensible respect creators users software code general concept part moglen termed revolution privileged owners media distribution channels software march 13 2009 speech given seattle university moglen said free software movement 'when everybody owns press freedom press belongs everybody seems inevitable inference ’ moving publishers get used ’ become us ’ become first amendment mean 'congress shall make law ... abridging freedom speech press ... – tended argue course 20th century – 'congress shall make law infringing sacred right sulzbergers different subject digital rights management moglen said also live world right tinker substantial threat said movie record companies must eat concede must eat though like eat less
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Operating systems
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simple gateway control protocol simple gateway control protocol sgcp communications protocol used within voice internet protocol voip system superseded media gateway control protocol mgcp another implementation media gateway control protocol architecture simple gateway control protocol published several internet engineering task force ietf draft versions may july 1998 mauricio arango christian huitema telcordia technologies formerly bellcore protocol architecture decomposes telecommunications gateway located boundary public switched telephone network internet protocol ip network internet media gateway controller mgc ip network providing call device control multiple media gateways mgs handle actual media conversion analog digital circuits pstn simply connect residential telephones implementations architecture refer controller softswitch communication multiple media gateway controllers handled protocols session initiation protocol sip shortly publication sgcp merged internet protocol device control ipdc proposal sponsored level3 communications fall 1998 led definition media gateway control protocol jointly submitted ietf authors sgcp ipdc october 1998 mgcp used conceptual basis additions media gateway device protocol lucent resulting megaco/h.248 protocol gained formal standards-level status ietf international telecommunication union itu
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Internet protocols
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mesa computer graphics mesa also called mesa3d mesa 3d graphics library open source software implementation opengl vulkan graphics api specifications mesa translates specifications vendor-specific graphics hardware drivers important users two graphics drivers mostly developed funded intel amd respective hardware amd promotes mesa drivers radeon radeonsi deprecated amd catalyst intel supported mesa driver proprietary graphics drivers e.g nvidia geforce driver catalyst replace mesa providing implementation graphics api open-source effort write mesa nvidia driver called nouveau mostly developed community besides 3d applications games modern display servers x.org glamor wayland weston use opengl/egl therefore graphics typically go mesa mesa hosted freedesktop.org initiated august 1993 brian paul still active project mesa subsequently widely adopted contains numerous contributions various individuals corporations worldwide including graphics hardware manufacturers khronos group administer opengl specification linux development also partially driven crowdfunding mesa known housing implementation graphic apis historically main api mesa implemented opengl along khronos group related specifications like openvg opengl es recently egl mesa implement apis indeed glide deprecated direct3d 9 since july 2013. mesa also specific unix-like operating systems windows example mesa provides opengl api directx mesa implements translation layer graphics api opengl graphics hardware drivers operating system kernel supported version different graphic apis depends driver hardware driver implementation therefore status specially true classic drivers gallium3d drivers share common code tend homogenize supported extensions versions mesa maintains support matrix status current opengl conformance visualized mesa 10 complies opengl 3.3 intel amd/ati nvidia gpu hardware mesa 11 announced drivers opengl 4.1 compliant mesa 12 contains opengl 4.2 4.3 intel vulkan 1.0 support mesa 13 brought intel support opengl 4.4 4.5 features supported intel gen 8+ radeon gcn nvidia fermi kepler khronos-test 4.5-label experimental amd vulkan 1.0 support community driver radv opengl es 3.2 possible intel skylake gen9 1st stable version 2017 17.0 new year counting ready features certified opengl 4.5 opengl 4.5 intel haswell opengl 4.3 nvidia maxwell pascal gm107+ huge performance gain measured maxwell 1 geforce gtx 750 ti gm1xx maxwell-2-cards geforce gtx 980 gm2xx underclocked without nvidia information khronos cts test suite opengl 4.4 4.5 opengl es 3.0+ 2017-01-24 open source tests mesa 13 17 possible without costs 2nd stable version 2017 17.1.0 came 10 may 2017 interesting improvements opengl 4.2+ intel ivy bridge opengl 3.3+ intel open swr rasterizer 2 highlights note due modularized nature opengl mesa actually support extensions newer versions opengl without claiming full support versions example july 2016 mesa supported opengl es 3.1 also opengl es 3.2 extensions except five well number extensions part opengl opengl es version open question mesa linux high dynamic range hdr many problems open points pipe clean basic implementation 3rd version 17.2 available since september 2017 new opengl 4.6 features velocity improvements 3d intel amd 1.4 tests fail opengl 4.5 nouveau kepler 4th version 17.3 ready since december 2017 many improvements many drivers available opengl 4.6 nearly fully available spir-v ready amd vulkan driver radv fully conformant khronos-test 1st version 2018 18.0 available since march 2018 scheme 2017 full opengl 4.6 support ready many features improvements successfully tested rc3 10-bit support intel i965 colors also highlight new support intel cannon lake amd vega actual linux version amd evergreen chips rv800 r900 near opengl 4.5 support old amd r600 rv700 chips support opengl 3.3 features opengl 4.x freedreno driver adreno hardware near opengl 3.3 support 2nd version 2018 18.1 available since may target vulkan 1.1.72 intel anv amd radv driver opengl 4.6 spir-v also main target permanent work possible completion features optimization drivers older hardware like amd r600/evergreen nvidia tesla fermi kepler intel sandybridge ivybridge haswell broadwell arm architecture made also great improvements adreno 3xx/4xx/5xx broadwell vc4/vc5 raspi main target opengl es 3rd version 2018 18.2 available calendar stable september opengl 4.6 spir-v vulkan 1.1.80 wip soft driver virtual machines virgl ready opengl 4.3 opengl es 3.2 radeonsi also ready opengl es 3.2 astc texture compression support compatibility modus support opengl 4.4 3.1 18.1 highlights radeonsi amd gcn cards new vulkan 1.1 features intel amd available see details vulkan mesamatrix 4th version 2018 18.3 released stable version 18.3.1 december 2018 many features detail support newer hardware main parts full support opengl 4.6 ready 1st version 2019 19.0 released march full support opengl 4.6 ready many improvements way drivers 2nd version 2019 19.1 transition tgsi nir one main feature way opengl 4.6 spir-v opencl radeonsi runs well dev-version nir 3rd version 2019 19.2 opengl 4.6 ready intel iris driver khronos group officially announced vulkan api march 2015 officially released vulkan 1.0 february 16 2016 vulkan breaks compatibility opengl completely abandons monolithic state machine concept developers gallium3d called vulkan something along lines gallium3d 2.0 – gallium3d separates code implements opengl state machine code specific hardware gallium3d ingests tgsi vulkan ingests spir-v standard portable intermediate representation version v vulkan intel released implementation vulkan driver hardware day specification officially released mainlined april became part mesa 12.0 released july 2016 already i965 driver n't written according gallium3d specifications vulkan driver makes even less sense flange top gallium3d similarly technical reason flange nir yet intel employees implemented vulkan driver way expected amd proprietary vulkan driver released march announced released free open-source software future mainlined mesa also abandons gallium3d radv free project amd available since version 13 conformance khronos-test came version 17.3 actual full support vulkan 1.0 1.1 since mesa 18.1 nvidia released proprietary geforce driver vulkan support launch day imagination technologies powervr qualcomm adreno arm mali done least announced proprietary vulkan drivers android operating systems whether additional free open-source vulkan implementations gpus show remains seen mesa software driver virgl starts vulkan development 2018 gsoc projects support virtual machines kind memory barrier separates one buffer rest memory called fence fences ensure buffer overwritten rendering display operations completed implicit fencing used synchronization graphics drivers gpu hardware fence signals buffer longer used one component operated reused another past linux kernel implicit fencing mechanism fence directly attached buffer cf gem handles fds userspace unaware explicit fencing exposes fences userspace userspace gets fences direct rendering manager drm subsystem gpu explicit fencing required vulkan offers advantages tracing debugging linux kernel 4.9 added android synchronization framework mainline generic buffer management gbm api provides mechanism allocating buffers graphics rendering tied mesa gbm intended used native platform egl drm openwfd handle creates used initialize egl create render target buffers mesa gbm abstraction graphics driver specific buffer management apis instance various libdrm_* libraries implemented internally calling mesa gpu drivers example wayland compositor weston rendering using opengl es 2 initializes calling egl since server runs bare kms driver uses egl drm platform could really called gbm platform since relies mesa gbm interface xdc2014 nvidia employee andy ritger proposed enhance egl order replace gbm three possible ways calculations necessary encoding decoding video streams example nouveau developed part mesa also includes linux kernel component developed part linux kernel supports purevideo-branded asics provides access vdpau partly xvmc free radeon driver supports unified video decoder video coding engine vdpau openmax please note v4l2 kernel-to-user-space interface video bit streams delivered webcams tv tuners available free open-source device drivers graphic chipsets stewarded mesa existing free open-source implementation apis developed inside mesa currently two frameworks write graphics drivers classic gallium3d overview drivers available mesa given device drivers amd/ati r100 r800 intel nvidia cards 3d acceleration previously drivers existed ibm/toshiba/sony cell apu playstation 3 s3 virge savage chipsets via chipsets matrox g200 g400 free open-source drivers compete proprietary closed-source drivers depending availability hardware documentation man-power free open-source driver lag behind less supporting 3d acceleration new hardware also 3d rendering performance usually significantly slower notable exceptions today still true nouveau nvidia gpus amds radeon gpus open driver mostly matches exceeds proprietary driver performance time 3d graphics cards became mainstream pcs individuals partly supported companies began working adding support hardware-accelerated 3d rendering mesa direct rendering infrastructure dri one approaches interface mesa opengl 3d rendering api libraries device drivers hardware reaching basic level usability dri support officially added mesa significantly broadened available range hardware support achievable using mesa library adapting dri mesa library finally took role front end component full scale opengl framework varying backend components could offer different degrees 3d hardware support dropping full software rendering capability total system used many different software components design requires components interact carefully interfaces relatively fixed nonetheless components interacting mesa stack open source experimental work often done altering several components well interfaces experiments prove successful incorporated next major minor release applies e.g update dri specification developed 2007-2008 timeframe result experimentation dri2 operates without locks improved back buffer support special git branch mesa created dri3 supported intel driver since 2013 default linux distributions since 2016 enable vulkan support also default amd hardware since late 2016 x.org server 1.18.3 newer mesa also contains implementation software rendering called swrast allows shaders run cpu fallback graphics hardware accelerators present gallium software rasterizer known softpipe built support llvm llvmpipe generates cpu code runtime since mesa 10.x opengl 3.3+ supported softpipe 10.3 llvmpipe 10.2 actual 80 features opengl 4.x implemented mesa 17.3 see mesamatrix mesa 12.0 new intel rasterizer openswr available high advantages clusters large data sets focused engineering visualisation game art imagery work x86 processors hand opengl 3.1+ supported acceleration values 29 51 related llvmpipe measured examples change option gallium_driver= swr necessary opengl 3.3+ supported openswr since mesa 17.1 virgl rasterizer virtual machines implemented mesa 11.1 since 2015 opengl 3.3 support showed mesamatrix since mesa 18 actual new mesa 18.2 supports others opengl 4.3 opengl es 3.2 80 opengl 4.4 4.5 features also ready vulkan development starts gsoc 2018 projects idea bundling multiple drivers single mega driver proposed eric anholt allows single copy shared mesa code used among multiple drivers instead existing driver separately offering better performance separate shared library due removal internal library interface state trackers vdpau xvmc become separate libraries shader-db collection 20,000 shaders gathered various computer games benchmarks well scripts compile collect statistics shader-db intended help validate optimization noticed unexpected number shaders hand-written generated means shaders originally written hlsl translated glsl translator program e.g hlsl2glsl problem generated code often far optimal matt turner said much easier fix translator program make mesa compiler carry burden dealing bloated shaders shader-db considered free open-source software use legally one must license computer games shaders part least valve corporation granted mesa debian developers free personal licenses games distributed steam so-called user-mode graphics device drivers umd mesa commonalities generally called device driver couple differences one goal mesa optimization code executed respective gpu another sharing code instead documenting pieces software wikipedia article shall instead look intermediate representations used process compiling optimizing see abstract syntax tree ast static single assignment form ssa form spir-v certain version standard portable intermediate representation idea graphics applications output spir-v instead glsl contrast latter spir-v binary avoid implementation differences glsl compiler frontends different driver implementations major source application incompatiblities bugs also spir-v binary usually also passed general optimizations also degree spir-v binary representation offers degree obfuscation might appeal software vendors form intellectual property protection however spir-v contains ample information reflection tools exist translate spir-v back high quality human readable high level code umd needs apply optimizations specific supported hardware nir extended next releases base spir-v support llvmpipe radeonsi noveau change next nir tgsi tungsten graphics shader infrastructure tgsi introduced 2008 tungsten graphics gallium3d-style umds ingest tgsi umds codice_2 codice_3 output machine code instead llvm ir llvm optimizations compilation machine code mean certain minimum version llvm installed well mesa glsl compiler generates ir driver different requirements lir differentiates hir high-level ir lir low-level ir gallium3d set interfaces collection supporting libraries intended ease programming device drivers 3d graphics chipsets multiple operating systems rendering video acceleration apis feature matrix provided galliumstatus efforts writing free open-source device drivers graphics chips separately documented wikipedia free open-source graphics device driver development gallium3d started 2008 tungsten graphics implementation available free open-source software part mesa 3d hosted freedesktop.org primary goal making driver development easier bundling otherwise duplicated code several different drivers single point support modern hardware architectures done providing better division labor example leaving memory management kernel dri driver gallium3d part mesa since 2009 currently used free open-source graphics driver nvidia nouveau project r300–r900 free open-source gpu device drivers gallium3d eases programming device drivers splitting graphics device driver three parts accomplished introduction two interfaces gallium3d state tracker interface gallium3d winsys interface three components called gallium3d state tracker gallium3d hardware device driver gallium3d winsys gallium3d provides unified api exposing standard hardware functions shader units found modern hardware thus 3d apis opengl 1.x/2.x opengl 3.x openvg gpgpu infrastructure even direct3d found wine compatibility layer need single back-end called state tracker targeting gallium3d api contrast classic-style dri device drivers require different back-end hardware platform several apis need translation opengl expense code duplication vendor device drivers due proprietary closed-source nature written way meaning e.g amd catalyst implements opengl direct3d vendor drivers geforce implementations gallium3d direct rendering manager drm kernel drivers manage memory direct rendering interface dri2 drivers gpu processing oriented transition period userspace modesetting kernelspace modesetting mesa 3d drivers radeon driver intel drivers ended supporting dri1 dri2 used dri2 available system gallium3d additionally requires level shader support available older cards like e.g ati r100-r200 users cards need keep using mesa 3d dri2 3d usage tungsten graphics shader infrastructure tgsi intermediate representation like llvm intermediate representation new standard portable intermediate representation spir used vulkan api opencl 2.1 shaders written opengl shading language translated/compiled tgsi optimizations made tgsi shaders compiled shaders instruction set used gpu addition using modular structure gallium3d effort underway use llvm compiler suite create module optimize shader code fly library represents shader program using extensible binary intermediate representation called tungsten graphics shader infrastructure tgsi llvm translates glsl shaders optimized target hardware several free open-source graphics device drivers written based information gained clean-room reverse engineering adopted driver model provided gallium3d e.g nouveau others see free open-source graphics device driver complete list main reason may gallium3d driver model lessens amount code required written course licensed free software license code time anybody rewritten implement dri- driver model original authors gallium3d keith whitwell brian paul tungsten graphics acquired vmware 2008 fall 2011 least 10 known mature working gallium3d drivers open-source drivers nvidia graphics cards name nouveau team develops drivers using gallium3d framework 2008-07-13 nouveau development done exclusively gallium framework old dri driver removed master branch mesa repository freedesktop.org 2009-02-11 gallium-0.2 branch merged mainline master branch mesa development done mesa mainline 2009-02-25 gallium3d run linux well freebsd kernels 2009-05-01 zack rusin tungsten graphics added openvg state tracker mesa 3d enables scalable vector graphics hardware-accelerated gallium3d-based driver 2009-07-17 mesa3d 7.5 released first version include gallium3d 2010-09-10 initial support evergreen gpus added r600g driver 2010-09-21 two gallium3d drivers ati hardware known r300g r600g r300-r500 r600-evergreen gpus respectively 2010-09-21 major commits made code support direct3d 10 11 time might offer ability use recent direct3d implementations gnu/linux systems 2011-11-30 intel 965g cell gallium drivers removed master branch mesa unmaintained broken 2013-11-30 mesa 10 opengl 3.2 3.3 opencl 1.0+ 2014-11-18 major commits made code support direct3d 9 2015-09-15 mesa 11 opengl 4.0 4.1 opencl 1.2 incomplete 2015-12-15 mesa 11.1 driver virgl virtual machines opengl 3.3 2016-07-08 mesa 12 opengl 4.2 4.3 vulkan 1.0 intel anv amd radv 2016-11-01 mesa 13 opengl 4.4 opengl es 3.2 2017-02-13 mesa 17.0 opengl 4.5 freedreno driver opengl 3.0 3.1 2017-05-10 mesa 17.1 opengl 4.2+ intel ivy bridge intel driver windows opengl 3.3+ intel open swr rasterizer important cluster computer huge simulations 2017-12-08 mesa 17.3 amd vulkan driver radv full compliant khronos test vulkan 1.0 2018-05-18 mesa 18.1 vulkan 1.1 intel anv amd radv 2018-09-07 mesa 18.2 opengl 4.3 soft driver virgl important virtual machines cloud cluster computer opengl es 3.1 freedreno adreno a5xx project initiator brian paul graphics hobbyist thought would fun implement simple 3d graphics library using opengl api might use instead vogl ordinary gl like library beginning 1993 spent eighteen months part-time development released software internet software well received people began contributing development mesa started rendering 3d computer graphics cpu despite internal architecture mesa designed open attaching graphics processor-accelerated 3d rendering first phase rendering done indirectly display server leaving overhead noticeable speed lagging behind theoretical maximum diamond monster 3d using voodoo graphics chipset one first 3d hardware devices supported mesa first true graphics hardware support added mesa 1997 based upon glide api new 3dfx voodoo i/ii graphics cards successors major problem using glide acceleration layer habit glide run full screen suitable computer games glide took lock screen memory thus display server blocked gui tasks
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Operating systems
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kernel-based virtual machine kernel-based virtual machine kvm virtualization module linux kernel allows kernel function hypervisor merged linux kernel mainline kernel version 2.6.20 released february 5 2007 kvm requires processor hardware virtualization extensions intel vt amd-v. kvm also ported operating systems freebsd illumos form loadable kernel modules kvm originally designed x86 processors since ported s/390 powerpc ia-64 arm kvm provides hardware-assisted virtualization wide variety guest operating systems including linux bsd solaris windows haiku reactos plan 9 aros research operating system macos addition android 2.2 gnu/hurd debian k16 minix 3.1.2a solaris 10 u3 darwin 8.0.1 together operating systems newer versions listed known work certain limitations additionally kvm provides paravirtualization support linux openbsd freebsd netbsd plan 9 windows guests using virtio api includes paravirtual ethernet card disk i/o controller balloon device vga graphics interface using spice vmware drivers avi kivity began development kvm qumranet technology startup company acquired red hat 2008 kvm surfaced october 2006 merged linux kernel mainline kernel version 2.6.20 released 5 february 2007 kvm maintained paolo bonzini kvm perform emulation instead exposes /dev/kvm interface userspace host use linux qemu versions 0.10.1 later one userspace host qemu uses kvm available virtualize guests near-native speeds otherwise falls back software-only emulation internally kvm uses seabios open source implementation 16-bit x86 bios kvm support hot plug vcpus dynamic memory management live migration since february 2007 among features kvm parts licensed various gnu licenses
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Operating systems
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text mining text mining also referred text data mining roughly equivalent text analytics process deriving high-quality information text high-quality information typically derived devising patterns trends means statistical pattern learning text mining usually involves process structuring input text usually parsing along addition derived linguistic features removal others subsequent insertion database deriving patterns within structured data finally evaluation interpretation output 'high quality text mining usually refers combination relevance novelty interest typical text mining tasks include text categorization text clustering concept/entity extraction production granular taxonomies sentiment analysis document summarization entity relation modeling i.e learning relations named entities text analysis involves information retrieval lexical analysis study word frequency distributions pattern recognition tagging/annotation information extraction data mining techniques including link association analysis visualization predictive analytics overarching goal essentially turn text data analysis via application natural language processing nlp analytical methods typical application scan set documents written natural language either model document set predictive classification purposes populate database search index information extracted term text analytics describes set linguistic statistical machine learning techniques model structure information content textual sources business intelligence exploratory data analysis research investigation term roughly synonymous text mining indeed ronen feldman modified 2000 description text mining 2004 describe text analytics latter term used frequently business settings text mining used earliest application areas dating 1980s notably life-sciences research government intelligence term text analytics also describes application text analytics respond business problems whether independently conjunction query analysis fielded numerical data truism 80 percent business-relevant information originates unstructured form primarily text techniques processes discover present knowledge – facts business rules relationships – otherwise locked textual form impenetrable automated processing subtasks—components larger text-analytics effort—typically include text mining technology broadly applied wide variety government research business needs three groups may use text mining records management searching documents relevant daily activities legal professionals may use text mining e-discovery governments military groups use text mining national security intelligence purposes scientific researchers incorporate text mining approaches efforts organize large sets text data i.e. addressing problem unstructured data determine ideas communicated text e.g. sentiment analysis social media support scientific discovery fields life sciences bioinformatics business applications used support competitive intelligence automated ad placement among numerous activities many text mining software packages marketed security applications especially monitoring analysis online plain text sources internet news blogs etc national security purposes also involved study text encryption/decryption range text mining applications biomedical literature described including computational approaches assist studies protein docking protein interactions protein-disease associations addition large patient textual datasets clinical field datasets demographic information population studies adverse event reports text mining facilitate clinical studies precision medicine text mining algorithms facilitate stratification indexing specific clinical events large patient textual datasets symptoms side effects comorbidities electronic health records event reports reports specific diagnostic tests one online text mining application biomedical literature pubgene publicly accessible search engine combines biomedical text mining network visualization gopubmed knowledge-based search engine biomedical texts text mining techniques also enable us extract unknown knowledge unstructured documents clinical domain text mining methods software also researched developed major firms including ibm microsoft automate mining analysis processes different firms working area search indexing general way improve results within public sector much effort concentrated creating software tracking monitoring terrorist activities text mining used large media companies tribune company clarify information provide readers greater search experiences turn increases site stickiness revenue additionally back end editors benefiting able share associate package news across properties significantly increasing opportunities monetize content text mining starting used marketing well specifically analytical customer relationship management coussement van den poel 2008 ref name= 10.1016/j.im.2008.01.005 /ref apply improve predictive analytics models customer churn customer attrition text mining also applied stock returns prediction sentiment analysis may involve analysis movie reviews estimating favorable review movie analysis may need labeled data set labeling affectivity words resources affectivity words concepts made wordnet conceptnet respectively text used detect emotions related area affective computing text based approaches affective computing used multiple corpora students evaluations children stories news stories issue text mining importance publishers hold large databases information needing indexing retrieval especially true scientific disciplines highly specific information often contained within written text therefore initiatives taken nature proposal open text mining interface otmi national institutes health common journal publishing document type definition dtd would provide semantic cues machines answer specific queries contained within text without removing publisher barriers public access academic institutions also become involved text mining initiative computational methods developed assist information retrieval scientific literature published approaches include methods searching determining novelty clarifying homonyms among technical reports automatic analysis vast textual corpora created possibility scholars analyze millions documents multiple languages limited manual intervention key enabling technologies parsing machine translation topic categorization machine learning automatic parsing textual corpora enabled extraction actors relational networks vast scale turning textual data network data resulting networks contain thousands nodes analyzed using tools network theory identify key actors key communities parties general properties robustness structural stability overall network centrality certain nodes automates approach introduced quantitative narrative analysis whereby subject-verb-object triplets identified pairs actors linked action pairs formed actor-object content analysis traditional part social sciences media studies long time automation content analysis allowed big data revolution take place field studies social media newspaper content include millions news items gender bias readability content similarity reader preferences even mood analyzed based text mining methods millions documents analysis readability gender bias topic bias demonstrated flaounas et al showing different topics different gender biases levels readability possibility detect mood patterns vast population analyzing twitter content demonstrated well text mining computer programs available many commercial open source companies sources see list text mining software lack flexibilities european copyright database law mining in-copyright works web mining without permission copyright owner illegal uk 2014 recommendation hargreaves review government amended copyright law allow text mining limitation exception second country world following japan introduced mining-specific exception 2009 however owing restriction copyright directive uk exception allows content mining non-commercial purposes uk copyright law allow provision overridden contractual terms conditions european commission facilitated stakeholder discussion text data mining 2013 title licenses europe fact focus solution legal issue licenses limitations exceptions copyright law led representatives universities researchers libraries civil society groups open access publishers leave stakeholder dialogue may 2013 contrast europe flexible nature us copyright law particular fair use means text mining america well fair use countries israel taiwan south korea viewed legal text mining transformative meaning supplant original work viewed lawful fair use example part google book settlement presiding judge case ruled google digitization project in-copyright books lawful part transformative uses digitization project displayed—one use text data mining recently websites often used text-based searches found documents containing specific user-defined words phrases use semantic web text mining find content based meaning context rather specific word additionally text mining software used build large dossiers information specific people events example large datasets based data extracted news reports built facilitate social networks analysis counter-intelligence effect text mining software may act capacity similar intelligence analyst research librarian albeit limited scope analysis text mining also used email spam filters way determining characteristics messages likely advertisements unwanted material text mining plays important role determining financial market sentiment increasing interest paid multilingual data mining ability gain information across languages cluster similar items different linguistic sources according meaning challenge exploiting large proportion enterprise information originates unstructured form recognized decades recognized earliest definition business intelligence bi october 1958 ibm journal article h.p luhn business intelligence system describes system ... utilize data-processing machines auto-abstracting auto-encoding documents creating interest profiles 'action points organization incoming internally generated documents automatically abstracted characterized word pattern sent automatically appropriate action points yet management information systems developed starting 1960s bi emerged '80s '90s software category field practice emphasis numerical data stored relational databases surprising text unstructured documents hard process emergence text analytics current form stems refocusing research late 1990s algorithm development application described prof. marti a. hearst paper untangling text data mining almost decade computational linguistics community viewed large text collections resource tapped order produce better text analysis algorithms paper attempted suggest new emphasis use large online text collections discover new facts trends world suggest make progress need fully artificial intelligent text analysis rather mixture computationally-driven user-guided analysis may open door exciting new results hearst 1999 statement need fairly well describes state text analytics technology practice decade later
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Computational linguistics
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mac os x server 1.0 mac os x server 1.0 released march 16 1999 first operating system released retail market apple computer based next technology final release product code-named rhapsody interim combination openstep system mach os openstep api mac os 8 although mac os x server 1.0 graphical look feel variation platinum theme mac os 8 infrastructure based openstep thus nextstep operating system instead classic mac os resulting product gave users preview operating system become mac os x referred macos mac os x server never officially known simply mac os x ultimately rendered obsolete mac os x v10.0 2001 macos server server 1.0 contains mix features classic mac os nextstep mac os x like classic mac os single menu bar across top screen file management performed workspace manager nextstep instead classic mac os finder user interface still uses display postscript-based window server nextstep instead quartz-based windowserver would appear year later mac os x public beta unlike version classic mac os windows unsaved content display black dot window close button like nextstep dock aqua appearance included added later mac os x carbon essentially subset classic mac os api calls also absent meant native applications os x server 1.0 written yellow box api went become known cocoa furthermore apple firewire supported server 1.0 also includes first version netboot server allows computers boot disk image local network particularly useful school public-machine setting allowed machines booted single os copy stored server 1.0 made difficult users damage os installing software – soon signed machine would re-boot fresh os netboot server run classic mac os applications mac os x server 1.0 includes blue box essentially ran copy mac os 8.5.1 could updated mac os 8.6 version 1.2 later separate process emulation layer blue box would eventually renamed classic environment mac os x featuring latest version mac os 9
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Operating systems
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socket 495 socket 495 sometimes referred µpga2 cpu socket intel pentium iii celeron mobile processors socket also used microsoft xbox console bga ball grid array format socket replaced socket 615 µpga1 used pentium ii early celeron mobile processors socket 495 pin cpu socket designed house processor socket 495 package socket 1.27mm pitch designed support heatsink
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Computer architecture
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beonex communicator beonex communicator discontinued open-source internet suite based mozilla application suite mas ben bucksch german mozilla developer intended higher security privacy level commercial products internet suite contains web browser email news client html editor based mozilla composer irc client based chatzilla beonex business services offered suite free provided documentation easy install routines third-party plug-ins tried sell support customer-specific changes browser main goal implement kerberos openpgp ldap beonex marked failed mid-2004 discontinued reaching production release stage mozilla organization stated mozilla application suite developers testing purposes meant end users 5 january 2001 beonex included linux distribution kmlinux version s-0.4 removed version s-0.5 released 23 march 2001 beonex 0.8 released june 2002 received positive reviews speed beonex launcher beol spoken b-o-l additional upcoming product never left alpha status stripped-down version beonex communicator web browser combined email client chat client preview releases version 0.9 mid-2002 bucksch showed new features wanted integrate version gained stable status announced 2 march 2004 new releases planned mozilla foundation decided future policy 2005 mozilla foundation officially changed policies created mozilla corporation provide end-user support beonex communicator 0.8.2-stable several known security issues beonex never received much market share browser transmit referrers default possibility create fake referrers browser deletes cookies upon exiting disables several javascript functions could served attack vectors beonex also allows changing user agent following comparison table releases netscape mas included complete table see gecko layout engine contrast netscape beonex included nearly features except proprietary parts like integrated net2phone aol instant messenger online chatting chatzilla integrated sidebar search engines also pre-configured beonex less resource-intensive netscape beonex includes migration tool import old profiles netscape communicator beonex communicator fork mas rather separate branch significant changes made html email javascript turned default thus displays email plain text bold cursive additions added later mas 1.1 search engines compatible mycroft project located sidebar providing features
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Internet protocols
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spy vs. spy 1984 video game spy vs. spy game written michael riedel commodore 64 published first star software 1984 port atari 8-bit family released simultaneously two-player split-screen game based mad magazine long running cartoon strip spy vs. spy slapstick antics two spies trying kill improbably elaborate traps weapons ported apple ii zx spectrum acorn electron atari st bbc micro commodore 16 msx amstrad cpc amiga master system game boy game boy color nintendo entertainment system emulated game boy advance object game collect various secret items briefcase exit building door airport opposing player timer runs searching items traps laid take opponent player careless spy personal countdown timer depletes 30 seconds upon death arena embassy constructed series interconnected rooms laid grid pattern higher levels rooms therefore larger play area well hand-to-hand combat achieved wiggling joystick directional pad left right spies proximity spies place traps furniture doors occupy playing area traps triggered spy searches piece furniture item opens booby trapped door resulting cartoon style animation showing subject shot blown etc floating heaven angel strategy introduced limiting quantity trap spy use allowing traps triggered either spy pieces furniture also contain 'remedies match specific traps – allow trap defused fetched one time video magazine described rousing action-strategy contest praised game excellent graphics befit ting game rooted visual medium reviewer also noted one successfully captured original feel source offered satisfying result ahoy agreed review calling faithful adaptation comics praising simultaneous two-player one-player options antic called one original clever games atari computers yet magazine praised simultaneous two-player display concluded recommend game highly enough zx spectrum version rated number 20 sinclair official top 100 games time remake including original version released ios 2012 longer available two sequels original 1984 game produced spy vs. spy ii island caper spy vs. spy iii arctic antics third game also released ibm pc kept basic gameplay tweaking core features spy vs. spy ii island caper adds side-scrolling play area spies longer start fixed number traps must collect raw materials build spy vs. spy iii arctic antics switches location tropical island arctic spies fight throwing snowballs setting traps decreases body heat bar tools include saw cut holes ice second player fall lost body heat restored moving heated igloo
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Computer architecture
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longene longene linux-based operating system kernel intended binary compatible application software device drivers made microsoft windows linux 1.0-rc2 consists linux kernel module implementing aspects windows kernel modified wine distribution designed take advantage native interface longene written c programming language free open source software licensed terms gnu general public license version 2 gplv2 although project alpha stage development 2015 many windows programs already work well official website gone august restored 2019 meanwhile source code remains available github longene aims add windows kernel mechanisms including system calls windows registry windows driver model deferred procedure call others linux kernel form new kernel new kernel allow linux windows applications device drivers work without virtualization emulation order prevent bloating function available reactos linux kernel linux implementation used functions implemented using linux loadable kernel modules loaded unloaded easily longene two sets system calls corresponding tables windows syscall set linux syscall set windows applications call syscall table via software interrupt int 0x2e linux applications call syscall table via int 0x80 longene project develop windows linux userland libraries libraries offered others projects wine reactos gnu ndiswrapper september 2005 longene project gained sponsorship insigma technology 浙大网新 china-based consulting corporation project leader decao mao 毛德操 proposed idea route longene wrote series articles market intellectual property rights techniques explain people needed project implement longene articles mao wrote compiled form white paper project according white paper implement longene one needs add several parts linux kernel longene uses wine base implementing windows api project re-implements wine modules use part joint kernel longene defers using wine modules sufficiently implemented project versions longene released several wine modules successfully implemented kernel new stable version used base implementing future modules windows api implemented wine developed modules scratch since longene kernel work windows nt kernel wine userspace kernel emulation wineserver needed device drivers longene imports ndiswrapper kernel modifications made ndiswrapper missing functionality windows driver model using reactos code reference windows driver kit implementation based reactos code uses combination redirecting drivers linux kernel resources additional libraries implement functions implemented linux earlier version unifiedkernel-2.6.13 released february 15 2006 version actualized windows system call mechanism developers currently working longene 2.0 support windows applications running non-x86 architecture hardware arm loongson additionally developers working amd64 support porting ndiswrapper code project yet implemented planned magic linux – magic linux chinese linux distribution based red hat linux version 2.1 magic linux released december 15 2008 includes main version dvd linux kernel 2.6.25.20 compact version cd linux kernel 2.6.25.20 longene version cd longene 0.2.2 minimum hardware requirements run
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Computer architecture
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cloud storage cloud storage model computer data storage digital data stored logical pools physical storage spans multiple servers sometimes multiple locations physical environment typically owned managed hosting company cloud storage providers responsible keeping data available accessible physical environment protected running people organizations buy lease storage capacity providers store user organization application data cloud storage services may accessed colocated cloud computing service web service application programming interface api applications utilize api cloud desktop storage cloud storage gateway web-based content management systems cloud computing believed invented joseph carl robnett licklider 1960s work arpanet connect people data anywhere time 1983 compuserve offered consumer users small amount disk space could used store files chose upload 1994 launched personalink services online platform personal business communication entrepreneurship storage one first web-based referenced commercials think electronic meeting place cloud amazon web services introduced cloud storage service aws s3 2006 gained widespread recognition adoption storage supplier popular services smugmug dropbox pinterest 2005 box announced online file sharing personal cloud content management service businesses cloud storage based highly virtualized infrastructure like broader cloud computing terms accessible interfaces near-instant elasticity scalability multi-tenancy metered resources cloud storage services utilized off-premises service amazon s3 deployed on-premises vion capacity services cloud storage typically refers hosted object storage service term broadened include types data storage available service like block storage object storage services like amazon s3 oracle cloud storage microsoft azure storage object storage software like openstack swift object storage systems like emc atmos emc ecs hitachi content platform distributed storage research projects like oceanstore vision cloud examples storage hosted deployed cloud storage characteristics cloud storage outsourcing data storage increases attack surface area companies permanent services products provide change outsourcing data storage another company needs careful investigation nothing ever certain contracts set stone worthless company ceases exist circumstances change companies several options available avoid issues one option use private cloud instead public cloud well providers offer private cloud storage another option ingest data encrypted format key hold within premise infrastructure access often use cloud storage gateways premise gateways options encrypt compress data prior transfer well mirror storage across multiple cloud storage providers remove risk single providers shutdown gateways offer well option cache data recently used algorithm premise along data analytics data cached fetched valuable form instead recently used form
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Computer file systems
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application checkpointing checkpointing technique add fault tolerance computing systems basically consists saving snapshot application state restart point case failure particularly important long running applications executed failure-prone computing systems distributed computing checkpointing technique helps tolerate failures otherwise would force long-running application restart beginning basic way implement checkpointing stop application copy required data memory reliable storage e.g. parallel file system continue execution case failure application restarts need start scratch rather read latest state checkpoint stable storage execute two main approaches checkpointing systems coordinated checkpointing uncoordinated checkpointing coordinated checkpointing approach processes must ensure checkpoints consistent usually achieved kind two-phase commit protocol algorithm uncoordinated checkpointing process checkpoints state independently must stressed simply forcing processes checkpoint state fixed time intervals sufficient ensure global consistency need establishing consistent state i.e. missing messages duplicated messages may force processes roll back checkpoints turn may cause processes roll back even earlier checkpoints extreme case may mean consistent state found initial state so-called domino effect one original common means application checkpointing save state feature interactive applications user application could save state variables data storage medium time using either continue working exit application later time restart application restore saved state implemented save command menu option application many cases became standard practice ask user unsaved work exiting application wanted save work sort functionality became extremely important usability applications particular work could completed one sitting playing video game expected take dozens hours writing book long document amounting hundreds thousands pages work done long period time data entry document rows spreadsheet problem save state requires operator program request save non-interactive programs including automated batch processed workloads ability checkpoint applications also automated batch applications began handle tens hundreds thousands transactions transaction might process one record one file several different files need application restartable point without need rerun entire job scratch became imperative thus checkpoint/restart capability born number transactions processed snapshot checkpoint state application could taken point application failed next checkpoint could restarted giving checkpoint information last place transaction file transaction successfully completed application could restart point checkpointing would tend expensive generally done every record reasonable compromise cost checkpoint vs. value computer time needed reprocess batch records thus number records processed checkpoint might range 25 200 depending cost factors relative complexity application resources needed successfully restart application fti library aims provide computational scientists easy way perform checkpoint/restart scalable fashion fti leverages local storage plus multiple replications erasures techniques provide several levels reliability performance fti provides application-level checkpointing allows users select data needs protected order improve efficiency avoid space time energy waste offers direct data interface users need deal files and/or directory names metadata managed fti transparent fashion user desired users dedicate one process per node overlap fault tolerance workload scientific computation post-checkpoint tasks executed asynchronously future technologies group lawrence national laboratories developing hybrid kernel/user implementation checkpoint/restart called blcr goal provide robust production quality implementation checkpoints wide range applications without requiring changes made application code blcr focuses checkpointing parallel applications communicate mpi compatibility software suite produced scidac scalable systems software isic work broken 4 main areas checkpoint/restart linux cr checkpointable mpi libraries resource management interface checkpoint/restart development process management interfaces dmtcp distributed multithreaded checkpointing tool transparently checkpointing state arbitrary group programs spread across many machines connected sockets modify user program operating system among applications supported dmtcp open mpi python perl many programming languages shell scripting languages use tightvnc also checkpoint restart x window applications long use extensions e.g opengl video among linux features supported dmtcp open file descriptors pipes sockets signal handlers process id thread id virtualization ensure old pids tids continue work upon restart ptys fifos process group ids session ids terminal attributes mmap/mprotect including mmap-based shared memory dmtcp supports ofed api infiniband experimental basis recent protocols perform collaborative checkpointing storing fragments checkpoint nearby nodes helpful avoids cost storing parallel file system often becomes bottleneck large-scale systems uses storage closer found use particularly large-scale supercomputing clusters challenge ensure checkpoint needed recovering failure nearby nodes fragments checkpoints available docker underlying technology contain checkpoint restore mechanism criu user space checkpoint library mementos software system transform general-purpose tasks interruptible program platforms frequent power outages designed batteryless embedded devices rfid tags smart cards rely harvesting energy ambient background mementos frequently senses available energy system decides checkpoint program continue computation case checkpointing data stored non-volatile memory energy become sufficient reboot data retrieved memory program continues stored state mementos implemented msp430 family microcontrollers mementos named christopher nolan memento idetic set automatic tools helps application-specific integrated circuit asic developers automatically embed checkpoints designs targets high-level synthesis tools adds checkpoints register-transfer level verilog code uses dynamic programming approach locate low overhead points state machine design since checkpointing hardware level involves sending data dependent registers non-volatile memory optimum points required minimum number registers store idetic deployed evaluated energy harvesting rfid tag device
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Computer architecture
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ibm unica netinsight ibm unica netinsight web analytics application utilizes extract transform load methodology populate database queried using browser-based interface netinsight family tools unica nettracker affinium netinsight first released june 2006 version 7.0 release version 8.0 affinium netinsight renamed unica netinsight dropping along rest unica products affinium brand ibm acquires unica corporation unica netinsight software adopts ibm name ibm unica netinsight april 2014 ibm announced unica netinsight would discontinued netinsight extract transform load process read log files virtually format including logs web servers proxy servers streaming media servers ftp servers well processing normal server log files netinsight use log files derived page tags replace augment log file data netinsight stores processed log files database oracle database microsoft sql server ibm db2 netezza appliance
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Web technology
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cryptorights foundation cryptorights foundation inc. crf 501 c 3 non-profit organization based san francisco cryptorights foundation helps human rights groups ngos use encryption protect online communications contributed encryption standards openpgp ipsec gnupg organization founded 26 february 1998 total solar eclipse near maximum totality active volcanic caribbean island montserrat boat chartered attendees international financial cryptography association conference anguilla dave del torto group fellow ″cypherpunk″ cryptology experts significant technology projects include development highfire human rights firewall distributed communications platform private ngo communications miniaturized pc called firebox size cable modem related highwire wireless human rights communications networking project became open source software defined radio source code maintained gnuradio crf provides free security training support human rights journalism organizations use cryptography crf team also developed gpg plug-in squirrelmail
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Computer security
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dlx dlx pronounced deluxe risc processor architecture designed john l. hennessy david a. patterson principal designers stanford mips berkeley risc designs respectively two benchmark examples risc design named berkeley design dlx essentially cleaned modernized simplified mips cpu dlx simple 32-bit load/store architecture somewhat unlike modern mips cpu dlx intended primarily teaching purposes dlx design widely used university-level computer architecture courses two known implementations aspida vamp aspida project resulted core many nice features open source supports wishbone asynchronous design supports multiple isa asic proven vamp dlx-variant mathematically verified part verisoft project specified pvs implemented verilog runs xilinx fpga full stack compiler kernel tcp/ip built original mips architecture one methods used gain performance force instructions complete one clock cycle forced compilers insert no-ops cases instruction would definitely take longer one clock cycle thus input output activities like memory accesses specifically forced behaviour leading artificial program bloat general mips programs forced lot wasteful nop instructions behaviour unintended consequence dlx architecture force single clock cycle execution therefore immune problem dlx design modern approach handling long instructions used data-forwarding instruction reordering case longer instructions stalled functional units re-inserted instruction stream complete externally design behaviour makes appear execution occurred linearly dlx instructions broken three types r-type i-type j-type r-type instructions pure register instructions three register references contained 32-bit word i-type instructions specify two registers use 16 bits hold immediate value finally j-type instructions jumps containing 26-bit address opcodes 6 bits long total 64 possible basic instructions select one 32 registers 5 bits needed dlx like mips design bases performance use instruction pipeline dlx design fairly simple one classic risc concept pipeline contains five stages
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Computer architecture
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amazon neptune amazon neptune fully managed graph database product amazon.com used web service part amazon web services announced november 29 2017 amazon neptune supports popular graph models property graph w3c rdf respective query languages apache tinkerpop gremlin sparql including amazon web services products amazon neptune general availability ga announced may 30 2018 currently available 11 aws regions neptune hipaa eligible december 12 2018 announced amazon neptune in-scope payment card industry data security standard iso compliance programs amazon neptune supports open source apache tinkerpop gremlin graph traversal language w3c standard resource description framework ’ rdf sparql query language used neptune instance allow user build queries navigate highly connected data sets provides high performance graph models neptune also uses aws product features amazon s3 amazon ec2 amazon cloudwatch amazon neptune database clusters created stored amazon virtual private cloud vpc allows user isolate database private network using neptune vpc configuration user configure firewall settings needs order control network access database instances amazon neptune integrated aws identity access management iam allows user create aws iam groups control actions groups aws iam users neptune allows user encrypt databases using keys created aws key management service kms database instance running neptune encryption encrypts stored data backups snapshots replicas cluster amazon neptune allows user use https encrypt data transfer clients neptune service endpoints using transport layer security tls data stored cluster volume virtual volume utilizing ssd drives sizes volumes dynamic increase depending much data stored database maximum 64 tb amazon neptune sla policy designed offer monthly uptime percentage greater 99.9 increasing database performance availability integrating engine virtual storage based ssd drives specially made database workloads neptune maintains copies user data multiple availability zones case failures neptune automatically detects failed segments disk volume repairs neptune generally available us east n. virginia us east ohio us west oregon europe ireland europe london europe frankfurt asia pacific singapore asia pacific sydney asia pacific tokyo asia pacific mumbai asia pacific seoul aws regions pricing determined aws regions region different prices available services on-demand instance pricing lets user pay instance use hour instead fixed sum price also differs depending instance class similarly user pays storage consumed database payments advance price based storage rate i/o rate billed gb per month per million request increments respectively pricing model beneficial short-term small-scale projects available aws regions price backup storage also billed per gb-month increments albeit different rates data transfer priced per gb increments amount depends whether data transferred amazon neptune much data transferred per month tb per month september 12 2018 announced neptune achieved hipaa eligibility enabling process data sets containing protected health information phi december 12 2018 announced amazon neptune in-scope payment card industry data security standard iso 9001 iso 27001 iso 27017 iso 27018 compliance programs user use amazon neptune applications subject pci compliance require iso certification may 17 2019 announced neptune achieved ssae_16 eligibility neptune powers graph use cases recommendation engines fraud detection knowledge graphs drug discovery network security social networking notable customers amazon neptune include samsung electronics pearson intuit siemens astrazeneca finra lifeomic blackfynn amazon alexa
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Databases
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socket 939 socket 939 cpu socket released amd june 2004 supersede previous socket 754 athlon 64 processors socket 939 succeeded socket am2 may 2006 second socket designed amd amd64 range processors socket 939 processors motherboards became available june 2004 superseded socket am2 may 2006 amd ceased production socket focus current future platforms however least one new socket 939 motherboard produced utilizing modern amd chipset since amd transitioned socket am2 2009 motherboard maker asrock released new socket 939 motherboard motherboard utilizes amd 785g igp chipset sb710 southbridge single dual-core processors manufactured socket athlon 64 athlon 64 fx athlon 64 x2 sempron opteron names opteron 190 featuring 2.8 ghz clock speed 1 mb level 2 cache per core fastest dual-core processor manufactured socket however availability processor limited opteron 185 locked multiplier athlon 64 fx-60 unlocked multiplier slightly slower clock speed 2.6 ghz fastest widely available dual-core processors socket opteron 156 ran slightly faster 3 ghz making fastest single core processor supporting socket 939 interface socket 939 supports dual channel ddr sdram memory 6.4 gb/s memory bandwidth processors socket support 3dnow sse2 sse3 revision e later instruction sets features one 16 bit hypertransport link running 1000 mt/s regards video expansion slots socket 939 systems found agp slots pci-e slots processors using socket 64kb level 1 instruction data caches either 256kb 512kb 1 mb level 2 cache
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Computer architecture
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