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tripwire company tripwire inc. software company based portland oregon develops markets sells information technology security compliance automation graduate student purdue university gene kim tripwire co-founder former chief technology officer along professor gene spafford created initial version software 1992 academic source release pioneered many techniques used intrusion detection received widespread support among corporate education government security professionals 1997 gene kim co-founded tripwire inc rights tripwire name technology attained commercial version product tripwire servers released soon thereafter 2000 tripwire contributed source code functionally equivalent academic source release open source community enable open source tripwire 2005 tripwire released first version tripwire enterprise company flagship product designed help organizations configuration control detecting assessing reporting remediating file configuration changes january 2010 tripwire announced release tripwire log center log security information event management siem software stores correlates reports log security event data two products integrated enable correlation change event data august 21 2009 tripwire acquired activeworx technologies crosstec corporation includes log center security center event management snort management center revenues grew 74 million 2009 october 2009 company 261 employees number grew 336 june 2010 may–june 2010 company 5,500 customers announced filed registration statement securities exchange commission proposed initial public offering common stock year later company announced sale private equity firm thoma bravo llc ending 86 million ipo plans ceo jim johnson cited firm failure reach 100 million revenue milestone 2010 well changing ipo market expectations reasons going ipo day following acquisition company laid 50 350 employees johnson expects company eventually go public though unlikely happen 2015 acquisition ncircle 2013 tripwire added asset discovery vulnerability management portfolio tripwire ip360™ enables organizations identify system vulnerabilities advanced intelligence prioritizes critical issues fix december 2014 belden inc announced plans buy tripwire 710 million acquisition completed january 2 2015
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Computer security
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infragard infragard non-profit organization serving public-private partnership u.s. businesses federal bureau investigation organization information sharing analysis effort serving interests combining knowledge base wide range private sector government members infragard association individuals facilitates information sharing intelligence businesses academic institutions state local law enforcement agencies participants dedicated prevent hostile acts united states infragard mutual nondisclosure agreements among members individuals fbi promotes trusted discussions vulnerabilities solutions companies individuals may hesitant place public domain provide access additional threat information fbi infragard began cleveland ohio field office 1996 since expanded become national-level program infragard coordinators every fbi field office originally local effort gain support information technology industry academia fbi investigative efforts cyber arena since expanded much wider range activities surrounding nation critical infrastructure program expanded fbi field offices 1998 fbi assigned national program responsibility infragard former national infrastructure protection center nipc directed radm james b. plehal fbi cyber division 2003 since 2003 infragard alliances fbi said developed trust-based public-private sector partnership ensure reliability integrity information exchanged various terrorism intelligence criminal security matters supports fbi priorities areas counterterrorism foreign counterintelligence cybercrime infragard focused protecting 16 critical infrastructures outlined presidential directive 21 critical infrastructure security resilience sharing threat information assisting fbi finding prosecuting attack critical infrastructure physical cyber means provide training active shooter scenarios cyber defense threats nation organization committed providing tools resources needed operate nation critical infrastructure protect enterprises maintain services necessary safe prosperous nation infragard chapters also participate assure critical infrastructure owners operators—estimated 85 private sector—are engaged represented local regional planning efforts working 16 critical infrastructure sectors organization provides resources information prevention also building resilience response capabilities infragard chapters around nation also provide cyber physical security training sessions focus latest threats identified fbi sessions include threat briefings technical sessions cyber physical attack vectors response training resources help cisos csos protect enterprise infragard approaches threats critical infrastructure tactical strategic level addressing needs front lines security well decision makers tasked assessing enterprise vulnerabilities allocating resources protect information sharing organization government criticized protecting civil liberties concerned membership would surrogate eyes ears fbi group also subject hacking attacks intended embarrass fbi local chapters regularly meet discuss latest threats listen talks subject matter experts security issues membership open u.s. citizens cost july 2012 organization reported membership 54,677 including fbi infragard focuses development management protection critical infrastructure infragard nationwide focus group reviews threats could disrupt critical infrastructure nationwide month named electromagnetic pulse special interest group emp sig all-hazards approach looks manmade natural electromagnetic pulse emp cyber attack coordinated physical attack pandemics insider threats mitigating actions could minimize threats mitigation strategies include hardening prevention strategies addition development local infrastructure could make local communities robust sustainable see emp sig press release guidance document see also website association universities involved public policy policy studies organization produces technology policy conference called dupont summit infragard national emp sig brought public private sector leaders discuss emerging threat issues http //www.ipsonet.org/conferences/the-dupont-summit/dupont-summit-2012/infragard-emp-sig partnerships government agencies private organizations critics concerned civil liberties american civil liberties union aclu warned evidence infragard may closer corporate tips program turning private-sector corporations — may position observe activities millions individual customers — surrogate eyes ears fbi concluding program institutionalizes close secretive ties organizations raises serious questions scope activities future others describing infragard state architecture internet—and many possible methods attack— requires governments corporations private parties work together protect network security head threats occur responding aclu criticism chairwoman kathleen kiernan infragard national members alliance inma denies infragard anything beneficial americans stating elitist group way shape form says 're trying protect everybody u.s. citizen planet eligible apply infragard 2011 lulzsec claimed responsibility attacking chapter websites managed local members connecticut atlanta order embarrass fbi simple hacks group leaked infragard member e-mails database local users group defaced website posting following message let flow stupid fbi battleships accompanied video lulzsec posted following message regarding attack
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Computer security
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dropbox carousel dropbox carousel photo video management app offered dropbox third-party native app available android ios allowed users store manage organize photos photos organized date time event backed dropbox competed space online photo storage services google google photos apple icloud yahoo flickr chris lee dropbox head product development carousel described app add-on dropbox “ dedicated experience photos videos ” space “ reliving personal memories ” mailbox founder gentry underwood unveiled carousel gathering san francisco april 9 2014 much features carousel come snapjoy photo start-up dropbox acquired december 19 2012 carousel launched marked amongst many others series acquisitions made dropbox prep opening stock public offering acquisitions would help demonstrate expansive product offerings pitching potential profitability investors december 2015 dropbox announced carousel would shut carousel features would integrated primary dropbox application march 31 2016 carousel deactivated carousel prompted users free local storage synced backed-up local photos cloud flashback feature enabled default showed past photos videos taken day year years back flashback used algorithm designed identify human faces resulting greater likelihood user picture people user close circle appearing scrollable timeline earlier scroll wheel bottom let user scroll photo specific date finger swipe
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Distributed computing architecture
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maureen baginski maureen a. baginski former signals intelligence sigint director national security agency nsa executive assistant director intelligence federal bureau investigation fbi beginning intelligence career baginski graduated ba slavic languages linguistics university albany also received honorary doctorate humane letters 2005 service nation baginski began career intelligence 1979 russian language instructor nsa cold war held various positions nearly quarter-century nsa including lead analyst soviet union assistant deputy director technology systems chief officer director executive assistant director nsa/central security service senior operations officer national security operations center sigint director nsa third highest position baginski sigint director september 11 2001 critical nsa response terrorist attacks also directing extended sigint enterprise order acquire produce disseminate foreign sigint variety government military customers documentary film “ good american ” then-senior nsa executive thomas drake quotes baginski saying “ 9/11 gift nsa ’ gon na get money need ” immediate aftermath 9/11 retired nsa analyst bill binney star film describes baginski ’ reaction “ sickening. ” 2003 baginski left position nsa become executive assistant director intelligence fbi executive assistant director intelligence fbi 2003-2005 baginski successfully led bureau first-ever intelligence program charge adapting fbi intelligence capabilities information technologies created intelligence-sharing platform helped identify stop terror plots head intelligence fbi baginski helped develop intelligence career service intelligence professionals would able advance careers fbi many high-ranking government officials including president george w. bush fbi director mueller acknowledged applauded baginski significant changes fbi improved capabilities safeguard united states america upon retirement fbi director mueller asked baginski remain senior advisor fbi position accepted since retiring fbi baginski held multiple positions within private sector board member bearingpoint inc. argon st si international inc. baginski also president national security systems sparta inc. chief executive officer national security partners llc chairwoman emeriti afcea throughout distinguished career public sector baginski received several awards including two presidential rank awards two director central intelligence national achievement medals director military intelligence ’ leadership award nsa ’ exceptional civilian service award fbi intelligence analysts association award
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Computer security
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compaq presario 3000 compaq presario 3000 series line notebook computers produced 2000 2001 compaq noted intel processors desktop-like feature list heat heavy weight 16-inch lcd screens 3000 series sported intel chipset pentium 4 chips came variety speeds ranging 2.0 ghz 2.67 ghz however performance varied slightly models noted r3000 model appeared amd processor source model list compaq site notebook computers product range came hitachi hard disk drive teac optical media drive also came on-board altec lansing stereo speakers synaptics touchpads systems preinstalled windows xp though also designed run windows vista supplied quick restore disc returned system factory condition event change ownership wish reinstall os system failure main memory upgradeable via two 200-pin so-dimm slots using ddr pc2100 ddr pc2700 rated modules memory controller addressed maximum 1024 mb 1024 mib ram main memory also memory graphics processing unit sharing memory way reduced usable main memory reported operating system 64 mb compaq presario 3000 notebook pc series 3070us came equipped speaker placed arrow keys tends rust palm hands resting top makes laptop discolored easy repaint part new paint applied clogs holes blocks audio
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Computer architecture
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vps/vm vps/vm virtual processing system/virtual machine operating system ran ibm system/370 – ibm 3090 computers boston university general use 1977 around 1990 limited use least 1993 1980s vps/vm main operating system boston university often ran 250 users time rival vm/cms computing systems could run 120 users user ran virtual machine vm ibm hypervisor operating system vm provided virtual ibm 370 machine vps operating system ran vm code modified allow vps virtual machines share pages storage read write access vps utilized shared nucleus well pages used facilitate passing data one vps virtual machine another organization similar mvs substituting address spaces virtual machines according craig estey worked boston university academic computing center 1974 1977 vps original name racs remote access computing system originally developed mcgill university montreal 1966 onward name got shortened rax running least 1973 bu probably earlier although period joint development 1972 mcgill bu started diverge mcgill rebranded version rax music/sp time music/sp wiki entry details fair amount applicable bu/rax vps development evolutionary rather revolutionary changes necessary phased time system called rax rebranded vps mostly resulting system good enough effort afoot monetize commercially music/sp remained standalone os bu ibm 370/145 ran ibm vm/370 virtual machine hypervisor rax became client os originally used one vm users rax became hypervisor aware eventually gave rax user vm parent os vm/370 invisible rax user eventually rax control resembled multicore/distributed architecture many virtual machines single shared memory copy rax client work completed renamed vps ibm-based operating system quite like dos/vse time sharing options vps/vm provided user ibm 3270 full screen terminal green screen user interface like vm/cms user 11 megabyte virtual machine strange 3 megabyte memory gap middle 1984 onwards could run several programs time operating system sparsely documented written first charles brown bu doctoral student john h. porter physics phd later became head vps project marian moore wrote much later vm code necessary run vps system josie bondoc wrote later vps additions like unix piping many mvs/vm programs ran vps/vm xedit compilers pascal pl/1 c cobol mvs/vm programs ran os simulation program simulated os/vm supervisor calls svcs margorie orr supervised os simulation program development maintenance programmers wrote parts os simulation package maintained margorie orr timothy greiser daniel levbre john coldwell lotz paul cheffers michael krugman wrote early main utilities ifmsg jcl language vps also mail early email program sendmail written francis costanzo implemented email bitnet system pre sql databases installed vps focus nomad2 michael gettes wrote early quick help system file system hierarchical originally file unique 8 character filename eventually grew onerous user given private directory tapes ibm disk files supported well native vps text files simple shell patterns supported except paw computer program written paul cheffers graphics department glenn bresnahan essentially ported unix utilities mid 1980s william marshall much early system documentation well providing pl/1 support joe dempty user services director diana robanske statistics consultant ran student assistance services 1980-1985 john houlihan also user services statistics consultant vps/vm working pre-gui ibm operating system could often run users ibm tso-based systems university-based systems provided editors compilers vps provided services 10,000 bu university community 10 years vps/vm policy operating system main utilities written ibm 370 assembler language decision restricted development system ultimately could compete unix-based systems eventually replaced however vps eventually modeled many features then-current operating systems around world keen trainer many companies needed ibm370 assembler programmers 1980s
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Operating systems
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bos/360 bos/360 basic operating system/360 early ibm system/360 operating system bos one four system/360 operating system versions developed ibm general products division gpd endicott new york fill gap low end system/360 line became apparent os/360 able run smallest systems bps basic programming support designed run systems minimum 8,192 bytes memory disk bos intended disk systems least 8,192 bytes one 2311 disk drive dos tos developed systems least 16,384 bytes either disks tape drives bos released october 1965 nearly two years os/360 thus bos disk based operating system available launch machine marketed disk based bos consisted following components ibm 1070 process communication supervisor dedicated process control system ran extension bos
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Operating systems
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biba model biba model biba integrity model developed kenneth j. biba 1975 formal state transition system computer security policy describes set access control rules designed ensure data integrity data subjects grouped ordered levels integrity model designed subjects may corrupt data level ranked higher subject corrupted data lower level subject general model developed address integrity core principle direct inverse bell–lapadula model general preservation data integrity three goals security model directed toward data integrity rather confidentiality characterized phrase read write contrast bell-lapadula model characterized phrase read write biba model users create content integrity level monk may write prayer book read commoners one read high priest conversely users view content integrity level monk may read book written high priest may read pamphlet written lowly commoner another analogy consider military chain command general may write orders colonel issue orders major fashion general original orders kept intact mission military protected thus read integrity conversely private never issue orders sergeant may never issue orders lieutenant also protecting integrity mission write biba model defines set security rules first two similar bell–lapadula model first two rules reverse bell–lapadula rules
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Computer security
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brian snow brian snow born september 5 1943 served u.s. national security agency 1971 2006 including six-year term technical director information assurance directorate iad defensive arm nsa charged protecting u.s. information security time research management positions nsa played key role promoting open collaborative relationship agency broader community security professionals early career snow mathematics professor ohio university helped develop college computer science department 1971 started working nsa 1970s 1980s designed cryptographic components secure systems several cryptographic systems employed u.s. government military used algorithms purposes nuclear command control tactical voice communications network security technical person high managerial responsibilities neal koblitz alfred menezes written snow strong supporter transition rsa elliptic curve cryptography ecc public key cryptographic technology cybersecurity policy expert susan landau attributes nsa harmonious collaboration industry academia selection advanced encryption standard aes 2000 — agency support choice strong encryption algorithm designed europeans rather americans — part snow represented nsa cochairman technical working group aes competition terrorist attacks 11 september 2001 nsa believed public support dramatic expansion surveillance activities according koblitz menezes period nsa trusted partner academia industry development cryptographic standards came end part change nsa post-september 11 era snow replaced technical director could longer effectively oppose proposed actions offensive arm nsa snow last years nsa retirement 2006 along clinton brooks led group drew draft ethics code intelligence officers since retiring nsa snow worked security ethics consultant member u.s. national academy sciences committee future research goals directions foundational science cybersecurity 2019 brian snow inducted national cyber security hall fame
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Computer security
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glftpd glftpd freely available ftp server runs unix linux bsd operating systems number features like logins restricted particular set ip addresses transfer quotas per-user per-group basis user/groups stored system files make attractive private warez servers including topsites legitimate uses though—a number web development books recommend amongst general purpose ftp servers linux certification exams sair required knowledge integrate eggdrop irc channels glftpd stands greyline file transfer protocol daemon named initial developer greyline first public release glftpd dates back beginning 1998. glftpd well known detailed user permissions extensive scripting features securely efficiently transferring files sites using fxp support glftpd available irc efnet glftpd glhelp
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Internet protocols
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srcml srcml source l document-oriented xml representation source code created collaborative effort michael l. collard jonathan i. maletic abbreviation srcml short source markup language srcml wraps source code text information abstract syntax tree ast tags single xml document original text preserved original source code document recreated srcml markup exception possibility newline normalization purpose srcml provide full access source code lexical documentary structural syntactic levels format also provides easy support fact-extraction transformation supported srcml toolkit maintained srcml website shown perform scalable lightweight fact-extraction transformation srcml toolkit consists command-line program called srcml translates source code srcml provided code file command line translates srcml source code srcml archive provided command line program also supports direct queries transformations srcml archives using tools like xpath xslt relaxng srcml toolkit actively maintained currently support c c++ c java srcml format consists text original source code file plus xml tags specifically text wrapped srcml elements indicate syntactic structure code short explicitly identifies syntactic structures code tags used srcml listed along category fall within srcml uses xml namespaces list prefix used denote namespace namespaces note srcml archive entire project contained within single root unit element individual file contained unit element within root unit element following shows srcml used single files following example converts c++ file main.cpp srcml file main.cpp.xml following command extract source code file main.cpp.xml place c++ file main.cpp following shows src2srcml srcml2src used entire project following example converts project 'project srcml file project.xml following command extract source code files file project.xml place directory project srcml allows use current xml apis tools write transformations also allows use xslt directly using argument—xslt= name .xls srcml2src command using srcml markup xslt allows user apply program transformations xml-like structure srcml obtain transformed xml written back source code representation using srcml2src tool application srcml program transformation explained detail collard et al following command run xslt program program.xsl srcml archive project.xml simplest form fact extraction using srcml leverages xpath order address parts srcml document pull information various entities characteristics source code course limited standard xml api may used application srcml fact extraction explained detail kagdi et al cpp directive cpp file cpp include cpp define cpp undef cpp line cpp cpp ifdef cpp ifndef cpp else cpp elif cpp endif cpp cpp pragma cpp errorliteral operator modifier example create srcml archive entire software project following command runs xpath path srcml archive project.xml work done providing convenient extension functions srcml brings lot advantages difference analysis source code one advantages ability query differences specific sections codebase well across versions codebase application srcml difference analysis explained detail maletic et al example srcml used xpath expression could used find classes source document //src class another example might finding comments within functions /src function//src comment due fact srcml based xml xml tools used srcml provides rich functionality
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Programming language topics
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isochronous media access controller isochronous media access controller i-mac media access control whereby data must transferred isochronously—in words data must transmitted steady rate without interruption
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Internet protocols
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contact telecom contact telecom telecommunications services company develops data processing software services telecommunications industry established 1998 based manchester new hampshire contact telecom offers carriers service providers telecommunication companies internet service providers wireless voice ip competitive local exchange carriers incumbent local exchange carriers cable companies cloud computing providers way manage invoice usage data cost management revenue assurance customer care initiatives flagship service billing data analyzer bda automates data processing drive company overall profitability models
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Distributed computing architecture
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backup information technology backup data backup copy computer data taken stored elsewhere may used restore original data loss event verb form referring process back whereas noun adjective form backup backups used recover data loss data deletion corruption recover data earlier time backups provide simple form disaster recovery however backup systems able reconstitute computer system complex configuration computer cluster active directory server database server backup system contains least one copy data considered worth saving data storage requirements large information repository model may used provide structure storage different types data storage devices used copying backups data already secondary storage onto archive files. ref group note name=archivefilemaynotcontainold/historicalmaterial contrast everyday use term archive data stored archive file necessarily old historical interest. /ref also different ways devices arranged provide geographic dispersion data security portability data selected extracted manipulated storage process include methods dealing live data including open files well compression encryption de-duplication additional techniques apply enterprise client-server backup backup schemes may include dry runs validate reliability data backed limitations human factors involved backup scheme backup strategy requires information repository secondary storage space data aggregates backups data sources repository could simple list backup media dvds etc dates produced could include computerized index catalog relational database backup data needs stored requiring backup rotation scheme system backing data computer media limits number backups different dates retained separately appropriate re-use data storage media overwriting backups longer needed scheme determines piece removable storage used backup operation long retained backup data stored unstructured repository may simply stack tapes dvd-rs external hdds minimal information backed method easiest implement unlikely achieve high level recoverability lacks automation repository using backup method contains complete source data copies taken one specific points time copying system images method frequently used computer technicians record known good configurations however imaging generally useful way deploying standard configuration many systems rather tool making ongoing backups diverse systems incremental backup stores data changed since reference point time duplicate copies unchanged data n't copied typically full backup files infrequent intervals serving reference point incremental repository subsequently number incremental backups made successive time periods restores begin last full backup apply incrementals backup systems create series incrementals thus providing equivalent frequently full backup done modify single archive file speeds restores recent versions files true continuous data protection cdp refers backup instantly saves copy every change made data allows restoration data point time comprehensive advanced data protection near-cdp backup applications frequently marketed cdp automatically take incremental backups specific intervals example every 15 minutes one hour 24 hours therefore allow restores fixed interval near-cdp backup applications use journaling typically based periodic snapshots read-only copy data frozen particular point time near-cdp except apple time machine intent-logs every change host system often saving byte block-level differences rather file-level differences backup method differs simple disk mirroring enables roll-back log thus restoration old images data intent-logging allows precautions consistency live data protecting self-consistent files requiring applications quiesced made ready backup near-cdp practicable ordinary personal backup applications opposed cdp must run conjunction virtual machine equivalent therefore generally used enterprise client-server backups reverse incremental backup method stores recent archive file mirror source data series differences mirror current state previous states reverse incremental backup method starts non-image full backup full backup performed system periodically synchronizes full backup live copy storing data necessary reconstruct older versions either done using hard links—as apple time machine using binary diffs differential backup saves data changed since last full backup means maximum two backups repository used restore data however time last full backup thus accumulated changes data increases time perform differential backup restoring entire system requires starting recent full backup applying last differential backup differential backup copies files created changed since last full backup regardless whether differential backups made since whereas incremental backup copies files created changed since recent backup type full incremental variations incremental backup include multi-level incrementals block-level incrementals compare parts files instead entire files regardless repository model used data copied onto archive file data storage medium medium used also referred type backup destination magnetic tape long time commonly used medium bulk data storage backup archiving interchange previously less expensive option longer case smaller amounts data tape sequential access medium rate continuously writing reading data fast many tape formats proprietary specific certain markets like mainframes particular brand personal computer 2014 lto become primary tape technology remaining viable super formats ibm 3592 also referred ts11xx series oracle storagetek t10000 use hard disk storage increased time become progressively cheaper hard disks usually easy use widely available accessed quickly however hard disk backups close-tolerance mechanical devices may easily damaged tapes especially transported mid-2000s several drive manufacturers began produce portable drives employing ramp loading accelerometer technology sometimes termed shock sensor 2010 industry average drop tests drives technology showed drives remaining intact working 36-inch non-operating drop onto industrial carpeting manufacturers also offer 'ruggedized portable hard drives include shock-absorbing case around hard disk claim range higher drop specifications period years stability hard disk backups shorter tape backups external hard disks connected via local interfaces like scsi usb firewire esata via longer-distance technologies like ethernet iscsi fibre channel disk-based backup systems via virtual tape libraries otherwise support data deduplication reduce amount disk storage capacity consumed daily weekly backup data optical storage uses lasers store retrieve data recordable cds dvds blu-ray discs commonly used personal computers generally cheap past capacities speeds discs lower hard disks tapes although advances optical media slowly shrinking gap many optical disc formats worm type makes useful archival purposes since data changed optical storage systems allow cataloged data backups without human contact discs allowing longer data integrity french study 2008 indicated lifespan typically-sold cd-rs 2–10 years one manufacturer later estimated longevity cd-rs gold-sputtered layer high 100 years sony optical disc archive 2016 reach read rate 250mb/s solid-state drives ssds use integrated circuit assemblies store data flash memory thumb drives usb flash drives compactflash smartmedia memory sticks secure digital card devices relatively expensive low capacity convenient backing relatively low data volumes solid-state drive contain movable parts making less susceptible physical damage huge throughput around 500 mbit/s 6 gbit/s available ssds become capacious cheaper flash memory backups stable fewer years hard disk backups remote backup services cloud backups involve service providers storing data offsite used protect events fires floods earthquakes could destroy locally stored backups cloud-based backup provides layer data protection however users must trust provider maintain privacy integrity data confidentiality enhanced use encryption speed availability limited user online connection users large amounts data may need use cloud seeding large-scale recovery various methods used manage backup media striking balance accessibility security cost media management methods mutually exclusive frequently combined meet user needs using on-line disks staging data sent near-line tape library common example online backup storage typically accessible type data storage begin restore milliseconds internal hard disk disk array maybe connected san example online backup type storage convenient speedy vulnerable deleted overwritten either accident malevolent action wake data-deleting virus payload nearline storage typically less accessible less expensive online storage still useful backup data storage mechanical device usually used move media units storage drive data read written generally safety properties similar on-line storage example tape library restore times ranging seconds minutes off-line storage requires direct action provide access storage media example inserting tape tape drive plugging cable data accessible via computer except limited periods written read back largely immune on-line backup failure modes access time varies depending whether media on-site off-site backup media may sent off-site vault protect disaster site-specific problem vault simple system administrator home office sophisticated disaster-hardened temperature-controlled high-security bunker facilities backup media storage data replica off-site also on-line e.g. off-site raid mirror replica fairly limited value backup backup site disaster recovery center used store data enable computer systems networks restored properly configure event disaster organisations heir data recovery centres others contract third-party due high costs backing rarely considered preferred method moving data dr site typical way would remote disk mirroring keeps dr data date possible backup operation starts selecting extracting coherent units data data modern computer systems stored discrete units known files files organized filesystems deciding back given time involves tradeoffs backing much redundant data information repository fill quickly backing insufficient amount data eventually lead loss critical information files actively updated called live present challenge back effective way back live data temporarily quiesce e.g. close files take snapshot resume live operations point snapshot backed normal methods snapshot instantaneous function filesystems presents copy filesystem frozen specific point time often copy-on-write mechanism snapshotting file changed results corrupted file unusable also case across interrelated files may found conventional database applications microsoft exchange server term fuzzy backup used describe backup live data looks like ran correctly represent state data single point time backup options data files quiesced include information stored computer stored files accurately recovering complete system scratch requires keeping track non-file data frequently useful required manipulate data backed optimize backup process manipulations improve backup speed restore speed data security media usage and/or reduced bandwidth requirements out-of-date data automatically deleted personal backup applications—as opposed enterprise client-server backup applications automated data grooming customized—the deletion globally delayed disabled various schemes employed shrink size source data stored uses less storage space compression frequently built-in feature tape drive hardware redundancy due backing similarly configured workstations reduced thus storing one copy technique applied file raw block level potentially large reduction called deduplication occur server data moves backup media sometimes referred source/client side deduplication approach also reduces bandwidth required send backup data target media process also occur target storage device sometimes referred inline back-end deduplication sometimes backups duplicated second set storage media done rearrange archive files optimize restore speed second copy different location different storage medium—as disk-to-disk-to-tape capability enterprise client-server backup high-capacity removable storage media backup tapes present data security risk lost stolen encrypting data media mitigate problem however encryption cpu intensive process slow backup speeds security encrypted backups effective security key management policy many computers backed destination storage devices ability use single storage device several simultaneous backups useful however cramming scheduled backup window via multiplexed backup used tape destinations process rearranging backup sets archive file known refactoring example backup system uses single tape day store incremental backups protected computers restoring one computers could require many tapes refactoring could used consolidate backups single computer onto single tape creating synthetic full backup especially useful backup systems incrementals forever style backups sometimes backups copied staging disk copied tape process sometimes referred d2d2t acronym disk disk tape useful problem matching speed final destination device source device frequently faced network-based backup systems also serve centralized location applying data manipulation techniques
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Computer security
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off-by-one error off-by-one error oboe also commonly known obob off-by-one bug ob1 error logic error involving discrete equivalent boundary condition often occurs computer programming iterative loop iterates one time many problem could arise programmer makes mistakes using less equal less used comparison fails take account sequence starts zero rather one array indices many languages also occur mathematical context consider array items items n inclusive processed many items intuitive answer may n − one exhibiting fencepost error correct answer n – 1 reason ranges computing often represented half-open intervals range n inclusive represented range inclusive n 1 exclusive avoid fencepost errors example loop iterates five times 0 4 inclusive written half-open interval 0 5 loop body executed first index equal 0 becomes 1 2 3 finally 4 successive iterations point index becomes 5 index 5 false loop ends however comparison used less equal loop would carried six times index takes values 0 1 2 3 4 5 likewise index initialized 1 rather 0 would four iterations index takes values 1 2 3 4 alternatives cause off-by-one errors another error occur do-while loop used place loop vice versa do-while loop guaranteed run least array-related confusion may also result differences programming languages numbering 0 common languages start array numbering 1 pascal arrays user-defined indices makes possible model array indices problem domain fencepost error occasionally called telegraph pole lamp-post picket fence error specific type off-by-one error early description error appears works vitruvius following problem illustrates error naive answer 10 wrong fence 10 sections 11 posts reverse error occurs number posts known number sections assumed actual number sections one less number posts generally problem stated follows correct answer may line posts open-ended n form loop posts occur end fence instance fence runs two walls precise problem definition must carefully considered setup one situation may give wrong answer situations fencepost errors come counting things rather spaces vice versa neglecting consider whether one count one ends row fencepost errors also occur units length example time pyramid consisting 120 blocks placed 10-year intervals blocks scheduled take 1,190 years build 1,200 installation first block last block one earliest fencepost errors involved time julian calendar originally calculated leap years incorrectly due counting inclusively rather exclusively yielding leap year every three years rather every four fencepost error rare occasions refer error induced unexpected regularities input values instance completely thwart theoretically efficient binary tree hash function implementation error involves difference expected worst case behaviours algorithm larger numbers one often major issue smaller numbers however specific cases accuracy paramount committing off-by-one error disastrous sometimes issue also repeated therefore worsened someone passing incorrect calculation following person makes kind mistake course error might also reversed example error occur computational language matlab codice_1 linear interpolation function whose parameters codice_2 codice_3 programmer misunderstands third parameter number increments might hope codice_4 would achieve sequence instead would get common off-by-one error results security-related bug caused misuse c standard library codice_5 routine common misconception codice_5 guaranteed null termination write beyond maximum length reality write terminating null character one byte beyond maximum length specified following code contains bug off-by-one errors common using c library consistent respect whether one needs subtract 1 byte – functions like codice_7 codice_8 never write past length given codice_7 subtracts 1 retrieves length − 1 bytes whereas others like codice_5 write past length given programmer remember functions need subtract 1 systems little endian architectures particular result overwriting least significant byte frame pointer cause exploitable condition attacker hijack local variables calling routine one approach often helps avoid problems use variants functions calculate much write based total length buffer rather maximum number characters write functions include codice_11 codice_12 often considered safer make easier avoid accidentally writing past end buffer code example calling codice_13 instead would remove bug
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Computer security
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fork file system computer file system fork set data associated file-system object file systems without forks allow single set data contents file systems forks allow multiple contents every non-empty file must least one fork often default type depending file system file may one associated forks turn may contain primary data integral file metadata unlike extended attributes similar file system feature typically fixed size forks variable size possibly even larger file primary data fork size file sum sizes fork file systems without forks one may instead use multiple separate files associated particularly sidecar files metadata however connection files automatically preserved file system must instead handled program works files another alternative container file stores additional data within given file format archive file allows storing several files metadata within file within single fork requires programs process container file archive file rather file system handling forks alternatives require additional work programs using data benefit portability file systems support forks file system forks associated apple hierarchical file system hfs apple hfs original apple macintosh file system mfs allowed file system object two kinds forks data fork resource fork resource fork designed store non-compiled data would used system graphical user interface gui localizable text strings file icon used finder menus dialog boxes associated application however feature flexible additional uses found splitting word processing document content presentation storing part separate resources compiled software code also stored resource often applications would consist resource fork data fork one hfs+ obscure features file may arbitrary number custom named forks addition traditional data resource forks feature gone largely unused apple never added support mac os 8.1-10.3.9 beginning 10.4 partial implementation made support apple extended inline attributes mac os x v10.4 users running unix command line utilities tar included mac os x would risk data loss utilities updated handle resource forks files v10.4 starting 1985 novell netware file system nwfs successor novell storage services nss designed ground use variety methods store file metadata metadata resides novell directory services nds stored directory structure disk stored novell terms 'multiple data streams file multiple data streams also allow macintosh clients attach use netware servers ntfs file system introduced windows nt 3.1 supports file system forks known alternate data streams ads refs new file system introduced windows server 2012 originally support ads windows 8.1 64-bit server 2012 r2 support ads lengths 128k added refs ads originally intended add compatibility existing operating systems support forks computer program may directed open ads specifying name ads colon sign file path spite support programs including windows explorer dir command windows vista ignore ads windows explorer copies ads warns target file system support calculates main stream size list file folder streams dir command windows vista supports showing ads windows powershell v3.0 later supports manipulating ads windows 2000 uses ads store thumbnails image files store summary information title author file without changing main stream windows xp microsoft realized ads susceptible loss files containing moved ntfs volumes thus windows xp stores main stream whenever file format supports windows vista discontinued support adding summary information altogether microsoft decided sensitive ads handle use ads purposes stop service pack 2 windows xp introduced attachment execution service stores details origin downloaded files ads called zone identifier effort protect users downloaded files may present risk internet explorer windows 8 extended function smartscreen internet explorer also uses ads store favicons internet shortcut files solaris version 9 later allows files forks forks called extended attributes solaris although within usual meaning extended attribute maximum size solaris-type extended attribute maximum size file read written fashion files internally actually stored accessed like normal files ownership permissions differ parent file sub-directories administratively disabled names contain characters extended attributes network file system version 4 similar solaris-style extended attributes file system supports different forks applications aware security risks arise allowing legacy software access data without appropriate shims place primary culprit problems different system utilities disk explorer antivirus software archivers aware different forks following problems arise
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Computer file systems
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linuxcare linuxcare founded san francisco 1998 dave sifry arthur tyde dave laduke company initial goal 800 number linux operate 24 hours day due dot-com bubble early millennium years version linuxcare morphed levanta eventually closed doors 2008 1999 linuxcare developed linuxcare bootable toolbox also known linuxcare bbc bootable business card bbc live cd bootable linux distribution designed run entirely cd 1999 new concept preceded one linux distribution designed exclusively run cd demolinux demolinux designed show whole desktop experience linux distribution linuxcare bbc designed used mainly utility cd first live cd focus bbc distribution 50mb designed fit mini cd shaped like standard business card included utilities designed assist system administrators primarily text console operating system minimal blackbox x11 ui included linuxcare produced initial launch unversioned release pressed business card cds distributed linuxworld 1999 versions 1.2 1.5 1.6 later released online pressed released conventions linux user groups 1999 2001 may 8 2001 seth schoen announced original three developers linuxcare bootable toolbox left linuxcare fork project new community project named lnx-bbc release 1.6 released may 2001 served transition release linuxcare lnx-bbc projects offering release respective sites lnx-bbc produced three bbc releases 1.618 august 2001 2.0 january 2003 2.1 may 1 2003 early versions assembled hand later versions utilized gar software build system built around gnu automake lnx-bbc discontinued 2.1 release linuxcare brand repurchased arthur tyde incorporated llc dr. scott s. elliott partners state california new company provides services businesses related cloud computing linuxcare llc offices san francisco manila
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Operating systems
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car cdr computer programming car codice_1 cdr codice_2 primitive operations cons cells non-atomic s-expressions introduced lisp programming language cons cell composed two pointers car operation extracts first pointer cdr operation extracts second thus expression codice_3 evaluates codice_4 codice_5 evaluates codice_6 cons cells used implement singly linked lists rather trees complicated structures car operation returns first element list cdr returns rest list reason operations sometimes given names first rest head tail lisp originally implemented ibm 704 computer late 1950s popular explanation car cdr stand contents address register contents decrement register quite match ibm 704 architecture ibm 704 programmer-accessible address register three address modification registers called index registers ibm 704 successors 36-bit word length 15-bit address space computers two instruction formats one type short 3-bit operation code prefix two 15-bit fields separated 3-bit tag first 15-bit field operand address second held decrement count tag specified one three index registers indexing subtractive process 704 hence value loaded index register called decrement 704 hardware special instructions accessing address decrement fields word result efficient use two fields store within single word two pointers needed list thus car contents address part register term register context refers memory location precursors lisp included functions took machine address argument loaded corresponding word memory extracted appropriate bits 704 assembler macro codice_1 704 assembler macro codice_2 machine word could reassembled cons took four arguments p prefix tag parts dropped early stages lisp design leaving car cdr two-argument cons compositions codice_1 codice_2 given short less pronounceable names form lisp codice_15 equivalent codice_16 value codice_17 similarly codice_18 codice_19 value codice_20 lisps example common lisp scheme systematically define variations two four compositions codice_1 codice_2 many languages particularly functional languages languages influenced functional paradigm use singly linked list basic data structure provide primitives functions similar codice_1 codice_2 named variously codice_25 codice_26 codice_27 codice_28 etc lisp however cons cell used build linked lists also build pair nested pair structures i.e codice_2 cons cell need list case languages provide different primitives typically distinguish pair structures list structures either typefully semantically particularly typed languages lists pairs trees different accessor functions different type signatures haskell example codice_1 codice_2 become codice_32 codice_33 dealing pair type exact analogues codice_1 codice_2 thus rare languages
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Programming language topics
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list macos components list macos earlier called mac os x components features included current mac operating system automator application developed apple inc. macos implements point-and-click drag drop creation workflows automating repetitive tasks batches quicker alteration thus saving time effort human intervention manually change file separately automator enables repetition tasks across wide variety programs including finder safari calendar contacts others also work third-party applications microsoft office adobe photoshop pixelmator icon features robot holding pipe reference pipelines computer science term connected data workflows automator first released mac os x tiger 10.4 automator provides graphical user interface automating tasks without knowledge programming scripting languages tasks recorded performed user selected list output previous action become input next action automator comes library actions file renaming finding linked images creating new mail message etc act individual steps workflow document workflow document used carry repetitive tasks workflows saved reused unix command line scripts applescripts also invoked actions actions linked together workflow workflow saved application workflow file contextual menu item options set workflow created workflow run workflow file created automator saved /users/ user name /library/services calculator basic calculator application made apple inc. bundled macos three modes basic scientific programmer basic includes number pad buttons adding subtracting multiplying dividing well memory keys scientific mode supports exponents trigonometric functions programmer mode gives user access options related computer programming calculator program long history going back beginning macintosh platform simple four-function calculator program standard desk accessory earliest system versions though higher math capability included third-party developers provided upgrades apple released graphing calculator application first powerpc release 7.1.2 mac os standard component mac os 9 apple currently ships different application called grapher calculator reverse polish notation support also speak buttons pressed result returned calculator appeared first desk accessory first version macintosh system 1984 macintosh 128k original incarnation developed chris espinosa appearance designed part steve jobs espinosa flustered jobs dissatisfaction prototype designs conceived application called steve jobs roll calculator construction set allowed jobs tailor look calculator liking design maintained basic math operations final release classic mac os 2002 dashboard calculator widget included versions macos mac os x tiger onwards basic mode desktop counterpart since release os x yosemite also simple calculator widget available notifications area since release mac os x leopard simple arithmetic functions calculated spotlight feature include standard addition subtraction division multiplication exponentiation use percent sign denote percentage apple chess 3d chess game macos developed apple inc supports chess variants crazyhouse suicide chess originates openstep mac os x 10.2 based open source software apple redistributes source code apple sample code license contacts called address book os x mountain lion computerized address book included apple inc. macos includes various synchronizing capabilities integrates macos applications features address book two viewing modes view card column view card user switch modes control upper-left portion window close box releases prior lion view card column address book window divided three panes first pane title group pane lists directories user-made group users add new groups pulling file menu new group typing command-shift-n selecting user-made group second column title name lists names people cards group names selected group alphabetical order first last name depending user preference third pane card corresponding selected name card include information user classify customizable categories like home work many fields duplicate entries example person card describes several email addresses user edit fields pressing edit button bottom-left third pane address book search ldap network directories users customize ldap tab preferences users search selecting directories first pane selecting directory second pane typing search search box top-left third pane results appear third pane computer must connected local area network directories reside location changed network connection lost address book ’ look contacts directories network computer set access directory services one local area network address book automatically searches directory services addresses one also set address book search lightweight directory access protocol ldap servers addresses ldap internet protocol used looking contact information servers information network directories appears one searching search network directory select directories group column directory directory column type text search field add someone network directory one personal address book drag card directory group column instructions setting one computer access directory services one local area network open directory utility choose help directory utility help dictionary application includes in-built dictionary thesaurus photo booth application user take pictures quicktime player application play video sound files safari web browser time machine application user back files activity monitor system monitor macos operating system also incorporates task manager functionality activity monitor appeared mac os x v10.3 subsumed functionality programs process viewer task manager cpu monitor found previous version os x os x 10.9 activity monitor significantly revamped gained 5th tab energy addition cpu memory disk network airport utility program allows users configure airport wireless network manage services associated devices connected airport routers comes pre-installed macos available download microsoft windows ios airport utility unique offers network configuration native application opposed web application provides graphical overview airport devices attached network provides tools manage one individually allows users configure network preferences assign back mac accounts network configure usb attached printers hard drives current versions 6.3.6 recent versions macos 5.6.1 microsoft windows older versions mac os x 1.3.4 ios january 30 2013 apple released airport utility 6.0 macos featuring redesign user interface focused increasing usability novice users reception mixed media outlets reporting professionals network administrators frustrated removed features reported end users however ’ notice feature omissions users requiring removed features still access previous version airport utility using workaround audio midi setup utility program comes macos operating system adjusting computer audio input output configuration settings managing midi devices first introduced mac os x 10.5 leopard simplified way configure midi devices users need aware prior release midi devices require step mention might omitted midi devices third-party manufactures bluetooth file exchange utility comes macos operating system used exchange files bluetooth-enabled device example could used send image cellphone receive image documents pda assists users installing windows mac using boot camp colorsync utility software ships macos used management color profiles filters used apple pdf workflow applying filters pdf documents interface composed two parts document browser utility window document browser lets zoom image apply filter utility window several options profile first aid profiles devices filters calculator profile first aid allows repair colorsync color profiles conform international color consortium specification profiles allows browse profiles installed system grouped location class space graphically compare two profiles profile map displayed rotatable scalable 3d object plotted cielab cieluv yxy yuv ciexyz devices section allows see list registered colorsync devices displays printers see colorsync profile applied one also override default setting filters section allows build modify pdf filters available rest operating system filter set appear one three domains application pdf workflows printing filters set printing appear drop-down menu save pdf ... button standard mac os x print dialog box filters set pdf workflow appear quartz filters drop-down menu colorsync section print dialog box default filters ship mac os x user-created filters color management image effects pdf retouch domain selection comments color management section allows assigning profile choosing default profile rendering intent converting profile intermediate transform intermediate transform section allows adjustment brightness tint hue saturation bilevel high pass filter profile assignment either grayscale rgb cmyk data file applied either text graphics images shading complex filters created stacking multiple effects changes made pdf file saved new pdf file calculator convert rgb cmyk color value schemes features interactive color-picker identifying color screen duplicating feature another bundled utility digitalcolor meter colorsync apple inc. color management api classic mac os macos apple developed original 1.0 version colorsync mac-only architecture made operating system release 1993 year apple co-founded international color consortium icc develop cross-platform profile format became part colorsync 2.0 system color management module cmm linocolorcmm developed linotype-hell ag part heidelberger druckmaschinen ag cmm used microsoft windows 2000 xp rubric image color management icm apple help adobe ported colorsync 2.0 sdk microsoft windows colorsync 3.0 windows version initially planned discontinued colorsync 4.0 latest version introduced mac os x 10.1 human color perception complex subtle process different devices widely different color gamuts ranges color display deal issues colorsync provides several different methods color matching instance perceptual matching tries preserve closely possible relative relationships colors even colors must systematically distorted order get fit within gamut destination device human eye sensitive color differences rather absolute colors method tends produce best-looking results subjectively speaking many common uses methods work better cases dictated icc system profile connection space colorsync cie xyz color space image input output devices scanners printers displays characterized providing icc profile defines color information interpreted relative reference color space profile might provided device manufacturer better quality results might generated performing actual measurements device colorimeter thus image scanned scanner image file include copy scanner profile characterize meaning color information image sent output device matching process converts color information time rendering source profile attached image destination profile attached output device resulting colors print display closely possible original image console log viewer developed apple inc. included macos allows users search system logged messages alert user certain types messages logged console generally used troubleshooting problem computer macos well applications used send constant stream messages system form log files console allows read system logs help find certain ones monitor filter contents clicking show log list toolbar bring log list log list opens sidebar shows different logs system maintains list helps viewing many different logs maintained various parts system bringing together one place clicking particular log category logs shown system log queries contains logs entire system includes system logs well individual application logs selecting messages gives live look computer activities updated live includes activities system well applications running logs section console formatted uniformly include timestamp name process application actual message log message displayed includes paperclip icon next means shortened version longer report clicking icon show complete report addition viewing messages users also create custom queries criteria like custom queries filter messages also shown messages section order make new query choose new system log query file menu migration assistant application migrating information another computer computer use may windows computer mac system information application shows system information macintosh product voiceover application user listen spoken descriptions computer finder default file manager graphical interface shell macos archive utility bomarchivehelper mac os x 10.5 default archive file handler macos usually invoked automatically opening file one supported formats used create compressed zip archives choosing create archive 'file leopard compress finder file contextual menu located /system/library/coreservices/applications/archive utility.app mac os x 10.10 /system/library/coreservices/archive utility.app 10.5 later /system/library/coreservices/bomarchivehelper.app 10.4 prior archive utility inclusion mac os x v10.3 beginning mac os 7.6 apple bundled freeware stuffit expander operating system invoking archive utility manually shows minimal gui letting user change archive utility preferences choose files compress uncompress bom abbreviation bill materials bill materials files .bom files used macos installer program document files installer bundle installed file permissions file metadata thus bill materials read installer archive utility helps extracting files specified bom crash reporter standard crash reporter macos crash reporter send crash logs apple inc. engineers review crash reporter three modes operations developer tool crashreporterprefs used change modes using terminal command defaults write com.apple.crashreporter dialogtype basic|developer|server basic mode crash reporter notices application crashed twice succession offer rename application preference file try corrupted preference files common cause crashes reporting crash top text field window crash log bottom field user comments users may also copy paste log e-mail client send third-party application developer developer use classic environment usually referred classic hardware software abstraction layer powerpc versions mac os x allows legacy applications compatible mac os 9 run mac os x name classic also sometimes used software vendors refer application programming interface available classic applications differentiate programming mac os x classic version mac os classic environment supported powerpc-based macintosh computers running versions mac os x 10.4 tiger supported 10.5 leopard intel-based macintosh computers running version mac os x classic environment descendant rhapsody blue box virtualization layer served proof concept previously apple a/ux also offered virtualized mac os environment top unix operating system uses mac os 9 system folder new world rom file bridge differences older powerpc macintosh platforms xnu kernel environment classic environment created key element apple strategy replace classic mac os versions 9 mac os x standard operating system os used macintosh computers eliminating need use older os directly classic environment loaded login faster activation needed later command whenever mac os application requires launched reduce use system resources needed requires full version mac os 9 installed system loads instance os sandbox environment replacing low-level system calls equivalent calls mac os x via updated system files classic support system enabler sandbox used launch classic mac os applications—there one instance classic process running given user one user per machine may running classic time user chooses launch classic environment needed launching classic application first launches classic environment configured appear window resembling display computer booting mac os 9 classic environment finished loading application launches classic application foreground menu bar top screen changes look like older mac os system menu dialog boxes user-interface elements retain traditional appearance classic environment provides way run classic applications apple g5 systems well g4 based computers sold january 2003 machines boot mac os 9 earlier without bridging capabilities classic environment software see sheepshaver classic supported versions mac os x run apple systems incorporating intel microprocessors includes new shipping apple computers september 2006 last version mac os x support classic environment powerpcs mac os x v10.4 tiger classic environment compatibility usually good provided application using require direct access hardware engage full-screen drawing however complete clone mac os 9 finder included mac os x v10.2 later support reveal object apple events used mac os 9 applications causing reveal finder functionality applications lost early releases mac os x would often fail draw window frames classic applications correctly classic environment windowing made double buffered mac os x panther older applications games sometimes failed update screen properly original macintosh port doom however classic environment resurrected older applications previously unusable macintosh quadra power macintosh series mac os x replaced mac os 9 virtual memory system standard less fragile implementation classic environment performance also generally acceptable exceptions application run directly powerpc code would possible intel-based macs motorola 68k code handled motorola 68lc040 emulator mac os 9 uses application functions actually faster classic environment mac os 9 equivalent hardware due performance improvements newer operating system device drivers applications largely use heavy disk processing often quickly ported mac os x developers hand applications rely heavy processing share resources mac os 9 co-operative multitasking model interrupted non-classic processes mac os x preemptive multitasking greater processing power systems run mac os x compared systems intended run mac os 8 9 helps mitigate performance degradation classic environment virtualization mac os 9 earlier versions mac os x software update standalone tool program part coreservices os x could automatically inform users new updates new features bug security fixes operating system applications device drivers firmware updates required user enter administrative password required system restart could set check updates daily weekly monthly addition could download store associated .pkg file type used installer installed later date maintained history installed updates starting mac os x 10.5 leopard updates required reboot logged user prior installation automatically restarted computer complete earlier versions os x updates installed critical files replaced next system startup beginning os x 10.8 software update became part app store application beginning macos mojave 10.14 became part system preferences mac os x v10.4 x11.app optional install included install dvd mac os x v10.5 mac os x v10.6 mac os x v10.7 installed x11.app default os x mountain lion 10.8 apple dropped dedicated support x11.app users directed open source xquartz project contributes instead
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Operating systems
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sam fisher splinter cell samuel fisher fictional character protagonist tom clancy splinter cell series video games developed ubisoft well series tie-in novels endorsed tom clancy full name first seen tom clancy splinter cell first game series using computer v-22 osprey encrypt home call fisher originally voiced veteran actor michael ironside first five installments series 2013 eric johnson assumed voice physical role ironside later returned role 2018 participating crossover downloadable content height 5 10 weight 170lbs samuel fisher lcdr usn-ret former member third echelon top-secret black bag operation sub-branch within national security agency nsa currently commander/head field operative fourth echelon newly created covert special operations/counter-terrorism group reports president united states fisher born 1957 affluent baltimore suburbs towson maryland much known childhood known sam attended military boarding school death parents child accepted united states naval academy graduated 1977 bachelor degree political science commissioned ensign u.s. navy soon personnel file flagged recruitment navy seals joined passing grueling selection process training program mid-1980s fisher attached cia though still active duty navy working official diplomatic cover georgia time part ussr met nsa crypt-analyst named regan burns married 1984/85 small ceremony rhein-main air base frankfurt germany learning regan pregnant 31 may 1985 regan gave birth child named sarah fisher regan divorced three years marriage gaining custody sarah regan reverted maiden name changed sarah well regan died ovarian cancer sometime 2000 fisher gained guardianship sarah moved back u.s. took bureaucratic job cia worked weapons development well studied experimental weaponry information warfare order spend time focus upbringing fisher mission iceland informed sarah allegedly killed drunk driver late 2007 early 2008 however three years later heard rumor death accident went malta investigate captured third echelon malta grim revealed sarah alive sam wanted see daughter help investigate tom reed third echelon hq grim played recording lambert made death new york explaining sarah death faked prevent used leverage mole inside third echelon compromise sam agency learning revelation sam reluctantly continued help grim stopping reed assassinating united states president reuniting daughter retiring government work bored civilian life fisher accept job old associate best-friend victor coste paladin nine security specialized high-tech defense solutions kidnapping recovery work coste injured blacklist attack anderson air base guam offered president patricia caldwell commander fourth echelon consisted sam alongside civilian hacker charlie cole former cia officer isaac briggs lastly co-worker third echelon anna grimsdottir sam direct supervisor handler third echelon irving lambert colonel usa-ret deceased 2008 maintained constant radio contact sam missions providing updates support even one fisher oldest friends especially closest assisting lambert several third echelon employees provided additional reconnaissance logistical technical support sam operating field vernon 'junior wilkes deceased anna grímsdóttir frances coen william redding introduced chaos theory reassigned sometime double agent another sam fisher oldest friends douglas shetland major usmc-ret former usmc recon officer ceo private military corporation plays prominent role third game established fisher served shetland kuwait gulf war shetland unit operating alongside navy seals became close friends stationed aboard uss nimitz shortly fisher rescues hostage situation east timor mission second game shetland asks rest seals sam replies establishing left u.s. navy reserve 1996 saying came alone n't navy decade role shetland pmc displace international chaos theory becomes clear sam hunted kills roof bathhouse tokyo victor 'vic coste another one sam fisher oldest closest friends two served together navy seals iraq persian gulf war 1991 time iraq vic sam part four-man navy seal team ambushed soldiers iraqi republican guard routine foot patrol traversing along road leading baghdad two four men within squad killed ambush sam squad leader time captured vic coste left dead disobeyed direct orders hold position wait evacuation coste single-handedly fought way sam behind enemy lines rescued despite heavily outnumbered outgunned debt sam never forgotten result vic one people sam trusts unconditionally often turns covert assistance field sam 177 cm 5 ft 10 tall weighs 78 kg 170 pounds greying brown-black hair green eyes still athletic build physique man early 60s first person recruited field agent splinter cell program third echelon highly clandestine black ops project highly decorated veteran jsoc devgru cia special activities division fisher master art stealth trained various undercover covert infiltration tactics specializes night-time combat close-quarters combat urban warfare fieldcraft-related skills well addition sam extremely proficient tradecraft skills surveillance tactics computer hacking handling explosives use nearly conventional firearm ambidextrously also highly trained expert various forms martial arts far excels israeli self-defense combat system krav maga utilized center axis relock modern shooting stance used close-quarters combat invented paul castle prefers work alone field established novels sam known command startling number languages including native english spanish german russian korean chinese arabic burmese georgian persian assignment stationed fort meade working third echelon fisher resided townhouse towson farmhouse rural germantown maryland according novelizations series according 2013 graphic novel splinter cell echoes takes place end conviction events happened beginning splinter cell blacklist sam resides two-story house falls church virginia daughter currently lives atlanta georgia stayed book moving new york sam signature sidearm fn five-seven also preferred weapon choice throughout splinter cell franchise washington monument level conviction retrieves five-seven victor coste refers sam favorite pistol fisher conducted operations world bolivia canada cuba former east germany democratic republic congo mainland china iceland israel east timor indonesia guam japan kyrgyzstan russia ukraine turkey azerbaijan libya iraq iran afghanistan north south korea mexico panama peru paraguay myanmar serbia part yugoslavia georgia france also conducted operations inside united states places los angeles international airport denver international airport sabine pass chicago philadelphia fort meade new york city new orleans washington d.c. ellsworth federal penitentiary kansas cia headquarters langley virginia novel version tom clancy splinter cell establishes sam hated time cia working mid-late 1980s mostly official cover i.e diplomatic aide bank mission chaos theory reveals fisher served panama operation cause part cia team raided bank conflict searching manuel noriega drug money around time conflict panama ended january 1990 fisher called back active duty seals deployed iraqi republic spent next several months leading gulf war sleeping ditch road baghdad kuwait prior iraqi invasion kuwait august 1990 already present western military intervention u.s.-led coalition forces began beginning gulf war january 1991 covert operative whose existence completely deniable u.s. government fisher approaches target objectives gruff no-nonsense manner maintains lighthearted relationship colleagues even momentary hostages even going kill fisher little patience government bureaucracy behind-the-scenes political maneuvering realist well aware overarching political ramifications behind assignments specific manner authorized completion fisher maintains cynical jaded sarcastic sense humor covert illegal often morally ambiguous nature work pandora tomorrow lambert informs fisher nobody knows whether norman soth u.s. intelligence agent terrorist fisher replies things n't mutually exclusive time highly loyal staunch believer ideals work ultimately protects quickly angered casual and/or intentional slaughter innocent civilians unarmed military personnel enemies original splinter cell fisher original trial agent nascent third echelon initiative inaugural splinter cell program thus interactions handler colonel lambert relatively straightforward respectful time fisher drop occasional sarcastic wisecrack particularly unusual obtuse instructions instance final level pandora tomorrow sam elevator shuts enemies cut power lambert informs elevator stopped sam retorts sarcastic thanks lambert splinter cell chaos theory fisher blunt appears fairly disappointed lambert orders avoid enemy fatalities part mission parameters frequently holding captured enemies knife-point dialog creative highly intimidating though often morbidly humorous audience splinter cell conviction fisher personality takes leap towards ruthlessness intimidating threats lethal force chaos theory become standard practice fisher often tortures subjects interrogation creative use surrounding objects pianos fire extinguishers windowsills tie-in novels expand fisher character portray detached preferring solitude buying non-perishables cds wants online living first novel explained one-sentence paragraph fisher like way avoids relationships due demands job though eventually engages relationship krav maga instructor katia katia killed sniper shot meant however close relationship daughter sarah used bait trap first novel sarah kidnapped order get fisher novels fisher also mentions ability fall asleep command unlike people sleep tired says asset line work often requires obtain sleep awkward places tom hardy playing younger sam fisher film adaptation splinter cell expected released 2019 2008 age ranked fisher seventh greatest xbox character time stating man action rather words lone wolf sometimes 've got respect hand pc zone staff listed fisher eighth worst character pc gaming history declaring great iconic character one freefall due genuine lack imagination part creators text critique targets splinter cell double agent 2010 game informer readers voted fisher twelfth top character 2000s decade although fisher ultimately make cut game informer staff considered inclusion 30 characters defined decade collection bryan vore saying splinter cell ... easy assume sam fisher simply poor man solid snake quickly gamers thanks quiet deadly efficiency gruff yet sarcastic demeanor willingness disobey orders n't believe 2011 guinness world records gamer edition lists character twenty-fourth popular video game character ugo networks featured fisher list coolest helmets headgear video games number 5 remarking unrecognizable without three-eyed night vision goggles perched forehead 2012 gamesradar ranked 37th memorable influential badass protagonist games adding voiced michael ironside wears awesome night vision goggles good enough right fine ... like macgyver-meets-james bond-meets-batman since list updated annually 2013 complex ranked sam fisher number 18 list greatest soldiers video games calling little bit like american james bond—only without things james bond besides kill dudes
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Computer security
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pmset computing pmset command line utility manipulate power management settings darwin macos operating systems assign sleep settings schedule sleep wake times display power information pmset utility first appeared darwin 6.0.1 mac os x 10.2 jaguar updated periodically since introduction still available darwin 17.0 macos 10.13 high sierra utility sets lists power management settings functionality provided utility available gui interface energy saver preference pane however pmset allows greater flexibility access several options available gui utility set different power management settings depending usage scenario different settings applied machine running charger battery ups three appropriate flags follows additional arguments supplied assigning power management settings power management arguments discussed greater detail invoking command specified arguments modify power management options arguments already set unmodified pmset unless arguments specifically included utility schedule wake sleep power power events events recurring based arbitrary weekday time combinations scheduled future dates times syntax scheduling event follows previously stored events overwritten upon running command schedule multiple events must entered one command string example set shutdown event every day week 23:59 wake power event every day week 7:00 enter following get flag displays information current power management configuration log recent activity additional arguments supplied flag display current settings additional get arguments discussed greater detail get flag follows view currently scheduled events type utility also able configure hibernation safe sleep options change energy saver profiles pmset utility recognizes following arguments arguments passed serial form order bad syntax unrecognized argument cause entire command fail resulting error message brief help screen power management settings changed privileged user settings may adjusted independently circumstances machine attached charger running battery case laptop running ups available settings also adjusted four scenarios simultaneously default option usage flag specified power management options specified different profiles appending -c charger -b battery -u ups -a flags following example set machine sleep 10 minutes sleep display five minutes powered battery following command assign slightly different power management settings circumstances machine powered charger machine set sleep 30 minutes display set never sleep set charger issuing commands interfere arguments entered serial form set modify several power management parameters one command following command set machine never sleep sleep 0 enable sudden motion sensor sms 1 set display sleep 20 minutes displaysleep 20 disable processor speed reduction reduce 0 enable intermediate display dimness halfdim 1 enable machine wake lid opened lidwake 1 prevent system sleeping tty session ssh active ttyskeepawake 1 disable waking machine ac adapter inserted acwake 0 disable automatic restart power removed restored autorestart 0 enable dynamic change processor speed based system load dps 1 enable wake modem ring ring 1 enable wake receipt magic ethernet packet womp 1 disable hard disk sleep disksleep 0 example include usage flag settings specified apply usage scenarios subsequent commands specify usage flag affect settings usage scenario instance pmset -b sleep 10 cause machine sleep 10 minutes battery attached settings apply battery attached settings example apply charger ups attached least darwin 9.4 os x 10.5.4 leopard changes made pmset saved persistent preferences file /library/preferences/systemconfiguration/com.apple.powermanagement.plist file modified manually using defaults command changes taken immediately power management system manual edits com.apple.powermanagement.plist also stand risk overwritten command pmset touch reread existing settings disk apply system autopoweroff enabled machine got hibernate mode even hibernatemode 0 value autopoweroffdelay may seconds despite man page mavericks nov 9 2012 documenting minutes pmset command able schedule system sleep shutdown wakeup power events schedule argument setting one-time power events repeat setting daily weekly events scheduling events done privileged user schedule argument recognizes following additional arguments utility unforgiving improper syntax errors syntax cause command fail display brief help message syntax scheduled event follows one type event sleep wake et cetera specified date chosen must future utility expects able store information pmu may work reliably non-apple hardware date time string must enclosed quotation marks syntax repeating event follows scheduled wake sleep power events stored persistent preferences file /library/preferences/systemconfiguration/com.apple.autowake.plist file manually edited using defaults command changes made stand serious risk overwritten also edits immediately taken system list flag -g displays information current power configuration flag alone additional arguments display current power management settings additional arguments display specific information get functions pmset require privileged access utility recognizes following arguments one get argument passed pmset must preceded get flag instance display scheduled events type pmset -g sched utility return error one get argument provided first ignored sleep displaysleep show imposed value 0 disabled together list process ids impose value processes backup programs need machine stay awake example backup finished following examples demonstrate output pmset command apple powerbook g4 running mac os x 10.5.4 leopard following example put relevant computer sleep immediately following example apply laptops powered battery set machine sleep 5 minutes inactivity put display sleep 2 minutes spin hard disk 3 minutes privileged users issue command command issued successfully without syntax errors pmset exit silently exit code 0 verify system took new configuration issue command pmset -g. following example apply machines powered ups set machine perform emergency shutdown 5 percent battery remains ups 5 minutes estimated draw time remains whichever comes first privileged users issue command command issued successfully without syntax errors pmset exit silently exit code 0 verify system took new configuration issue command pmset -g. following example apply usage scenarios set machine wake receipt magic ethernet packet wake modem detects ring prevent system sleeping tty session active privileged users issue command command issued successfully without syntax errors pmset exit silently exit code 0 verify system took new configuration issue command pmset -g. following example sets one-time scheduled power event machine set shut 01/10/2009 10:00 pm 10 january 2009 – note us centric mm/dd/yyy time syntax privileged users issue command command issued successfully without syntax errors pmset exit silently exit code 0 verify system took new configuration issue command pmset -g sched following example sets repeating power event machine wake power every weekday 8:00 privileged users issue command command issued successfully without syntax errors pmset exit silently exit code 0 verify system took new configuration issue command pmset -g sched example output pmset -g. time machine powered charger simultaneously charging battery command prints current configuration example output pmset -g sched example machine already configured repeating event start wake every weekday 8:00 command prints repeating event note next occurrence appears scheduled power event example output pmset -g. time machine backed output shows pid backup program
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Operating systems
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babbage programming language babbage high level assembly language gec 4000 series minicomputers named charles babbage english computing pioneer
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Programming language topics
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semanticgov semanticgov european union-funded research development project lasted 2006 2009 aimed building infrastructure software models services etc necessary enabling offering semantic web services public administration pa semanticgov aimed address longstanding challenges faced public administrations achieving interoperability amongst pa agencies within country well amongst countries easing discovery pa services customers facilitating execution complex services often involving multiple pa agencies interworkflows semanticgov project aimed capitalizing service oriented architectures paradigm implemented state-of-the-art semantic web services technology supported rigorous reusable public administration domain analysis modelling line major european programmes initiatives field e.g european interoperability framework previous work conducted eu idabc programme i2010 group member states representatives competitiveness innovation cip programme semanticgov project objectives support pa client identify needed services providing infrastructure mapping client needs pa services b discover service interest federal/national pa service directory c. execute monitor service workflow providing infrastructure on-the-fly semi-automated composition execution monitoring complex pa services ii support european citizens businesses access pan-european egovernment services pegs providing communal semantic gateway resolve semantic incompatibilities amongst different administration systems semanticgov project meant simply provide new electronic government solutions a. enhance administrative capacity national public administration systems providing new paradigm service provision b. pave way administrative dimension european unification aka “ common european administrative space ” facilitating communication amongst eu national administrative systems list consortium partners follows
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Web technology
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divvycloud divvy cloud corporation privately held venture-backed american cybersecurity company headquarters arlington virginia core product protects cloud container environments misconfigurations policy violations threats iam challenges automated real-time remediation divvycloud customers achieve continuous security compliance fully realize benefits cloud container technology divvycloud supports aws microsoft azure google cloud platform alibiba cloud kubernetes divvycloud category technology classified gartner cloud security posture management divvycloud founded may 2013 former electronic arts employees brian johnson chris deramus tenure electronic arts responsible large-scale infrastructure mmorpg titles writing proprietary tools manage complex environment left electronic arts created divvycloud may 2019 divvycloud secured 19 million funding round led providence strategic growth arm providence equity partners contributions existing investors missionog rtp ventures investment brought total capital raised date 29 million following 6 million series round september 2017 company numerous awards including cyber defense magazine editor ’ choice winner 2019 infosec awards cloud security category 2019 cyber security excellence awards
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Computer security
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linked timestamping linked timestamping type trusted timestamping issued time-stamps related linked timestamping creates time-stamp tokens dependent entangled authenticated data structure later modification issued time-stamps would invalidate structure temporal order issued time-stamps also protected data structure making backdating issued time-stamps impossible even issuing server top authenticated data structure generally published hard-to-modify widely witnessed media like printed newspaper public blockchain long-term private keys use avoiding pki-related risks suitable candidates authenticated data structure include simplest linear hash chain-based time-stamping scheme illustrated following diagram linking-based time-stamping authority tsa usually performs following distinct functions linked timestamping inherently secure usual public-key signature based time-stamping consequential time-stamps seal previously issued ones hash chain authenticated dictionary use could built one way modifying issued time-stamps nearly hard finding preimage used cryptographic hash function continuity operation observable users periodic publications widely witnessed media provide extra transparency tampering absolute time values could detected users whose time-stamps relatively comparable system design absence secret keys increases system trustworthiness keys leak hash algorithms considered future-proof modular arithmetic based algorithms e.g rsa linked timestamping scales well hashing much faster public key cryptography need specific cryptographic hardware limitations common technology guaranteeing long-term attestation value issued time-stamps digitally signed data periodic over-time-stamping time-stamp token missing key-related risks plausible safety margin reasonably chosen hash function over-time-stamping period hash-linked token could order magnitude longer public-key signed token haber stornetta proposed 1990 link issued time-stamps together linear hash-chain using collision-resistant hash function main rationale diminish tsa trust requirements tree-like schemes operating rounds proposed benaloh de mare 1991 bayer haber stornetta 1992 benaloh de mare constructed one-way accumulator 1994 proposed use time-stamping used aggregation one-way accumulator requires one constant-time computation round membership verification surety started first commercial linked timestamping service january 1995 linking scheme described security analyzed following article haber sornetta buldas et al continued optimization formal analysis binary tree threaded tree based schemes skip-list based time-stamping system implemented 2005 related algorithms quite efficient security proof hash-function based time-stamping schemes presented buldas saarepera 2004 explicit upper bound formula_1 number time stamps issued aggregation period suggested probably impossible prove security without explicit bound so-called black-box reductions fail task considering known practically relevant efficient security proofs black-box negative result quite strong next 2005 shown bounded time-stamping schemes trusted audit party periodically reviews list time-stamps issued aggregation period made universally composable remain secure arbitrary environments compositions protocols instances time-stamping protocol buldas laur showed 2007 bounded time-stamping schemes secure strong sense satisfy so-called knowledge-binding condition security guarantee offered buldas saarepera 2004 improved diminishing security loss coefficient formula_1 formula_3 hash functions used secure time-stamping schemes necessarily collision-resistant even one-way secure time-stamping schemes probably possible even presence universal collision-finding algorithm i.e universal attacking program able find collisions hash function suggests possible find even stronger proofs based properties hash functions illustration hash tree based time-stamping system works rounds formula_4 formula_5 formula_6 ... one aggregation tree per round capacity system formula_1 determined tree size formula_8 formula_9 denotes binary tree depth current security proofs work assumption hard limit aggregation tree size possibly enforced subtree length restriction iso 18014 part 3 covers 'mechanisms producing linked tokens american national standard financial services trusted timestamp management security ansi asc x9.95 standard june 2005 covers linking-based hybrid time-stamping schemes ietf rfc standard draft linking based time-stamping rfc 4998 evidence record syntax encompasses hash tree time-stamp integrity guarantee long-term archiving
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Computer security
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open process open nextstep macos command line process opens file folder url gui though user double clicked files opened default application type folders opened finder file system gui urls opened default browser
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Operating systems
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glite-amga arda metadata grid application amga general purpose metadata catalogue part european middleware initiative middleware distribution originally developed egee project part glite middleware became clear many grid applications needed metadata information files organize work-flow amga developed supported european middleware initiative amga metadata service allows users attach metadata information files stored grid metadata relationally organized data typically stored relational database system rdbms addition metadata amga also stored independently associated files allows amga used general access tool relational databases grid amga features simple learn metadata access language useful adoption amga smaller grid applications considerably lowers technical hurdle make use relational data access via sql92 also supported one main features amga one unique possibility replicate metadata different amga instances allowing federation metadata e.g health-e-child project also increase scalability improve access times globally deployed grid done wisdom project performance efficiency access across wans independently targeted access protocol optimised bulk transfer metadata across wans using data streaming security grid major concern amga features different authentication methods via grid-proxy- certificates well flexible accesses control mechanisms individual data items based acls particular security features made amga de facto standard metadata relational database access grid biomedical applications prominent projects making use amga field wisdom amga used campaigns avian flu malaria health e-child project
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Distributed computing architecture
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xda developers xda developers also known simply xda often stylized xda-developers mobile software development community launched 20 december 2002 although discussion primarily revolves around android members also talk many operating systems mobile development topics many software hardware hacks rooting methods phone tablet specific tweaks originate members xda forum xda developers also hosts xda portal source android mobile phone development news well xda labs android app repository acts third-party application provider launched 2010 2016 respectively xda-developers.com created nah6 crypto products bv launched december 20th 2002 10 january 2011 xda-developers bought jb online media llc name xda developers originally derived xda marketed personal digital assistant pda extra features 2013 xda partnered swappa become official marketplace users buy sell devices site main purpose discussion troubleshooting development android sailfish os windows phone webos ubuntu touch firefox os tizen phones site also offers windows mobile android users general information devices rom upgrades technical support q reviews device applications accessories separate forums exist model phones manufactured google sony htc samsung lg electronics motorola nokia many others forums also available tablets many devices recently added new domain link shortener restricted devs joshua solan manages owns xda developers via company jb online media llc february 2009 microsoft asked xda developers remove roms created oems response petition raised signed 10,000 xda developers members petition put aside microsoft pursue removal customized images microsoft felt using custom images based roms originally provided microsoft acceptable roms work specific models portable devices original rom designed cnet asia suggested xda developers offers potential solutions problems many android-based mobile devices mobile phone reviews testers cnet preferred using xda developers roms carrying detailed reviews
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Operating systems
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check point go check point go usb drive combines encrypted usb flash drive virtualization vpn computer security technologies turn pc secure corporate desktop plugging check point go usb port microsoft windows os-based pc laptop users launch secure virtual workspace segregated host pc allows users securely access company files applications remote location including insecure host environments hotel business center internet café check point go uses hardware software encryption protect user credentials documents sensitive data data compromised transit event device lost system uses authentication process enforces minimum levels password strength well certificates security tokens multifactor authentication remote connectivity device interfaces software corporate server support company policies security updates security gateways check point go formerly abra first introduced check point software technologies ltd. sandisk corporation march 2010 address security compliance issues companies remote employees workers increasingly demanding remote access company applications data personal equipment accessing network pose risk corporate networks creating potential avenue corporate data loss allowing unsecure connections companies cite check point go system provides solution companies want let employees purchase manage pcs laptops needing high security including encryption computing devices outside workplace well contractors/vendors require access company network working site since release product industry awards including product 2010 computerworld named one “ 25 hot products watch ” 2010 rsa conference crn magazine checkpoint go went end-of-sale 31-dec-2013 support ending 31-dec-2018 check point go inserted usb port pc user presented login screen upon successful login new explorer.exe instance started check point go secure workspace subsequent processes started child processes new explorer check point go uses software installed host pc run applications microsoft word microsoft excel user ’ documents remain secure check point go environment – virtual workspace runs parallel host environment file registry input/output calls secure application inside check point go redirected flash drive applications running check point go desktop including new explorer operate virtual file system registry virtual files registry data instantly written flash drive immediately encrypted currently check point go work windows workstations due incompatibility enterprise client settings
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Computer security
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comparison disk encryption software technical feature comparison different disk encryption software different modes operation supported software note encrypted volume use one mode operation
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Computer file systems
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subnetwork access protocol subnetwork access protocol snap mechanism multiplexing networks using ieee 802.2 llc protocols distinguished 8-bit 802.2 service access point sap fields snap supports identifying protocols ethernet type field values also supports vendor-private protocol identifier spaces used ieee 802.3 ieee 802.4 ieee 802.5 ieee 802.11 ieee 802 physical network layers well non-ieee 802 physical network layers fddi use 802.2 llc snap lsap fields added packets transmitting node order allow receiving node pass received frame appropriate device driver understands given protocol open systems interconnect osi model uses sap define communication layers like network transport session layers seven-layered model identify protocol process incoming message within given layer programs exchange data mutually agreed upon protocol mechanism pair programs support common protocol communicate thus multiple protocols coexist within layer necessary determine protocol invoked process service data unit delivered lower layer common reference sap including source service access point ssap destination service access point dsap refers boundary data link layer network layer common think sap terms use layer 2 specifically logical link control llc sub-layer defined ieee 802.2 standards link service access point lsap includes destination service access point dsap source service access point ssap enables mac station communicate upper layers via different protocols standard network layer protocols assigned reserved llc addresses recorded iso/iec tr 11802-1 one half llc address space reserved assignment protocols accommodated two ways one way local assignment lsaps half llc address space available second way use particular reserved llc address value assigned use conjunction sub-network access protocol snap called snap address snap address identifies mac sap single lsap thus protocol using snap must employ protocol identifier thus subnetwork access protocol snap mechanism multiplexing networks using ieee 802.2 llc protocols distinguished 8-bit 802.2 service access point sap fields snap supports identifying protocols ethernet type field values also supports vendor-private protocol identifier spaces used ieee 802.3 ieee 802.4 ieee 802.5 ieee 802.11 ieee 802 physical network layers well non-ieee 802 physical network layers fddi use 802.2 llc snap extension 802.2 llc specified ieee 802 overview architecture document 5-octet snap header follows 802.2 llc header destination sap dsap source sap ssap contain hexadecimal values aa ab snap header consists 3-octet ieee organizationally unique identifier oui followed 2-octet protocol id oui hexadecimal 000000 protocol id ethernet type ethertype field value protocol running top snap oui oui particular organization protocol id value assigned organization protocol running top snap snap usually used unnumbered information 802.2 protocol data units pdus control field value 3 lsap values usually hexadecimal aa 802.2 llc header snap packet usually aa aa 03 however snap used pdu types well ethernet 8 octets occupied llc snap headers reduce size available payload protocols internet protocol 1492 bytes compared use ethernet ii framing therefore protocols ethertype values packets usually transmitted ethernet ii headers rather llc snap headers network types llc snap headers required order multiplex different protocols link layer mac layer n't ethertype field alternative framing would larger available payload one might ask separate sub-network header necessary answer augment decision made layout llc header time llc header designed thought single octet 256 possible values header would enough specify protocol values vendors would want register values began reserved discovered llc header would soon run open values hexadecimal aa ab values reserved additional header—the snap header—was developed support ethertype values well multiple spaces private protocol values per ietf rfc 1042 ip datagrams arp datagrams transmitted ieee 802 networks using llc snap headers except ethernet/ieee 802.3 transmitted ethernet ii headers per rfc 894
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Internet protocols
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simple update protocol simple update protocol sup protocol developed friendfeed simplify speed rss atom websites supported sup meaning updates services appeared friendfeed within seconds support dropped eventually friendfeed shutdown 2015-04-09 sites include disqus identi.ca reddit brightkite supported sup shutdown april 2012 youtube supported sup according youtube v2 api sup documentation yet reference says youtube data api v2 officially deprecated march 4 2014 youtube data api v3 supports push notifications via pubsubhubbub instead longer sup section
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Internet protocols
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lesk algorithm lesk algorithm classical algorithm word sense disambiguation introduced michael e. lesk 1986 lesk algorithm based assumption words given neighborhood section text tend share common topic simplified version lesk algorithm compare dictionary definition ambiguous word terms contained neighborhood versions adapted use wordnet implementation might look like frequently used example illustrating algorithm context pine cone following dictionary definitions used seen best intersection pine 1 ⋂ cone 3 2 simplified lesk algorithm correct meaning word given context determined individually locating sense overlaps dictionary definition given context rather simultaneously determining meanings words given context approach tackles word individually independent meaning words occurring context comparative evaluation performed vasilescu et al 2004 shown simplified lesk algorithm significantly outperform original definition algorithm terms precision efficiency evaluating disambiguation algorithms senseval-2 english words data measure 58 precision using simplified lesk algorithm compared 42 original algorithm note vasilescu et al implementation considers back-off strategy words covered algorithm consisting frequent sense defined wordnet means words possible meanings lead zero overlap current context word definitions default assigned sense number one wordnet simplified lesk algorithm smart default word sense vasilescu et al. 2004 computeoverlap function returns number words common two sets ignoring function words words stop list original lesk algorithm defines context complex way unfortunately lesk ’ approach sensitive exact wording definitions absence certain word radically change results algorithm determines overlaps among glosses senses considered significant limitation dictionary glosses tend fairly short provide sufficient vocabulary relate fine-grained sense distinctions lot work appeared offering different modifications algorithm works use resources analysis thesauruses synonyms dictionaries morphological syntactic models instance may use information synonyms different derivatives words definitions words definitions lot studies concerning lesk extensions
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Computational linguistics
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object file object file file containing object code meaning relocatable format machine code usually directly executable various formats object files object code packaged different object files object file may also work like shared library addition object code object files may contain metadata used linking debugging including information resolve symbolic cross-references different modules relocation information stack unwinding information comments program symbols debugging profiling information object file format computer file format used storage object code related data many different object file formats originally type computer unique format advent unix portable operating systems formats coff elf defined used different kinds systems possible file format used linker input output thus library executable file format design and/or choice object file format key part overall system design affects performance linker thus programmer turnaround developing format used executables design also affects time programs take begin running thus responsiveness users object file formats structured separate sections data section containing certain type data sections known segments due term memory segment previously common form memory management program loaded memory loader loader allocates various regions memory program regions correspond segments object file thus usually known names others stack exist run time cases relocation done loader linker specify actual memory addresses however many programs architectures relocation necessary due handled memory management unit position-independent code systems segments object file copied paged memory executed without needing processing systems may done lazily segments referenced execution example via memory-mapped file backed object file types data supported typical object file formats segments different object files may combined linker according rules specified segments defined conventions exist segments shared object files instance dos different memory models specify names special segments whether may combined debugging information may either integral part object file format coff semi-independent format may used several object formats stabs dwarf gnu project binary file descriptor library bfd library provides common api manipulation object files variety formats
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Programming language topics
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think blue linux think blue linux sometimes thinkblue linux port linux ibm s/390 later zseries mainframe computers done millenux subsidiary german company thinking objects software gmbh distribution consisted primarily collection red hat linux 6.1 packages rpms top ibm port linux kernel distribution product scheduled cease early 2006 packages date linux distributions support ibm mainframes modern linux distributions support ibm mainframes making special dedicated distribution unnecessary
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Operating systems
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data access data access generic term referring process it-specific meaning connotations involving access rights broader legal and/or political sense former typically refers software activities related storing retrieving acting data housed database repository two fundamental types data access exist data access crucially involves authorization access different data repositories data access help distinguish abilities administrators users example administrators may ability remove edit add data general users may even read rights lack access particular information historically repository including different database file system etc might require use different methods languages many repositories stored content different incompatible formats years standardized languages methods formats developed serve interfaces often proprietary always idiosyncratic specific languages methods standards include sql 1974- odbc ca 1990- jdbc xqj ado.net xml xquery xpath 1999- web services standards enable translation data unstructured html free-text files structured xml sql structures connection strings dburls attempt standardise methods connecting databases right_of_access_to_personal_data
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Databases
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ai winter history artificial intelligence ai winter period reduced funding interest artificial intelligence research term coined analogy idea nuclear winter field experienced several hype cycles followed disappointment criticism followed funding cuts followed renewed interest years decades later term first appeared 1984 topic public debate annual meeting aaai called american association artificial intelligence chain reaction begins pessimism ai community followed pessimism press followed severe cutback funding followed end serious research meeting roger schank marvin minsky—two leading ai researchers survived winter 1970s—warned business community enthusiasm ai spiraled control 1980s disappointment would certainly follow three years later billion-dollar ai industry began collapse hype common many emerging technologies railway mania dot-com bubble ai winter primarily collapse perception ai government bureaucrats venture capitalists despite rise fall ai reputation continued develop new successful technologies ai researcher rodney brooks would complain 2002 stupid myth ai failed ai around every second day 2005 ray kurzweil agreed many observers still think ai winter end story nothing since come ai field yet today many thousands ai applications deeply embedded infrastructure every industry enthusiasm optimism ai increased since low point early 1990s beginning 2012 artificial intelligence especially sub-field machine learning gained commercial acceptance funding increased dramatically two major winters 1974–1980 1987–1993 several smaller episodes including following cold war us government particularly interested automatic instant translation russian documents scientific reports government aggressively supported efforts machine translation starting 1954 outset researchers optimistic noam chomsky new work grammar streamlining translation process many predictions imminent 'breakthroughs however researchers underestimated profound difficulty word-sense disambiguation order translate sentence machine needed idea sentence otherwise made mistakes apocryphal example spirit willing flesh weak translated back forth russian became vodka good meat rotten similarly sight mind became blind idiot later researchers would call commonsense knowledge problem 1964 national research council become concerned lack progress formed automatic language processing advisory committee alpac look problem concluded famous 1966 report machine translation expensive less accurate slower human translation spending 20 million dollars nrc ended support careers destroyed research ended machine translation still open research problem 21st century met success google translate yahoo babel fish earliest work ai used networks circuits connected units simulate intelligent behavior examples kind work called connectionism include walter pitts warren mccullough first description neural network logic marvin minsky work snarc system late 1950s approaches abandoned researchers began explore symbolic reasoning essence intelligence following success programs like logic theorist general problem solver however one type connectionist work continued study perceptrons invented frank rosenblatt kept field alive salesmanship sheer force personality optimistically predicted perceptron may eventually able learn make decisions translate languages mainstream research perceptrons came abrupt end 1969 marvin minsky seymour papert published book perceptrons perceived outlining limits perceptrons could connectionist approaches abandoned next decade important work paul werbos discovery backpropagation continued limited way major funding connectionist projects difficult find 1970s early 1980s winter connectionist research came end middle 1980s work john hopfield david rumelhart others revived large scale interest neural networks rosenblatt live see however died boating accident shortly perceptrons published 1973 professor sir james lighthill asked uk parliament evaluate state ai research united kingdom report called lighthill report criticized utter failure ai achieve grandiose objectives concluded nothing done ai could n't done sciences specifically mentioned problem combinatorial explosion intractability implied many ai successful algorithms would grind halt real world problems suitable solving toy versions report contested debate broadcast bbc controversy series 1973 debate general purpose robot mirage royal institution lighthill versus team donald michie john mccarthy richard gregory mccarthy later wrote combinatorial explosion problem recognized ai beginning report led complete dismantling ai research england ai research continued universities edinburgh essex sussex created bow-wave effect led funding cuts across europe writes james hendler research would revive large scale 1983 alvey research project british government began fund ai war chest £350 million response japanese fifth generation project see alvey number uk-only requirements sit well internationally especially us partners lost phase 2 funding 1960s defense advanced research projects agency known arpa known darpa provided millions dollars ai research almost strings attached darpa director years j. c. r. licklider believed funding people projects allowed ai leaders marvin minsky john mccarthy herbert a. simon allen newell spend almost way liked attitude changed passage mansfield amendment 1969 required darpa fund mission-oriented direct research rather basic undirected research pure undirected research kind gone 1960s would longer funded darpa researchers show work would soon produce useful military technology ai research proposals held high standard situation helped lighthill report darpa study american study group suggested ai research unlikely produce anything truly useful foreseeable future darpa money directed specific projects identifiable goals autonomous tanks battle management systems 1974 funding ai projects hard find ai researcher hans moravec blamed crisis unrealistic predictions colleagues many researchers caught web increasing exaggeration initial promises darpa much optimistic course delivered stopped considerably short felt could n't next proposal promise less first one promised result moravec claims staff darpa lost patience ai research literally phrased darpa 'some people going taught lesson two-million-dollar-a-year contracts cut almost nothing moravec told daniel crevier autonomous tank project failure battle management system dynamic analysis replanning tool proved enormously successful saving billions first gulf war repaying darpas investment ai justifying darpa pragmatic policy darpa deeply disappointed researchers working speech understanding research program carnegie mellon university darpa hoped felt promised system could respond voice commands pilot sur team developed system could recognize spoken english words spoken particular order darpa felt duped 1974 cancelled three million dollar year grant many years later successful commercial speech recognition systems would use technology developed carnegie mellon team hidden markov models market speech recognition systems would reach 4 billion 2001 1980s form ai program called expert system adopted corporations around world first commercial expert system xcon developed carnegie mellon digital equipment corporation enormous success estimated saved company 40 million dollars six years operation corporations around world began develop deploy expert systems 1985 spending billion dollars ai in-house ai departments industry grew support including software companies like teknowledge intellicorp kee hardware companies like symbolics lisp machines inc. built specialized computers called lisp machines optimized process programming language lisp preferred language ai 1987 three years minsky schank prediction market specialized ai hardware collapsed workstations companies like sun microsystems offered powerful alternative lisp machines companies like lucid offered lisp environment new class workstations performance general workstations became increasingly difficult challenge lisp machines companies like lucid franz lisp offered increasingly powerful versions lisp example benchmarks published showing workstations maintaining performance advantage lisp machines later desktop computers built apple ibm would also offer simpler popular architecture run lisp applications 1987 become powerful expensive lisp machines desktop computers rule-based engines clips available alternatives left consumers reason buy expensive machine specialized running lisp entire industry worth half billion dollars replaced single year commercially many lisp companies failed like symbolics lisp machines inc. lucid inc. etc companies like texas instruments xerox abandoned field however number customer companies companies using systems written lisp developed lisp machine platforms continued maintain systems cases maintenance involved assumption resulting support work early 1990s earliest successful expert systems xcon proved expensive maintain difficult update could learn brittle i.e. could make grotesque mistakes given unusual inputs fell prey problems qualification problem identified years earlier research nonmonotonic logic expert systems proved useful special contexts another problem dealt computational hardness truth maintenance efforts general knowledge kee used assumption-based approach see nasa texsys supporting multiple-world scenarios difficult understand apply remaining expert system shell companies eventually forced downsize search new markets software paradigms like case-based reasoning universal database access maturation common lisp saved many systems icad found application knowledge-based engineering systems intellicorp kee moved lisp c++ variant pc helped establish object-oriented technology including providing major support development uml see uml partners 1981 japanese ministry international trade industry set aside 850 million fifth generation computer project objectives write programs build machines could carry conversations translate languages interpret pictures reason like human beings 1991 impressive list goals penned 1981 met indeed met 2001 2011 ai projects expectations run much higher actually possible 1983 response fifth generation project darpa began fund ai research strategic computing initiative originally proposed project would begin practical achievable goals even included artificial general intelligence long term objective program direction information processing technology office ipto also directed supercomputing microelectronics 1985 spent 100 million 92 projects underway 60 institutions half industry half universities government labs ai research generously funded sci jack schwarz ascended leadership ipto 1987 dismissed expert systems clever programming cut funding ai deeply brutally eviscerating sci schwarz felt darpa focus funding technologies showed promise words darpa surf rather dog paddle felt strongly ai next wave insiders program cited problems communication organization integration projects survived funding cuts including pilot assistant autonomous land vehicle never delivered dart battle management system noted successful survey reports early 2000s suggests ai reputation still less stellar many researchers ai mid 2000s deliberately called work names informatics machine learning analytics knowledge-based systems business rules management cognitive systems intelligent systems intelligent agents computational intelligence indicate work emphasizes particular tools directed particular sub-problem although may partly consider field fundamentally different ai also true new names help procure funding avoiding stigma false promises attached name artificial intelligence late 1990s early 21st century ai technology became widely used elements larger systems field rarely credited successes 2006 nick bostrom explained lot cutting edge ai filtered general applications often without called ai something becomes useful enough common enough labeled ai anymore rodney brooks stated around time stupid myth ai failed ai around every second day technologies developed ai researchers achieved commercial success number domains machine translation data mining industrial robotics logistics speech recognition banking software medical diagnosis google search engine fuzzy logic controllers developed automatic gearboxes automobiles 2006 audi tt vw touareg vw caravell feature dsp transmission utilizes fuzzy logic number škoda variants škoda fabia also currently include fuzzy logic-based controller camera sensors widely utilize fuzzy logic enable focus heuristic search data analytics technologies developed evolutionary computing machine learning subdivision ai research community techniques applied wide range real world problems considerable commercial success data analytics technology utilizing algorithms automated formation classifiers developed supervised machine learning community 1990s example tdidt support vector machines neural nets ibl used pervasively companies marketing survey targeting discovery trends features data sets researchers economists frequently judged status ai winter reviewing ai projects funded much trends funding often set major funding agencies developed world currently darpa civilian funding program called eu-fp7 provide much funding ai research us european union 2007 darpa soliciting ai research proposals number programs including grand challenge program cognitive technology threat warning system ct2ws human assisted neural devices sn07-43 autonomous real-time ground ubiquitous surveillance-imaging system argus-is urban reasoning geospatial exploitation technology urgent perhaps best known darpa grand challenge program developed fully automated road vehicles successfully navigate real world terrain fully autonomous fashion darpa also supported programs semantic web great deal emphasis intelligent management content automated understanding however james hendler manager darpa program time expressed disappointment government ability create rapid change moved working world wide web consortium transition technologies private sector eu-fp7 funding program provides financial support researchers within european union 2007–2008 funding ai research cognitive systems interaction robotics programme €193m digital libraries content programme €203m fet programme €185m marked increase ai funding development deployment commercial use led idea ai winter long concerns occasionally raised new ai winter could triggered overly ambitious unrealistic promise prominent ai scientists overpromising part commercial vendors several explanations put forth cause ai winters general ai progressed government-funded applications commercial ones new dynamics came play hype commonly cited cause explanations necessarily mutually exclusive ai winters partly understood sequence over-inflated expectations subsequent crash seen stock-markets exemplified railway mania dotcom bubble common pattern development new technology known hype cycle event typically technological breakthrough creates publicity feeds create peak inflated expectations followed trough disillusionment since scientific technological progress ca n't keep pace publicity-fueled increase expectations among investors stakeholders crash must follow ai technology seems exception rule another factor ai place organisation universities research ai often takes form interdisciplinary research ai therefore prone problems types interdisciplinary research face funding channeled established departments budget cuts tendency shield core contents department expense interdisciplinary less traditional research projects downturns country national economy cause budget cuts universities core contents tendency worsen effect ai research investors market likely put money less risky ventures crisis together may amplify economic downturn ai winter worth noting lighthill report came time economic crisis uk universities make cuts question programs go early computing history potential neural networks understood never realized fairly simple networks require significant computing capacity even today standards common see relationship basic research technology pipeline advances basic research give birth advances applied research turn leads new commercial applications often argued lack basic research lead drop marketable technology years line view advanced james hendler 2008 claimed fall expert systems late '80s due inherent unavoidable brittleness expert systems funding cuts basic research 1970s expert systems advanced 1980s applied research product development end decade pipeline run dry expert systems unable produce improvements could overcome brittleness secured funding fall lisp machine market failure fifth generation computers cases expensive advanced products overtaken simpler cheaper alternatives fits definition low-end disruptive technology lisp machine makers marginalized expert systems carried new desktop computers instance clips fall lisp machine market fall expert systems strictly speaking two separate events still failure adapt change outside computing milieu cited one reason 1980s ai winter several philosophers cognitive scientists computer scientists speculated ai might failed lies future hubert dreyfus highlighted flawed assumptions ai research past early 1966 correctly predicted first wave ai research would fail fulfill public promises making critics like noam chomsky argued ai headed wrong direction part heavy reliance statistical techniques chomsky comments fit larger debate peter norvig centered around role statistical methods ai exchange two started comments made chomsky symposium mit norvig wrote response
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Programming language topics
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anti-worm anti-worm sometimes helpful worm computer worm designed something author feels helpful though necessarily permission executing computer owner concept anti-worm helpful worm proactive method dealing virus computer worm outbreaks type worm delivers payload helpful actions instead malicious actions like malicious computer worms anti-worms reach computers scanning ip ranges placing copy vulnerable hosts anti-worm patches computer vulnerability uses affected computer find vulnerable hosts anti-worms ability spread fast regular computer worms utilizing scan infect repeat model malicious computer worms use anti-worms used combat effects code red blaster santy worms welchia example helpful worm utilizing deficiencies exploited blaster worm welchia infected computers automatically began downloading microsoft security updates windows without users consent welchia automatically reboots computers infects installing updates one updates patch fixed exploit examples helpful worms den_zuko cheeze codegreen millenium santy worm released shortly christmas 2004 spread quickly using google search vulnerable versions phpbb worm exploited bug phpbb software infect host defacing website deleting messages stored forums worm poised spread hundreds thousands websites running phpbb forum approximately 10 days worm launch someone released another worm combat santy worm patch vulnerable phpbb forum anti-santy worm spread quickly affecting thousands servers running phpbb anti-santy worm however caused problems many site administrators reported anti-worm crashed systems flooding requests resulting denial-of-service attack still others reported patch work whether anti-worm significant positive impact curtailing spread santy worm unknown within several hours santy release google blocked search string worm using find vulnerable hosts thus worm could find new hosts infect way determine google actions anti-santy worm protect hosts many computer security experts denounced so-called anti-worm position code run system without system owner consent even though anything malicious helpful worms log events automatically reboot computer without user consent part installation process put strain network spread download updates worm code even author good intentions wreak havoc network overflow traffic capacity network author know exact configuration systems code run could render system useless intended purpose jurisdictions computer crime laws covering worms distinguish worms anti-worms though factors take account considering whether prosecute author code
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Computer security
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cross-application scripting cross-application scripting cas vulnerability affecting desktop applications n't check input exhaustive way cas allows attacker insert data modifies behaviour particular desktop application makes possible extract data inside users systems attackers may gain full privileges attacked application exploiting cas vulnerabilities attack degree independent underlying operating system hardware architecture initially discovered emanuele gentili presented two researchers alessandro scoscia emanuele acri participated study technique implications presented first time security summit 2010 milan format string attack similar concept attack cas could considered generalization attack method aspects technique previously demonstrated clickjacking techniques like web interfaces modern frameworks realization graphical applications particular gtk+ qt allow use tags inside widgets attacker gains possibility inject tags gains ability manipulate appearance behaviour application exactly phenomenon seen use cross-site scripting xss web pages kind behavior named cross-application scripting cas typically desktop applications get considerable amount input support large number features certainly web interface makes harder developer check whether input program might get untrusted sources filtered correctly cross-application scripting application equivalent xss web applications cross-application request forgery carf equivalent cross-site request forgery csrf desktop applications carf concept “ link ” “ protocol ” inherited web extended involves components graphical environment cases operating system exploiting vulnerabilities amenable csrf requires interaction user requirement n't particularly limiting user easily led execute certain actions graphical interface altered right way many misleading changes look applications obtained use cas new kind “ phishing ” whose dangerousness amplified lack tools detect kind attack outside websites emails contrast xss techniques manipulate later execute commands users browser cas possible talk directly operating system graphical interface
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Computer security
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itil security management itil security management originally information technology infrastructure library describes structured fitting security organization itil security management based iso 27001 standard iso/iec 27001:2005 covers types organizations e.g commercial enterprises government agencies not-for profit organizations iso/iec 27001:2005 specifies requirements establishing implementing operating monitoring reviewing maintaining improving documented information security management system within context organization overall business risks specifies requirements implementation security controls customized needs individual organizations parts thereof iso/iec 27001:2005 designed ensure selection adequate proportionate security controls protect information assets give confidence interested parties basic concept security management information security primary goal information security control access information value information must protected values include confidentiality integrity availability inferred aspects privacy anonymity verifiability goal security management comes two parts slas define security requirements along legislation applicable contracts requirements act key performance indicators kpis used process management interpreting results security management process security management process relates itil-processes however particular section obvious relations relations service level management incident management change management processes security management continuous process compared w. edwards deming quality circle plan check act inputs requirements clients requirements translated security services security metrics client plan sub-process affect sla sla input client process provider develops security plans organization plans contain policies operational level agreements security plans plan implemented implementation evaluated check evaluation plans plan implementation maintained act activities results/products process documented external reports written sent clients clients able adapt requirements based information received reports furthermore service provider adjust plan implementation based findings order satisfy requirements stated sla including new requirements first activity security management process “ control ” sub-process control sub-process organizes manages security management process control sub-process defines processes allocation responsibility policy statements management framework security management framework defines sub-processes development implementation evaluations action plans furthermore management framework defines results reported clients meta-process model control sub-process based uml activity diagram gives overview activities control sub-process grey rectangle represents control sub-process smaller beam shapes inside represent activities take place inside meta-data model control sub-process based uml class diagram figure 2.1.2 shows metamodel control sub-process figure 2.1.2 meta-process model control sub-process control rectangle white shadow open complex concept means control rectangle consists collection sub concepts figure 2.1.3 process data model control sub-process shows integration two models dotted arrows indicate concepts created adjusted corresponding activities figure 2.1.3 process-data model control sub-process plan sub-process contains activities cooperation service level management lead information security section sla furthermore plan sub-process contains activities related underpinning contracts specific information security plan sub-process goals formulated sla specified form operational level agreements ola ola ’ defined security plans specific internal organization entity service provider besides input sla plan sub-process also works policy statements service provider said earlier policy statements defined control sub-process operational level agreements information security set implemented based itil process requires cooperation itil processes example security management wishes change infrastructure order enhance security changes done change management process security management delivers input request change change change manager responsible change management process plan consists combination unordered ordered sub activities sub-process contains three complex activities closed activities one standard activity control sub-process plan sub-process modeled using meta-modeling technique left side figure 2.2.1 meta-data model plan sub-process plan rectangle open complex concept aggregation type relationship two closed complex concepts one standard concept two closed concepts expanded particular context following picture figure 2.2.1 process-data diagram plan sub-process picture shows integration two models dotted arrows indicate concepts created adjusted corresponding activities plan sub-process figure 2.2.1 process-data model plan sub-process implementation sub-process makes sure measures specified plans properly implemented implementation sub-process measures defined changed definition change measures takes place plan sub-process cooperation change management process left side figure 2.3.1 meta-process model implementation phase four labels black shadow mean activities closed concepts expanded context arrows connect four activities meaning activities unordered reporting carried completion four activities implementation phase concepts created /or adjusted concepts created and/or adjusted modeled using meta-modeling technique right side figure 2.3.1 meta-data model implementation sub-process implementation documents open concept expanded upon context consists four closed concepts expanded irrelevant particular context order make relations two models clearer integration two models illustrated figure 2.3.1 dotted arrows running activities concepts illustrate concepts created/ adjusted corresponding activities figure 2.3.1 process-data model implementation sub-process evaluation necessary measure success implementation security plans evaluation important clients possibly third parties results evaluation sub-process used maintain agreed measures implementation evaluation results lead new requirements corresponding request change request change defined sent change management three sorts evaluation self-assessment internal audit external audit self-assessment mainly carried organization processes internal audits carried internal it-auditors external audits carried external independent it-auditors besides already mentioned evaluation based communicated security incidents occurs important activities evaluation security monitoring it-systems verify security legislation security plan implementation trace react undesirable use it-supplies figure 2.4.1 process-data model evaluation sub-process process-data diagram illustrated figure 2.4.1 consists meta-process model meta-data model evaluation sub-process modeled using meta-modeling technique dotted arrows running meta-process diagram left meta-data diagram right indicate concepts created/ adjusted corresponding activities activities evaluation phase standard activities short description evaluation phase concepts see table 2.4.2 concepts listed defined table 2.4.2 concept definition evaluation sub-process security management organizational it-infrastructure changes security risks change time requiring revisions security section service level agreements security plans maintenance based results evaluation sub-process insight changing risks activities produce proposals proposals either serve inputs plan sub-process travel cycle adopted part maintaining service level agreements cases proposals could lead activities action plan actual changes made change management process figure 2.5.1 process-data diagram implementation sub-process picture shows integration meta-process model left meta-data model right dotted arrows indicate concepts created adjusted activities implementation phase figure 2.5.1 process-data model maintenance sub-process maintenance sub-process starts maintenance service level agreements maintenance operational level agreements activities take place particular order request change request change activity take place request change activity concluded reporting activity starts request change reporting activity start directly first two activities concepts meta-data model created/ adjusted maintenance phase list concepts definition take look table 2.5.2 table 2.5.2 concept definition plan sub-process security management figure 2.6.1 complete process-data model security management process security management process stated introduction relations almost itil-processes processes within processes activities concerning security required concerning process process manager responsible activities however security management gives indications concerning process structure activities internal e-mail subject multiple security risks requiring corresponding security plan policies example itil security management approach used implement e-mail policies security management team formed process guidelines formulated communicated employees providers actions carried control phase subsequent planning phase policies formulated policies specific e-mail security formulated added service level agreements end phase entire plan ready implemented implementation done according plan implementation policies evaluated either self-assessments via internal external auditors maintenance phase e-policies adjusted based evaluation needed changes processed via requests change
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Computer security
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md5deep md5deep software package used computer security system administration computer forensics communities run large numbers files several different cryptographic digests originally authored jesse kornblum time special agent air force office special investigations still maintains name md5deep misleading version 2.0 md5deep package contains several different programs able perform md5 sha-1 sha-256 tiger192 whirlpool digests named digest type followed word deep thus name may confuse people thinking provides md5 algorithm package supports many md5deep invoked several different ways typically users operate recursively md5deep walks one directory time giving digests file found recursing subdirectories within recursive behavior approximately depth-first search benefit presenting files lexicographical order unix-like systems similar functionality often obtained combining find hashing utilities md5sum sha256sum tthsum md5deep exists windows unix-based systems including os x present os x fink homebrew macports projects binary packages exist free unix systems many vendors initially resist including md5deep mistakenly believe functions reproduced one line shell scripting matching function program however done easily shell md5deep written employee u.s. government government time public domain software surrounding graphical front-ends may copyrighted
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Computer security
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local security authority subsystem service local security authority subsystem service lsass process microsoft windows operating systems responsible enforcing security policy system verifies users logging windows computer server handles password changes creates access tokens also writes windows security log forcible termination lsass.exe result welcome screen losing accounts prompting restart machine lsass.exe crucial system file name often faked malware lsass.exe file used windows located directory codice_1 running location lsass.exe likely virus spyware trojan worm due way systems display fonts malicious developers may name file something like isass.exe capital instead lowercase l efforts trick users installing executing malicious file instead trusted system file
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Operating systems
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linux malware linux malware includes viruses trojans worms types malware affect linux operating system linux unix unix-like computer operating systems generally regarded well-protected immune computer viruses 2018 yet single widespread linux virus malware infection type common microsoft windows attributable generally malware lack root access fast updates linux vulnerabilities like unix systems linux implements multi-user environment users granted specific privileges form access control implemented gain control linux system cause serious consequences system malware would gain root access system past suggested linux little malware low market share made less profitable target rick moen experienced linux system administrator counters 2008 quantity malware targeting linux noted increasing shane coursen senior technical consultant kaspersky lab said time growth linux malware simply due increasing popularity particularly desktop operating system ... use operating system directly correlated interest malware writers develop malware os tom ferris researcher security protocols commented one kaspersky reports stating people minds non-windows secure case think nobody writes malware linux mac os x necessarily true linux users run linux-based anti-virus software scan insecure documents email comes going windows users securityfocus scott granneman stated predominantly used mail servers may send mail computers running operating systems linux virus scanners generally use definitions scan known viruses computer platforms example open source clamav detects ... viruses worms trojans including microsoft office macro viruses mobile malware threats viruses listed pose potential although minimal threat linux systems infected binary containing one viruses run system would temporarily infected linux kernel memory resident read-only infection level would depend user privileges ran binary binary run root account would able infect entire system privilege escalation vulnerabilities may permit malware running limited account infect entire system worth noting true malicious program run without special steps taken limit privileges trivial add code snippet program user may download let additional code download modified login server open mail relay similar program make additional component run time user logs special malware writing skills needed special skill may needed tricking user run trojan program first place use software repositories significantly reduces threat installation malware software repositories checked maintainers try ensure repository malware-free subsequently ensure safe distribution software checksums made available make possible reveal modified versions may introduced e.g hijacking communications using man-in-the-middle attack via redirection attack arp dns poisoning careful use digital signatures provides additional line defense limits scope attacks include original authors package release maintainers possibly others suitable administrative access depending keys checksums handled reproducible builds ensure digitally signed source code reliably transformed binary application classical threat unix-like systems vulnerabilities network daemons ssh web servers used worms attacks specific targets servers patched quite quickly vulnerability found widespread worms kind specific targets attacked vulnerability publicly known guarantee certain installation secure also servers without vulnerabilities successfully attacked weak passwords linux servers may also used malware without attack system e.g web content scripts insufficiently restricted checked used malware attack visitors attacks use complicated malware attack linux servers get full root access hackers able attack modifying anything like replacing binaries injecting modules may allow redirection users different content web typically cgi script meant leaving comments could mistake allow inclusion code exploiting vulnerabilities web browser older linux distributions relatively sensitive buffer overrun attacks program care size buffer kernel provided limited protection allowing attacker execute arbitrary code rights vulnerable application attack programs gain root access even launched non-root user via setuid bit particularly attractive attack however 2009 kernels include address space layout randomization aslr enhanced memory protection extensions making attacks much difficult arrange area concern identified 2007 cross-platform viruses driven popularity cross-platform applications brought forefront malware awareness distribution openoffice.org virus called badbunny stuart smith symantec wrote following makes virus worth mentioning illustrates easily scripting platforms extensibility plug-ins activex etc abused often forgotten pursuit match features another vendor ... ability malware survive cross-platform cross-application environment particular relevance malware pushed via web sites long someone uses something like drop javascript infecter web server regardless platform case operating system linux vulnerable malware tricks user installing social engineering december 2009 malicious waterfall screensaver contained script used infected linux pc denial-of-service attacks discovered number anti-virus applications available run linux operating system applications looking exploits could affect users microsoft windows applications useful computers typically servers pass files ms windows users look linux-specific threats applications look actual threats linux computers running linux malware also detected analyzed using memory forensics tools following following partial list known linux malware however wild rendered obsolete linux updates never threat known malware even important threat new malware attacks directed specific sites use vulnerabilities previously unknown community unused malware
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Operating systems
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eddie kidd jump challenge eddie kidd jump challenge stunt bike video game released acorn electron bbc micro commodore 64 msx zx spectrum first released 1984 licensed british stunt performer eddie kidd player takes role eddie kidd must make series jumps like real kidd player must start jumping bmx oil barrels work jumping cars motorbike player starts riding away jump get big enough run must set correct speed correctly selecting gears hit ramp enough speed clear obstacles much miss landing ramp air player lean forward back land correctly game first released late 1984 zx spectrum published software communications martech label version ported msx 1985 similar version released bbc micro acorn electron modified version game much zoomed camera angle screen display released commodore 64 also 1985 game cassette came sticker numbered competition entry card could used win prizes including bmx bikes computers tvs game reissued budget price part mastertronic ricochet label 1987 crash gave game overall score 56 concluding good simulation game exciting particularly addictive difficulty curve criticised early bmx-based levels skipped described doddle skill mastered game holds challenge clare edgeley sinclair user agreed replay bmx section failing advanced jumps seems waste time gave similar score 6/10 computer video games gave scores 7/10 8/10 particularly praising zoomed graphics improved sound commodore 64 version calling superb outshining spectrum game miles
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Computer architecture
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automated similarity judgment program automated similarity judgment program asjp collaborative project applying computational approaches comparative linguistics using database word lists database open access consists 40-item basic-vocabulary lists well half world languages continuously expanded addition isolates languages demonstrated genealogical groups database includes pidgins creoles mixed languages constructed languages words database transcribed simplified standard orthography asjpcode database used estimate dates language families diverged daughter languages method related still different glottochronology determine homeland urheimat proto-language investigate sound symbolism evaluate different phylogenetic methods several purposes asjp originally developed means objectively evaluating similarity words meaning different languages ultimate goal classifying languages computationally based lexical similarities observed first asjp paper two semantically identical words compared languages judged similar showed least two identical sound segments similarity two languages calculated percentage total number words compared judged similar method applied 100-item word lists 250 languages language families including austroasiatic indo-european mayan muskogean asjp consortium founded around 2008 came involve around 25 professional linguists interested parties working volunteer transcribers and/or extending aid project ways main driving force behind founding consortium cecil h. brown søren wichmann daily curator project third central member consortium eric w. holman created software used project word lists used originally based 100-item swadesh list statistically determined subset 40 100 items produced good slightly better classificatory results whole list subsequently word lists gathered contain 40 items less attestations lacking papers published since 2008 asjp employed similarity judgment program based levenshtein distance ld approach found produce better classificatory results measured expert opinion method used initially ld defined minimum number successive changes necessary convert one word another change insertion deletion substitution symbol within levenshtein approach differences word length corrected dividing ld number symbols longer two compared words produces normalized ld ldn ldn divided ldnd two languages calculated dividing average ldn word pairs involving meaning average ldn word pairs involving different meanings second normalization intended correct chance similarity asjp uses following 40-word list similar swadesh–yakhontov list differences asjp version 2016 uses following symbols encode phonemes p b f v w 8 z c n r l z c j 5 k g x n q x h 7 l 4 g e e 3 u represent 7 vowels 34 consonants found standard qwerty keyboard
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Computational linguistics
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serializability concurrency control databases transaction processing transaction management various transactional applications e.g. transactional memory software transactional memory centralized distributed transaction schedule serializable outcome e.g. resulting database state equal outcome transactions executed serially i.e without overlapping time transactions normally executed concurrently overlap since efficient way serializability major correctness criterion concurrent transactions executions considered highest level isolation transactions plays essential role concurrency control supported general purpose database systems strong strict two-phase locking ss2pl popular serializability mechanism utilized database systems various variants since early days 1970s serializability theory provides formal framework reason analyze serializability techniques though mathematical nature fundamentals informally without mathematics notation introduced serializability used keep data data item consistent state serializability property transaction schedule history relates isolation property database transaction schedules serializable likely generate erroneous outcomes well known examples transactions debit credit accounts money related schedules serializable total sum money may preserved money could disappear generated nowhere violations possibly needed invariant preservations caused one transaction writing stepping erasing written another transaction become permanent database happen serializability maintained specific order transactions requested application enforced independently underlying serializability mechanisms mechanisms typically indifferent specific order generate unpredictable partial order typically compatible multiple serial orders transactions partial order results scheduling orders concurrent transactions data access operations depend many factors major characteristic database transaction atomicity means either commits i.e. operations results take effect database aborts rolled-back operations results effect database nothing semantics transaction real systems transactions abort many reasons serializability sufficient correctness schedules also need possess recoverability abort property recoverability means committed transactions read data written aborted transactions whose effects exist resulting database states serializability currently compromised purpose many applications better performance cases application correctness harmed compromising recoverability would quickly violate database integrity well transactions results external database schedule recoverability property recoverable schedule recovers aborts i.e. aborts harm integrity committed transactions resulting database false without recoverability likely integrity violations resulting incorrect database data need special typically manual corrective actions database implementing recoverability general form may result cascading aborts aborting one transaction may result need abort second transaction third results waste already partially executed transactions may result also performance penalty avoiding cascading aborts aca cascadelessness special case recoverability exactly prevents phenomena often practice special case aca utilized strictness strictness allows efficient database recovery failure note recoverability property needed even database failure occurs database recovery failure needed rather needed correctly automatically handle aborts may unrelated database failure recovery failure many applications unlike finances absolute correctness needed example retrieving list products according specification cases matter much product whose data updated short time ago appear list even meets specification typically appear list tried short time later commercial databases provide concurrency control whole range isolation levels fact controlled serializability violations order achieve higher performance higher performance means better transaction execution rate shorter average transaction response time transaction duration snapshot isolation example popular widely utilized efficient relaxed serializability method many characteristics full serializability still short unfit many situations another common reason nowadays distributed serializability relaxation see requirement availability internet products services requirement typically answered large-scale data replication straightforward solution synchronizing replicas updates database object including updates single atomic distributed transaction however many replicas transaction large may span enough number several computers networks likely unavailable thus transaction likely end abort miss purpose consequently optimistic replication lazy replication often utilized e.g. many products services google amazon yahoo like serializability relaxed compromised eventual consistency case relaxation done applications expected harmed technique classes schedules defined relaxed serializability properties either contain serializability class incomparable mechanisms enforce serializability need execute real time almost real time transactions running high rates order meet requirement special cases serializability sufficient conditions serializability enforced effectively utilized two major types serializability exist view-serializability conflict-serializability view-serializability matches general definition serializability given conflict-serializability broad special case i.e. schedule conflict-serializable also view-serializable necessarily opposite conflict-serializability widely utilized easier determine covers substantial portion view-serializable schedules determining view-serializability schedule np-complete problem class problems difficult-to-compute excessively time-consuming known solutions operations upon data read write write either insert modify delete two operations conflicting different transactions upon datum data item least one write pair conflicting operations conflict type either read-write write-read write-write conflict transaction second operation pair said conflict transaction first operation general definition conflicting operations also complex operations may consist several simple read/write operations requires noncommutative changing order also changes combined result operation needs atomic using proper system support order considered operation commutativity check example read-read operations commutative unlike read-write possibilities thus read-read conflict another complex example operations increment decrement counter write operations modify counter need considered conflicting write-write conflict type since commutative thus increment-decrement conflict e.g. already supported old ibm ims fast path precedence time order pairs conflicting non-commutative operations important checking equivalence serial schedule since different schedules consisting transactions transformed one another changing orders different transactions operations different transactions interleaving since changing orders commutative operations non-conflicting change overall operation sequence result i.e. schedule outcome outcome preserved order change non-conflicting operations typically conflicting operations change order means schedule transformed serial schedule without changing orders conflicting operations changing orders non-conflicting preserving operation order inside transaction outcome schedules schedule conflict-serializable definition conflicts reason blocking transactions delays non-materialized conflicts aborting transactions due serializability violation prevention possibilities reduce performance thus reducing number conflicts e.g. commutativity possible way increase performance transaction issue/request conflicting operation conflict another transaction conflicting operation delayed executed e.g. blocked lock executed materialized conflicting operations relevant conflict serializability see schedule compliance conflict serializability tested precedence graph serializability graph serialization graph conflict graph committed transactions schedule directed graph representing precedence transactions schedule reflected precedence conflicting operations transactions following observation key characterization conflict serializability cycles committed transactions prevented aborting undecided neither committed aborted transaction cycle precedence graph transactions otherwise turn cycle committed transactions committed transaction aborted one transaction aborted per cycle required sufficient number break eliminate cycle aborts possible happen mechanisms unnecessary serializability probability cycle generation typically low nevertheless situation carefully handled typically considerable amount overhead since correctness involved transactions aborted due serializability violation prevention restarted executed immediately serializability-enforcing mechanisms typically maintain precedence graph data structure rather prevent break cycles implicitly e.g. ss2pl strong strict two-phase locking ss2pl common mechanism utilized database systems since early days 1970s ss name ss2pl newer though enforce conflict serializability strictness special case recoverability allows effective database recovery failure schedule mechanism datum locked transaction accessing read write operation item marked associated lock certain type depending operation performed specific transaction implementation various models different lock types exist models locks may change type transaction life result access another transaction may blocked typically upon conflict lock delays completely prevents conflict materialized reflected precedence graph blocking conflicting operation depending lock type transaction access operation type employing ss2pl mechanism means locks data behalf transaction released transaction ended either committed aborted ss2pl name resulting schedule property well also called rigorousness ss2pl special case proper subset two-phase locking 2pl mutual blocking transactions results deadlock execution transactions stalled completion reached thus deadlocks need resolved complete transactions execution release related computing resources deadlock reflection potential cycle precedence graph would occur without blocking conflicts materialized deadlock resolved aborting transaction involved potential cycle breaking cycle often detected using wait-for graph graph conflicts blocked locks materialized also defined graph non-materialized conflicts conflicts materialized reflected precedence graph affect serializability indicates transaction waiting release one locks transaction transactions cycle graph means deadlock aborting one transaction per cycle sufficient break cycle transactions aborted due deadlock resolution restarted executed immediately known mechanisms include conflict serializability techniques general form provide recoverability special enhancements needed adding recoverability concurrency control techniques three major types main differences technique types conflict types generated pessimistic method blocks transaction operation upon conflict generates non-materialized conflict optimistic method block generates materialized conflict semi-optimistic method generates conflict types conflict types generated chronological orders transaction operations invoked independently type conflict cycle committed transactions materialized conflicts precedence graph conflict graph represents serializability violation avoided maintaining serializability cycle non-materialized conflicts wait-for graph represents deadlock situation resolved breaking cycle cycle types result conflicts broken technique type conflicts detected considered similar overhead materialized non-materialized conflicts typically using mechanisms like locking either blocking locks blocking recording conflict materialized conflicts blocking method typically context switching occurs upon conflict additional incurred overhead otherwise blocked transactions related computing resources remain idle unutilized may worse alternative conflicts occur frequently optimistic methods typically advantage different transaction loads mixes transaction types one technique type i.e. either optimistic pessimistic may provide better performance unless schedule classes inherently blocking i.e. implemented without data-access operations blocking e.g. 2pl ss2pl sco see chart also implemented using optimistic techniques e.g. serializability recoverability multi-version concurrency control mvcc common way today increase concurrency performance generating new version database object time object written allowing transactions read operations several last relevant versions object depending scheduling method mvcc combined serializability techniques listed except serializablesi originally mvcc-based utilized general-purpose dbms products mvcc especially popular nowadays relaxed serializability see method snapshot isolation si provides better performance known serializability mechanisms cost possible serializability violation certain cases serializablesi efficient enhancement si make serializable intended provide efficient serializable solution serializablesi analyzed via general theory mvcc distributed serializability serializability schedule transactional distributed system e.g. distributed database system system characterized distributed transactions also called global transactions i.e. transactions span computer processes process abstraction general sense depending computing environment e.g. operating system thread possibly network nodes distributed transaction comprises one several local sub-transactions states described database transaction local sub-transaction comprises single process processes typically fail together e.g. single processor core distributed transactions imply need atomic commit protocol reach consensus among local sub-transactions whether commit abort protocols vary simple one-phase handshake among processes fail together sophisticated protocols like two-phase commit handle complicated cases failure e.g. process node communication etc failure distributed serializability major goal distributed concurrency control correctness proliferation internet cloud computing grid computing small portable powerful computing devices e.g. smartphones need effective distributed serializability techniques ensure correctness among distributed applications seems increase distributed serializability achieved implementing distributed versions known centralized techniques typically distributed versions require utilizing conflict information either materialized non-materialized conflicts equivalently transaction precedence blocking information conflict serializability usually utilized generated locally rather different processes remote locations thus information distribution needed e.g. precedence relations lock information timestamps tickets distributed system relatively small scale message delays across system small centralized concurrency control methods used unchanged certain processes nodes system manage related algorithms however large-scale system e.g. grid cloud due distribution information substantial performance penalty typically incurred even distributed versions methods vs. centralized ones used primarily due computer communication latency also information distributed related techniques typically scale well well-known example respect scalability problems distributed lock manager distributes lock non-materialized conflict information across distributed system implement locking techniques
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Databases
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aiccu aiccu automatic ipv6 connectivity client utility popular cross-platform utility automatically configuring ipv6 tunnel free software available bsd license utility originally provided sixxs tunnel broker also used variety tunnel brokers aiccu written maintained jeroen massar various patches persons incorporated persons acknowledged field contributions aiccu successor windows-only linux/bsd-variety heartbeat tool provided sixxs solely use heartbeat protocol ayiya protocol came existence decided support new protocol would better merge windows unix trees one program give better appearance name heartbeat tool changed reflect providing mere support heartbeats aiccu award excellence implementation category 2004 edition ipv6 application contest following tunneling protocols currently supported aiccu primarily uses tic protocol retrieve configuration parameters tunnel automatically user wants configured aiccu finds available tunnel brokers looking txt dns records _aiccu.sixxs.net latter allows local network add tunnel broker adding records domains configured search path non-local tunnel brokers added requesting sixxs staff add entry global dns records following operating systems/platforms/distributions supported aiccu various distributions aiccu package included distribution main usage aiccu combination sixxs tunnel broker service isps implemented parts protocols aiccu support instance czech isp netbox uses aiccu configure tunnels automatically users providing tic tunnel information control protocol implementation ignores username/password/tunnel_id uses source address tic connection originates determine return tunnel configuration using tic protocol aiccu uses configure tunnel
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Internet protocols
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empress embedded database empress embedded database relational database management system embedded applications including medical systems network routers nuclear power plant monitors satellite management systems empress acid compliant relational database management system rdbms two-phase commit several transaction isolation levels real-time embedded applications supports persistent in-memory storage data works text binary multimedia well traditional data first version empress created john kornatowski ivor ladd 1979 originally named mistress based research done mrs microcomputer database management system university toronto published association computing machinery sigsmall sigmod 1981 commercial version one first available relational database management systems rdbms named empress first customer ship early 1981 empress first commercial database available linux linux release dates back early 1995 empress supports many application programming interfaces several programming languages c programming language apis including low-level kernel mr routines embedded sql mscall odbc also apis c++ java layered architecture design provides levels system optimization application development applications developed using apis may run standalone and/or server modes empress runs major android linux- real-time- windows-supported platforms
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Databases
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analog program analog free web log analysis computer program runs windows mac os linux unix-like operating systems first released june 21 1995 stephen turner generic freeware license changed gnu general public license november 2004 software downloaded several computing platforms source code downloaded compiled desired analog support 35 languages provides ability reverse dns lookups log files indicate web site hits originate analyze several different types web server logs including apache iis iplanet 200 configuration options generate 32 reports also supports log files multiple virtual hosts program comparable webalizer awstats though use many images preferring stick simple bar charts lists communicate similar information analog export reports number formats including html xhtml xml latex delimited output mode example csv importing programs delimited computer output analog often used generate structured graphically rich reports using third party report magic program popularity analog largely unknown download count information released historic dissemination 1998 survey graphic visualization usability center gvu analog reportedly used 24.9 19.9 year nearest rival web trends holding 20.3 market clear analog usage changed decade leading 2010 usage profile impacted on-line analysis services google analytics analog operate individual web-farm basis single process requiring modification web page web script code order use stand-alone utility possible visiting clients block logging traffic directly client analog officially updated since version 6.0 release december 2004 original author moved commercial traffic analysis updates analog continued informally user community end 2009 official mailing list currently formally compiled updated redistributable analog analog ce focused fixing issues analog xml dtd adding new operating system web browser detection original code branch analog first released june 1995 research project creator dr. stephen turner working research fellow sidney sussex college university cambridge larger release milestones include full list changes release recorded analog new changelog full list changes maintenance release recorded analog c amie edition page
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Web technology
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toi programming language toi imperative type-sensitive language provides basic functionality programming language language designed developed ground-up paul longtine written c toi created intent educational experience serves learning tool toy hence name looking familiarize inner-workings programming language 0 void null data runtime context keeps track individual threads metadata context gives definition 'environment code executed key part operational computer language notion 'namespace notion 'namespace refers ability declare name along needed metadata call upon name retrieve values associated name definition namespace provide following key mechanisms scope argument single byte format follows scopes handled referencing either global scope local scope local scope denoted 0 scope argument referring names scope initialized evaluating new block code different block code called new scope added new namespace level namespace levels act context switches within function contexts example local namespace must 'returned local namespace context needs preserved return pushing 'namespace levels ensures every n function calls traverse n instances previous namespaces example take namespace level graphic level namespace instance function called another namespace level created local level increases like global scope names lsb == 1 scope argument persistent runtime handle function definitions objects names declared global scope local level references scope argument 0 refer accessing names namespace argument refers namespace variable exists namespace argument equals 0 current namespace referenced global namespace 1 default namespaces must declared using variables definition provide following mechanisms given variable v v defines following attributes variable handled generic container previous section notion namespace levels introduced much like names scoped generic variable containers must communicate scope terms location within given set scopes called 'ownership given runtime variable containers exist following structures stack instance bytecode arguments namespaces concept ownership differentiates variables existing one structures set place prevent accidental deallocation variable containers copied instead passed references structures functions virtual machine pointer set instructions program metadata parameters defined paradigm objects units encapsulate separate namespace collection methods bytecode arranged following order opcode single byte denoting subroutine call following arguments executed different opcodes different argument lengths 0 arguments others 3 arguments bytecode instruction single-byte opcode followed maximum 3 arguments following forms specification instructions short description instruction instruction category keywords 1 stack manipulation 2 variable management 3 type management types air moment 'll detail types time comes 4 binary ops ops take two top elements stack perform operation push result stack 5 conditional expressions things comparison forth behaves like arithmetic instructions besides instruction pushes boolean tos 6 loops 7 code flow instructions dictate code flow 8 generic object interface expects object tos f functions/classes 0 special bytes going code bytecode section first abstract notation code broken binary tree node argument parent node next instruction instruction nodes nodes produce instruction multiple based bytecode interpretation instruction example line code would translate functions expressed individual binary trees root file treated individual binary tree also function various instruction nodes follows various instruction nodes within tree call specific functions take arguments specified lookahead lookbehind formulate correct bytecode equivalent developer language paul longtine operates publicly available website blog called banna.tech named online alias 'banna
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Programming language topics
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lga 2066 lga 2066 also called socket r4 cpu socket intel debuted skylake-x kaby lake-x cascade lake-x processors june 2017 2018 replaces intel lga 2011-3 r3 performance high-end desktop workstation platforms based x299 basin falls c422 chipsets lga 3647 socket p replace lga 2011-3 r3 server platforms based skylake-sp xeon purley desktop processors lga 2066 socket listed table
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Computer architecture
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openbsd journal openbsd journal online newspaper dedicated coverage openbsd software related events openbsd journal founded 2000 operated 1 april 2004 1 april 2004 editors james phillips jose nazario announced site ceased operation daniel hartmeier backed contents journal order preserve investigation articles structure lead creation cgi-based engine would enable access deadly.org content backup server consequently functionality adding new articles implemented previous editors allowed re-publish articles openbsd journal therefore reintroduced 9 april 2004 openbsd journal widely recognized openbsd-related information primary reporter events hackathons site also hosts openbsd developers blogs current editors openbsd journal
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Operating systems
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opsource opsource inc. cloud managed services hosting company headquartered santa clara california company also offices ashburn virginia ireland india data centers california virginia united kingdom opsource part ict company dimension data acquired opsource 2011 cloud business unit 2002 michael piacente dan rasmussen john rowell treb ryan founded opsource sunnyvale california company initially began provide application support microsoft hotmail product customers 2005 term software service saas becoming popular opsource began focus saas helping isvs focus software development marketing sales part product opsource created saas enablement product helped isvs adobe business objects bmc take product market created saas incubation program small businesses 2006 opsource launched annual saas summit conference held san francisco area since 2010 event renamed cloud presented conjunction software information industry association 2009 opsource released cloud computing service bills utility computing basis opsource received 56.5m funding artiman ventures crosslink capital intel capital key venture partners ntt nippon telegraph telephone corporation velocity mark spagnolo past ceo uunet flag telecom universal access metromedia fiber network chairman board opsource acquired dublin ireland based lecayla technologies 2008 founded 2004 lecayla technologies metering billing services allowed isvs offer software applications utility perpetual licensing hybrid pricing basis june 30 2011 opsource inc. acquired dimension data holdings named steve nola ceo dimension data cloud solutions new division included opsource opsource two main products managed hosting cloud computing managed hosting dedicated hosting service support multiple applications operating systems databases originally called optimal on-demand services designed support software service market opsource offers 100 uptime guarantee customers host applications managed hosting product cloud computing delivered infrastructure service offering cloud computing customers physical infrastructure instead avoiding capital expenditure renting usage third-party provider consume resources service pay resources use utility computing model paying services consumed opsource cloud offers 100 network uptime 1ms intra network latency guarantee opsource cloud product competes similar offerings rackspace amazon ibm service levels receive support via usual means e-mail telephone ticket systems designed fit needs different businesses 2010 always demand top 100 category winner br 2010 top 20 coolest cloud vendors
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Distributed computing architecture
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svi-728 svi-728 first home computer spectravideo complied fully msx home computer specification introduced 1985 design virtually identical earlier sv-328 comply fully msx standard svi-738 portable version computer
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Computer architecture
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khtml khtml browser engine developed kde project engine used konqueror web browser although seen significant development since 2016 still actively maintained engines descended khtml used world widely used browsers among google chrome safari opera vivaldi microsoft edge switch chromium distributed terms gnu lesser general public license khtml free software built kparts framework written c++ khtml relatively good support web standards render many pages possible extra abilities quirks internet explorer also supported even though non-standard khtml preceded earlier engine called khtmlw kde html widget developed torben weis martin jones implemented support html 3.2 http 1.0 html frames w3c dom css scripting khtml came existence november 4 1998 copy khtmlw library slight refactoring addition unicode support changes support move qt 2 waldo bastian among work creating early version khtml real work khtml actually started may october 1999 realization choice facing project either significant effort move khtml forward use mozilla adding support scripting highest priority may 1999 lars knoll began research eye toward implementing w3c dom specification finally announcing august 16 1999 checked amounted complete rewrite khtml library — changing khtml use standard w3c dom internal document representation turn allowed beginnings javascript support added october 1999 integration harri porten kjs following shortly afterwards closing months 1999 first months 2000 knoll work antti koivisto dirk mueller add css support refine stabilize khtml architecture work completed march 2000 among things changes enabled khtml become second browser internet explorer correctly support hebrew arabic languages written right-to-left — mozilla support kde 2.0 first kde release october 23 2000 include khtml rendering engine new konqueror file web browser replaced monolithic kde file manager ksvg first developed 2001 nikolas zimmermann rob buis however 2003 decided fork then-current ksvg implementation two new projects kdom/ksvg2 improve state dom rendering khtml underneath formidable svg 1.0 render state kcanvas abstract rendering done within khtml/ksvg2 single shared library multiple backends e.g. cairo/qt etc. ksvg2 also part webkit following standards supported khtml engine khtml kjs adopted apple 2002 use safari web browser apple publishes source code fork khtml engine called webkit 2013 google began development fork webkit called blink
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Web technology
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phyllis fox phyllis ann fox american mathematician computer scientist fox raised colorado undergraduate studies wellesley college earning b.a mathematics 1944 1944 1946 worked general electric operator differential analyser project earned second baccalaureate b.s electrical engineering university colorado 1948 moved graduate studies massachusetts institute technology earning m.s 1949 electrical engineering doctorate sc.d mathematics 1954 supervision chia-chiao lin time also worked assistant whirlwind project mit jay forrester 1954 1958 fox worked numerical solution partial differential equations univac computing center united states atomic energy commission courant institute mathematical sciences new york university 1958 following husband returned forester system dynamics research group mit became part team wrote dynamo programming language became collaborator first lisp interpreter principal author first lisp manual 1963 moved mit newark college engineering became full professor 1972 time also consulted bell labs moved 1973 work highly portable numerics library port retired bell labs 1984
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Programming language topics
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android ice cream sandwich android ice cream sandwich ninth version android mobile operating system developed google unveiled october 19 2011 android 4.0 builds upon significant changes made tablet-only release android honeycomb effort create unified platform smartphones tablets android 4.0 focused simplifying modernizing overall android experience around new set human interface guidelines part efforts introduced new visual appearance codenamed holo built around cleaner minimalist design new default typeface named roboto also introduced number new features including refreshed home screen near-field communication nfc support ability beam content another user using technology updated web browser new contacts manager social network integration ability access camera control music playback lock screen visual voicemail support face recognition device unlocking face unlock ability monitor limit mobile data usage internal improvements android 4.0 received positive reviews critics praised cleaner revamped appearance operating system comparison previous versions along improved performance functionality however critics still felt android 4.0 stock apps still lacking quality functionality comparison third-party equivalents regarded operating system new features particularly face unlock feature gimmicks statistics issued google indicate 0.3 android devices accessing google play run ice cream sandwich following tablet-only release honeycomb announced google i/o 2011 next version android code named ice cream sandwich ics would emphasized providing unified user experience smartphones tablets june 2011 details also began surface surrounding new nexus phone samsung accompany ics would notably exclude hardware navigation keys android blog rootzwiki released photos august 2011 showing nexus running build ics depicting new application menu layout resembling honeycomb new interface blue-colored accenting official launch event android 4.0 new nexus phone originally scheduled october 11 2011 ctia trade show san diego however respect death apple co-founder steve jobs google samsung postponed event october 19 2011 hong kong android 4.0 launch device galaxy nexus officially unveiled october 19 2011 andy rubin explained 4.0 intended provide enticing intuitive user experience across smartphones tablets matias duarte google vice president design explained development ice cream sandwich based around question soul new machine user studies concluded existing android interface complicated thus prevented users empowered devices overall visual appearance android streamlined ice cream sandwich building upon changes made tablet-oriented android 3.0 first project google duarte admitted team cut back support smaller screens honeycomb prioritize sufficient tablet support wanted android oems stop silly things like taking phone ui stretching 10-inch tablet judging android major competitors duarte felt interface ios skeuomorphic kitschy windows phone metro design language looked much like airport lavatory signage operating systems tried hard enforce conformity without leaving room content express ice cream sandwich team aimed provide interface design guidelines would evoke modern appearance still allowing flexibility application developers characterized revised look ice cream sandwich toned geeky nerd quotient comparison honeycomb carried futuristic appearance compared critics aesthetics tron january 2012 following official launch ice cream sandwich duarte google launched android design portal features human interface guidelines best practices resources developers building android apps designed ice cream sandwich galaxy nexus first android device ship android 4.0 android 4.0.3 released december 16 2011 providing bug fixes new social stream api internal improvements day google began rollout ice cream sandwich predecessor galaxy nexus nexus s. however december 20 2011 nexus roll-out paused company could monitor feedback related update march 29 2012 android 4.0.4 released promising performance improvements camera screen rotation bug fixes google play services support 4.0 ended february 2019 user interface android4.0 represents evolution design introduced honeycomb although futuristic aesthetics honeycomb scaled back favor flatter cleaner feel neon blue accenting hard edges drop shadows depth ice cream sandwich also introduces new default system font roboto designed in-house replace droid font family roboto primarily optimized use high-resolution mobile displays new visual appearance ice cream sandwich implemented widget toolkit known holo ensure access holo style across devices—even use customized interface skin elsewhere android devices certified ship google play store formerly android market must provide capability apps use unmodified holo theme honeycomb devices render navigation buttons— back home recent apps —on system bar across bottom screen removing need physical equivalents menu button present previous generations android devices deprecated favor presenting buttons actions within apps action bars menu items fit bar action overflow menus designated three vertical dots hardware search buttons also deprecated favor search buttons within action bars devices without menu key temporary menu key displayed on-screen running apps coded support new navigation scheme devices use hardware menu key action overflow buttons hidden apps mapped menu key default home screen ice cream sandwich displays persistent google search bar across top screen dock across bottom containing app drawer button middle four slots app shortcuts alongside folders apps formed dragging app hovering another app drawer split two tabs one apps latter holding widgets placed home screen pages widgets resizable contain scrolling content android4.0 contains increased use swiping gestures apps notifications removed recent apps menu dismissed notifications area sliding away number stock google apps use new form tabs users navigate different panes either tapping name strip swiping left right phone app updated holo design ability send pre-configured text message responses response incoming calls visual voicemail integration within call log display web browser app incorporates updated versions webkit v8 supports syncing google chrome override mode loading desktop-oriented version website rather mobile-oriented version well offline browsing contacts section phone app split new people app offers integration social networks google+ display recent posts synchronize contacts profile device user camera app redesigned reduction shutter lag face detection new panorama mode ability take still photos video recorded camcorder mode photo gallery app contains basic photo editing tools lock screen supports face unlock includes shortcut launching camera app house playback controls music players keyboard incorporates improved autocomplete algorithms improvements voice input allow continuous dictation ability take screenshots holding power volume buttons together also added devices supporting near-field communication nfc android beam allows users share links content compatible apps holding back device back another nfc-equipped android device tapping screen prompted certain system apps particularly pre-loaded carriers uninstalled disabled hides application prevents launching application removed storage android4.0 introduced features managing data usage mobile networks users display total amount data used period time display data usage per-app background data usage disabled globally per-app basis cap set automatically disable data usage reaches certain quota calculated device android 4.0 inherits platform additions honeycomb also adds support ambient temperature humidity sensors bluetooth health device profile near-field communication nfc wi-fi direct operating system also provides improved support stylus mouse input along new accessibility calendar keychain spell checking social networking virtual private network apis multimedia support android4.0 also adds support adts aac matroska containers vorbis vp8 webp streaming vp8 openmax al http live streaming 3.0 android4.0 released positive reception ars technica praised holo user interface sense identity visual coherence previously lacking comparison previous versions android also believing new interface style could help improve quality third-party apps stock apps android4.0 also praised slightly better functionality comparison previous versions features noted improvements text voice input along data usage controls especially given increasing use metered data plans overall performance improvements comparison gingerbread however face unlock feature panned insecure gimmick although providing improved experience previous version stock applications email client panned still inferior third-party alternatives engadget also acknowledged maturing quality android experience ice cream sandwich praised modern feel new interface comparison android 2.3 along new features provided google stock apps operating system conclusion engadget felt android4.0 gorgeous os offers great performance and—for part—does n't feel like half-baked effort however engadget still felt android4.0 new features face unlock beta feel noted lack facebook integration new people app operating system still intuitive new users competitors pc magazine acknowledged influence windows phone 7 new people app improved benchmark performance web browser considered android beam face unlock gimmicks criticized lack support certain apps adobe flash launch
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Operating systems
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xcoff xcoff extended coff improved expanded version coff object file format defined ibm used aix early versions powerpc macintosh also supported xcoff beos xcoff additions include use csects provide subsection granularity cross-references use stabs debugging information handling shared libraries also elaborate plain coff recently ibm defined xcoff64 version supporting 64-bit aix used xcoff32 mean original file format
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Operating systems
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alexander petrov hacker alexander petrov two men responsible ddos hire extortion multinational law enforcement group british american russian private individuals law enforcement agents captured alexander petrov two accomplices ivan maksakov denis stepanov three heading extortion ring extorting money various online services e.g banks internet casinos web based businesses reportedly damages caused ring millions dollars range october 8 2007 petrov maksakov stenanov found guilty sentenced eight years prison russian federation 100,000 ruble penalty
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Computer security
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robot operating system robot operating system ros ros robotics middleware i.e collection software frameworks robot software development although ros operating system provides services designed heterogeneous computer cluster hardware abstraction low-level device control implementation commonly used functionality message-passing processes package management running sets ros-based processes represented graph architecture processing takes place nodes may receive post multiplex sensor data control state planning actuator messages despite importance reactivity low latency robot control ros real-time os rtos possible however integrate ros real-time code lack support real-time systems addressed creation ros 2.0 major revision ros api take advantage modern libraries technologies core ros functionality add support real-time code embedded hardware software ros ecosystem separated three groups language-independent tools main client libraries c++ python lisp released terms bsd license open source software free commercial research use majority packages licensed variety open source licenses packages implement commonly used functionality applications hardware drivers robot models datatypes planning perception simultaneous localization mapping simulation tools algorithms main ros client libraries geared toward unix-like system primarily dependence large collections open-source software dependencies client libraries ubuntu linux listed supported variants fedora linux macos microsoft windows designated experimental supported community native java ros client library rosjava however share limitations enabled ros-based software written android os rosjava also enabled ros integrated officially supported matlab toolbox used linux macos microsoft windows javascript client library roslibjs also developed enables integration software ros system via standards-compliant web browser sometime 2007 first pieces eventually would become ros beginning come together stanford university eric berger keenan wyrobek phd students working kenneth sailsbury robotics laboratory stanford leading personal robotics program working robots manipulation tasks human environments two students noticed many colleagues held back diverse nature robotics excellent software developer might hardware knowledge required someone developing state art path planning might know computer vision required attempt remedy situation two students set make baseline system would provide starting place others academia build upon words eric berger “ something ’ suck different dimensions ” first steps towards unifying system two build pr1 hardware prototype began work software borrowing best practices early open source robotic software frameworks particularly switchyard system morgan quigley another stanford phd student working support stair stanford artificial intelligence robot stanford artificial intelligence laboratory early funding us 50,000 provided joanna hoffman alain rossmann supported development pr1 seeking funding development eric berger keenan wyrobek met scott hassan founder willow garage technology incubator working autonomous suv solar autonomous boat hassan shared berger wyrobek vision “ linux robotics ” invited come work willow garage willow garage started january 2007 first commit ros code made sourceforge seventh november 2007 willow garage began developing pr2 robot follow-up pr1 ros software run groups twenty institutions made contributions ros core software growing number packages worked ros form greater software ecosystem fact people outside willow contributing ros particularly stanford stair project meant ros multi-robot platform beginning willow garage originally projects progress scrapped favor personal robotics program focused producing pr2 research platform academia ros open source robotics stack would underlie academic research tech startups much like lamp stack web-based startups december 2008 willow garage met first three internal milestones continuous navigation pr2 period two days distance pi kilometers soon early version ros 0.4 mango tango released followed first rviz documentation first paper ros early summer second internal milestone pr2 navigate office open doors plug reached followed august initiation ros.org website early tutorials ros posted december preparing release ros 1.0 january 2010 milestone 3 producing tons documentation tutorials enormous capabilities willow garage engineers developed preceding 3 years following willow garage achieved one longest held goals giving away 10 pr2 robots worthy academic institutions long goal founders felt pr2 could kick-start robotics research around world ended awarding eleven pr2s different institutions including university freiburg germany bosch georgia tech ku leuven belgium mit stanford tu munich germany uc berkeley u penn usc university tokyo japan combined willow garage highly successful internship program run 2008 2010 melonee wise helped spread word ros throughout robotics world first official ros distribution release ros box turtle released march 2nd 2010 marking first time ros official distributed set versioned packages public use developments lead first drone running ros first autonomous car running ros adaption ros lego mindstorms pr2 beta program well underway pr2 robot officially released commercial purchase september 9th 2010 2011 banner year ros launch ros answers q/a forum ros users february 15th introduction highly successful turtlebot robot kit april 18th total number ros repositories passing 100 may 5th willow garage began 2012 creating open source robotics foundation osrf april osrf immediately awarded software contract darpa later year first roscon held st. paul mn first book ros ros example published baxter first commercial robot run ros announced rethink robotics soon passing fifth anniversary november ros began running every continent december 3rd 2012 february 2013 osrf became primary software maintainers ros foreshadowing announcement august willow garage would absorbed founders suitable technologies point ros released seven major versions ros groovy users globe chapter ros development would finalized clearpath robotics took support responsibilities pr2 early 2014 years since osrf took primary development ros new version released every year interest ros continues grow roscons occurred every year since 2012 co-located either icra iros two flagship robotics conferences meetups ros developers organized variety countries number ros books published many educational programs initiated september 1st 2014 nasa announced first robot run ros space robotnaut 2 international space station 2017 osrf changed name open robotics tech giants amazon microsoft began take interest ros time microsoft porting core ros windows september 2018 followed amazon web services releasing robomaker november perhaps important development osrf/open robotics years thus far discount explosion robot platforms began support ros enormous improvements ros version proposal ros2 significant api change ros intended support real time programming wider variety computing environments utilize modern technology ros2 announced roscon 2014 first commits ros2 repository made february 2015 followed alpha releases august 2015 first distribution release ros2 ardent apalone released december 8th 2017 ushering new era next-generation ros development ros designed open-source mind intending users would able choose configuration tools libraries interacted core ros users could shift software stacks fit robot application area little actually core ros beyond general structure within programs must exist communicate one sense ros underlying plumbing behind nodes message passing however reality ros plumbing rich mature set tools wide-ranging set robot-agnostic capabilities provided packages greater ecosystem additions ros ros processes represented nodes graph structure connected edges called topics ros nodes pass messages one another topics make service calls nodes provide service nodes set retrieve shared data communal database called parameter server process called ros master makes possible registering nodes setting node-to-node communication topics controlling parameter server updates messages service calls pass master rather master sets peer-to-peer communication node processes register master decentralized architecture lends well robots often consist subset networked computer hardware may communicate off-board computers heavy computation commands node represents single process running ros graph every node name registers ros master take actions multiple nodes different names exist different namespaces node defined anonymous case randomly generate additional identifier add given name nodes center ros programming ros client code form ros node takes actions based information received nodes sends information nodes sends receives requests actions nodes topics named buses nodes send receive messages topic names must unique within namespace well send messages topic node must publish said topic receive messages must subscribe publish/subscribe model anonymous node knows nodes sending receiving topic sending/receiving topic types messages passed topic vary widely user-defined content messages sensor data motor control commands state information actuator commands anything else node may also advertise services service represents action node take single result services often used actions defined beginning end capturing single-frame image rather processing velocity commands wheel motor odometer data wheel encoder nodes advertise services call services one another parameter server database shared nodes allows communal access static semi-static information data change frequently infrequently accessed distance two fixed points environment weight robot good candidates storage parameter server ros core functionality augmented variety tools allow developers visualize record data easily navigate ros package structures create scripts automating complex configuration setup processes addition tools greatly increases capabilities systems using ros simplifying providing solutions number common robotics development tools provided packages like algorithm rather providing implementations hardware drivers algorithms various robotic tasks packages provide task robot-agnostic tools come core modern ros installations rviz three-dimensional visualizer used visualize robots environments work sensor data highly configurable tool many different types visualizations plugins rosbag command line tool used record playback ros message data rosbag uses file format called bags log ros messages listening topics recording messages come playing messages back bag largely original nodes produced data ros computation graph making bags useful tool recording data used later development rosbag command line tool rqt_bag provides gui interface rosbag catkin ros build system replaced rosbuild ros groovy catkin based cmake similarly cross-platform open source language-independent rosbash package provides suite tools augment functionality bash shell tools include rosls roscd roscp replicate functionalities ls cd cp respectively ros versions tools allow users use ros package names place filepath package located package also adds tab-completion ros utilities includes rosed edits given file chosen default text editor well rosrun runs executes ros packages rosbash supports functionalities zsh tcsh lesser extent roslaunch tool used launch multiple ros nodes locally remotely well setting parameters ros parameter server roslaunch configuration files written using xml easily automate complex startup configuration process single command roslaunch scripts include roslaunch scripts launch nodes specific machines even restart processes die execution ros contains many open source implementations common robotics functionality algorithms open source implementations organized packages many packages included part ros distributions others may developed individuals distributed code sharing sites github packages note include ros releases may incompatible releases often referred code name rather version number ros currently releases version every year may odd numbered years release supported two years even numbered years release designated long-term support release supported five years loosely follows ubuntu release cycle ros2 currently releases new version every six months december july releases supported single year ros-industrial open-source project bsd legacy apache 2.0 preferred license extends advanced capabilities ros manufacturing automation robotics ros-industrial repository includes interfaces common industrial manipulators grippers sensors device networks also provides software libraries automatic 2d/3d sensor calibration process path/motion planning applications like scan-n-plan developer tools like qt creator ros plugin training curriculum specific needs manufacturers ros-i supported international consortium industry research members project began collaborative endeavor yaskawa motoman robotics southwest research institute willow garage support use ros manufacturing automation github repository founded january 2012 shaun edwards swri currently consortium divided three groups ros-industrial consortium americas led swri located san antonio texas ros-industrial consortium europe led fraunhofer ipa located stuttgart germany ros-industrial consortium asia pacific led advanced remanufacturing technology centre artc nanyang technological university ntu located singapore consortia supports global ros-industrial community conducting ros-i training providing technical support setting future roadmap ros-i well conducting pre-competitive joint industry projects develop new ros-i capabilities
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Operating systems
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runtime system runtime system also called run-time system runtime environment run-time environment primarily implements portions execution model confused runtime lifecycle phase program runtime system operation languages form runtime system provides environment programs run environment may address number issues including layout application memory program accesses variables mechanisms passing parameters procedures interfacing operating system otherwise compiler makes assumptions depending specific runtime system generate correct code typically runtime system responsibility setting managing stack heap may include features garbage collection threads dynamic features built language every programming language specifies execution model many implement least part model runtime system one possible definition runtime system behavior among others behavior directly attributable program definition includes part runtime system things putting parameters onto stack function call behavior disk i/o parallel execution related behaviors definition essentially every language runtime system including compiled languages interpreted languages embedded domain-specific languages even api invoked stand alone execution models pthreads runtime system implementation execution model behavior scholarly papers runtime systems focus implementation details parallel runtime systems notable example parallel runtime system cilk popular parallel programming model addition proto-runtime toolkit created simplify creation parallel runtime systems addition execution model behavior runtime system may also perform support services type checking debugging code generation optimization runtime system also gateway running program interacts runtime environment contains state values accessible program execution also active entities interacted program execution like disk drives people via keyboards example environment variables features many operating systems part runtime environment running program access via runtime system likewise hardware devices dvd drive active entities program interact via runtime system unique application runtime environment rte within operating system os allows rte run meaning boot power-down entire os dedicated application running within rte code tries run failures application break rte breaks os stops processing requires re-boot boot read-only memory extremely secure simple single-mission system created simple example basic runtime system runtime system c language particular set instructions inserted executable image compiler among things instructions manage processor stack create space local variables copy function-call parameters onto top stack often clear criteria deciding language behavior considered inside runtime system versus behavior part source program c setup stack part runtime system opposed part semantics individual program maintains global invariant holds executions systematic behavior implements execution model language opposed implementing semantics particular program text directly translated code computes results one way observe separation semantics particular program runtime environment compile program object file containing functions versus compiling entire program executable binary object file contain assembly code relevant functions executable binary contain additional code used implement runtime environment object file one hand may missing information runtime environment resolved linking hand code object file still depends assumptions runtime system example function may read parameters particular register stack location depending calling convention used runtime environment another example case using application programming interface api interact runtime system calls api look calls regular software library however point call execution model changes runtime system implements execution model different language library written terms person reading code normal library would able understand library behavior knowing language library written however person reading code api invokes runtime system would able understand behavior api call knowing language call written point via mechanism execution model stops language call written switches execution model implemented runtime system example trap instruction one method switching execution models difference distinguishes api-invoked execution model posix threads usual software library posix threads calls software library calls invoked via api posix threads behavior understood terms language call rather posix threads calls bring play outside execution model implemented posix threads runtime system runtime system often os kernel extreme example physical cpu viewed implementation runtime system specific assembly language view execution model implemented physical cpu memory systems analogy runtime systems higher-level languages implemented using languages creates hierarchy runtime systems cpu itself—or actually logic microcode layer below—acting lowest-level runtime system compiled interpreted languages provide interface allows application code interact directly runtime system example codice_1 class java language class allows code animated one thread things start stop threads normally core aspects language behavior task scheduling resource management accessible fashion higher-level behaviors implemented runtime system may include tasks drawing text screen making internet connection often case operating systems provide kinds behaviors well available runtime system implemented abstraction layer translates invocation runtime system invocation operating system hides complexity variations services offered different operating systems also implies os kernel viewed runtime system set os calls invoke os behaviors may viewed interactions runtime system limit runtime system may provide services p-code machine virtual machine hide even processor instruction set approach followed many interpreted languages awk languages like java meant compiled machine-independent intermediate representation code bytecode arrangement simplifies task language implementation adaptation different machines improves efficiency sophisticated language features reflection also allows program executed machine without explicit recompiling step feature become important since proliferation world wide web speed execution runtime systems feature just-in-time compilation machine code modern aspect runtime systems parallel execution behaviors behaviors exhibited mutex constructs pthreads parallel section constructs openmp runtime system parallel execution behaviors may modularized according proto-runtime approach notable early examples runtime systems interpreters basic lisp environments also included garbage collector forth early example language designed compiled intermediate representation code runtime system virtual machine interpreted code another popular theoretical example donald knuth mix computer c later languages supported dynamic memory allocation runtime system also included library managed program memory pool object-oriented programming languages runtime system often also responsible dynamic type checking resolving method references
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Programming language topics
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abap abap advanced business application programming originally allgemeiner berichts-aufbereitungs-prozessor german general report creation processor high-level programming language created german software company sap se currently positioned alongside java language programming sap netweaver application server part sap netweaver platform building business applications abap one many application-specific fourth-generation languages 4gls first developed 1980s originally report language sap r/2 platform enabled large corporations build mainframe business applications materials management financial management accounting.abap establish integration independent softwares abap used abbreviation allgemeiner berichts-aufbereitungs-prozessor german generic report preparation processor later renamed english advanced business application programming abap one first languages include concept logical databases ldbs provides high level abstraction basic database level supports every platform language units abap language originally used developers develop sap r/3 platform also intended used sap customers enhance sap applications – customers develop custom reports interfaces abap programming language geared towards technical customers programming experience extracted base computing languages java c c++ python abap remains language creating programs client-server r/3 system sap first released 1992 computer hardware evolved 1990s sap applications systems written abap 2001 basic functions written abap 1999 sap released object-oriented extension abap called abap objects along r/3 release 4.6 sap current development platform netweaver supports abap java abap abstraction business applications operating system database ensures applications depend directly upon specific server database platform easily ported one platform another sap netweaver currently runs unix aix hp-ux solaris linux microsoft windows i5/os ibm system formerly iseries as/400 z/os ibm system z formerly zseries s/390 supported databases hana sap ase formerly sybase ibm db2 informix maxdb oracle microsoft sql server support informix discontinued sap basis release 7.00 abap programs reside inside sap database stored separate external files like java c++ programs database abap code exists two forms source code viewed edited abap workbench tools generated code binary representation somewhat comparable java bytecode abap programs execute control runtime system part sap kernel runtime system responsible processing abap statements controlling flow logic screens responding events user clicking screen button respect seen virtual machine comparable java vm key component abap runtime system database interface turns database-independent abap statements open sql statements understood underlying dbms native sql database interface handles communication relational database behalf abap programs also contains extra features buffering tables frequently accessed data local memory application server sap data exists sap software runs context sap system system consists central relational database one application instances accessing data programs database sap system contains least one instance may contain mostly reasons sizing performance system multiple instances load balancing mechanisms ensure load spread evenly available application servers installations web application server landscapes typically consist three systems one development one testing quality assurance one production landscape may contain systems e.g. separate systems unit testing pre-production testing may contain fewer e.g. development production without separate qa nevertheless three common configuration abap programs created undergo first testing development system afterwards distributed systems landscape actions take place control change transport system cts responsible concurrency control e.g. preventing two developers changing code time version management deployment programs qa production systems web application server consists three layers database layer application layer presentation layer layers may run different physical machines database layer contains relational database database software application layer knowledge contains instance instances system application processes including business transactions abap development run application layer presentation layer handles interaction users system online access abap application servers go via proprietary graphical interface called sap gui via web browser abap software deployed software components examples transaction sap terminology execution program normal way executing abap code sap system entering transaction code instance va01 transaction code create sales order transactions called via system-defined user-specific role-based menus also started entering transaction code directly command field present every sap screen transactions also invoked programmatically means abap statements call transaction leave transaction general notion transaction called logical unit work luw sap terminology short form transaction code t-code programming languages abap program either executable unit library provides reusable code programs independently executable abap distinguishes two types executable programs reports follow relatively simple programming model whereby user optionally enters set parameters e.g. selection subset data program uses input parameters produce report form interactive list term report somewhat misleading reports also designed modify data reason programs called reports list-oriented nature output produce module pools define complex patterns user interaction using collection screens term “ screen ” refers actual physical image user sees screen also flow logic refers abap code implicitly invoked screens divided pbo process output pai process input section sap documentation term “ dynpro ” dynamic program refers combination screen flow logic non-executable program types include module gets included generation time calling unit often used subdivide large programs br subroutine pools contain abap subroutines blocks code enclosed form/endform statements invoked perform br function groups libraries self-contained function modules enclosed function/endfunction invoked call function br object classes interfaces similar java classes interfaces first define set methods attributes second contain empty method definitions class implementing interface must provide explicit code br type pools define collections data types constants abap programs composed individual sentences statements first word statement called abap keyword statement ends period words must always separated least one space statements indented wish keywords additions operands abap runtime system differentiate upper lowercase statements extend beyond one line several statements single line though recommended lines begin asterisk first column recognized comment lines abap runtime system ignored double quotations marks indicate remainder line comment two possible ways develop abap availability depends release abap system abap workbench part abap system accessed via sapgui contains different tools editing programs important transaction codes shown parentheses object navigator transaction se80 provides single integrated interface various tools abap development tools adt formally known abap eclipse set plugins eclipse platform develop abap scenario abap developer installs required tools computer works locally whereas continuous synchronization backend performed abap dictionary contains metadata data sap system closely linked abap workbench reference data e.g. table view data type obtained dictionary developers use abap dictionary transactions directly se80 object navigator inside abap workbench display maintain metadata dictionary object changed program references changed object automatically reference new version next time program runs abap interpreted necessary recompile programs reference changed dictionary objects brief description important types dictionary objects follows brief description abap syntax begins ubiquitous hello world program report test write 'hello world example contains two statements codice_1 codice_2 program displays list screen case list consists single line hello world codice_1 statement indicates program report program could module pool replacing codice_1 statement codice_5 consecutive statements identical first leftmost part combined chained statement using chain operator codice_6 common part statements written left colon differing parts written right colon separated commas colon operator attached directly preceding token without space applies commas token list seen examples chaining often used codice_2 statements codice_2 accepts one argument instance wanted display three fields structure called flightinfo would code write flightinfo-cityfrom write flightinfo-cityto write flightinfo-airpto chaining statements results readable intuitive form write flightinfo-cityfrom flightinfo-cityto flightinfo-airpto chain statement first part colon limited statement name alone entire common part consecutive statements placed colon example replace b lastname replace b firstname replace b cityname could rewritten chained form replace b lastname firstname cityname abap 2 ways defining text comment example report bookings select flightinfo code abap whitespace-sensitive x a+b c assigns variable x substring variable starting b length defined variable c. x b c assigns variable x sum variable result call method b parameter c. contrast languages like c/c++ java define limited set language-specific statements provide functionality via libraries abap contains extensive amount built-in statements statements traditionally used sentence-like structures avoided symbols making abap programs relatively verbose however recent versions abap language terser style possible example statement based syntax whose syntax originates cobol versus expression-based syntax c/java add tax price price price tax abap provides set built-in data types addition every structure table view data element defined abap dictionary used type variable also object classes interfaces used types built-in data types date variables constants type contain number days since january 1 1 ad time variables constants type contain number seconds since midnight special characteristic types accessed integers character strings internal format yyyymmdd dates hhmmss times used date time handling example code snippet calculates last day previous month note sy-datum system-defined variable containing current date data last_eom type d. last end-of-month date last_eom sy-datum last_eom+6 2 '01 last_eom last_eom 1 abap variables explicitly declared order used declared either individual statements explicit typing since abap 7.40 inline inferred typing normally declarations placed top code module program subroutine function first executable statement placement convention enforced syntax rule declaration consists name type length applicable additional modifiers e.g number implied decimals packed decimal field optionally initial value data counter type data origin type country data t_flights type table flightinfo data booking type ref cl_flt_booking notice use colon chain together consecutive data statements since abap 7.40 variables declared inline following syntax data variable_name 'value type declaration must possible infer type statically e.g method signature database table structure syntax also possible opensql statements select ekko data lt_ekko ebeln eq lv_ebeln abap language supports object-oriented programming feature known abap objects helps simplify applications make controllable abap objects fully compatible existing language one use existing statements modularization units programs use abap objects also use abap objects existing abap programs syntax checking stronger abap objects programs syntactical forms usually older ones certain statements permitted objects form capsule combines character respective behavior objects enable programmers map real problem proposed software solution one-to-one basis typical objects business environment example ‘ customer ’ ‘ order ’ ‘ invoice ’ release 3.1 onwards business object repository bor sap web application server abap contained examples objects bor object model integrated abap objects next release migrating bor object types abap class library comprehensive introduction object orientation whole would go far beyond limits introduction abap objects documentation introduces selection terms used universally object orientation also occur abap objects subsequent sections goes discuss detail terms used abap objects end section contains list reading selection titles object orientation object-oriented programming objects usually following properties abap core data services abap cds implementation general cds concept abap abap cds makes possible define semantic data models central database application server abap models defined independently database system entities models provide enhanced access functions compared existing database tables views defined abap dictionary making possible optimize open sql-based applications particularly clear abap uses sap hana database since in-memory characteristics implemented optimum manner. br data models defined using data definition language ddl data control language dcl provided abap cds abap cds syntax objects defined using languages integrated abap dictionary managed br cds source code programmed eclipse-based abap development tools adt data definition language ddl data control language dcl use different editors internal tables important feature abap language internal table defined similarly vector struct c++ vector objects java main difference languages abap provides collection statements easily access manipulate contents internal tables note abap support arrays way define multi-element data object use internal table internal tables way store variable data sets fixed structure working memory abap provides functionality dynamic arrays data stored row-by-row basis row structure internal tables preferably used store format content database tables within program furthermore internal tables connection structures important means defining complex data structures abap program following example defines internal table two fields format database table vbrk types begin t_vbrk data gt_vbrk type standard table t_vbrk data gs_vbrk type t_vbrk types tt_vbrk type standard table t_vbrk following list gives rough overview important milestones history language abap details see abap release-specific changes
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Programming language topics
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kaii-yōkai denshō database database yōkai mystery stories collected japanese folklore database published international research center japanese studies prototype created march 19 2002 first live version released june 20 2002. project supervisor kazuhiko komatsu japanese folklorist professor study yōkai database includes verbal information without visual information data collected item database abstract around 100 characters full text searchable database searched name region item found
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Databases
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java mobile media api mobile media api mmapi api specification java platform cdc cldc devices mobile phones depending implemented apis allow applications play record sounds video capture still images mmapi developed java community process jsr 135 multimedia java api based around four main types classes codice_1 package—the codice_2 codice_3 codice_4 various types codice_5 java programmers wishing use jsr 135 would first make use static methods codice_2 class although methods codice_7 main method used codice_8 takes either uri mime type cases uris used common uri protocols used include mime type optional inferred data passed supplied codice_8 method returns implementation codice_3 interface even use capture protocol uri core methods applicable players starting stopping media requesting loop also codice_11 object implementing codice_4 interface receive various events related clip starting stopping media finishing etc codice_3 classes also codice_14 method returns implementation particular codice_5 codice_5 handles optional apis applicable media types given codice_3 may may able supply implementation given codice_5 set controls implemented codice_3 limited however standard ones defined codice_22 package jsr others may defined jsr 234 advanced multimedia supplements subset jsr 135 defined jsr 118 midp 2.0 regardless protocol media type involved codice_3 moves discrete states lifecycle states listed table java specifications implementations differ despite best efforts specification authors ensure consistency two obvious areas differences controls supported acceptable uri types first place obscure areas whether mixing supported many games would like play midi music track layer pcm sound effects top another source extreme variance performance example http clip requested point clip get downloaded specification recognises providing two codice_3 methods called advance actually playing codice_25 codice_26 depending implementation may work getting clip playable state thus making quicker actually play clip needed implementations sophisticated enough actually stream clip request whilst played symbian os contains complete implementation jsr 135 even highly dependent underlying multimedia capabilities device device manufacturers may choose expose obscure parts java recording implementation consistency ensured forcing implementations pass java technology compatibility kit tck ensures supported uri schema mime type control tested test every permutation optional parts
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Programming language topics
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brewer nash model brewer nash model constructed provide information security access controls change dynamically security model also known chinese wall model designed provide controls mitigate conflict interest commercial organizations built upon information flow model brewer nash model information flow subjects objects way would create conflict interest
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Computer security
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dg/l dg/l programming language developed data general corp nova eclipse eclipse/mv families minicomputers 1970s early 1980s actually two separate versions language extended version algol 60 supported integers single double precision floating point complex numbers fixed arbitrary precision strings also supported full arbitrary precision bcd arithmetic strings large number convenient program flow features designed mid 70s lacked user defined data structures dg/l substantial runtime library day used systems programming within outside data general originally called algol/5 product renamed dg/l shortly first commercial release 1978 officially name meaningless apparently supposed imply data general language first commercial release targeting 16 bit eclipse nova several subsequent updates major versions released approximately one year appendix data general 1982 revision dg/l language reference manual 093-00229-01 describes dg/l based algol 60 programming language gives data types operations statements algol 60 lacks specific differences extensions algol 60 standard introduced dg/l carried data general previous algol implementation 1971
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Programming language topics
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trust boundary trust boundary term computer science security used describe boundary program data execution changes level trust term refers distinct boundary within system trusts sub-systems including data example execution trust boundary would application attains increased privilege level root data trust boundary point data comes untrusted source example user input network socket trust boundary violation refers vulnerability computer software trusts data validated crossing boundary
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Computer security
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fsarchiver fsarchiver disk cloning utility linux fsarchiver save partitions containing different popular file systems disk image continuation partimage project one authors implements new features partimage lacks fsarchiver strives feature-rich less ux partimage result used software toolsets functionality two widely used features partimage lacks support multi-core compression support commonly used ext4 filesystem windows users fsarchiver includes experimental support ntfs fsarchiver supports modern linux file systems ext4 reiser4 btrfs notable features include modern multi-threaded compression disk image files combined file-based images opposed block-based images similar tools use enhance compression ignoring unused clusters
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Computer security
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microarchitecture simulation microarchitecture simulation important technique computer architecture research computer science education tool modeling design behavior microprocessor components alu cache memory control unit data path among others simulation allows researchers explore design space well evaluate performance efficiency novel microarchitecture features example several microarchitecture components branch predictors re-order buffer trace cache went numerous simulation cycles become common components contemporary microprocessors today addition simulation also enables educators teach computer organization architecture courses hand-on experiences system-level simulation computer hardware please refer full system simulation microarchitecture simulation classified multiple categories according input types level details specifically input trace collected execution program real microprocessor called trace-driven simulation program called execution-driven simulation trace-driven simulation reads fixed sequence trace records file input trace records usually represent memory references branch outcomes specific machine instructions among others trace-driven simulation known comparatively fast results highly reproducible also requires large storage space hand execution-driven simulation reads program simulates execution machine instructions fly program file typically several magnitudes smaller trace file however execution-driven simulation much slower trace-driven simulation process instruction one-by-one update statuses microarchitecture components involved thus selection input types simulation trade-off space time particular detailed trace highly accurate simulation requires large storage space whereas accurate execution-driven simulation takes long time execute instructions program apart input types level details also used classify simulation particular piece software simulates microprocessor executing program cycle-by-cycle basis known cycle-accurate simulator whereas instruction set simulator models execution program microprocessor eyes instruction scheduler along coarse timing instruction execution computer science classes computer architecture hand-on experiences adopt instruction set simulators tools teaching whereas cycle-accurate simulators deployed mostly research projects due complexities resource consumption microarchitecture simulators deployed variety purposes allows researchers evaluate ideas without need fabricate real microprocessor chip expensive time consuming instance simulating microprocessor thousand cores along multiple levels cache memory incurs little cost comparing fabrication prototyping chip researchers also play several configurations cache hierarchy using different cache models simulator instead fabricate new chip every time want test something different another usage microarchitecture simulator education given course computer architecture teaches students many different microprocessor features architectures microarchitecture simulator ideal modeling experimenting different features architectures course semester example students may start microarchitecture simulator models simple microprocessor design beginning semester semester progresses additional features instruction pipelining register renaming reservation stations out-of-order execution scoreboarding modeled added simulator introduced classroom microarchitecture simulator provides flexibility reconfiguration testing minimal costs
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Computer architecture
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linux unified key setup linux unified key setup luks disk encryption specification created clemens fruhwirth 2004 originally intended linux disk encryption software implements different incompatible undocumented formats luks implements platform-independent standard on-disk format use various tools facilitates compatibility interoperability among different programs also assures implement password management secure documented manner reference implementation luks operates linux based enhanced version cryptsetup using dm-crypt disk encryption backend microsoft windows luks-encrypted disks used defunct librecrypt formerly doxbox luks designed conform tks1 secure key setup scheme
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Computer file systems
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cyberweapon cyberweapon malware agent employed military paramilitary intelligence objectives requirements term vary widely common criteria seem malware agent part distinction malware agent sponsored —that commissioned developed and/or actually used—not black-hat hacker organized criminal group instead state non-state actor latter potentially including terrorist groups entities proposed fourth-generation warfare 4gw doctrines cyberweapon performs action would normally require soldier spy would considered either illegal act war performed directly human agent sponsor peacetime legal issues include violating privacy target sovereignty host nation actions include limited cyberweapon almost certainly results either direct indirect financial damages target group direct financial gains sponsor transfer funds primary objective class agent unlike malware used script kiddies organize botnets ownership physical location normal role machines attacked largely irrelevant cyberweapons show high selectivity either employment operation attack cyberweapons usually identify target using different methods likewise malware employed fraudsters theft personal financial information demonstrates lower selectivity wider distribution note self-replication requirement cyberweapons viruses viruses necessarily cyberweapons without capability however alternate vector required get agent onto target system likewise compromised access alone provided rootkit diagnostic employment cyberweapon term frequently used press articles avoid instead using terms like internet weapon virus mainstream researchers debate requirements term still referring employment agent weapon software development community particular uses term rarely following malware agents generally meet criteria formally referred manner industry security experts described way government military statements 2017 data breaches showed supposedly secure hacking tools used government agencies obtained − sometimes exposed − third parties furthermore reported losing control tools government appears leave exploits open re-used scammers criminals anyone else − purpose claudio guarnieri technologist amnesty international states learn disclosures leaks last months unknown vulnerabilities maintained secret even 've clearly lost plain irresponsible unacceptable also year wikileaks released vault 7 documents series contain details cia exploits tools julian assange stating working disarm publication disarmament cyber weapons may come form contacting respective software vendors information vulnerabilities products well potential help autonomous development open source software patches
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Computer security
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alastair sweeny alastair sweeny born august 15 1946 canadian publisher historian author born toronto ontario attended st. andrew college received bachelor degree trinity college university toronto master letters doctor philosophy trinity college dublin sweeny managed research programs produced reference learning materials consulted many private public sector organizations including adviser canadian government task force national unity pepin-robarts commission library archives canada parks canada federation saskatchewan indian nations national indian veterans association assembly first nations canadian heritage elibrary proquest nelson thomson learning quebecor media electric library canada canwest global 1989 produced canadisk canada first multimedia cd-rom joint venture encyclopædia britannica 1990s developed learning materials apple computer eworld online service produced original encarta book quotations 1999 microsoft inc. bloomsbury publishing london 1990s helped get canada schoolnet way developed day canadian history online service bell globemedia sweeny produced written corporate history number canadian companies including investors group alberta energy company encana magna international gendis inc.. done background research canadian authors w. l. morton research biography lord strathcona peter c. newman hudson bay company series background history richard gwyn 49th paradox canada north america pierre berton promised land jeffrey simpson spoils power author several books including biography sir george-étienne cartier 1976 canquiz 2002 business biography blackberry blackberry planet published john wiley canada ltd september 2009 book canada oilsands industry black bonanza published wiley april 2010 book fire along frontier great battles war 1812 published dundurn press mark bicentennial war 1812 sweeny currently executive director non-profit educational foundation civics channel dedicated research teaching learning areas citizenship society politics human rights justice system co-author producer civics canada online well print version civics canada 2005 sponsored canadawiki portal also vice president northern blue publishing waterloo ontario co-author producer history canada online canada digital history canada first people history canada native aboriginal nations
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Operating systems
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blackbird online platform blackbird codename online content authoring platform developed microsoft mid-90s intended online publishing tool first version msn microsoft network blackbird born microsoft acquisition daily planet software tool first conceived prior advent internet web know today time aol compuserve primary online venues introduction web mass consumers begin even low-bandwidth dialup connections dominated blackbird based concept object-based backend file system microsoft data centers microsoft cairo /nt low-bandwidth-streaming rendering client page-based layout similar aldus pagemaker based online streaming embedded interactive client-side activex objects ole fundamentally based sgml standard direct ancestor html client-side layout unfortunately became microsoft-promoted alternative html brief time commercial internet web browser born scripting capability html yet demonstrated means serve dynamic media-rich applications documents contained processing logic similar user would experience desktop environment pages blackbird application would able contain video audio graphs ole based document formats without need plug-ins technology already demonstrated microsoft dial-up service time msn plans progress port internet use dedicated protocol work platform cancelled due overwhelming move html/www/internet standards commercialized consuming computing world example netscape time need backend server-side scripting technologies lacking performance problems also plagued pre-releases beta testing 1995 microsoft hence refocused efforts online development around web/html standards including asp activex blackbird designer refashioned visual interdev technology integrated first version visual studio vs 97 web-standards based core trademarked microsoft visual studio ancestor one leading web development tools dating commercial birth web today prior name codename derived cold war era stealth spy plane lockheed sr-71 blackbird centerpiece blackbird ole container format already use windows applications allow objects documents communicate share information blackbird documents would stored called blackbird data format bdf structured format based ole storage sgml-based markup language blackbird markup language bml also created help automate creation documents though documents based markup would processed native data format used ole objects would suffer performance disadvantages give developers flexibility microsoft planned include utility would allow conversion bdf bml well html direction additionally would application resource installer packaged custom fonts ole controls resource files blackbird application package would download user activated application first time otherwise update package already user system microsoft also advertised blackbird would take advantage features within windows 95 like shortcuts would allow user automatically schedule delivery content three components platform — authoring system called blackbird designer visual drag-and drop environment similar included visual basic blackbird server ran windows nt blackbird client runtime module lets users access run blackbird applications urls blackbird applications ole monikers microsoft argued blackbird development would cross-platform since ole support already existed macintosh work progress porting unix systems guarantee security company planned act certifying authority ole controls ocxs encourage third parties certifying authorities blackbird announced march 1995 part upcoming microsoft network august clear microsoft intended run widely internet protocols technology later demonstrated msn microsoft released beta version developer tools end 1996 plans new version announced designer renamed visual studio disclosed would use proprietary blackbird file formats rather standard html soon became clear original project effectively scrapped designer later became visual interdev general web content creation tool creating html developing server pages using asp key web technology glue first version visual studio visual studio 97 visual interdev key web ingredient visual studio internet advent microsoft web development tools binding previously mass-successful products visual basic visual c++ internet also included ability author activex controls — ole controls could embedded html pages plug-in would key parts microsoft active platform strategy later revealed blackbird severe performance problems over-complex architecture made excessive use multi-threading prototypes trident html layout engine completed shown goals complex layout blackbird could achieved html better performance led executives rethink project mark anders former head iis team microsoft cited blackbird example microsoft tendency over-complicate software compared projects like longhorn blackbird later referenced united states anti-trust suit microsoft argued prosecution netscape efforts transform web suite internet os seen competition plans proprietary internet led adopt aggressive internet strategy netscape many documents cited prosecution described competition windows however pointed netscape planned compete possible internet platform microsoft windows os
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Operating systems
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turbodos turbodos multi user cp/m like operating system z80 8086 cpus developed software 2000 inc released around 1982 s100 bus based systems northstar horizon commercial systems line multiprocessor systems including csi-50 csi-75 sci-100 csi-150 multiprocessor nature turbodos unusual feature unlike operating systems time networking processors either afterthought support file transfer protocol turbodos designed ground multiprocessor operating system modular construction operating system generation based relocating linking loader program makes incorporation different hardware driver modules quite easy particularly bus-oriented machines ieee-696 s-100 bus commonly used turbodos systems turbodos highly modular consisting forty separate functional modules distributed relocatable form modules building blocks combine various ways produce family compatible operating systems section describes modules detail describes combine various configurations possible turbodos configurations include numerous subtle variations possible categories architecture turbodos viewed three-level hierarchy highest level hierarchy process level turbodos support many concurrent processes level intermediate level hierarchy kernel level kernel supports 93 c-functions t-functions controls sharing computer resources processor time memory peripheral devices disk files processes make requests kernel entrypoint module osntry decodes c-function t-function number invokes appropriate kernel module c functions include cp/m bdos functions selected mp/m functions lowest level hierarchy driver level contains device-dependent drivers necessary interface turbodos particular hardware used drivers must provided peripherals including console printers disks communications channels network interface drivers also required real-time clock periodic interrupt source bank-switched memory applicable turbodos designed interface almost kind peripheral hardware operates efficiently interrupt-driven dma-type interfaces also work fine using polled programmed-i/o devices turbodos loader osload.com program containing abbreviated version kernel drivers purpose load full turbodos operating system disk file osserver.sys memory system cold-start functional modules distributed relocatable format .rel gen command specialized linker builds executable version system turbodos resident commands commands executable files standard commands
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Operating systems
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tokyo cabinet kyoto cabinet tokyo cabinet kyoto cabinet two libraries routines managing key-value databases tokyo cabinet sponsored japanese social networking site mixi multithreaded embedded database manager announced authors modern implementation dbm kyoto cabinet designated successor tokyo cabinet tokyo cabinet features on-disk b+ trees hash tables key-value storage support transactions
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Databases
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bittorrent bittorrent abbreviated bt communication protocol peer-to-peer file sharing p2p used distribute data electronic files internet bittorrent one common protocols transferring large files digital video files containing tv shows video clips digital audio files containing songs peer-to-peer networks estimated collectively account approximately 43 70 internet traffic depending location february 2013 bittorrent responsible 3.35 worldwide bandwidth half 6 total bandwidth dedicated file sharing send receive files person uses bittorrent client internet-connected computer bittorrent client computer program implements bittorrent protocol popular clients include μtorrent xunlei transmission qbittorrent vuze deluge bitcomet tixati bittorrent trackers provide list files available transfer allow client find peer users known seeds may transfer files programmer bram cohen former university buffalo student designed protocol april 2001 released first available version 2 july 2001 recent version 2013 bittorrent clients available variety computing platforms operating systems including official client released bittorrent inc. bittorrent 15–27 million concurrent users time bittorrent utilized 150 million active users based figure total number monthly bittorrent users may estimated quarter billion bittorrent protocol used reduce server network impact distributing large files rather downloading file single source server bittorrent protocol allows users join swarm hosts upload to/download simultaneously protocol alternative older single source multiple mirror sources technique distributing data work effectively networks lower bandwidth using bittorrent protocol several basic computers home computers replace large servers efficiently distributing files many recipients lower bandwidth usage also helps prevent large spikes internet traffic given area keeping internet speeds higher users general regardless whether use bittorrent protocol first release bittorrent client search engine peer exchange users wanted upload file create small torrent descriptor file would upload torrent index site first uploader acted seed downloaders would initially connect peers see diagram right wish download file would download torrent client would use connect tracker list ip addresses seeds peers swarm peer completed download complete file could turn function seed file distributed divided segments called pieces peer receives new piece file becomes source piece peers relieving original seed send piece every computer user wishing copy bittorrent task distributing file shared want entirely possible seed send single copy file eventually distribute unlimited number peers piece protected cryptographic hash contained torrent descriptor ensures modification piece reliably detected thus prevents accidental malicious modifications pieces received nodes node starts authentic copy torrent descriptor verify authenticity entire file receives pieces typically downloaded non-sequentially rearranged correct order bittorrent client monitors pieces needs pieces upload peers pieces size throughout single download example 10 mb file may transmitted ten 1 mb pieces forty 256 kb pieces due nature approach download file halted time resumed later date without loss previously downloaded information turn makes bittorrent particularly useful transfer larger files also enables client seek readily available pieces download immediately rather halting download waiting next possibly unavailable piece line typically reduces overall time download eventual transition peers seeders determines overall health file determined number times file available complete form distributed nature bittorrent lead flood-like spreading file throughout many peer computer nodes peers join swarm likelihood successful download particular node increases relative traditional internet distribution schemes permits significant reduction original distributor hardware bandwidth resource costs distributed downloading protocols general provide redundancy system problems reduce dependence original distributor provide sources file generally transient therefore single point failure one way server-client transfers bittorrent client capable preparing requesting transmitting type computer file network using protocol 2005 way share files creating small text file called torrent files contain metadata files shared trackers keep track seeds peers users want download file first obtain torrent file connect tracker seeds 2005 first vuze bittorrent client introduced distributed tracking using distributed hash tables allowed clients exchange data swarms directly without need torrent file 2006 peer exchange functionality added allowing clients add peers based data found connected nodes though ultimately transfer files network bittorrent download differs one way server-client download typical http ftp request example several fundamental ways taken together differences allow bittorrent achieve much lower cost content provider much higher redundancy much greater resistance abuse flash crowds regular server software however protection theoretically comes cost downloads take time rise full speed may take time enough peer connections established may take time node receive sufficient data become effective uploader contrasts regular downloads http server example vulnerable overload abuse rise full speed quickly maintain speed throughout beginning bittorrent non-contiguous download methods made harder support streaming playback however recently clients offering streaming options bittorrent protocol provides way index torrent files result comparatively small number websites hosted large majority torrents many linking copyrighted works without authorization copyright holders rendering sites especially vulnerable lawsuits bittorrent index list .torrent files typically includes descriptions information torrent content several types websites support discovery distribution data bittorrent network public torrent-hosting sites pirate bay allow users search download collection torrent files users typically also upload torrent files content wish distribute often sites also run bittorrent trackers hosted torrent files two functions mutually dependent torrent file could hosted one site tracked another unrelated site private host/tracker sites operate like public ones except may restrict access registered users may also keep track amount data user uploads downloads attempt reduce leeching web search engines allow discovery torrent files hosted tracked sites examples include pirate bay torrentz isohunt btdigg sites allow user ask content meeting specific criteria containing given word phrase retrieve list links torrent files matching criteria list often sorted respect several criteria relevance seeders-leechers ratio one popular useful due way protocol behaves download bandwidth achievable sensitive value metasearch engines allow one search several bittorrent indices search engines dht search engines monitors dht network indexes torrents via metadata exchange peers tribler bittorrent client among first incorporate built-in search capabilities tribler users find .torrent files held random peers taste buddies adds ability bittorrent protocol using gossip protocol somewhat similar exeem network shut 2005 software includes ability recommend content well dozen downloads tribler software roughly estimate download taste user recommend additional content may 2007 researchers cornell university published paper proposing new approach searching peer-to-peer network inexact strings could replace functionality central indexing site year later team implemented system plugin vuze called cubit published follow-up paper reporting success somewhat similar facility slightly different approach provided bitcomet client torrent exchange feature whenever two peers using bitcomet torrent exchange enabled connect exchange lists torrents name info-hash torrent share storage torrent files previously downloaded user chose enable sharing torrent exchange thus client builds list torrents shared peers connected current session even maintain list sessions instructed time user search torrent collection list certain torrent sort list categories user chooses download torrent list .torrent file automatically searched info-hash value dht network found downloaded querying client create initiate downloading task users find torrent interest torrent index site using search engine built client download open bittorrent client client connects tracker seeds specified torrent file receives list seeds peers currently transferring pieces file client connects peers obtain various pieces swarm contains initial seeder client connects directly begins request pieces clients incorporate mechanisms optimize download upload rates effectiveness data exchange depends largely policies clients use determine send data clients may prefer send data peers send data back tit tat exchange scheme encourages fair trading strict policies often result suboptimal situations newly joined peers unable receive data n't pieces yet trade two peers good connection exchange data simply neither takes initiative counter effects official bittorrent client program uses mechanism called optimistic unchoking whereby client reserves portion available bandwidth sending pieces random peers necessarily known good partners called preferred peers hopes discovering even better partners ensure newcomers get chance join swarm although swarming scales well tolerate flash crowds popular content less useful unpopular niche market content peers arriving initial rush might find content unavailable need wait arrival seed order complete downloads seed arrival turn may take long happen termed seeder promotion problem since maintaining seeds unpopular content entails high bandwidth administrative costs runs counter goals publishers value bittorrent cheap alternative client-server approach occurs huge scale measurements shown 38 new torrents become unavailable within first month strategy adopted many publishers significantly increases availability unpopular content consists bundling multiple files single swarm sophisticated solutions also proposed generally use cross-torrent mechanisms multiple torrents cooperate better share content peer distributing data file treats file number identically sized pieces usually byte sizes power 2 typically 32 kb 16 mb peer creates hash piece using sha-1 hash function records torrent file pieces sizes greater 512 kb reduce size torrent file large payload claimed reduce efficiency protocol another peer later receives particular piece hash piece compared recorded hash test piece error-free peers provide complete file called seeders peer providing initial copy called initial seeder exact information contained torrent file depends version bittorrent protocol convention name torrent file suffix codice_1 torrent files announce section specifies url tracker info section containing suggested names files lengths piece length used sha-1 hash code piece used clients verify integrity data receive though sha-1 shown signs cryptographic weakness bram cohen initially consider risk big enough backward incompatible change example sha-3 bittorrent preparing move sha-256 early days torrent files typically published torrent index websites registered least one tracker tracker maintained lists clients currently connected swarm alternatively trackerless system decentralized tracking every peer acts tracker azureus first bittorrent client implement system distributed hash table dht method alternative incompatible dht system known mainline dht released mainline bittorrent client three weeks later though development since 2002 subsequently adopted µtorrent transmission rtorrent ktorrent bitcomet deluge clients dht adopted private flag – analogous broadcast flag – unofficially introduced telling clients restrict use decentralized tracking regardless user desires flag intentionally placed info section torrent disabled removed without changing identity torrent purpose flag prevent torrents shared clients access tracker flag requested inclusion official specification august 2008 accepted yet clients ignored private flag banned many trackers discouraging practice bittorrent offer users anonymity one usually see ip addresses peers swarm one client firewall program may expose users insecure systems attacks countries copyright organizations scrape lists peers send takedown notices internet service provider users participating swarms files copyright jurisdictions copyright holders may launch lawsuits uploaders downloaders infringement police may arrest suspects cases various means used promote anonymity example bittorrent client tribler makes available tor-like onion network optionally routing transfers peers obscure client requested data exit node would visible peers swarm tribler organization provides exit nodes one advantage tribler clearnet torrents downloaded small decrease download speed one hop routing i2p provides similar anonymity layer although case one download torrents uploaded i2p network bittorrent client vuze allows users concerned anonymity take clearnet torrents make available i2p network bittorrent clients designed provide anonymity used tor debate whether torrenting tor acts drag network private torrent trackers usually invitation require members participate uploading downside single centralized point failure oink pink palace what.cd examples private trackers shut seedbox services download torrent files first company servers allowing user direct download file one ip address would visible seedbox provider third parties virtual private networks encrypt transfers substitute different ip address user anyone monitoring torrent swarm see address growing number individuals organizations using bittorrent distribute licensed works e.g indie bands distributing digital files new songs independent adopters report without using bittorrent technology dramatically reduced demands private networking hardware bandwidth could afford distribute files uses bittorrent file sharing may violate laws jurisdictions see legal issues section bittorrent 100 million users greater share network bandwidth netflix hulu combined early 2015 estimates bittorrent represents 20 broadband traffic routers use network address translation nat must maintain tables source destination ip addresses ports typical home routers limited 2000 table entries expensive routers larger table capacities bittorrent frequently contacts 20–30 servers per second rapidly filling nat tables known cause home routers ceasing work correctly bittorrent protocol still development may therefore still acquire new features enhancements improved efficiency 2 may 2005 azureus 2.3.0.0 known vuze released introducing support trackerless torrents system called distributed database system distributed hash table implementation allows client use torrents working bittorrent tracker following month bittorrent inc. released version 4.2.0 mainline bittorrent client supported alternative dht implementation popularly known mainline dht outlined draft website incompatible azureus recent measurement shows users mainline dht 10 million 25 million daily churn least 10 million mainline dht arguably largest realistic dht world current versions official bittorrent client µtorrent bitcomet transmission bitspirit share compatibility mainline dht dht implementations based kademlia version 3.0.5.0 azureus also supports mainline dht addition distributed database use optional application plugin potentially allows azureus/vuze client reach bigger swarm another idea surfaced vuze virtual torrents idea based distributed tracker approach used describe web resource currently used instant messaging implemented using special messaging protocol requires appropriate plugin anatomic p2p another approach uses decentralized network nodes route traffic dynamic trackers bittorrent clients also use peer exchange pex gather peers addition trackers dht peer exchange checks known peers see know peers 3.0.5.0 release vuze major bittorrent clients compatible peer exchange web seeding implemented 2006 ability bittorrent clients download torrent pieces http source addition swarm advantage feature website may distribute torrent particular file batch files make files available download web server simplify long-term seeding load balancing use existing cheap web hosting setups theory would make using bittorrent almost easy web publisher creating direct http download addition would allow web seed disabled swarm becomes popular still allowing file readily available feature two distinct specifications supported libtorrent 26+ clients use first created john theshad0w hoffman created bittornado first specification requires running web service serves content info-hash piece number rather filename specification created getright authors rely basic http download space using byte serving september 2010 new service named burnbit launched generates torrent url using webseeding server-side solutions provide initial seeding file webserver via standard bittorrent protocol number external seeders reach limit stop serving file original source technique called broadcatching combines rss feeds bittorrent protocol create content delivery system simplifying automating content distribution steve gillmor explained concept column ziff-davis december 2003 discussion spread quickly among bloggers ernest miller chris pirillo etc. article entitled broadcatching bittorrent scott raymond explained rss feed track content bittorrent ensures content integrity cryptographic hashing data feed subscribers receive uncorrupted content one first popular software clients free open source broadcatching miro free software clients penguintv katchtv also supporting broadcatching bittorrent web-service movedigital added ability make torrents available web application capable parsing xml standard rest-based interface 2006 though since discontinued additionally torrenthut developing similar torrent api provide features help bring torrent community web 2.0 standards alongside release first php application built using api called pep parse really simple syndication rss 2.0 feed automatically create seed torrent enclosure found feed since bittorrent makes large proportion total traffic isps chosen throttle slow bittorrent transfers reason methods developed disguise bittorrent traffic attempt thwart efforts protocol header encrypt phe message stream encryption/protocol encryption mse/pe features bittorrent clients attempt make bittorrent hard detect throttle november 2015 vuze bitcomet ktorrent transmission deluge µtorrent moopolice halite qbittorrent rtorrent latest official bittorrent client v6 support mse/pe encryption september 2006 reported software could detect throttle bittorrent traffic masquerading http traffic reports august 2007 indicated comcast preventing bittorrent seeding monitoring interfering communication peers protection efforts provided proxying client-tracker traffic via encrypted tunnel point outside comcast network comcast recently called truce bittorrent inc. intention shaping traffic protocol-agnostic manner questions ethics legality comcast behavior led renewed debate net neutrality united states general although encryption make difficult determine shared bittorrent vulnerable traffic analysis thus even mse/pe may possible isp recognize bittorrent also determine system longer downloading uploading data terminate connection injecting tcp rst reset flag packets another unofficial feature extension bittorrent metadata format proposed john hoffman implemented several indexing websites allows use multiple trackers per file one tracker fails others continue support file transfer implemented several clients bitcomet bittornado bittorrent ktorrent transmission deluge µtorrent rtorrent vuze frostwire trackers placed groups tiers tracker randomly chosen top tier tried moving next tier trackers top tier fail torrents multiple trackers decrease time takes download file also consequences bittorrent specification free use many clients open source bittorrent clients created common operating systems using variety programming languages official bittorrent client µtorrent qbittorrent transmission vuze bitcomet popular clients bittorrent implementations mldonkey torrentflux designed run servers example used centralize file sharing single dedicated server users share access network server-oriented bittorrent implementations also hosted hosting providers co-located facilities high bandwidth internet connectivity e.g. datacenter provide dramatic speed benefits using bittorrent regular home broadband connection services imageshack download files bittorrent user allowing download entire file http finished opera web browser supports bittorrent wyzo bitlet allows users download torrents directly browser using java applet increasing number hardware devices made support bittorrent include routers nas devices containing bittorrent-capable firmware like openwrt proprietary versions protocol implement drm encryption authentication found within managed clients pando unimplemented unofficial feature similarity enhanced transfer set technique improving speed peer-to-peer file sharing content distribution systems share data set proposed researchers pucha andersen kaminsky works spotting chunks identical data files exact near match one needed transferring data client exact data present experiments suggested set help greatly less popular files much popular data many peers already downloading andersen believes technique could immediately used developers bittorrent file sharing system bittorrent inc. working oversi new policy discover protocols query isp capabilities network architecture information oversi isp hosted netenhancer box designed improve peer selection helping peers find local nodes improving download speeds reducing loads isp network although protocol legal problems stem using protocol traffic copyright infringing works much controversy use bittorrent trackers bittorrent metafiles store file contents whether publishers bittorrent metafiles violate copyrights linking copyrighted works without authorization copyright holders controversial various jurisdictions pursued legal action websites host bittorrent trackers high-profile examples include closing suprnova.org torrentspy lokitorrent btjunkie mininova oink pink palace what.cd pirate bay torrent website formed swedish group noted legal section website letters replies subject alleged copyright infringements publicly displayed 31 may 2006 pirate bay servers sweden raided swedish police allegations mpaa copyright infringement however tracker running three days later study used value nbc universal merger comcast envisional examined 10,000 torrent swarms managed publicbt active downloaders excluding pornographic unidentifiable content found one swarm offered legitimate content united states 200,000 lawsuits filed copyright infringement bittorrent since 2010 30 april 2012 uk high court ordered five isps block bittorrent search engine pirate bay see list websites blocked united kingdom one concern udp flood attack bittorrent implementations often use µtp communication achieve high bandwidths underlying protocol used udp allows spoofing source addresses internet traffic possible carry denial-of-service attacks p2p lab environment users running bittorrent clients act amplifiers attack another service however always effective attack isps check source address correct leeches users download share bittorrent collaborative distributed platform section community wants solutions punish discourage behaviour several studies bittorrent indicated exist files containing malware available download via bittorrent particular one small sample indicated 18 executable programs available download contained malware another study claims much 14.5 bittorrent downloads contain zero-day malware bittorrent used distribution mechanism 47 zero-day malware found due sha1 collisions attacker alter execution path executable serving altered chunks victim downloading executable using bittorrent protocol despite fact proof concept exists attack may succeed limited cases small chunk size 32kb selecting larger chunks i.e 256kb amount resources required find sha1 collision tremendous makes attack virtually impossible
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Internet protocols
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ibm 7090/94 ibsys ibsys discontinued tape-based operating system ibm supplied ibm 7090 ibm 7094 computers similar operating system several significant differences also called ibsys provided ibm 7040 ibm 7044 computers ibsys based fortran monitor system fms likely bell labs besys q.v rather share operating system ibsys really basic monitor program read control card images placed decks program data cards individual jobs ibsys control card began column 1 immediately followed control name selected various ibsys utility programs needed set run job card deck images read magnetic tapes prepared offline usually directly punched card reader
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Operating systems
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hessling editor hessling editor open source text editor first released august 1992 ten years written maintained mark hessling along original author also maintainer regina open source rexx interpreter ported unix platforms according developers text editor modeled vm/cms editor xedit adding best features mansfield software kedit folding controlled command permits one display work lines file contain given pattern example command codice_1 display lines include string global changes one makes slice example replace string command reflected file cases convenient way make global changes file order restore visibility lines one needs enter without target string similar xedit uses ibms rexx macro language makes highly configurable versatile provides ability create powerful extensions editor and/or customize specialized needs example one create edit commands would allows one manipulate columns text e.g copy/move insert/delete column text within file rexx one also integrate os commands external functions edit session since version 3.0 also user-configurable syntax highlighting xedit gui editors syntax highlighting language definition codice_2 file format comparable kedit codice_3 format free software distributed terms gnu general public license available many operating systems posix unix platforms program text-mode native x11 qnx os/2 dos beos amiga windows 95/98/me/nt/2000/xp
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Operating systems
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sparc64 v sparc64 v zeus sparc v9 microprocessor designed fujitsu sparc64 v basis series successive processors designed servers later supercomputers servers series sparc64 v+ vi vi+ vii vii+ x x+ xii sparc64 vi successors vii+ used fujitsu sun later oracle sparc enterprise m-series servers addition servers version sparc64 vii also used commercially available fujitsu fx1 supercomputer october 2017 sparc64 xii latest server processor used fujitsu oracle m12 servers supercomputer series based sparc64 vii sparc64 viifx ixfx xifx sparc64 viiifx used k computer sparc64 ixfx commercially available primehpc fx10 july 2016 sparc64 xifx latest supercomputer processor used fujitsu primehpc fx100 supercomputer late 1990s hal computer systems subsidiary fujitsu designing successor sparc64 gp sparc64 v. first announced microprocessor forum 1999 hal sparc64 v would operated 1 ghz wide superscalar organization superspeculation l1 instruction trace cache small fast 8 kb l1 data cache separate l2 caches instructions data designed fujitsu cs85 process 0.17 μm cmos process six levels copper interconnect would consisted 65 million transistors 380 mm die originally scheduled late 2001 release fujitsu granpower servers canceled mid-2001 hal closed fujitsu replaced fujitsu design first fujitsu sparc64 vs fabricated december 2001 operated 1.1 1.35 ghz fujitsu 2003 sparc64 roadmap showed company planned 1.62 ghz version release late 2003 early 2004 canceled favor sparc64 v+ sparc64 v used fujitsu primepower servers sparc64 v first presented microprocessor forum 2002 introduction highest clock frequency sparc 64-bit server processors production highest spec rating sparc processor sparc64 v four-issue superscalar microprocessor out-of-order execution based fujitsu gs8900 mainframe microprocessor sparc64 v fetches eight instructions instruction cache first stage places 48-entry instruction buffer next stage four instructions taken buffer decoded issued appropriate reserve stations sparc64 v six reserve stations two serve integer units one address generators two floating-point units one branch instructions integer address generator floating-point unit eight-entry reserve station reserve station dispatch instruction execution unit instruction dispatched firstly depends operand availability age older instructions given higher priority newer ones reserve stations dispatch instructions speculatively speculative dispatch instructions dispatched execution units even operands yet available execution begins stage six six instructions dispatched register files read stage seven sparc architecture separate register files integer floating-point instructions integer register file eight register windows jwr joint work register contains 64 entries eight read ports two write ports jwr contains subset eight register windows previous current next register windows purpose reduce size register file microprocessor operate higher clock frequencies floating-point register file contains 64 entries six read ports two write ports execution begins stage nine six execution units two integer two loads stores two floating-point two integer execution units designated exa exb arithmetic logic unit alu shift unit exa multiply divide units loads stores executed two address generators ags designated aga agb simple alus used calculate virtual addresses two floating-point units fpus designated fla flb fpu contains adder multiplier fla graphics unit attached execute add subtract multiply divide square root multiply–add instructions unlike successor sparc64 vi sparc64 v performs multiply–add separate multiplication addition operations thus two rounding errors graphics unit executes visual instruction set vis instructions set single instruction multiple data simd instructions instructions pipelined except divide square root executed using iterative algorithms fma instruction implemented reading three operands operand register multiplying two operands forwarding result third operand adder adding produce final result results execution units loads written register file maintain program order written update buffers reside committed sparc64 v separate update buffers integer floating-point units 32 entries integer register eight read ports four write ports half write ports used results integer execution units half data returned loads floating-point update buffer six read ports four write ports commit takes place stage ten earliest sparc64 v commit four instructions per cycle stage eleven results written register file becomes visible software sparc64 v two-level cache hierarchy first level consists two caches instruction cache data cache second level consists on-die unified cache level 1 l1 caches capacity 128 kb two-way set associative 64-byte line size virtually indexed physically tagged instruction cache accessed via 256-bit bus data cache accessed two 128-bit buses data cache consists eight banks separated 32-bit boundaries uses write-back policy data cache writes l2 cache 128-bit unidirectional bus second level cache capacity 1 2 mb set associativity depends capacity microprocessor 128-bit system bus operates 260 mhz bus operate two modes single-data rate sdr double-data ddr rate yielding peak bandwidth 4.16 8.32 gb/s respectively sparc64 v consisted 191 million transistors 19 million contained logic circuits fabricated 0.13 µm eight-layer copper metallization complementary metal–oxide–semiconductor cmos silicon insulator soi process die measured 18.14 mm 15.99 mm die area 290 mm 1.3 ghz sparc64 v power dissipation 34.7 w. fujitsu primepower servers use sparc64 v supply slightly higher voltage microprocessor enable operate 1.35 ghz increased power supply voltage operating frequency increased power dissipation ~45 w. sparc64 v+ code-named olympus-b development sparc64 v. improvements sparc64 v included higher clock frequencies 1.82–2.16 ghz larger 3 4 mb l2 cache first sparc64 v+ 1.89 ghz version shipped september 2004 fujitsu primepower 650 850 december 2004 1.82 ghz version shipped primepower 2500 versions 3 mb l2 cache february 2006 four versions introduced 1.65 1.98 ghz versions 3 mb l2 caches shipped primepower 250 450 2.08 2.16 ghz versions 4 mb l2 caches shipped mid-range high-end models contained approximately 400 million transistors 18.46 mm 15.94 mm die area 294.25 mm fabricated 90 nm cmos process ten levels copper interconnect sparc64 vi code-named olympus-c two-core processor first multi-core sparc64 processor succeeded sparc64 v+ fabricated fujitsu 90 nm 10-layer copper cmos silicon insulator soi process enabled two cores l2 cache integrated die core modified sparc64 v+ processor one main improvements addition two-way coarse-grained multi-threading cmt fujitsu called vertical multi-threading vmt cmt thread executed determined time-sharing thread executing long-latency operation execution switched thread addition cmt required duplication program counter control integer floating-point registers one set every thread floating-point fused multiply-add fma instruction also added first sparc processor cores share 6 mb on-die unified l2 cache l2 cache 12-way set associative 256-byte lines cache accessed via two unidirectional buses 256-bit read bus 128-bit write bus sparc64 vi new system bus jupiter bus sparc64 vi consisted 540 million transistors die measures 20.38 mm 20.67 mm 421.25 mm sparc64 vi originally introduced mid-2004 fujitsu primepower servers development primerpowers canceled fujitsu sun microsystems announced june 2004 would collaborate new servers called advanced product line apl servers scheduled introduced mid-2006 delayed april 2007 introduced sparc enterprise sparc64 vi processors featured sparc enterprise announcement 2.15 ghz version 5 mb l2 cache 2.28 2.4 ghz versions 6 mb l2 caches sparc64 vii previously called sparc64 vi+ code-named jupiter development sparc64 vi announced july 2008 quad-core microprocessor core capable two-way simultaneous multithreading smt replaces two-way coarse-grained multithreading termed vertical multithreading vmt fujitsu thus execute eight threads simultaneously changes include ras features integer register file protected ecc number error checkers increased around 3,400 consists 600 million transistors 21.31 mm × 20.86 mm 444.63 mm large fabricated fujitsu 65 nm cmos copper interconnect process sparc64 vii featured sparc enterprise socket-compatible predecessor sparc64 vi field-upgradeable sparc64 viis could coexist whilst operating native clock frequency alongside sparc64 vis first versions sparc64 vii 2.4 ghz version 5 mb l2 cache used sparc enterprise m4000 m5000 2.52 ghz version 6 mb l2 cache 28 october 2008 2.52 ghz version 5 mb l2 cache introduced sparc enterprise m3000 13 october 2009 fujitsu sun introduced new versions sparc64 vii code-named jupiter+ 2.53 ghz version 5.5 mb l2 cache m4000 m5000 2.88 ghz version 6 mb l2 cache m8000 m9000 12 january 2010 2.75 ghz version 5 mb l2 cache introduced m3000 sparc64 vii+ jupiter-e referred m3 oracle development sparc64 vii clock frequency increased 3 ghz l2 cache size doubled 12 mb version announced 2 december 2010 high-end sparc enterprise m8000 m9000 servers improvements resulted approximately 20 increase overall performance 2.66 ghz version mid-range m4000 m5000 models 12 april 2011 2.86 ghz version two four cores 5.5 mb l2 cache announced low-end m3000 vii+ socket-compatible predecessor vii existing high-end sparc enterprise m-series servers able upgrade vii+ processors field sparc64 viiifx venus eight-core processor based sparc64 vii designed high-performance computing hpc result viiifx succeed vii existed concurrently consists 760 million transistors measures 22.7 mm 22.6 513.02 mm fabricated fujitu 45 nm cmos process copper interconnects 1,271 i/o pins viiifx peak performance 128 gflops typical power consumption 58 w 30 °c efficiency 2.2 gflops/w viiifx four integrated memory controllers total eight memory channels connects 64 gb ddr3 sdram peak memory bandwidth 64 gb/s viiifx developed next-generation supercomputer project also called kei soku keisenki project keisoku initiated japan ministry education culture sports science technology january 2006 project aimed produce world fastest supercomputer performance 10 pflops march 2011 companies contracted develop supercomputer fujitsu hitachi nec supercomputer originally envisioned hybrid architecture containing scalar vector processors fujitsu-designed viiifx scalar processor vector processor jointly designed hitachi nec however due financial crisis 2007–2008 hitachi nec announced may 2009 would leave project manufacturing hardware responsible would result financial losses afterwards fujitsu redesigned supercomputer use viiifx processor type 2010 supercomputer would built project named k computer located riken advanced institute computational science aics kobe japan obtains performance 88,128 viiifx processors june 2011 top500 project committee announced k computer still incomplete 68,544 processors topped linpack benchmark 8.162 pflops realizing 93 peak performance making fastest supercomputer world time viiifx core based sparc64 vii numerous modifications hpc namely high performance computing-arithmetic computational extensions hpc-ace fujitsu-designed extension sparc v9 architecture front-end coarse-grained multi-threading removed l1 instruction cache halved size 32 kb number branch target address cache btac entries reduced 1,024 8,192 associativity reduced two eight extra pipeline stage inserted instruction decoder stage accommodated greater number integer floating-point registers defined hpc-ace sparc v9 architecture designed 32 integer 32 floating-point number registers sparc v9 instruction encoding limited number registers specifiable 32 specify extra registers hpc-ace prefix instruction would immediately follow one two sparc v9 instructions prefix instruction contained primarily portions register numbers could fit within sparc v9 instruction extra pipeline stage four sparc v9 instructions combined two prefix instructions preceding stage combined instructions decoded next pipeline stage back-end also heavily modified number reservation station entries branch integer instructions reduced six ten respectively integer floating-point register files registers added integer register file gained 32 total 256 floating-point registers extra integer registers part register windows defined sparc v9 always accessible via prefix instruction 256 floating-point registers could used scalar floating-point instructions integer floating-point simd instructions extra pipeline stage added beginning floating-point execution pipeline access larger floating-point register file 128-bit simd instructions hpc-ace implemented adding two extra floating-point units total four simd execution perform four single- double-precision fused-multiply-add operations eight flops per cycle number load queue entries increased 20 16 l1 data cache halved size 32 kb number commit stack entries determined number instructions could in-flight back-end reduced 48 64 sparc64 ixfx improved version sparc64 viiifx designed fujitsu lsi first revealed announcement primehpc fx10 supercomputer 7 november 2011 along primehpc fx10 commercialization technologies first appeared viiifx k computer compared viiifx organizational improvements included doubling number cores 16 doubling amount shared l2 cache 12 mb increasing peak ddr3 sdram memory bandwidth 85 gb/s ixfx operates 1.848 ghz peak performance 236.5 gflops consumes 110 w power efficiency 2 gflops per watt consisted 1 billion transistors implemented 40 nm cmos process copper interconnects sparc64 x 16-core server microprocessor announced 2012 used fujitsu m10 servers also marketed oracle sparc64 x based sparc64 vii+ significant enhancements core chip organization cores improved inclusion pattern history table branch prediction speculative execution loads execution units support hpc-ace extension originally sparc64 viiifx deeper pipeline 3.0 ghz clock frequency accelerators cryptography database decimal floating-point number arithmetic conversion functions 16 cores share unified 24 mb 24-way set-associative l2 cache chip organization improvements include four integrated ddr3 sdram memory controllers glueless four-way symmetrical multiprocessing ten serdes channels symmetrical multiprocessing scalability 64 sockets two integrated pci express 3.0 controllers sparc64 x contains 2.95 billion transistors measures 23.5 mm 25 mm 637.5 mm fabricated 28 nm cmos process copper interconnects sparc64 x+ enhanced sparc64 x processor announced 2013 features minor improvements core organization higher 3.5 ghz clock frequency obtained better circuit design layout contained 2.99 billion transistors measured 24 mm 25 mm 600 mm fabricated process sparc64 x 8 april 2014 3.7 ghz speed-binned parts became available response introduction new xeon e5 e7 models intel impending introduction power8 ibm fujitsu introduced sparc64 xifx august 2014 hot chips symposium used fujitsu primehpc fx100 supercomputer succeeded primehpc fx10 xifx operates 2.2 ghz peak performance 1.1 tflops consists 3.75 billion transistors fabricated taiwan semiconductor manufacturing company 20 nm high-κ metal gate hkmg process microprocessor report estimated die area 500 mm typical power consumption 200 w. xifx 34 cores 32 compute cores used run user applications 2 assistant cores used run operating system system services delegation user applications operating system dedicated cores improves performance ensuring private caches compute cores shared disrupted non-application instructions data 34 cores organized two core memory groups cmgs consisting 16 compute cores 1 assistant core sharing 12 mb l2 unified cache division cores cmgs enabled 34 cores integrated single die easing implementation cache coherence avoiding need l2 cache shared 34 cores two cmgs share memory ccnuma organization xifx core based sparc64 x+ organizational improvements xifx implements improved version hpc-ace extensions hpc-ace2 doubled width simd units 256 bits added new simd instructions compared sparc64 ixfx xifx improvement factor 3.2 double precision 6.1 single precision complement increased width simd units l1 cache bandwidth increased 4.4 tb/s improvements soc organization memory interconnect interfaces integrated memory controllers replaced four hybrid memory cube hmc interfaces decreased memory latency improved memory bandwidth according microprocessor report ixfx first processor use hmcs xifx connected 32 gb memory provided eight 4 gb hmcs hmcs 16-lane versions lane operating 15 gbit/s cmg two hmc interfaces hmc interface connected two hmcs via ports cmg 240 gb/s 120 gb/s 120 gb/s memory bandwidth xifx replaced ten serdes channels external tofu interconnect controller ten-port integrated controller second-generation tofu2 interconnect tofu2 6d mesh/torus network 25 gb/s full-duplex bandwidth 12.5 gb/s per direction 125 gb/s ten ports improved routing architecture sparc64-xii cores run 3.9 ghz 20 nanometer processes tsmc l3 cache 5.5 billion transistors 153 gb/sec memory bandwidth unix vendor able run solaris 10 bare metal fujitsu announced international supercomputing conference june 2016 future exascale supercomputer feature processors design implement armv8 architecture processors also implement extensions armv8 architecture equivalent hpc-ace2 fujitsu developing arm holdings
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Computer architecture
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cloudsim cloudsim framework modeling simulation cloud computing infrastructures services originally built primarily cloud computing distributed systems clouds laboratory university melbourne australia cloudsim become one popular open source cloud simulators research academia cloudsim completely written java initially developed stand-alone cloud simulator cloudsim extended independent researchers multiple tutorials blog posts available cloudsim addition online course introducing cloudsim simulation framework covering installation architecture execution description sample simulations quick references quick tutorials flows
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Distributed computing architecture
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user behavior analytics user behavior analytics uba defined gartner cybersecurity process detection insider threats targeted attacks financial fraud uba solutions look patterns human behavior apply algorithms statistical analysis detect meaningful anomalies patterns—anomalies indicate potential threats instead tracking devices security events uba tracks system users big data platforms like apache hadoop increasing uba functionality allowing analyze petabytes worth data detect insider threats advanced persistent threats problem uba responds described nemertes research ceo johna till johnson security systems provide much information tough uncover information truly indicates potential real attack analytics tools help make sense vast amount data siem ids/ips system logs tools gather uba tools use specialized type security analytics focuses behavior systems people using uba technology first evolved field marketing help companies understand predict consumer-buying patterns turns uba extraordinarily useful security context developments uba technology led gartner evolve category user entity behavior analytics ueba september 2015 gartner published market guide user entity analytics vice president distinguished analyst avivah litan provided thorough definition explanation ueba referred earlier gartner reports much depth expanding definition uba includes devices applications servers data anything ip address moves beyond fraud-oriented uba focus broader one encompassing malicious abusive behavior otherwise went unnoticed existing security monitoring systems siem dlp addition entity reflects devices may play role network attack may also valuable uncovering attack activity end users compromised malware lay dormant go undetected months rather trying find outsider entered uebas allow quicker detection using algorithms detect insider threats particularly computer security market many vendors ueba applications differentiated whether designed monitor on-premises cloud-based software service saas applications methods obtain source data type analytics use i.e. packaged analytics user-driven vendor-written service delivery method i.e. on-premises cloud-based according 2015 market guide released gartner ueba market grew substantially 2015 ueba vendors grew customer base market consolidation began gartner client interest ueba security analytics increased report projected next three years leading ueba platforms become preferred systems security operations investigations organizations serve be—and cases already is—much easier discover security events analyze individual offenders ueba many legacy security monitoring systems
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Computer security
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canvas fingerprinting canvas fingerprinting one number browser fingerprinting techniques tracking online users allow websites identify track visitors using html5 canvas element instead browser cookies similar means technique received wide media coverage 2014 researchers princeton university ku leuven university described paper web never forgets canvas fingerprinting works exploiting html5 canvas element described acar et al variations graphics processing unit gpu installed graphics driver cause variations fingerprint fingerprint stored shared advertising partners identify users visit affiliated websites profile created user browsing activity allowing advertisers target advertising user inferred demographics preferences since fingerprint primarily based browser operating system installed graphics hardware uniquely identify users small-scale study 294 participants amazon mechanical turk experimental entropy 5.7 bits observed authors study suggest entropy could likely observed wild patterns used fingerprint sufficient uniquely identify users fingerprint could combined sources entropy provide unique identifier claimed technique effectively fingerprinting gpu entropy orthogonal entropy previous browser fingerprint techniques screen resolution browser javascript capabilities tor project reference documentation states plugins plugin-provided information believe html5 canvas single largest fingerprinting threat browsers face today tor browser notifies user canvas read attempts provides option return blank image data prevent fingerprinting however tor browser currently unable distinguish legitimate uses canvas element fingerprinting efforts warning taken proof website intent identify track visitors browser add-ons like privacy badger donottrackme adblock plus manually enhanced easyprivacy list able block third-party ad network trackers block canvas fingerprinting provided tracker served third party server opposed implemented visited website may 2012 keaton mowery hovav shacham researchers university california san diego wrote paper pixel perfect fingerprinting canvas html5 describing html5 canvas could used create digital fingerprints web users social bookmarking technology company addthis began experimenting canvas fingerprinting early 2014 potential replacement cookies 5 top 100,000 websites used canvas fingerprinting deployed according addthis ceo richard harris company used data collected tests conduct internal research users able install opt-out cookie computer prevent tracked addthis canvas fingerprinting software developer writing forbes stated device fingerprinting utilized purpose preventing unauthorized access systems long used tracking users without consent 2014 technique widespread many websites least dozen high-profile web ads user tracking suppliers using
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Web technology
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xharbour xharbour free multi-platform extended clipper compiler offering multiple graphic terminals gts including console drivers guis hybrid console/guis xharbour backward-compatible clipper supports many language syntax extensions greatly extended run-time libraries extensive third party support like dynamic languages xharbour also available scripting language standalone application linkable library ms activescript engine windows script host html asp utilizing interpreter written xharbour language xharbour usenet newsgroup comp.lang.xharbour active community discussing xharbour related questions xharbour 6 scalar types nil string date logical number pointer 4 complex types array object codeblock hash scalar holds single value string number reference type arrays ordered lists scalars complex types indexed number starting 1 hashes associative arrays unordered collections type values indexed associated key may scalar complex type literal static representation scalar types complex types may also represent literal values hashes may use type including hashes key element hashes arrays may contain type value member including nesting arrays hashes codeblocks may references variables procedure/function method defined codeblocks may returned value means argument passed reference case codeblock outlive routine defined variables references detached variable detached variables maintain value long codeblock referencing still exists values shared codeblock may access variables codeblock outlive containing routine evaluated within lifetime routine defined changes detached variables means evaluation reflected back parent routine codeblocks evaluated number times means eval blockexp function types assigned named variables named variable identifiers 1 63 characters long start a-z|_ consist characters a-z|0-9|_ maximum 63 characters named variables case sensitive variables one following scopes local static global resolved compile time thus much faster private public variables dynamic entities accessed means runtime symbol table reason local static global variables exposed macro compiler macro code attempts reference generate runtime error due dynamic nature private public variables created destroyed runtime accessed modified means runtime macros accessed modified codeblocks created fly basic control structures include standard dbase clipper control structures well additional ones inspired c java programming languages conditionexp statement assignment expression evaluated prior first loop iteration expression evaluated compared value control variable prior iteration loop terminated evaluates numeric value greater numeric value control variable optional step expression evaluated iteration prior deciding whether perform next iteration var variable value scalar complex respective element collection value collection expression may array type combinations types hash table object type condexp ... represents 0 statement condition expression evaluate logical value case construct logically equivalent xharbour supports switch construct inspired c implementation switch begin sequence begin sequence structure allows well behaved abortion sequence even crossing nested procedures/functions means called procedure/function may issue break statement break expression force unfolding nested procedure/functions way back first outer begin sequence structure either respective end statement recover clause present break statement may optionally pass type expression may accepted recover statement allow recovery handing additionally xharbour error object supports candefault canretry cansubstitute properties allows error handlers perform preparations request retry operation resume return value replace expression triggering error condition try try construct similar begin sequence construct except automatically integrates error handling error intercepted recovered means catch statement forwarded outer catch handler otherwise finally section guaranteed executed try catch sections forward flow control means return break throw static procedure someprocedurename procedures/functions xharbour specified keywords codice_1 codice_2 naming rules variables 63 characters non case sensitive procedures functions may qualified scope qualifier static restrict usage scope module defined init exit optional qualifiers flag procedure automatically invoked calling application startup procedure quitting application respectively parameters passed procedure/function appear subroutine local variables may accept type including references changes argument variables reflected respective variables passed calling procedure/function/method unless explicitly passed reference using prefix procedure return value used expression context produce nil value function may return type means return statement anywhere body definition example procedure definition function call follows xharbour extends clipper replaceable database drivers rdd approach offers multiple rdds dbf dbfntx dbfcdx dbfdbt dbffpt xharbour multiple rdds used single application new logical rdds defined combination rdd rdd architecture allows inheritance given rdd may extend functionality existing rdd 3rd party rdds like rddsql rddsix rmdbfcdx advantage database server mediator exemplify rdd architecture features xharbour also offers odbc support means oop syntax ado support means ole one powerful features xbase languages macro operator xharbour ’ implementation macro operator allows runtime compilation valid xharbour expression compiled expression may used value i.e right side assignment compiled expression may used resolve left side assignment i.e private public variables database field additionally macro operator may compile execute function calls complete assignments even list arguments result macro may used resolve contexts compiled application iow xharbour application may extended and/or modified runtime compile execute additional code demand xharbour implementation feature complete xharbour interpreter xbscript uses heavily compile xharbour scripts syntax text value expression ... compiled value resulting execution compiled code result short form someid short form someid postfix typical hello world program would enclosed explicit procedure xharbour also available interpreted language flavors scripting engines
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Programming language topics
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barbarian 1987 video game barbarian 1987 computer platform game psygnosis first developed atari st ported amiga commodore 64 ms-dos msx amstrad cpc zx spectrum amiga port released 1987 others released 1988 like early psygnosis titles cover artwork part red dragon figure/landscape popular fantasy artist roger dean game spawned 1991 sequel barbarian ii released alongside leander ork platform-based action-adventures psygnosis game opens striking—for era—animation muscle-bound barbarian cutting chain sword amiga atari st versions animation accompanied loud digital sound effect game player hegor barbarian must traverse several dungeons underground habitats defeat brother evil sorcerer necron sword bow arsenal weapons running jumping many platform games comprises large part gameplay title game used unique control system make lack one joystick button many systems player would first press one button menu actions would appear along bottom screen player selected desired action cycling choices joystick pressing button desired action highlighted original versions game tried emulate visual style game cover opening animation game used detailed colorful sprites variety thoughtful sound effects accompany onscreen action dos version played digitized speech opening sequence featured sound effects using pc speaker game reviewed 1989 dragon 150 courtney harrington role computers column harrington gave game 4 5 stars review amstrad action issue 40 gave game 81 stating fun lacking long term
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Computer architecture
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message send protocol message send protocol msp application layer protocol used send short message nodes network original version protocol published 1990 updated message send protocol 2 1992 one message send service defined connection-based application tcp service listens tcp connections port 18 connection established short message transmitted sender receiver connection sender closes connection sending message another message send service defined datagram-based application udp service listens udp datagrams port 18 datagram received receiver answering datagram sent back sender containing exactly data
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Internet protocols
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paul irish paul irish american front-end engineer developer advocate google chrome web browser widely recognized thought leader leading evangelist web technologies including javascript css 2011 named developer year net awards contributions web development landscape participation many popular open source projects irish created contributed led development many front-end web development projects javascript libraries irish created key contributor many websites effort encourage browser web developers move html5
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Programming language topics
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arla file system arla implementation afs distributed file system developed royal institute technology stockholm arla started björn grönvall 1993 assar westerlund johan danielsson joined project shortly thereafter project died usable fall 1997 project restarted starting björn implementation rxkad assar ported xfs arla component confused xfs filesystem freebsd love hörnqvist-åstrand began working followed magnus ahltorp working linux kernel module artur grabowski working openbsd kernel module today arla afs client support openbsd freebsd netbsd linux solaris tru64 mac os x windows support way delayed insufficient windows knowledge experimental afs server available yet considered stable
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Computer file systems
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graham-denning model graham-denning model computer security model shows subjects objects securely created deleted also addresses assign specific access rights mainly used access control mechanisms distributed systems three main parts model set subjects set objects set eight rules subject may process user makes request access resource object resource user process wants access model addresses security issues associated define set basic rights specific subjects execute security functions object model eight basic protection rules actions outline moreover object owner special rights subject another subject controller special rights model based access control matrix model rows correspond subjects columns correspond objects subjects element contains set rights subject object j subject subject k. example action contains rights subject object example execute executing one 8 rules example creating object matrix changed new column added object subject created becomes owner rule associated precondition example subject x wants delete object must owner x contains 'owner right harrison-ruzzo-ullman extended model defining system protection based commands made primitive operations conditions
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Computer security
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university new hampshire interoperability laboratory university new hampshire interoperability laboratory unh-iol independent test facility provides interoperability standards conformance testing networking telecommunications data storage consumer technology products founded 1988 employs approximately 25 full-time staff members 100 part-time undergraduate graduate students counts 150 companies members unh-iol began project university research computing center rcc 1988 rcc testing fiber distributed data interface fddi equipment intention deploying network rcc found equipment two vendors work together contacted vendors find solution two vendors cooperated rcc solve problem caused differences draft final fddi specification time period rcc testing 10base-t ethernet interfaces another project university recognized need interoperability testing networking equipment also opportunity provide students hands-on experience emerging technologies idea providing testing services companies vendor-neutral environment first unh-iol consortium 10base-t ethernet founded 1990 next decade unh-iol grew twelve consortia 100 member companies 2002 outgrown several smaller locations unh-iol moved 32,000 square foot facility outskirts unh campus one area unh-iol influential ipv6 standardization deployment 2003 2007 unh-iol organized moonv6 project multi-site ipv6 based network designed test interoperability ipv6 implementations time moonv6 project largest permanently deployed multi-vendor ipv6 network world unh-iol also north american laboratory offering iso/iec 17025 accredited testing designed specifically usgv6 test program unh-iol also known organizing hosting plugfests number industry trade organizations lab hosted plugests broadband forum nvm express scsi trade association ethernet alliance open compute project among others 2013 unh-iol awarded ieee-sa corporate award outstanding corporate leadership contribution ieee-sa january 2016 lab moved new 28,000 square foot location adjacent main unh campus durham nh unh-iol operates testing programs annual membership basis called consortia consortium collaboration equipment vendors test equipment manufacturers industry forums unh-iol particular technology collaborative testing model intended distribute costs associated maintaining high-quality testing program among consortium members unh-iol currently administers consortia 20 different technologies including
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Computer architecture
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curl programming language curl reflective object-oriented programming language interactive web applications whose goal provide smoother transition formatting programming makes possible embed complex objects simple documents without needing switch programming languages development platforms curl implementation initially consisted interpreter compiler added later curl combines text markup html scripting javascript heavy-duty computing java c c++ within one unified framework used range internal enterprise b2b b2c applications curl programs may compiled curl applets viewed using curl rte runtime environment plugin web browsers currently supported microsoft windows linux macos curl supports detached applets web deployed applet runs user desktop independent browser window much silverlight 3 adobe air curl language attempts address long-standing problem different building blocks make modern web document often require wildly different methods implementation different languages different tools different frameworks often completely different teams final — often difficult — hurdle getting blocks communicate consistent manner curl attempts side-step problems providing consistent syntactic semantic interface levels web content creation simple html complex object-oriented programming curl markup language like html—that plain text shown text time curl includes object-oriented programming language supports multiple inheritance curl applications required observe separation information style behavior html cascading style sheets css javascript imposed although style programming used curl desired curl language used html replacement presenting formatted text abilities range way compiled strongly typed object-oriented system programming language authoring html-level programming constructs curl extended user code language designed curl applications compiled native code client machine just-in-time compiler run high speed curl applets also written run off-line disconnected network occasionally connected computing fact curl ide application written curl simple curl applet helloworld might code run user least one curl versions 7.0 8.0 installed curl provides macros text-procedures addition anonymous procedures named methods alternative using text-procedure paragraph would recently style layout adopted builders groovy language jvm also familiar users css tcl/tk features web applications implemented combinations javascript libraries html css already found within curl language including features usually associated prototype script.aculo.us accordion panes curl sets callbacks manner also adopted groovy curl comments use vertical bar several variations simplest follows curl provides user-defined text procedures stylesheets curl used readily domain-specific lightweight markup major advantage plain text html markup text encoding set e.g. utf-8 text entered unicode-enabled editor without escaping characters like javascript curl unicode friendly poetry example would initially implemented defining poem stanza markup paragraph text formats stanza could refined include hidden navigation anchor page navigation using curl destination text procedure markup used different results one style text visible one context invisible another curl also permits top-level file inclusion source text markup included different parent files education example one could create source file test questions include student teacher version text
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Programming language topics
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ebcdic extended binary coded decimal interchange code ebcdic eight-bit character encoding used mainly ibm mainframe ibm midrange computer operating systems descended code used punched cards corresponding six-bit binary-coded decimal code used ibm computer peripherals late 1950s early 1960s supported various non-ibm platforms fujitsu-siemens bs2000/osd os-iv msp msp-ex sds sigma series unisys vs/9 burroughs mcp icl vme ebcdic devised 1963 1964 ibm announced release ibm system/360 line mainframe computers eight-bit character encoding developed separately seven-bit ascii encoding scheme created extend existing binary-coded decimal bcd interchange code bcdic devised efficient means encoding two zone number punches punched cards six bits distinct encoding using position 2 instead 1 maintained punched cards desirable hole punches close ensure integrity physical card ibm chief proponent ascii standardization committee company time prepare ascii peripherals card punch machines ship system/360 computers company settled ebcdic system/360 became wildly successful together clones rca spectra 70 icl system 4 fujitsu facom thus ebcdic ibm mainframe midrange peripherals operating systems use ebcdic inherent encoding toleration ascii example ispf z/os browse edit ebcdic ascii encoded files software many hardware peripherals translate encodings modern mainframes ibm zseries include processor instructions hardware level accelerate translation character sets ebcdic-oriented unicode transformation format called utf-ebcdic proposed unicode consortium designed allow easy updating ebcdic software handle unicode intended used open interchange environments even systems extensive ebcdic support popular example z/os supports unicode preferring utf-16 specifically z/os limited support utf-ebcdic ibm aix running rs/6000 descendants including ibm power systems linux running z systems operating systems running ibm pc descendants use ascii aix/370 aix/390 running system/370 system/390 mainframes fact code points different less problem inter-operating ascii fact sorting ebcdic put lowercase letters uppercase letters letters numbers exactly opposite ascii programming languages file formats network protocols designed ascii quickly made use available punctuation marks curly braces exist ebcdic making translation ebcdic ambiguous also prevented various attempts make internationalized versions ascii also replaced punctuation marks letters gaps letters made simple code worked ascii fail ebcdic example codice_1 would set codice_2 26 letters ascii alphabet 41 characters including number unassigned ones ebcdic fixing required complicating code function calls greatly resisted programmers using eight bits ebcdic may encouraged use eight-bit byte ibm ascii likely adopted systems 36 bits five seven-bit ascii characters fit one word eight-bit bytes became widespread ascii systems sometimes used unused bit purposes metacharacters mark borders records words made difficult change code work ebcdic pdp-11 bytes high bit set treated negative numbers behavior copied c causing unexpected problems ebcdic problems also hindered adoption extended ascii character sets table shows invariant subset ebcdic characters assignments ebcdic code pages also shows gray missing ascii ebcdic punctuation located ccsid 037 one code page variants ebcdic unassigned codes typically filled international region-specific characters various ebcdic code page variants characters gray often moved around swapped well table cell first row abbreviation control code printable characters character second row unicode code blank controls n't exist unicode open-source software advocate software developer eric s. raymond writes jargon file ebcdic loathed hackers meant members subculture enthusiastic programmers jargon file 4.4.7 gives following definition ebcdic design also source many jokes one joke went references ebcdic character set made classic infocom adventure game series zork machine room zork ii ebcdic used imply incomprehensible language
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Operating systems
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internet group management protocol access control internet group management protocol access control igmp-ac designed incorporating aaa protocol functionality existing ip multicast model enforce authentication authorization end user receiver joining leaving secured multicast group add aaa functionality access router one-hop router receiver act network access server nas igmp-ac extended version internet group management protocol provides generic client-server authentication protocol receiver end user act client aaa server act server access router one-hop router receiver perform forwarding task thus suitable authentication protocol e.g. extensible authentication protocol eap client-server entities encapsulated igmp-ac architecture igmp-ac disrupt usual function igmpv3 used classical multicast group access control mechanism igmp-ac take place join/leave secured restricted multicast group
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Internet protocols
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extended industry standard architecture extended industry standard architecture practice almost always shortened eisa frequently pronounced eee-suh bus standard ibm pc compatible computers announced september 1988 consortium pc clone vendors gang nine counter ibm use proprietary micro channel architecture mca ps/2 series comparison bus –which gang nine retroactively renamed isa bus avoid infringing ibm trademark pc/at computer– eisa extended 32 bits allows one cpu share bus bus mastering support also enhanced provide access 4 gb memory unlike mca eisa accept older xt isa boards — lines slots eisa superset isa eisa much favoured manufacturers due proprietary nature mca even ibm produced machines supporting somewhat expensive implement though much mca never became particularly popular desktop pcs however reasonably successful server market better suited bandwidth-intensive tasks disk access networking eisa cards produced either scsi network cards eisa also available non-ibm compatible machines alphaserver hp 9000-d sgi indigo2 mips magnum time strong market need bus speeds capabilities desktop computers vesa local bus later pci filled niche eisa vanished obscurity original ibm pc included five 8-bit slots running system clock speed 4.77 mhz pc/at introduced 1984 three 8-bit slots five 16-bit slots running system clock speed 6 mhz earlier models 8 mhz last version computer 16-bit slots superset 8-bit configuration 8-bit cards able plug 16-bit slot cards used skirt design physically interfered extended portion slot continue run 8-bit mode one key reasons success ibm pc pc clones followed active ecosystem third-party expansion cards available machines ibm restricted patenting bus widely published bus specifications pc-clone industry continued build momentum mid- late-1980s several problems bus began apparent first slot known time managed central standards group nothing prevent manufacturer pushing standard one common issues pc clones became common pc manufacturers began ratcheting processor speed maintain competitive advantage unfortunately isa bus originally locked processor clock meant 286 machines isa buses ran 10 12 even 16 mhz fact first system clock isa bus 8 mhz turbo 8088 clones clocked processors 8 mhz caused many issues incompatibility true ibm-compatible third-party card designed 8 mhz 4.77 mhz bus might work higher speed system even worse would work unreliably pc makers eventually decoupled slot clock system clock still standards body police industry companies like dell modified bus design architecture well entrenched single clone manufacturer leverage create standardized alternative compelling reason cooperate new standard first 386-based system compaq deskpro 386 hit market 1986 still supported 16-bit slots 386 pcs followed suit later isa bus remained part systems even late 1990s meanwhile ibm began worry losing control industry created 1987 ibm released ps/2 line computers included mca bus mca included numerous enhancements 16-bit bus including bus mastering burst mode software configurable resources 32-bit capabilities however effort reassert dominant role ibm patented bus placed stringent licensing royalty policies use manufacturers produce licensed mca machines notably ncr overall industry balked ibm restrictions steve gibson proposed clone makers adopt nubus instead group gang nine led compaq created new bus named extended enhanced industry standard architecture eisa 16-bit bus became known industry standard architecture isa provided virtually technical advantages mca remaining compatible existing 8-bit 16-bit cards enticing system card makers minimal licensing cost eisa bus slot two-level staggered pin system upper part slot corresponding standard isa bus pin layout additional features eisa bus implemented lower part slot connector using thin traces inserted insulating gap upper isa card card edge connector additionally lower part bus five keying notches isa card unusually long traces accidentally extend lower part slot intel introduced first eisa chipset also first chipset modern sense word 82350 september 1989 intel introduced lower cost variant 82350dt announced april 1991 began shipping june year first eisa computer announced hp vectra 486 october 1989 first eisa computers hit market compaq deskpro 486 systempro systempro one first pc-style systems designed network server built ground take full advantage eisa bus included features multiprocessing hardware raid bus-mastering network cards one benefits come eisa standard final codification standard isa slots cards held particular clock speed fixed industry standard 8.33 mhz thus even systems n't use eisa bus gained advantage isa standardized contributed longevity gang nine informal name given consortium personal computer manufacturing companies together created eisa bus rival members generally acknowledged compaq leadership one stating 1989 within gang nine 10 people sit table write letter president someone write letter compaq sitting typewriter members although mca bus slight performance advantage eisa bus speed 10 mhz compared 8.33 mhz eisa contained almost technological benefits mca boasted including bus mastering burst mode software configurable resources 32-bit data/address buses brought eisa nearly par mca performance standpoint eisa easily defeated mca industry support eisa replaced tedious jumper configuration common isa cards software-based configuration every eisa system shipped eisa configuration utility usually slightly customized version standard utilities written eisa chipset makers user would boot utility either floppy disk dedicated hard drive partition utility software would detect eisa cards system could configure hardware resources interrupts memory ports etc eisa card eisa card would include disk information described available options card eisa system motherboard user could also enter information isa cards system allowing utility automatically reconfigure eisa cards avoid resource conflicts similarly windows 95 plug-and-play capability able change configuration eisa cards could detect cards read configuration reconfigure plug play hardware avoid resource conflicts windows 95 would also automatically attempt install appropriate drivers detected eisa cards eisa success far guaranteed many manufacturers including gang nine researched possibility using mca example compaq actually produced prototype deskpro systems using bus however never put production clear mca lost compaq allowed mca license expire license actually cost relatively little primary costs associated mca industry revolted royalties paid per system shipped hand became clear ibm micro channel dying ibm licensed eisa use server systems
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Computer architecture
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nil programming language new implementation lisp nil programming language dialect language lisp developed massachusetts institute technology mit intended successor language maclisp 32-bit implementation part response digital equipment corporation dec vax computer project headed jon l white stated goal maintaining compatibility maclisp fixing many problems lisp language invented 1958 john mccarthy massachusetts institute technology mit inception lisp closely connected artificial intelligence ai research community especially pdp-10 systems 36-bit word size pdp-6 pdp-10 influenced usefulness two lisp 18-bit pointers one word pdp-6 project started early 1963 24-bit machine grew 36 bits lisp design goal lisp used implementation programming language micro planner foundation famous ai system shrdlu lisp particular maclisp named originated mit project mac also used implement macsyma computer algebra system 1970s ai research spawned commercial offshoots performance extant lisp systems became growing problem partly garbage collection lisp would use stop-and-copy garbage collection single heap memory allocation partly representation internal structures lisp became difficult run memory-limited stock computer hardware day led creating lisp machines dedicated hardware running lisp environments programs alternative use powerful commodity hardware becoming available especially digital equipment corporation dec vax nil implementation lisp developed mit mid late 1970s intended modern successor maclisp able run stock hardware contrast lisp machine lisp lisp machines originally designed first modern lisp dialect stock hardware development lisp machine lisp mit went become one main influences design common lisp pg 63/294 since users macsyma program represented large potential user base nil necessary nil would large complex system speed would imperative example high-speed bignums requirement support macsyma since nil would failure slow bignums consequently nil ended large base vax assembly language requirements led aggressive complex optimization strategy applied prematurely negative results final system concurrent effort write nil research group stanford university lawrence livermore national laboratory headed richard p. gabriel investigating design lisp run s-1 mark iia supercomputer s-1 lisp lisp never fully functional test bed implementing advanced compiler methods lisp eventually s-1 nil groups began collaborating although unsuccessful meeting goals used language nil important several ways first brought together jon l. white guy l. steele jr. richard p. gabriel later define common lisp second jonathan rees worked part nil project year away yale university returning yale hired computer science department write new lisp became optimizing native code scheme system named t. part nil begat name since nil
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Programming language topics
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iso/iec 27002 iso/iec 27002 information security standard published international organization standardization iso international electrotechnical commission iec titled information technology – security techniques – code practice information security controls iso/iec 27000-series standards descended corporate security standard donated shell uk government initiative early 1990s shell standard developed british standard bs 7799 mid-1990s adopted iso/iec 17799 2000 iso/iec standard revised 2005 renumbered iso/iec 27002 2007 align iso/iec 27000-series standards revised 2013 iso/iec 27002 provides best practice recommendations information security controls use responsible initiating implementing maintaining information security management systems isms information security defined within standard context cia triad standard starts 5 introductory chapters followed 14 main chapters within chapter information security controls objectives specified outlined information security controls generally regarded best practice means achieving objectives controls implementation guidance provided specific controls mandated since organizations implement wide range information security-related controls many recommended general terms iso/iec 27002 structuring information security controls infrastructure accordance iso/iec 27002 may advantageous since examples typical information security policies controls relating three parts iso/iec 27002 note merely illustration list example controls incomplete universally applicable iso/iec 27002 directly equivalent national standards several countries translation local publication often results several months delay main iso/iec standard revised released national standard bodies go great lengths ensure translated content accurately completely reflects iso/iec 27002 iso/iec 27002 advisory standard meant interpreted applied types sizes organization according particular information security risks face practice flexibility gives users lot latitude adopt information security controls make sense makes unsuitable relatively straightforward compliance testing implicit formal certification schemes iso/iec 27002 revised iso/iec jtc1/sc27 every years order keep current relevant revision involves instance incorporating references issued security standards iso/iec 27000 iso/iec 27004 iso/iec 27005 various good security practices emerged field since last published due significant 'installed base organizations already using iso/iec 27002 particularly relation information security controls supporting isms complies iso/iec 27001 changes justified wherever possible evolutionary rather revolutionary nature
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Computer security
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advanced continuous simulation language advanced continuous simulation language acsl pronounced axle computer language designed modeling evaluating performance continuous systems described time-dependent nonlinear differential equations like simcos tutsim acsl dialect continuous system simulation language cssl originally designed simulation councils inc sci 1967 attempt unify continuous simulations field acsl equation-oriented language consisting set arithmetic operators standard functions set special acsl statements macro capability allows extension special acsl statements acsl intended provide simple method representing mathematical models digital computer working equation description problem block diagram user writes acsl statements describe system investigation important feature acsl sorting continuous model equations contrast general purpose programming languages fortran program execution depends critically statement order applications acsl new areas developed constantly typical areas acsl currently applied include control system design aerospace simulation chemical process dynamics power plant dynamics plant animal growth toxicology models vehicle handling microprocessor controllers robotics acslx family products aegis technologies group inc modular modeling system mms nhance technologies inc
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Programming language topics
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comparison cluster software following tables compare general technical information notable computer cluster software software grossly separated four categories job scheduler nodes management nodes installation integrated stack table explanation table explanation
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Distributed computing architecture
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failover computing related technologies networking failover switching redundant standby computer server system hardware component network upon failure abnormal termination previously active application server system hardware component network failover switchover essentially operation except failover automatic usually operates without warning switchover requires human intervention systems designers usually provide failover capability servers systems networks requiring near-continuous availability high degree reliability server level failover automation usually uses heartbeat system connects two servers either using separate cable example rs-232 serial ports/cable network connection long regular pulse heartbeat continues main server second server second server bring systems online may also third spare parts server running spare components hot switching prevent downtime second server takes work first soon detects alteration heartbeat first machine systems ability send notification failover certain systems intentionally failover entirely automatically require human intervention automated manual approval configuration runs automatically human approved failover failback process restoring system component service previously state failure back original working state standby system go functioning back standby use virtualization software allowed failover practices become less reliant physical hardware process referred migration running virtual machine moved one physical host another little disruption service term failover although probably use engineers much earlier found 1962 declassified nasa report term switchover found 1950s describing hot cold standby systems current meaning immediate switchover running system hot delayed switchover system needs starting cold conference proceedings 1957 describes computer systems emergency switchover i.e failover scheduled failover maintenance
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Computer architecture
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stanford mips mips acronym microprocessor without interlocked pipeline stages research project conducted john l. hennessy stanford university 1981 1984 mips investigated type instruction set architecture isa called reduced instruction set computer risc implementation microprocessor large scale integration vlsi semiconductor technology effective exploitation risc architectures optimizing compilers mips together ibm 801 berkeley risc three research projects pioneered popularized risc technology mid-1980s recognition impact mips made computing hennessey awarded ieee john von neumann medal 2000 ieee shared david a. patterson eckert–mauchly award 2001 association computing machinery seymour cray computer engineering award 2001 ieee computer society david patterson turing award 2017 acm project initiated 1981 response reports similar projects ibm 801 university california berkeley risc mips conducted hennessy graduate students conclusion 1984 hennessey founded mips computer systems year commercialize technology developed project 1985 mips computer systems announced new isa also called mips first implementation r2000 microprocessor commercial mips isa implementations went widely used appearing embedded computers personal computers workstations servers supercomputers may 2017 commercial mips isa owned imagination technologies used mainly embedded computers late 1980s follow-up project called mips-x conducted hennessy stanford mips isa based 32-bit word supported 32-bit addressing word-addressed load/store architecture—all references memory used load store instructions copied data main memory 32 general-purpose registers gprs instructions integer arithmetic operated gprs possessed basic instruction set consisting instructions control flow integer arithmetic logical operations minimize pipeline stalls instructions except load store executed one clock cycle instructions integer multiplication division operations floating-point numbers architecture exposed hazards caused five-stage pipeline delay slots compiler scheduled instructions avoid hazards resulting incorrect computation whilst simultaneously ensuring generated code minimized execution time mips instructions 16 32 bit long decision expose hazards motivated desire maximize performance minimizing critical paths interlock circuits lengthened instructions packed 32-bit instruction words mips word-addressed 32-bit instruction word could contain two 16-bit operations included reduce size machine code mips microprocessor implemented nmos logic
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Computer architecture
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nebuad nebuad american online advertising company based redwood city california offices new york london funded investment companies sierra ventures menlo ventures one several companies originally developed behavioral targeting advertising systems sought deals isps enable analyse customer websurfing habits order provide relevant micro-targeted advertising phorm similar company operating europe adzilla project rialto also appear developing similar systems one point nebuad signed 30 customers mostly internet access providers agreements providers covered 10 percent broadband users america due fallout following public congressional concern nebuad largest isp customers pulled nebuad closed business uk august 2008 followed us may 2009 nebuad uk ltd dissolved february 2010 nebuad platform comprised three main parts hardware hosted within isp capable inserting content pages off-site server complex analyse categorise contents users internet communications relationships advertising networks willing present nebuad targeted advertising system consisted hardware device installed within isp client network device capable monitoring 50,000 users users could opt-out nebuad ’ information collection targeted ads way users prevent isps sending data nebuad first place since isps route customers traffic important vantage point monitor traffic to-and-from consumer using deep packet inspection dpi analysing traffic nebuad reported gained information customers particular interests less intrusive methods nebuad privacy policy claimed specifically store use information relating confidential medical information racial ethnic origins religious beliefs sexuality tied personally identifiable information 'sensitive personal information also advises information collect stored processed nebuad servers united states result information may subject access requests governments courts law enforcement least 2 customers middle america isp wow noticed unexpected cookies appearing sites nebuad.adjuggler.com using google read written wow support department contacted wow initially denied responsibility activity noticing problems google loading slowly creation non-google cookies one customer spent hours trying disinfect machine incorrectly thought infected spyware proved ineffective resorted reinstalling machine os scratch discover problem go away july 9 2008 wow suspended use nebuad services subscribers according nebuad sales less 1 users opt-out one isp expected earn least 2.50 per month user nebuad bought impressions ad networks including valueclick nebuad argued behavioral targeting enriches internet several fronts firstly website owners offered improved click-through rate ctr could increase profits reduce amount page-space dedicated advertising owners previously thought ad-unfriendly websites offered chance make money subject matter website interests visitors advertisers offered better targeted adverts hence reducing scattergun approach publishing many ads possible hope catching client users offered relevant adverts isps paid allowing nebuad access network per-user per-active profile basis nebuad used data web search terms page views page ad clicks time spent specific sites zip code browser info connection speed categorise user interests nebuad access user identification information isp may able discover traffic monitoring example email traffic may tie email address ip address bob dykes nebuad ceo claimed 2008 800 consumer interest segments today 're expanding multiple thousands generally nebuad provided additional revenue network operators may maintain lower consumers internet access bills critics dpi targeted advertising believe raw content internet communications entrusted isp handling without inspected modified sale privacy advocates criticize lack disclosure isps provided prior partnering nebuad weak opt-out method lack oversight third-party company contents internet communications conflicts united states wiretap laws company refusal name partner isps february 2008 one american cable operator wide open west wow started rolling nebuad roll-out completed first week march 2008 wow updated terms conditions include mention nebuad cases informed customers terms updated however customers explicitly notified nebuad later sometime third week march 2008 response inquiry members united states house representatives telecommunications subcommittee pilot test nebuad services embarq said notified consumers revising privacy policy 2 weeks prior sending users data streams nebuad knology user knoxville tennessee reported notified internet use monitored may 2008 charter communications announced planned monitor websites visited customers via partnership nebuad customers voiced concerns charter changed mind june plans implement nebuad agree isp employees including one employee planned re-route traffic avoid nebuad deep packet inspection hardware altogether members us congress ed markey chairman house subcommittee telecommunications internet joe barton ranking member house committee energy commerce argued services must opt-in comply provisions laid section 631 us communications act wrote charter request suspend test respectfully request move forward charter communications proposed venture nebuad opportunity discuss issues raised proposed venture writer wired news questioned whether charter users could really opt monitored able opt receiving targeted ads writer asked would breach anti-wiretapping laws engineer examined system confirmed way opt nebuad monitoring inbound outbound information intercepted sent nebuad offsite server processed even user opted service prevent isp sending data nebuad report robert m. topolski chief technology consultant free press public knowledge showed nebuad devices created cookies end-users machines injecting specious packet end data stream returned response web page requests submitted search engines including google yahoo content specious packet would added end web page rendered end-user browser contained html script tags cause browser request javascript http //a.faireagle.com critics concerned nebuad superimposed advertising ads advertisers placing additional advertising page concerns originated nebuad fair eagle operation patent application data mentioned inventions loose relationship claria corporation whose products history suggest tactics well following 2007 reported redmoon texas-based isp using nebuad technology inject redmoon advertising pages visited users fair eagle advertisement hardware provided nebuad inserted additional advertising alongside content web pages ads featured window fair eagle title bar injected ads stopped appearing toward end june 2007 senior staff members nebuad worked previously defunct ad company named claria corporation formerly gator corporation well known ad software known gator claria nebuad located redwood city california june 2006 creation nebuad.com coincides timing claria decision shut gator service nebuad repeatedly denied corporate connection claria describing hiring claria employees result company shedding employees tight market experienced advertising sales staff valley isps tried deployed prepared deploy nebuad included following following isps listed legal documents related class action notice see deployed nebuad hardware isps ended suspended relationship nebuad nebuad closed uk august 2008 us may 2009 proposed settlement class-action lawsuit nebuad underway october 2011 subscribers isps listed january 1 2007 july 1 2008 considered mandatory class members opt could choose opt terms proposed settlement nebuad would create settlement fund approximately 2,410,000 used administration settlement covering legal fees incentive award 5,000 individual brought complaint providing 1000 named representatives money going support non-profits providing consumer education privacy research
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Computer security
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