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tower druaga druaga designed masanobu endo best known creating xevious 1983 inspired games wizardry dungeons dragons conceived fantasy pac-man combat puzzle solving taking inspiration sumerian mesopotamian babylonian mythology began prototype game called quest interlocking mazes revised run arcade system original concept scrapped due endo disliking heavy use role-playing elements instead becoming action-oriented game japan tower druaga widely successful attracting millions fans use secrets hidden items cited important game genre laying foundation future games well inspiring idea sharing tips friends guidebooks druaga noted influential many games follow including ys hydlide dragon slayer legend zelda dragon quest creator koichi nakamura citing endo favorite game developer north america game met negative reception obtuse design many said near-impossible finish without guidebook alongside high difficulty controls success game japan would inspire several ports multiple platforms well spawning massive franchise known babylonian castle saga including multiple sequels spin-offs literature anime series produced gonzo tower druaga action role-playing maze video game controlling knight gilgamesh player must scale 60 floors tower rescue maiden ki druaga four-armed demon plans use artifact called blue crystal rod enslave mankind gilgamesh need locate key floor order open door allowing proceed next floor floor different types enemies slimes knights projectile-firing wizards ghosts travel walls fire-spewing dragons gilgamesh defeat enemies hitting sword — require multiple hits defeat gilgamesh also block projectiles facing shield floor also hidden item uncovered completing tasks defeating certain number enemies inputting specific code joystick items include pickaxe destroy walls boots drastically increase gilgamesh walking speed candle reveal ghosts items required fully beat game failing either cause player die make game unwinnable time limit also present floor player take long two indestructible spherical enemies named will-o-wisps charge towards gilgamesh player forget get required item instead sent back zapped earlier floor retrieve game mazes randomized playthrough although treasure appear player starting point tower druaga designed masanobu endo joined namco april 1982 releasing xevious following year overwhelming success japan endo took business trip north america bought copy dungeons dragons intrigued gameplay setting endo fan apple ii game wizardry set make next game action role-playing title returning japan designed basic prototype game called quest player would able explore inter-locking rooms defeating enemies using keys open doors — expanded version made run namco super pac-man arcade system titled return ishtar upon completion endo dissatisfied game heavy use role-playing elements leading game instead becoming action-oriented game puzzle solving conceived fantasy pac-man second prototype endo took inspiration sumerian mesopotamian babylonian mythology including epic gilgamesh tower babel several characters named mesopotamian indian gods including antagonist druaga goddess ishtar game made run hardware setup used mappy featured horizontal-scrolling vertical screen layout 60 floors inspired sunshine 60 tallest building asia time music game composed junko ozawa promotional arcade flyer used miniature dioramas cardboard cutouts instead drawings response namco president masaya nakamura hatred towards manga last frame poster gilgamesh wearing horned helmet fighting druaga meant imply players would need order finish game tower druaga released arcades japan june 1984 druaga would ported several japanese game systems including msx 1984 family computer 1985 fujitsu fm-7 1985 portable game boy version released 1990 16-bit remake pc-engine 1992 — gb version re-released 1996 part compilation title namco gallery vol 2 also included galaxian dig dug famista 4 1997 windows port released part namco history vol 2 alongside several early namco arcade titles 2003 famicom version re-released japan gamecube pre-order bonus several japanese mobile phone ports released first 2002 java version followed i-mode release 2003 2009 digital version released wii virtual console one four launch titles then-new virtual console arcade service alongside mappy gaplus star force famicom version released onto 3ds virtual console december 2012 exclusive japan druaga would included several namco museum compilations including namco museum vol 3 1996 namco museum battle collection 2005 namco museum virtual arcade 2009 namco museum switch 2017 japan tower druaga overwhelming critical success attracting millions fans use puzzle-solving action-oriented gameplay cited important landmark role-playing genre helped lay foundations future titles druaga cited influential many japanese role-playing games including ys hydlide dragon slayer legend zelda koichi nakamura creator dragon quest since cited masanobu endo favorite video game developer druaga also helped inspire idea note sharing players tower druaga met negative reception north america many criticizing game controls high difficulty design reviewing wii virtual console port dan whitehead eurogamer referred game design diabolically obtuse criticized gilgamesh slow movement notably deflecting projectiles whitehead also criticized hidden treasures elusive appealing towards dedicated players although stated interesting gameplay idea brett alan weiss allgame also criticized hidden items especially required later levels well player wimpy attack time limit marcel van duyn nintendo life said recommended truly sadistic gamers expressing distaste towards repetitive levels high difficulty obtuse secrets lucas m. thomas ign critical game lambasting arbitrary wall item requirements slow pace high difficulty calling woefully boring pointless play also noted player would need walkthrough order fully beat 2003 interview endo stated somewhat regretted making game difficult noting might made players paranoid finding secrets games success tower druaga would spawn wave sequels spin-off games collectively known babylonian castle saga series first released 1986 return ishtar based original prototype druaga developed endo game company game studio published namco arcades taking place right events original two players controlled gilgamesh ki made way bottom druaga tower blue crystal rod 1996 ported playstation part namco museum vol 4 famicom prequel game quest ki released 1988 — controlling ki player make top druaga tower search blue crystal rod leading events first game super famicom follow-up released 1994 blue crystal rod also known destiny gilgamesh gameplay much different compared earlier games instead graphical adventure game characters series 1996 two altered versions original game another tower darkness tower included hidden extras namco museum vol 3 made much harder original game altered requirements finding treasure game boy color spin-off seme com dungeon drururuaga released 2000 2004 namco partnered arika develop playstation 2 one babylonian castle saga games localized outside japan part mystery dungeon series game notorious extreme difficulty death would revoke player items half money online-based arcade game released 2005 druaga online story aon followed similar pc game 2009 tower druaga recovery babylim spin-off game labyrinth druaga released japanese mobile phones january 12 2011 1990 namco produced theme park attraction based tower druaga expo '90 osaka alongside show conclusion moved namco wonder eggs amusement park tokyo 1992 remaining park closing december 31 2000 sugoroku medal game released arcades 2000 sugoroku adventure tower druaga also featured characters namco valkyrie series gilgamesh red-striped shield blue crystal rod appear sophita alternative weapons soul edge gamecube game features gamemode inspired game titled hole druaga mii fighter costume based gilgamesh released super smash bros. nintendo 3ds wii u 2015 anime reboot series tower druaga aegis uruk produced japanese studio gonzo premiering april 4 2008 taking place roughly 60 years events arcade game followed sequel series tower druaga sword uruk premiering january 8 2009
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Computer architecture
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windows api windows api informally winapi microsoft core set application programming interfaces apis available microsoft windows operating systems name windows api collectively refers several different platform implementations often referred names example win32 api see versions section almost windows programs interact windows api windows nt line operating systems small number programs started early windows startup process use native api developer support available form software development kit microsoft windows sdk providing documentation tools needed build software based windows api associated windows interfaces windows api win32 focused mainly programming language c exposed functions data structures described language recent versions documentation however api may used programming language compiler assembler able handle well-defined low-level data structures along prescribed calling conventions calls callbacks similarly internal implementation api function developed several languages historically despite fact c object-oriented programming language windows api windows historically described object-oriented also many wrapper classes extensions microsoft others object-oriented languages make object-oriented structure explicit microsoft foundation class library mfc visual component library vcl gdi+ etc. instance windows 8 provides windows api winrt api implemented c++ object-oriented design functions provided windows api grouped eight categories internet explorer ie web browser also exposes many apis often used applications could considered part windows api ie included operating system since windows 95 osr2 provided web-related services applications since windows 98 specifically used provide classic windows multimedia api placed winmm.dll contains functions play sound files send receive midi messages access joysticks facilitate features so-called mci subsystem windows originates multimedia extensions available windows 3.0 separately integral part operating system since windows 3.1 time located mmsystem.dll apart part every windows version since windows 95 osr2 microsoft provided directx apis—a loosely related set graphics gaming services includes microsoft also provides several apis media encoding playback windows api designed mostly interaction operating system application communication among different windows applications microsoft developed series technologies alongside main windows api started dynamic data exchange dde superseded object linking embedding ole later component object model com automation objects activex controls .net framework always clear distinction technologies much overlap variety terms basically result grouping software mechanisms relate given aspect software development automation specifically relates exporting function application component application programming interface api controlled applications instead human users .net self-contained general methodology technology develop desktop web applications written variety just-in-time jit compiled languages windows.pas pascal/delphi unit contains windows-specific api declarations pascal equivalent windows.h used c. various wrappers developed microsoft took low level functions windows api allowed applications interact api abstract manner microsoft foundation class library mfc wrapped windows api functionality c++ classes thus allows object-oriented way interact api active template library atl template oriented wrapper com windows template library wtl developed extension atl intended smaller alternative mfc application frameworks windows least partly wrap windows api thus .net framework java likewise programming languages windows contain wrapper libraries windows api code pack microsoft .net framework .net wrapper library windows api windows api always exposed large part underlying structure windows systems programmers advantage giving much flexibility power applications also creates great responsibility applications handle various low-level sometimes tedious operations associated graphical user interface example beginning c programmer often write simple hello world first assignment working part program single printf line within main subroutine overhead linking standard i/o library also one line windows version still one working line code required many many lines overhead charles petzold wrote several books programming windows api said original hello world program windows 1.0 sdk bit scandal hello.c 150 lines long hello.rc resource script another 20 lines ... veteran programmers often curled horror laughter encountering windows hello-world program years various changes additions made windows systems windows api changed grew reflect windows api windows 1.0 supported fewer 450 function calls whereas modern versions windows api support thousands however general interface remained fairly consistent old windows 1.0 application still look familiar programmer used modern windows api microsoft made effort maintain backward compatibility achieve developing new versions windows microsoft sometimes implemented workarounds allow compatibility third-party software used prior version undocumented even inadvisable way raymond chen microsoft developer works windows api said could probably write months solely bad things apps get work often spite get particularly furious people accuse microsoft maliciously breaking applications os upgrades application failed run windows 95 took personal failure one largest changes windows api transition win16 shipped windows 3.1 older win32 windows nt windows 95 win32 originally introduced windows nt 3.1 win32s allowed use win32 subset windows 95 windows 95 widespread porting applications win32 began ease transition windows 95 developers outside inside microsoft complex scheme api thunks used could allow 32-bit code call 16-bit code win16 apis vice versa flat thunks allowed 32-bit code call 16-bit libraries scheme used extensively inside windows 95 libraries avoid porting whole os win32 one batch windows nt os pure 32-bit except parts compatibility 16-bit applications generic thunks available thunk win16 win32 windows 95 platform sdk shipped compiler could produce code needed thunks versions 64-bit windows also able run 32-bit applications via wow64 syswow64 folder located windows folder os drive contains several tools support 32-bit applications almost every new version microsoft windows introduced additions changes windows api name api however remained consistent different windows versions name changes kept limited major architectural platform changes windows microsoft eventually changed name current win32 api family windows api made catch-all term past future api versions wine project provides win32 api compatibility layer unix-like platforms linux kernel api programs written windows api reactos goes step aims implement full windows operating system working closely wine project promote code re-use compatibility doswin32 hx dos extender projects emulate windows api allow executing simple windows programs dos command line odin project emulate win32 os/2 superseding original win-os/2 emulation based microsoft code minor implementations include mewel zinc libraries intended implement subset win16 api dos see list platform-independent gui libraries windows interface source environment wise licensing program microsoft allowed developers recompile run windows-based applications unix macintosh platforms wise sdks based emulator windows api could run platforms efforts toward standardization included sun public windows interface pwi win16 see also sun windows application binary interface wabi willows software application programming interface windows apiw win16 win32 see also willows twin ecma-234 attempted standardize windows api bindingly develop software uses windows api compiler must able use microsoft-specific dlls listed com-objects outside win32 assume certain vtable layout compiler must either handle header files expose interior api function names supply files language c++ zortech later symantec digital mars watcom borland produced well known commercial compilers used often win16 win32s win32 supplied memory extenders allowing win32 programs run win16 microsoft redistributable win32s dll zortech compiler probably one first stable usable c++ compilers windows programming microsoft c++ compiler certain classes applications compiler system also able handle interface description language idl files collectively prerequisites compilers tools libraries headers known microsoft platform sdk time microsoft visual studio borland integrated development system integrated development environments ides could provide although sdk downloadable free separately entire ide suite microsoft windows sdk windows 7 .net framework 4 mingw cygwin projects also provide environment based gnu compiler collection gcc using stand-alone header file set make linking win32-specific dlls simple lcc-win32 c compiler maintained jacob navia freeware non-commercial use pelles c freeware c compiler maintained pelle orinius free pascal free software object pascal compiler supports windows api masm32 package mature project providing support windows api microsoft macro assembler masm using custom made converted headers libraries platform sdk flat assembler fasm allows building windows programs without using external linker even running linux windows specific compiler support also needed structured exception handling seh system serves two purposes provides substrate language-specific exception handling implemented kernel notifies applications exceptional conditions dereferencing invalid pointer stack overflow microsoft/borland c++ compilers ability use system soon introduced windows 95 nt however actual implementation undocumented reverse engineered wine project free compilers seh based pushing exception handler frames onto stack adding linked list stored thread local storage first field thread environment block exception thrown kernel base libraries unwind stack running handlers filters encountered eventually every exception unhandled application dealt default backstop handler pops windows common crash dialog
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Operating systems
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canonical company canonical ltd. uk-based privately held computer software company founded funded south african entrepreneur mark shuttleworth market commercial support related services ubuntu related projects canonical employs staff 30 countries maintains offices london austin boston shanghai beijing taipei isle man canonical ltd. created continues back several projects principally free open-source software foss tools designed improve collaboration free software developers contributors projects require contributor license agreement signed 2007 canonical launched international online shop selling support services ubuntu-branded goods later 2008 expanded united states-specific shop designed reduce shipment times time word ubuntu trademarked connection clothing accessories guardian interview may 2008 shuttleworth said canonical business model service provision canonical yet close profitability canonical stated would wait three five years become profitable shuttleworth regarded canonical positioning demand services related free software rose strategy compared red hat business strategies 1990s early-2009 new york times article shuttleworth said canonical revenue creeping towards company break-even point canonical achieved small operating profit 281,000 2009 however 2017 struggled maintain financial solvency took major financial hit development unity ubuntu touch leading operating loss 21.6 million fiscal year 2013 company reported operating profit 2 million 2017 shutting unity development team laying nearly 200 employees company plans focus server professional support solutions proved profitable shifting resources away ubuntu desktop cutting less profitable products services canonical plans maintain solvency achieve long-term profitability canonical 500 employees head office london 5th floor blue fin building southwark street previously moved 27th floor millbank tower summer 2006 canonical opened office montreal house global support services operation taipei 101 also home canonical office also oem team lexington massachusetts united states notable current employees canonical include notable past employees
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Computer architecture
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compaq deskpro compaq deskpro line business-oriented personal computers manufactured compaq discontinued merger hewlett-packard models produced containing microprocessors 8086 x86-based intel pentium 4 original compaq deskpro released 1984 available several disk configurations xt-class pc equipped 8 mhz 8086 cpu compaq unique display hardware combined color graphics adapter graphics high resolution monochrome display adapter text result considerably faster ibm pc much better quality text display compared ibm pc equipped graphics like earlier compaq portable hardware bios 100 compatible ibm pc model 5150 characteristic pc workalikes shared soon establishment ibm standard 1985 compaq released deskpro 286 looks quite similar ibm pc/at 1987 deskpro 386 launched intel released 80386 microprocessor beating ibm 7 months comparable 386 computer thus making name deskpro 386/25 released august 28 1989 cost 7,999 form factor compaq deskpro mostly desktop model lies upon desk monitor placed top compaq produced many tower upright models highly successful sales usually convertible desktop form factor sff small form factor desktop version also produced deskpro lifetime many different models include
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Computer architecture
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george ledin dr. george ledin jr. born january 28 1946 controversial professor computer science department sonoma state university one courses titled computer security malware ledin teaches malware techniques well defenses ledin strong critic antivirus software industry whose products considers almost useless
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Computer security
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brick breaker brick breaker videogame came preloaded blackberry available app store ios brick breaker platformer breakout clone player must smash wall bricks deflecting bouncing ball paddle paddle may move horizontally controlled blackberry trackwheel computer mouse touch finger case touchscreen player gets 3 lives start life lost ball hits bottom screen bricks destroyed player advances new harder level 34 levels many levels unbreakable silver bricks lives lost game many versions brick breaker shoot flaming fireballs play one ball player gets power brick breaker cult following professional players trying achieve high scores game addictiveness highlighted vancouver sun dozens forums support groups yes brick breaker addiction facebook page spouses complaining addicted mates
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Operating systems
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pwd unix-like operating systems codice_1 command print working directory writes full pathname current working directory standard output command shell builtin unix shells bourne shell ash bash ksh zsh implemented easily posix c functions codice_2 codice_3 also available operating systems spartados x panos kolibrios equivalent dos codice_4 microsoft windows codice_5 codice_6 command arguments windows powershell provides equivalent codice_7 cmdlet standard aliases codice_8 codice_1 openvms equivalent codice_10 version codice_1 bundled gnu coreutils written jim meyering numerical computing environments matlab gnu octave include codice_1 function similar functionality note posix requires default behavior -l switch provided posix shells set following environment variables using cd command
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Computer file systems
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mirc scripting language mirc scripting language often unofficially abbreviated msl scripting language embedded mirc irc client windows scripts stored either plain text files usually .mrc file extension ini files however stored extension multiple script files loaded one time although cases one script conflict another cause one longer work properly mirc scripting involves peculiar nomenclature entirely consistent rest programming world notably term identifier—which languages refers name variable function whether returns value —in mirc refers specifically value returning function intended singular access file time issue codice_7 codice_6 open close file access multiple accesses loop instance best handled codice_9 codice_10 codice_11 since opens file cases codice_12 codice_13 even efficient non scripted loop method code remote scripts format placed alias file command names preceded word codice_32 test comments include common codice_33 codice_34 example hello world alias remote script automatically respond certain text
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Programming language topics
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windows filtering platform microsoft computer-systems windows filtering platform wfp comprises set system services application programming interface first introduced windows vista 2006/2007 allows applications tie packet processing filtering pipeline next generation tcp/ip network stack provides features integrated communication administrators configure invoke processing logic per-application basis microsoft intended wfp use firewalls packet-processing connection-monitoring components antivirus antimalware software parental controls additionally wfp used implement nat store ipsec policy configuration filtering platform includes following components since windows 8 windows server 2012 wfp allows filtering second layer tcp/ip windows 7 functionality added netsh command allows rich diagnostics internal state wfp functionality useful debug root-cause issues packet drops ms kb 979223 documents serious memory leak affecting vista windows 7 issues deployments wfp include ms hotfix rollup 981889 windows 7 sp1 vista sp3 comes newer require fixes note problems persist regarding use multiple network buffer lists
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Operating systems
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ascii corporation ascii founded 1977 kazuhiko nishi keiichiro tsukamoto originally publisher magazine name ascii talks bill gates nishi led creation microsoft first overseas sales office ascii microsoft 1979 nishi also known role marketing msx 1983 8-bit standard computer well known former ussr japan 1984 ascii engaged semiconductor business followed expansion commercial online service 1985 brand ascii-net popularity home video game systems soared 1980s ascii became active development publishing software peripherals popular consoles family computer mega drive microsoft public stock offering 1986 ascii microsoft dissolved around time company also obliged reform result aggressive diversification first half 1980s company went public 1989 ascii revenue fiscal year ending march 1996 56 billion yen broken sectors publication 52.5 27.0 billion yen game entertainment 27.8 14.3 billion yen systems semiconductors 10.8 6 billion yen others despite struggles remain focused core businesses company continued suffer accumulated debts arrangement set csk corporation execute major investment ascii 1997 mid-90s ascii acquired company something good renamed ascii something good developed 3 sega saturn games ai shougi 1995 ai igo 1997 ai shougi 2 1998 ascii become popular software market branched created american satellite 1991 known ascii entertainment focus supporting interactive entertainment channel america startup company agetec ascii game entertainment technology spun independent corporation 1998 later became fully independent publisher one year later co-founder tsukamoto left ascii create company 1992 named impress november 26 2001 csk corporation unison capital partners l.p. announced approval transferring control subsidiary ascii unison capital partners l.p. effective 2002-03-30 part strategy focus csk group operations b2b businesses transfer approved december 21 2001 part deal ascii outstanding debt owed csk forgiven unison control ascii enterbrain publishing divisions would maintain autonomy ascii restructured concentrate pc publishing businesses may 28 2002 unison media partners announced ascii would become fully owned subsidiary via share exchange ascii would delisted effective october 1 2002 november 18 2002 astroarts subsidiary renamed ascii ascii renamed medialeaves former astroarts subsidiary would inherit publishing business former ascii january 29 2004 unison capital partners l.p. announced sale ascii parent company medialeaves kadokawa group holdings completed 2004-03 september 27 2007 kadokawa group holdings announced merger subsidiaries mediaworks ascii name ascii media works effective april 1 2008 merger approved 2008 january 10 2010 formerly named ascii company medialeaves merged enterbrain dissolving last ascii entity
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Computer architecture
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archi tool archi free open-source visual-modelling design tool creating archimate models modelling sketches archi initially funded 2010 2012 jisc part national project aimed supporting programme enterprise architecture uk higher education sector original project hosted institute educational cybernetics bolton university uk since january 2013 archi continued maintained volunteer basis creator phil beauvoir jean-baptiste sarrodie archi supports archimate 3.0 modelling language technical standard open group archi provides open source reference implementation archimate currently used one tools implement open group archimate model exchange file format plugins available github
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Web technology
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flame malware flame also known flamer skywiper skywiper modular computer malware discovered 2012 attacks computers running microsoft windows operating system program used targeted cyber espionage middle eastern countries discovery announced 28 may 2012 maher center iranian national computer emergency response team cert kaspersky lab crysys lab budapest university technology economics last stated report flame certainly sophisticated malware encountered practice arguably complex malware ever found flame spread systems local network lan record audio screenshots keyboard activity network traffic program also records skype conversations turn infected computers bluetooth beacons attempt download contact information nearby bluetooth-enabled devices data along locally stored documents sent one several command control servers scattered around world program awaits instructions servers according estimates kaspersky may 2012 flame initially infected approximately 1,000 machines victims including governmental organizations educational institutions private individuals time 65 infections happened iran israel palestine sudan syria lebanon saudi arabia egypt huge majority targets within iran flame also reported europe north america flame supports kill command wipes traces malware computer initial infections flame stopped operating public exposure kill command sent flame linked equation group kaspersky lab however costin raiu director kaspersky lab global research analysis team believes group cooperates creators flame stuxnet position superiority equation group definitely masters giving others maybe bread crumbs time time giving goodies integrate stuxnet flame flame a.k.a da flame identified may 2012 maher center iranian national cert kaspersky lab crysys lab laboratory cryptography system security budapest university technology economics kaspersky lab asked united nations international telecommunication union investigate reports virus affecting iranian oil ministry computers kaspersky lab investigated discovered md5 hash filename appeared customer machines middle eastern nations discovering pieces researchers dubbed program flame one main modules inside toolkit nowiki /nowiki frog.defaultattacks.a-installflame nowiki /nowiki according kaspersky flame operating wild since least february 2010 crysys lab reported file name main component observed early december 2007 however creation date could determined directly creation dates malware modules falsely set dates early 1994 computer experts consider cause attack april 2012 caused iranian officials disconnect oil terminals internet time iranian students news agency referred malware caused attack wiper name given malware creator however kaspersky lab believes flame may separate infection entirely wiper malware due size complexity program—described twenty times complicated stuxnet—the lab stated full analysis could require long ten years 28 may iran cert announced developed detection program removal tool flame distributing select organizations several weeks flame exposure news media symantec reported 8 june flame command control c c computers sent suicide command infected pcs remove traces flame according estimates kaspersky may 2012 initially flame infected approximately 1,000 machines victims including governmental organizations educational institutions private individuals time countries affected iran israel palestinian territories sudan syria lebanon saudi arabia egypt flame uncharacteristically large program malware 20 megabytes written partly lua scripting language compiled c++ code linked allows attack modules loaded initial infection malware uses five different encryption methods sqlite database store structured information method used inject code various processes stealthy malware modules appear listing modules loaded process malware memory pages protected read write execute permissions make inaccessible user-mode applications internal code similarities malware exploits two security vulnerabilities used previously stuxnet infect systems malware determines antivirus software installed customises behaviour example changing filename extensions uses reduce probability detection software additional indicators compromise include mutex registry activity installation fake audio driver malware uses maintain persistence compromised system flame designed deactivate automatically supports kill function makes eliminate traces files operation system receipt module controllers flame signed fraudulent certificate purportedly microsoft enforced licensing intermediate pca certificate authority malware authors identified microsoft terminal server licensing service certificate inadvertently enabled code signing still used weak md5 hashing algorithm produced counterfeit copy certificate used sign components malware make appear originated microsoft successful collision attack certificate previously demonstrated 2008 flame implemented new variation chosen-prefix collision attack like previously known cyber weapons stuxnet duqu employed targeted manner evade current security software rootkit functionality system infected flame spread systems local network via usb stick record audio screenshots keyboard activity network traffic program also records skype conversations turn infected computers bluetooth beacons attempt download contact information nearby bluetooth enabled devices data along locally stored documents sent one several command control servers scattered around world program awaits instructions servers unlike stuxnet designed sabotage industrial process flame appears written purely espionage appear target particular industry rather complete attack toolkit designed general cyber-espionage purposes using technique known sinkholing kaspersky demonstrated huge majority targets within iran attackers particularly seeking autocad drawings pdfs text files computing experts said program appeared gathering technical diagrams intelligence purposes network 80 servers across asia europe north america used access infected machines remotely 19 june 2012 washington post published article claiming flame jointly developed u.s. national security agency cia israel ’ military least five years prior project said part classified effort code-named olympic games intended collect intelligence preparation cyber-sabotage campaign aimed slowing iranian nuclear efforts according kaspersky chief malware expert geography targets also complexity threat leaves doubt nation-state sponsored research went kaspersky initially said malware bears resemblance stuxnet although may parallel project commissioned attackers analysing code kaspersky later said strong relationship flame stuxnet early version stuxnet contained code propagate via usb drives nearly identical flame module exploits zero-day vulnerability iran cert described malware encryption special pattern see coming israel daily telegraph reported due flame apparent targets—which included iran syria west bank—israel became many commentators prime suspect commentators named china u.s. possible perpetrators richard silverstein commentator critical israeli policies claimed confirmed senior israeli source malware created israeli computer experts jerusalem post wrote israel vice prime minister moshe ya'alon appeared hinted government responsible israeli spokesperson later denied implied unnamed israeli security officials suggested infected machines found israel may imply virus could traced u.s. western nations u.s. officially denied responsibility leaked nsa document mentions dealing iran discovery flame nsa gchq jointly-worked event
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Computer security
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msxml microsoft xml core services msxml legacy set services allowed applications written jscript vbscript microsoft development tools build windows-native xml-based applications supports xml 1.0 dom sax xslt 1.0 processor xml schema support including xsd xdr well xml-related technologies msxml products similar exposed programmatically ole automation subset com components developers program msxml components c c++ active scripting languages jscript vbscript managed .net interop msxml com components supported recommended com components msxml object programmatically instantiated clsid progid version msxml exposes set clsid progids example create msxml 6.0 domdocument object exposes codice_1 codice_2 codice_3 com interfaces progid msxml2.domdocument.6.0 must used msxml also supports version-independent progids version-independent progids version number associated example microsoft.xmlhttp progids first introduced msxml 1.0 however currently mapped msxml 3.0 objects msxml3.dll different versions msxml support slightly different sets functionality example msxml 3.0 supports xdr schemas support xsd schemas msxml 4.0 msxml 5.0 msxml 6.0 support xsd schemas however msxml 6.0 support xdr schemas support xml digital signatures provided msxml 5.0 new xml-related software development microsoft recommends using msxml 6.0 lightweight cousin xmllite native code-only projects msxml collection distinct products released supported microsoft product versions enumerated follows information version also available microsoft downloads website
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Operating systems
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spider.io spider.io company london specializes detection malware botnets generate web traffic used online advertising fraud company founded 2010 founder douglas de jager software used company includes storm shelf open source software handle large amounts data using solutions like hadoop later also mahout spider.io start writing software online advertising fraud detection later point choice shelf open source software looked sensible 2012 spider.io pointed vulnerability internet explorer mouse cursor position pc victim could tracked attacker claimed vulnerability exploited large scale example botnet detected analyzed spider.io 2013 chameleon botnet spider.io also raises awareness general easy generate fake web traffic sharing information techniques used 2014 spider.io acquired google inc.. time company seven employees google inc. important advertising fraud eliminated internet one reasons much income company comes online advertisements besides acquisition spider.io also employs many people combat fraud ways
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Computer security
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teragrid teragrid e-science grid computing infrastructure combining resources eleven partner sites project started 2001 operated 2004 2011 teragrid integrated high-performance computers data resources tools experimental facilities resources included petaflops computing capability 30 petabytes online archival data storage rapid access retrieval high-performance computer network connections researchers could also access 100 discipline-specific databases teragrid coordinated grid infrastructure group gig university chicago working partnership resource provider sites united states us national science foundation nsf issued solicitation asking distributed terascale facility program director richard l. hilderbrandt teragrid project launched august 2001 53 million funding four sites national center supercomputing applications ncsa university illinois urbana-champaign san diego supercomputer center sdsc university california san diego university chicago argonne national laboratory center advanced computing research cacr california institute technology pasadena california design meant extensible distributed open system start october 2002 pittsburgh supercomputing center psc carnegie mellon university university pittsburgh joined teragrid major new partners nsf announced 35 million supplementary funding teragrid network transformed etf project 4-site mesh dual-hub backbone network connection points los angeles starlight facilities chicago october 2003 nsf awarded 10 million add four sites teragrid well establish third network hub atlanta new sites oak ridge national laboratory ornl purdue university indiana university texas advanced computing center tacc university texas austin teragrid construction also made possible corporate partnerships sun microsystems ibm intel corporation qwest communications juniper networks myricom hewlett-packard company oracle corporation teragrid construction completed october 2004 time teragrid facility began full production august 2005 nsf newly created office cyberinfrastructure extended support another five years 150 million set awards included 48 million coordination user support grid infrastructure group university chicago led charlie catlett using high-performance network connections teragrid featured high-performance computers data resources tools high-end experimental facilities around usa work supported project sometimes called e-science 2006 university michigan school information began study teragrid may 2007 teragrid integrated resources included 250 teraflops computing capability 30 petabytes quadrillions bytes online archival data storage rapid access retrieval high-performance networks researchers could access 100 discipline-specific databases late 2009 teragrid resources grown 2 petaflops computing capability 60 petabytes storage mid 2009 nsf extended operation teragrid 2011 follow-on project approved may 2011 july 2011 partnership 17 institutions announced extreme science engineering discovery environment xsede nsf announced funding xsede project five years 121 million xsede led john towns university illinois national center supercomputing applications teragrid resources integrated service-oriented architecture resource provides service defined terms interface operation computational resources run set software packages called coordinated teragrid software services ctss ctss provides familiar user environment teragrid systems allowing scientists easily port code one system another ctss also provides integrative functions single-signon remote job submission workflow support data movement tools etc ctss includes globus toolkit condor distributed accounting account management software verification validation software set compilers programming tools environment variables teragrid uses 10 gigabits per second dedicated fiber-optical backbone network hubs chicago denver los angeles resource provider sites connect backbone node 10 gigabits per second users accessed facility national research networks internet2 abilene backbone national lambdarail teragrid users primarily came u.s. universities roughly 4,000 users 200 universities academic researchers united states obtain exploratory development allocations roughly cpu hours based abstract describing work done extensive allocations involve proposal reviewed quarterly peer-review process allocation proposals handled teragrid website proposers select scientific discipline closely describes work enables reporting allocation use teragrid scientific discipline july 2006 scientific profile teragrid allocations usage discipline categories correspond specific program area national science foundation starting 2006 teragrid provided application-specific services science gateway partners serve generally via web portal discipline-specific scientific education communities science gateways program teragrid aims broaden access least order magnitude terms number scientists students educators able use teragrid
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Distributed computing architecture
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enterprise architect software sparx systems enterprise architect visual modeling design tool based omg uml platform supports design construction software systems modeling business processes modeling industry based domains used businesses organizations model architecture systems process implementation models across full application development life-cycle systems modeling using uml provides basis modeling aspects organizational architecture along ability provide foundation designing implementing new systems changing existing systems aspects covered type modeling range laying organizational systems architectures business process reengineering business analysis service-oriented architectures web modeling application database design re-engineering development embedded systems along system modeling enterprise architect covers core aspects application development life-cycle requirements management design construction testing maintenance phases support traceability project management change control processes well facilities model driven development application code using internal integrated-development platform user base ranges programmers business analysts enterprise architects organizations ranging small developer companies multi-national corporations government organizations international industry standards bodies sparx systems initially released enterprise architect 2000 originally designed uml modeling tool modeling uml 1.1 product evolved include omg uml specifications 1.3 2.0 2.1 2.3 2.4.1 2.5 enterprise architect supports range open industry standards designing modeling software business systems uml 2.5 sysml 1.5 bpmn 2.0 dmn bpel soaml spem wsdl xsd dds archimate 3.0 arcgis ifml cmmn geography markup language gml odm owl rdf enterprise integration patterns eip enterprise architect also supports industry frameworks zachman framework togaf including feaf uaf updm framework supports dodaf modaf naf service-oriented modeling framework somf supportd frameworks supplied industry bodies trak geosciml niem supports core service-oriented architectures soaml service-oriented modeling framework somf enterprise-level architecture along round trip engineering wsdl xsd used facilitate bpel generation models published industry standards development bodies using enterprise architect include underlying uml modeling key aspects modeling tools support core aspects supported enterprise architect include profiles patterns mof ocl mda transforms corba idl uml validation run model common features requirements management supported enterprise architect include customization requirements documented linking requirements design implementation details providing requirement traceability design construction phases requirements subject change management workflow processing baseline comparison auditing enterprise architect supports number methods modeling business processes using uml foundation modeling language core languages business modeling analysis include bpmn bpel along various historic profiles enterprise architect also supports definition business rules ability generate executable code rules business modeling combined gap analysis view potential gaps proposed solutions model simulation supported behavioral diagrams state machines interaction sequence diagrams activities execution flow defined using triggers guards effects simulation supports re-runs alteration triggered events supports viewing variables call stack setting debug markers also support interaction emulated user-interface screens containing common ui fields bpmn diagrams using bpsim bpmn models simulated creating tabulated results analysis. monte carlo probability based simulations sysml parametric simulation using open modelica mathematical formulas sysml blocks parametric blocks simulated plotting graphs used analysis dmn simulation simulation supports interaction dmn models bpmn models using bpsim line model driven design principles enterprise architect supports mda transforms pim class structures psm class structures round-trip engineering code 10 software languages several key embedded hdl systems languages ada vhdl verilog also supports code generation behavioral models languages supported include actionscript c c c++ delphi java including java 1.5 aspects generics php python july 2019 enterprise architect capability reverse engineer object oriented python code parse _init_ method visual basic visual basic .net accordance model driven development principles enterprise architect provides integrated development environment supports code editing syntax highlighting intellisense building debugging code testing within model compilers interpreters supported microsoft windows native c c++ visual basic.net family c j vb sun microsystems java php gnu compilers c++ c ada gcc gdb .add-ins available integration ms visual studio eclipse wireframe modeling supports using templates modeling appearance dialogs presented users interacting application supported device dialogs include screen dialogs webpages android apple windows 8.1 phones tablets code based testing support xunit testing involves mda transformation classes nunit junit classes ability generate unit tests model automatically record results tested classes testpoint testing model based code testing parallel test contracts defined ‘ design contract ’ runs using debug definitions methods support test definitions test results logged related classes model integrated building debugging code enterprise architect allows developer perform abstract analysis software using profiling sequence diagram generation sequence diagram generation provides means analyze general process flow iron inconsistencies profiling summarizes thread routine code general efficiency system engineering supported sysml 1.4 modeling coupled executable code generation sysml supports modeling requirement definition system composition using sysml blocks parts parametric model simulation executable code generation supports embedded hdl system languages ada vhdl verilog coupled behavioral code generation standard code languages defined enterprise architect supports data modeling conceptual physical levels forward reverse engineering database schemas mda transformation logical platform independent physical dbms platform dependant diagram types supported include ddl notation erd notation idef1x notation information engineering notation supported dbmss include db2 firebird/interbase ms access 97 2000 2003 2007 2013 ms sql server editions 2005 including express azure mysql mariadb sqlite oracle 9i editions postgresql arcgis informix ingres sybase adaptive server anywhere sybase asa sybase adaptive server enterprise sybase ase features supporting project management include resource allocation tracking using gantt charts kanban diagrams event logging using model calendars workflow scripting setting workflow processes security model metrics key facilities supporting change management auditing baseline difference merge version control version control interface supports major version control applications subversion cvs team foundation server scc interface scc compatible version control system features support integration tools include xmi import/export supports xmi 1.1 1.2 2.1 specifications import .emx rhapsody files open services lifecycle collaboration oslc csv import/export archimate open exchange format import export version 13 automation interface – supports comprehensive api use com based language java among add-ins available interfaces vs .net eclipse microsoft office doors along third party add-ins interfacing likes jira
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Web technology
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bvckup 2 bvckup 2 unidirectional file synchronization app windows nt family developed swiss-based pipemetrics sa replicates files one location another original format uses delta copying speed operation program supports scheduling removable device tracking using shadow copy service transfer open locked files move renaming detection security attribute cloning email alerts however support compression encryption
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Computer security
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cloud management cloud management management cloud computing products services public clouds managed public cloud service providers include public cloud environment ’ servers storage networking data center operations users may also opt manage public cloud services third-party cloud management tool users public cloud services generally select three basic cloud provisioning categories managing private cloud requires software tools help create virtualized pool compute resources provide self-service portal end users handle security resource allocation tracking billing management tools private clouds tend service driven opposed resource driven cloud environments typically highly virtualized organized terms portable workloads hybrid cloud environments compute network storage resources must managed across multiple domains good management strategy start defining needs managed policies help govern domains include configuration installation images access control budgeting reporting access control often includes use single sign-on sso user logs gains access systems without prompted log cloud management combines software technologies design managing cloud environments software developers responded management challenges cloud computing variety cloud management platforms tools tools include native tools offered public cloud providers well third-party tools designed provide consistent functionality across multiple cloud providers administrators must balance competing requirements efficient consistency across different cloud platforms access different native functionality within individual cloud platforms growing acceptance public cloud increased multicloud usage driving need consistent cross-platform management rapid adoption cloud services introducing new set management challenges technical professionals responsible managing systems services cloud-management platforms tools ability provide minimum functionality following categories functionality natively provided orchestrated via third-party integration organizations may group criteria key use cases including cloud brokerage devops automation governance day-2 life cycle operations enterprises large-scale cloud implementations may require robust cloud management tools include specific characteristics ability manage multiple platforms single point reference intelligent analytics automate processes like application lifecycle management high-end cloud management tools also ability handle system failures automatically capabilities self-monitoring explicit notification mechanism include failover self-healing capabilities legacy management infrastructures based concept dedicated system relationships architecture constructs well suited cloud environments instances continually launched decommissioned instead dynamic nature cloud computing requires monitoring management tools adaptable extensible customizable cloud computing presents number management challenges companies using public clouds ownership equipment hosting cloud environment environment contained within networks public cloud customers full visibility control users public cloud services must also integrate architecture defined cloud provider using specific parameters working cloud components integration includes tying cloud apis configuring ip addresses subnets firewalls data service functions storage control functions based cloud provider ’ infrastructure services public cloud users must integrate cloud infrastructure management capacity management challenge public private cloud environments end users ability deploy applications using self-service portals applications sizes may appear environment consume unpredictable amount resources disappear time possible solution profiling applications impact computational resources result performance models allow prediction resource utilization changes according application patterns thus resources dynamically scaled meet expected demand critical cloud providers need provision resources quickly meet growing demand applications charge-back—or pricing resource use granular basis—is challenge public private cloud environments charge-back challenge public cloud service providers must price services competitively still creating profit users public cloud services may find charge-back challenging difficult groups assess actual resource costs granular basis due overlapping resources within organization may paid individual business unit electrical power private cloud operators charge-back fairly straightforward challenge lies guessing allocate resources closely possible actual resource usage achieve greatest operational efficiency exceeding budgets risk hybrid cloud environments combine public private cloud services sometimes traditional infrastructure elements present set management challenges include security concerns sensitive data lands public cloud servers budget concerns around overuse storage bandwidth proliferation mismanaged images managing information flow hybrid cloud environment also significant challenge on-premises clouds must share information applications hosted off-premises public cloud providers information may change constantly hybrid cloud environments also typically include complex mix policies permissions limits must managed consistently across public private clouds cmps provide means cloud service customer manage deployment operation applications associated datasets across multiple cloud service infrastructures including on-premises cloud infrastructure public cloud service provider infrastructure words cmps provide management capabilities hybrid cloud multi-cloud environments cloud management platform cmp provides broad cloud management functionality atop public cloud provider platforms private cloud platforms cmps manage cloud services resources distributed across multiple cloud platforms value cmps stands delivering maximum level consistency platforms without compromising depth functionality unfortunately meaning term cloud management platform cmp evolved past decade precise meaning term often unclear discussions management strategy one vendor using term may mean something completely different another selecting right management approach cloud services therefore complex task providers vendors confuse evaluation highlighting strengths avoiding weaknesses furthermore provider vendor focuses solving different aspects cloud management making difficult compare solutions minimum viable cmp must able provide support technology stack layers orchestrate capabilities across iaas paas saas etc must include cloud-agnostic tool support portability/migration across hybrid clouds integration framework take advantage existing automation tools used internally combine new cmp features ability provide native container support across virtual technologies prerequisite cmps either container ‘ native ’ architected using containers reengineered support containers along standard os deployments cmp ’ blueprinting function enable administrators create provide image-based solutions customized configurations integration assets databases cmdb role-based access control governance key consolidated control plane operations one primary roles cmp integration existing application lifecycle tools hypervisors cloud platforms given charter cmps must integrate internal external systems manage multi-cloud services ability support published apis provide customization needed critical capability key areas integration include like brokerage firm cloud services brokerage csb manages cloud services clients gartner explains csbs play intermediary role cloud computing management process since many datacenters hosting provided applications role service broker becomes important choosing suitable data center serve received request cloud services brokerages consolidate cloud services one sources allow customers access services one portal
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Distributed computing architecture
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john quarterman john s. quarterman born april 27 1954 american author long time internet participant wrote one classic books networking prior commercialization internet also written risk management quarterman grew bemiss community near valdosta georgia usa first used arpanet 1974 attending harvard worked unix arpanet software bbn original prime contractor arpanet 1977 1981 twice elected board directors usenix association professional association related unix operating system board instrumental vote 1987 approve first funding received uunet along psinet became one first two commercial internet service providers isps co-founded first internet consulting firm texas tic 1986 co-founded one first isps austin zilker internet park since sold jump point founder tispa texas isp association founder chief technology officer matrix netsystems inc. established matrix information directory services mids 1990 quarterman published first maps whole internet conducted first internet demographic survey started first continuing series performance data entire internet 1993 web since 1995 internet weather report also visible internet average plus comparisons isps visible isp ratings inter ctive week listed john quarterman one 25 unsung heroes internet 1998 saying ... president mids quarterman 43 net demographics gallup organization opinion polls internet world interviewed quarterman length full page picture june 1996 issue surveyors cyberspace september 21 2006 quarterman served panelist hank hultquist michele chaboudy joint meeting ieee central texas section communications signal processing chapters titled network neutrality altruism capitalism st. edward university austin texas also organized november 2 2006 panel net neutrality eff-austin featuring quarterman hank hultquist michael hathaway austin bay
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Operating systems
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space-based architecture space-based architecture sba software architecture pattern achieving linear scalability stateful high-performance applications using tuple space paradigm follows many principles representational state transfer rest service-oriented architecture soa event-driven architecture eda well elements grid computing space-based architecture applications built set self-sufficient units known processing-units pu units independent application scale adding units sba model closely related patterns proved successful addressing application scalability challenge shared nothing architecture sn used google amazon.com well-known companies model also applied many firms securities industry implementing scalable electronic securities trading applications application built principles space-based architecture typically following components articles/papers technical
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Distributed computing architecture
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richard proto richard proto noted american cryptographer former director research advanced technology united states national security agency elected nsa hall honor 2013 proto born fair section new connecticut graduated wilbur cross high school 1958 member 1958 team new england high school basketball championship boston garden proto received bachelor degree mathematics fairfield university 1962 master degree mathematics boston college 1964 proto joined united states national security agency nsa 1964 cryptologic mathematician communications security research development organization dedicated next thirty-five years nsa served key roles research organization operational side information security worked security component design security system architectures vulnerability finding risk management proto eventually served nsa director research advanced technology 1994 1999 proto credited creating nsa applied mathematics program train mathematicians apply knowledge range problems beyond traditional cryptologic mission also created laboratory telecommunications sciences focus resources mastering network technology proto authored 28 technical papers nsa responsible invention several information security devices two patented name career proto received presidential rank award distinguished service national intelligence distinguished service medal 2009 proto recognized nsa naming richard c. proto symposium center within nsa compound fort george g. meade maryland second time nsa formally named one facilities 2013 proto elected nsa hall honor 2013 distinguished service american cryptology
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Computer security
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security service telecommunication security service service provided layer communicating open systems ensures adequate security systems data transfers defined itu-t x.800 recommendation x.800 iso 7498-2 information processing systems – open systems interconnection – basic reference model – part 2 security architecture technically aligned model widely recognized general definition cnss instruction 4009 dated 26 april 2010 committee national security systems united states america another authoritative definition w3c web service glossary adopted nist sp 800-95 information security computer security disciplines dealing requirements confidentiality integrity availability so-called cia triad information asset organization company agency information managed computers respectively threats attack resources information devices manage exploiting one vulnerabilities resources protected one countermeasures security controls security services implement part countermeasures trying achieve security requirements organization order let different devices computers routers cellular phones communicate data standardized way communication protocols defined itu-t organization published large set protocols general architecture protocols defined recommendation x.200 different means air cables ways protocols protocol stacks communicate called communication network security requirements applicable information sent network discipline dealing security network called network security x.800 recommendation recommendation extends field application recommendation x.200 cover secure communications open systems according x.200 recommendation so-called osi reference model 7 layers one generically called n layer n+1 entity ask transmission services n entity level two entities n-entity interact means n protocol transmitting protocol data units pdu service data unit sdu specific unit data passed osi layer lower layer yet encapsulated pdu lower layer set data sent user services given layer transmitted semantically unchanged peer service user pdu given layer layer n sdu layer layer n-1 effect sdu 'payload given pdu process changing sdu pdu consists encapsulation process performed lower layer data contained sdu becomes encapsulated within pdu layer n-1 adds headers footers sdu transforming pdu layer n-1 added headers footers part process used make possible get data source destination following considered security services provided optionally within framework osi reference model authentication services require authentication information comprising locally stored information data transferred credentials facilitate authentication security services may provided means security mechanism table1/x.800 shows relationships services mechanisms applied connection oriented protocols connectionless protocols table 2/x.800 illustrates relationship security services layers managed security service mss network security services outsourced service provider
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Computer security
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simulation language computer simulation language used describe operation simulation computer two major types simulation continuous discrete event though modern languages handle complex combinations languages also graphical interface least simple statistic gathering capability analysis results important part discrete-event languages ability generate pseudo-random numbers variants different probability distributions
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Programming language topics
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fireball software fireball browser hijacking malware discovered security company check point takes target browsers turns zombies check point claims discovered fireball malware 2017 microsoft claims tracking malware since 2015 malware tracked chinese company called rafotech digital marketing agency based beijing bundling legitimate software provide users programs rafotech bundled fireball software deal wifi mustang browser sosodesk fvp image viewer rafotech claims 300 million users similar estimated number infections worldwide denies uses fake search engines security researchers dispute claim noting rafotech may also purchased additional distribution means threat actors fake search engines popular 14 ranked among top 10,000 websites reaching top 1,000 malware ability running code victim computers downloading arbitrary file hijacking manipulating infected user web traffic order generate advertisement revenue installs plugins additional configurations boost advertisements potential turn distributor additional malware malware spread mostly via bundling installed victim machine alongside wanted program often without user ’ consent digital marketing agency rafotech indicated producer software company accused host fake search engines redirect queries yahoo.com google.com fake search engines include tracking pixels used collect private information users fireball manipulates infected browsers turn default search engines home pages mentioned fake search engines enable software spy users infected browsers fireball malware conform usual characteristics bundled software check point asserts “ malware fake search engines ’ carry indicators connecting rafotech uninstalled ordinary user conceal true nature. ” furthermore fireball “ displays great sophistication quality evasion techniques including anti-detection capabilities multilayer structure flexible c c. ” another deception use legitimate-seeming digital certificates rafotech ’ fake search engines malware ’ carry identifying marks program capability run arbitrary code download applications harvest sensitive information banking medical details cyber criminals could leverage source code create new types malware estimated 250 million computers infected worldwide check point researches also claim malware might infected computers 20 corporate networks making high volume internet threat according source highest infection rates discovered indonesia india brazil speculated related browser hijackers operations form possibly largest infection operation history table 1 top countries infected fireball malware dispute numbers according microsoft tracking malware since 2015 results based fireball infections cleaned windows defender malicious software removal tool based collected data total infections 40 million check point researchers used number visits malware-carrying search pages device check ’ infected first open web browser 1 verify home-pages set 2 modify home-page 3 check default search engine verify modify 4 check browser extensions installed 1 use adware removal tool 2 remove unknown add-ons browser 3 restore browsers default settings
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Computer security
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drivesavers drivesavers inc. computer hardware data recovery digital forensics electronic discovery firm located novato california founded ceo jay hagan former company president scott gaidano 1985 1985 former jasmine technologies executives jay hagan scott gaidano founded drivesavers operating gaidano ’ condo 1,400 drivesavers originally offered hard drive repair data recovery services company dropped drive repair services within first eight months 1992 drivesavers signed agreement supermac technology assume technical support warranty obligations supermac mass storage products company merged data recovery disk repair 1994 retained drivesavers name 2008 drivesavers invested two million dollars build series five iso-certified cleanrooms disassemble rebuild damaged hard drives 2004-2009 company grew 35 85 employees drivesavers also works secretive branches government celebrities order provide comfort assistance clients upset stressed data loss situation drivesavers staff individual data crisis counselor counselor experience working suicide hotline drivesavers recovery firm licensed every major hard-drive manufacturer work drive void warranty recover data hard disk drives solid state drives smart phones servers digital camera media ios devices drivesavers certified hipaa-compliant undergoes annual reviews encryption training certificates guardianedge pgp pointsec utimaco diamond certified 2013–18 storage visions visionary company award 2014 flash memory summit innovative flash memory consumer application award 2018
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Computer security
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named entity information extraction named entity real-world object persons locations organizations products etc. denoted proper name abstract physical existence examples named entities include barack obama new york city volkswagen golf anything else named named entities simply viewed entity instances e.g. new york city instance city historical perspective term named entity coined muc-6 evaluation campaign contained enamex entity name expressions e.g persons locations organizations numex numerical expression formal definition derived rigid designator saul kripke expression named entity word named aims restrict possible set entities one many rigid designators stands referent designator rigid designates thing every possible world contrary flaccid designators may designate different things different possible worlds example consider sentence trump president united states trump united states named entities since refer specific objects donald trump united states however president named entity since used refer many different objects different worlds different presidential periods referring different persons even different countries organizations referring different people rigid designators usually include proper names well certain natural terms like biological species substances also general agreement named entity recognition community consider named entities temporal numerical expressions amounts money types units may violate rigid designator perspective task recognizing named entities text named entity recognition task determining identity named entities mentioned text called named entity disambiguation tasks require dedicated algorithms resources addressed
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Computational linguistics
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nexusdb nexusdb relational commercial database engine delphi c++ builder .net programming languages created nexusdb pty ltd developed successor turbopower flashfiler system delphi still available free download database engine supports standard alongside core sql functionality well direct cursor based data access nexusdb also provides database connectors easy access various development application environments website client/server trial edition online manual free version without source code embedded/single user downloaded via getit tool rad studio xe8 newer sql based third party database development tool database workbench developed upscene productions.. third party support exists fast report reportbuilder reporting tools
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Databases
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federal information security management act 2002 federal information security modernization act 2002 fisma et seq united states federal law enacted 2002 title iii e-government act 2002 act recognized importance information security economic national security interests united states act requires federal agency develop document implement agency-wide program provide information security information information systems support operations assets agency including provided managed another agency contractor source fisma brought attention within federal government cybersecurity explicitly emphasized risk-based policy cost-effective security fisma requires agency program officials chief information officers inspectors general igs conduct annual reviews agency information security program report results office management budget omb omb uses data assist oversight responsibilities prepare annual report congress agency compliance act fy 2008 federal agencies spent 6.2 billion securing government total information technology investment approximately 68 billion 9.2 percent total information technology portfolio law replaced federal information security modernization act 2014 sometimes known fisma2014 fisma reform fisma2014 struck subchapters ii iii chapter 35 title 44 united states code amending text new law new subchapter ii fisma assigns specific responsibilities federal agencies national institute standards technology nist office management budget omb order strengthen information security systems particular fisma requires head agency implement policies procedures cost-effectively reduce information technology security risks acceptable level according fisma term information security means protecting information information systems unauthorized access use disclosure disruption modification destruction order provide integrity confidentiality availability accordance fisma nist responsible developing standards guidelines associated methods techniques providing adequate information security agency operations assets excluding national security systems nist works closely federal agencies improve understanding implementation fisma protect information information systems publishes standards guidelines provide foundation strong information security programs agencies nist performs statutory responsibilities computer security division information technology laboratory nist develops standards metrics tests validation programs promote measure validate security information systems services nist hosts following fisma defines framework managing information security must followed information systems used operated u.s. federal government agency executive legislative branches contractor organization behalf federal agency branches framework defined standards guidelines developed nist fisma requires agencies information systems inventory place according fisma head agency shall develop maintain inventory major information systems including major national security systems operated control agency identification information systems inventory subsection shall include identification interfaces system systems networks including operated control agency first step determine constitutes information system question direct mapping computers information system rather information system may collection individual computers put common purpose managed system owner nist sp 800-18 revision 1 guide developing security plans federal information systems provides guidance determining system boundaries information information systems categorized based objectives providing appropriate levels information security according range risk levels first mandatory security standard required fisma legislation fips 199 standards security categorization federal information information systems provides definitions security categories guidelines provided nist sp 800-60 guide mapping types information information systems security categories overall fips 199 system categorization high water mark impact rating criteria information types resident system example one information type system rating low confidentiality integrity availability another type rating low confidentiality availability rating moderate integrity impact level integrity also becomes moderate federal information systems must meet minimum security requirements requirements defined second mandatory security standard required fisma legislation fips 200 minimum security requirements federal information information systems organizations must meet minimum security requirements selecting appropriate security controls assurance requirements described nist special publication 800-53 recommended security controls federal information systems process selecting appropriate security controls assurance requirements organizational information systems achieve adequate security multifaceted risk-based activity involving management operational personnel within organization agencies flexibility applying baseline security controls accordance tailoring guidance provided special publication 800-53 allows agencies adjust security controls closely fit mission requirements operational environments controls selected planned must documented system security plan combination fips 200 nist special publication 800-53 requires foundational level security federal information information systems agency risk assessment validates security control set determines additional controls needed protect agency operations including mission functions image reputation agency assets individuals organizations nation resulting set security controls establishes level security due diligence federal agency contractors risk assessment starts identifying potential threats vulnerabilities mapping implemented controls individual vulnerabilities one determines risk calculating likelihood impact given vulnerability could exploited taking account existing controls culmination risk assessment shows calculated risk vulnerabilities describes whether risk accepted mitigated mitigated implementation control one needs describe additional security controls added system nist also initiated information security automation program isap security content automation protocol scap support complement approach achieving consistent cost-effective security control assessments agencies develop policy system security planning process nist sp-800-18 introduces concept system security plan system security plans living documents require periodic review modification plans action milestones implementing security controls procedures place outlining reviews plans keeps plan current follows planned security controls system security plan major input security certification accreditation process system security certification accreditation process system security plan analyzed updated accepted certification agent confirms security controls described system security plan consistent fips 199 security category determined information system threat vulnerability identification initial risk determination identified documented system security plan risk assessment equivalent document system documentation risk assessment completed system controls must reviewed certified functioning appropriately based results review information system accredited certification accreditation process defined nist sp 800-37 guide security certification accreditation federal information systems security accreditation official management decision given senior agency official authorize operation information system explicitly accept risk agency operations agency assets individuals based implementation agreed-upon set security controls required omb circular a-130 appendix iii security accreditation provides form quality control challenges managers technical staffs levels implement effective security controls possible information system given mission requirements technical constraints operational constraints cost/schedule constraints accrediting information system agency official accepts responsibility security system fully accountable adverse impacts agency breach security occurs thus responsibility accountability core principles characterize security accreditation essential agency officials complete accurate trustworthy information possible security status information systems order make timely credible risk-based decisions whether authorize operation systems information supporting evidence needed security accreditation developed detailed security review information system typically referred security certification security certification comprehensive assessment management operational technical security controls information system made support security accreditation determine extent controls implemented correctly operating intended producing desired outcome respect meeting security requirements system results security certification used reassess risks update system security plan thus providing factual basis authorizing official render security accreditation decision accredited systems required monitor selected set security controls system documentation updated reflect changes modifications system large changes security profile system trigger updated risk assessment controls significantly modified may need re-certified continuous monitoring activities include configuration management control information system components security impact analyses changes system ongoing assessment security controls status reporting organization establishes selection criteria subsequently selects subset security controls employed within information system assessment organization also establishes schedule control monitoring ensure adequate coverage achieved security experts bruce brody former federal chief information security officer alan paller director research sans institute described fisma well-intentioned fundamentally flawed tool arguing compliance reporting methodology mandated fisma measures security planning rather measuring information security past gao chief technology officer keith rhodes said fisma helped government system security implementation everything security people view fisma checklist nothing going get done
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Computer security
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semeval semeval semantic evaluation ongoing series evaluations computational semantic analysis systems evolved senseval word sense evaluation series evaluations intended explore nature meaning language meaning intuitive humans transferring intuitions computational analysis proved elusive series evaluations providing mechanism characterize precise terms exactly necessary compute meaning evaluations provide emergent mechanism identify problems solutions computations meaning exercises evolved articulate dimensions involved use language began apparently simple attempts identify word senses computationally evolved investigate interrelationships among elements sentence e.g. semantic role labeling relations sentences e.g. coreference nature saying semantic relations sentiment analysis purpose semeval senseval exercises evaluate semantic analysis systems semantic analysis refers formal analysis meaning computational refer approaches principle support effective implementation first three evaluations senseval-1 senseval-3 focused word sense disambiguation time growing number languages offered tasks number participating teams beginning fourth workshop semeval-2007 semeval-1 nature tasks evolved include semantic analysis tasks outside word sense disambiguation triggered conception *sem conference semeval community decided hold evaluation workshops yearly association *sem conference also decision every evaluation task run every year e.g none wsd tasks included semeval-2012 workshop earliest days assessing quality word sense disambiguation wsd algorithms primarily matter intrinsic evaluation “ almost attempts made evaluate embedded wsd components ” recently extrinsic evaluations begun provide evidence value wsd end-user applications 1990 discussions sense disambiguation task focused mainly illustrative examples rather comprehensive evaluation early 1990s saw beginnings systematic rigorous intrinsic evaluations including formal experimentation small sets ambiguous words april 1997 martha palmer marc light organized workshop entitled tagging lexical semantics conjunction conference applied natural language processing time clear recognition manually annotated corpora revolutionized areas nlp part-of-speech tagging parsing corpus-driven approaches potential revolutionize automatic semantic analysis well kilgarriff recalled “ high degree consensus field needed evaluation ” several practical proposals resnik yarowsky kicked discussion led creation senseval evaluation exercises semeval-2010 many participants feel 3-year cycle long wait many shared tasks conference natural language learning conll recognizing textual entailments rte run annually reason semeval coordinators gave opportunity task organizers choose 2-year 3-year cycle semeval community favored 3-year cycle br although votes within semeval community favored 3-year cycle organizers coordinators settled split semeval task 2 evaluation workshops triggered introduction new *sem conference semeval organizers thought would appropriate associate event *sem conference collocate semeval workshop *sem conference organizers got positive responses task coordinators/organizers participants association yearly *sem 8 tasks willing switch 2012 thus born semeval-2012 semeval-2013 current plan switch yearly semeval schedule associate *sem conference every task needs run every year framework semeval/senseval evaluation workshops emulates message understanding conferences mucs evaluation workshops ran arpa advanced research projects agency renamed defense advanced research projects agency darpa stages semeval/senseval evaluation workshops senseval-1 senseval-2 focused evaluation wsd systems major languages available corpus computerized dictionary senseval-3 looked beyond lexemes started evaluate systems looked wider areas semantics semantic roles technically known theta roles formal semantics logic form transformation commonly semantics phrases clauses sentences represented first-order logic forms senseval-3 explored performances semantics analysis machine translation types different computational semantic systems grew beyond coverage wsd senseval evolved semeval aspects computational semantic systems evaluated semeval exercises provide mechanism examining issues semantic analysis texts topics interest fall short logical rigor found formal computational semantics attempting identify characterize kinds issues relevant human understanding language primary goal replicate human processing means computer systems tasks shown developed individuals groups deal identifiable issues take concrete form first major area semantic analysis identification intended meaning word level taken include idiomatic expressions word-sense disambiguation concept evolving away notion words discrete senses rather characterized ways used i.e. contexts tasks area include lexical sample all-word disambiguation multi- cross-lingual disambiguation lexical substitution given difficulties identifying word senses tasks relevant topic include word-sense induction subcategorization acquisition evaluation lexical resources second major area semantic analysis understanding different sentence textual elements fit together tasks area include semantic role labeling semantic relation analysis coreference resolution tasks area look specialized issues semantic analysis temporal information processing metonymy resolution sentiment analysis tasks area many potential applications information extraction question answering document summarization machine translation construction thesauri semantic networks language modeling paraphrasing recognizing textual entailment potential applications contribution types semantic analysis constitutes outstanding research issue example word sense induction disambiguation task three separate phases unsupervised evaluation wsi considered two types evaluation v measure rosenberg hirschberg 2007 paired f-score artiles et al. 2009 evaluation follows supervised evaluation semeval-2007 wsi task agirre soroa 2007 tables reflects workshop growth senseval semeval gives overview area computational semantics evaluated throughout senseval/semeval workshops multilingual wsd task introduced semeval-2013 workshop task aimed evaluating word sense disambiguation systems multilingual scenario using babelnet sense inventory unlike similar task like crosslingual wsd multilingual lexical substitution task fixed sense inventory specified multilingual wsd uses babelnet sense inventory prior development babelnet bilingual lexical sample wsd evaluation task carried semeval-2007 chinese-english bitexts cross-lingual wsd task introduced semeval-2007 evaluation workshop re-proposed semeval-2013 workshop facilitate ease integrating wsd systems natural language processing nlp applications machine translation multilingual information retrieval cross-lingual wsd evaluation task introduced language-independent knowledge-lean approach wsd task unsupervised word sense disambiguation task english nouns means parallel corpora follows lexical-sample variant classic wsd task restricted 20 polysemous nouns worth noting semeval-2014 two tasks multilingual/crosslingual i.e l2 writing assistant task crosslingual wsd task includes english spanish german french dutch ii multilingual semantic textual similarity task evaluates systems english spanish texts major tasks semantic evaluation include following areas natural language processing list expected grow field progresses following table shows areas studies involved senseval-1 semeval-2014 refers senseval se refers semeval e.g s1 refers senseval-1 se07 refers semeval2007 semeval tasks created many types semantic annotations type various schema semeval-2015 organizers decided group tasks together several tracks tracks type semantic annotations task hope achieve lists type semantic annotations involved semeval workshops task track allocation flexible task might develop track e.g taxonomy evaluation task semeval-2015 learning semantic relations track semeval-2016 dedicated track semantic taxonomy new semantic taxonomy enrichment task
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Computational linguistics
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ws-transaction ws-transaction web services specification developed bea systems ibm microsoft ws-transaction specification describes coordination types used extensible coordination framework described ws-coordination specification defines two coordination types atomic transaction individual operations business activity ba long running transactions developers use either coordination types building applications require consistent agreement outcome distributed activities
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Web technology
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first-class function computer science programming language said first-class functions treats functions first-class citizens means language supports passing functions arguments functions returning values functions assigning variables storing data structures programming language theorists require support anonymous functions function literals well languages first-class functions names functions special status treated like ordinary variables function type term coined christopher strachey context functions first-class citizens mid-1960s first-class functions necessity functional programming style use higher-order functions standard practice simple example higher-ordered function map function takes arguments function list returns list formed applying function member list language support map must support passing function argument certain implementation difficulties passing functions arguments returning results especially presence non-local variables introduced nested anonymous functions historically termed funarg problems name coming function argument early imperative languages problems avoided either supporting functions result types e.g algol 60 pascal omitting nested functions thus non-local variables e.g c early functional language lisp took approach dynamic scoping non-local variables refer closest definition variable point function executed instead defined proper support lexically scoped first-class functions introduced scheme requires handling references functions closures instead bare function pointers turn makes garbage collection necessity section compare particular programming idioms handled functional language first-class functions haskell compared imperative language functions second-class citizens c languages functions first-class citizens functions passed arguments functions way values function taking another function argument called higher-order function language haskell languages functions first-class often still allow one write higher-order functions use features function pointers delegates language c two samples number differences two approaches directly related support first-class functions haskell sample operates lists c sample operates arrays natural compound data structures respective languages making c sample operate linked lists would made unnecessarily complex also accounts fact c function needs additional parameter giving size array c function updates array in-place returning value whereas haskell data structures persistent new list returned old left intact haskell sample uses recursion traverse list c sample uses iteration natural way express function languages haskell sample could easily expressed terms fold c sample terms recursion finally haskell function polymorphic type supported c fixed type variables type constant codice_1 languages supporting anonymous functions pass function argument higher-order function language support anonymous functions bind name instead anonymous nested functions becomes natural refer variables outside body called non-local variables functions represented bare function pointers know anymore value outside function body passed closure needs built manually therefore speak first-class functions also note codice_2 specialized functions referring two codice_1s outside environment set generally requires boilerplate code codice_4 would nested function would still run problem reason supported c. returning function fact returning closure c example local variables captured closure go scope return function builds closure forcing closure later point result undefined behaviour possibly corrupting stack known upwards funarg problem assigning functions variables storing inside global datastructures potentially suffers difficulties returning functions one test literals values equality natural ask whether programming language support testing functions equality inspection question appears difficult one distinguish several types function equality type theory type functions accepting values type returning values type b may written → b b curry-howard correspondence function types related logical implication lambda abstraction corresponds discharging hypothetical assumptions function application corresponds modus ponens inference rule besides usual case programming functions type theory also uses first-class functions model associative arrays similar data structures category-theoretical accounts programming availability first-class functions corresponds closed category assumption instance simply typed lambda calculus corresponds internal language cartesian closed categories functional programming languages scheme ml haskell f scala first-class functions lisp one earliest functional languages designed aspects first-class functions properly understood resulting functions dynamically scoped later scheme common lisp dialects lexically scoped first-class functions many scripting languages including perl python php lua tcl/tk javascript io first-class functions imperative languages distinction made algol descendants pascal traditional c family modern garbage-collected variants algol family allowed nested functions higher-order taking function arguments higher-order functions return functions results except algol 68 allows reason known deal non-local variables nested-function returned result algol 68 produces runtime errors cases c family allowed passing functions arguments returning results avoided problems supporting nested functions gcc compiler allows extension usefulness returning functions primarily lies ability return nested functions captured non-local variables instead top-level functions languages generally considered first-class functions modern imperative languages often support garbage-collection making implementation first-class functions feasible first-class functions often supported later revisions language including c 2.0 apple blocks extension c c++ objective-c. c++11 added support anonymous functions closures language non-garbage collected nature language special care taken non-local variables functions returned results see
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Programming language topics
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mobileme mobileme branded itools 2000 2002 .mac 2008 discontinued subscription-based collection online services software offered apple inc. services gradually transitioned eventually replaced free icloud mobileme ceased june 30 2012 transfers icloud available july 31 2012 data available download date site finally closed completely date data deleted email addresses accounts transferred icloud marked unused originally launched january 5 2000 itools free collection internet-based services mac os 9 users apple relaunched .mac july 17 2002 became paid subscription service primarily designed mac os x users apple relaunched service mobileme july 9 2008 targeting mac os x microsoft windows iphone ipod touch users february 24 2011 apple discontinued offering mobileme retail stores later resellers new subscriptions also stopped october 12 2011 apple launched icloud replace mobileme new users current users access june 30 2012 service cease itools .mac designed primarily provide internet services mac owners members itools .mac received mac.com email address showing services tied mac hardware however release iphone 3g 2008 renamed service mobileme began providing internet services os x ios windows members mobileme given me.com email address though users current mac.com email address could also continue use domains interchangeable email account also longer restricted os x software mail ical could access personal data computer connected internet using web interface me.com number supported applications including microsoft outlook long user used version 2003 later apple support mobileme available via chat telephone latter restricted us/canada users mobileme allowed users track location ios devices via web portal me.com user could see device approximate location map along circle showing radius inaccuracy display message and/or play sound device even set silent change password device remotely erase contents app also released apple allowed users locate iphone another device running ios 4 feature first announced june 10 2009 included ios 3.0 feature mobileme users find iphone made free charge release ios 4.2.1 software update november 22 2010 devices introduced 2010 mobileme two different plans individual plan included 20 gb email file storage 200 gb monthly data transfer family pack plan included 40 gb storage split among one 20 gb individual primary four 5 gb sub-accounts sub-account email address online storage able use mobileme features family members also shared folder idisk could share access data among primary account sub-accounts read/write access folder limited free space available primary user idisk individual plan priced 99 family pack —at 149 members could buy additional storage 20 gb 40 gb allocations however sub-account storage could upgraded family account amount storage designated per account notes mail app mac computer notes app iphone synced via mobileme service however unable viewed edited online lists controlled mail app ical app mac computer viewable editable mobileme website calendar tab viewable editable iphone announcement ios 4 sync notes imap including mobileme implemented mobileme maintained synchronized address book calendar feature using push functions user made change contact event one device automatically synced mobileme servers extension user devices supported devices included iphone address book ical os x microsoft outlook 2003 later microsoft windows subscription calendars ical mac computer viewable online mobileme service although birthdays viewable online gathered information address book rather caldav icalendar .ics subscription calendars conversely iphone birthdays contacts iphone viewable calendar app method except looking individually contacts birthdays calendar added ios 4.3 subscription calendars available view calendar adding settings mail contacts calendar add account mobileme public photo video gallery feature photos videos could uploaded web browser me.com synced iphoto aperture os x uploaded iphone ipod touch users could also upload movies within applications available mac including iphoto imovie mobileme also provided user email address used uploading photos videos uploads viewers gallery either iphone ipod touch me.com sent dedicated email address synced back iphoto aperture galleries could made public private could password protected iphoto imovie os x mobileme featured idisk online storage repository accessible via web browser me.com finder os x various apps ios devices remote disk microsoft windows also allowed sharing files selecting given file using me.com/idisk idisk iphone app clicking share button generated unique link file protected password could shared email another way use idisk share several files easily placing idisk public folder could also password protected users mac os x v10.5 later could use ilife '08 ilife '09 ilife '11 application iweb publish websites hosted mobileme account either domain name controlled page me.com website users without iweb could also publish websites placing files web/sites folder idisk however web host n't support server-side language php mobileme used ajax dynamic html simulate look feel desktop applications within user web browser applications me.com included mail contacts calendar gallery find iphone idisk access plus account section me.com web applications built top open source sproutcore javascript framework users could also configure features email aliases domain names iweb publish feature supported browsers me.com mac windows safari 3.1 later firefox 3.5 later internet explorer 8 internet explorer 7 windows-only safari 3.0 firefox 3.0 would run web applications fully supported mobileme accessible linux using firefox 3 despite warning would presented user upon entry success also reported using konqueror browser linux however confirmed apple mobileme users could connect aim service mac.com me.com accounts mobileme connections secured ssl encryption addition ichat users using mobileme account could encrypt chats mobileme members using ichat users could also access mobileme chat account ios devices using free paid-for versions aim app provided aol ios app supported aim protocol users wished sync mobileme data pc download install apple mobileme control panel install user first download install latest version itunes install mobileme control panel installation user signed control panel using username password could control sync settings contacts calendars bookmarks idisk settings public folder access similar manner mobileme preference panel built mobileme mail beta released may 13 2010 included many new features photo inserting font changing wide screen views much released final version june 18 2010 mobileme calendar beta released july 6 2010 mobileme calendar beta included new web application me.com redesigned day week month views well new list view make scanning events easier performance also improved also featured new sharing options allowed invited users edit shared calendar supported invitations rsvps sent email invited persons answered clicking simple link n't mobileme members also supported caldav standard compatibility multiple devices however updates came decreased functionality capability publish ical calendars publicly viewable web pages removed users wishing view public calendar manually subscribe caldav compatible calendar device compatibility microsoft outlook suffered since outlook users could sync primary outlook calendar mobileme calendar anymore way integrate mobileme outlook mobileme calendar linked caldav meant mobileme calendar always seen outlook secondary calendar alarms notifications work table illustrates pricing structure previous apple discontinuing purchases june 6 2011 part move icloud current users encouraged use mobileme services inside icloud account migration happening automatically anyway could continue use mobileme services access me.com website shut june 30 2012 although limited access beyond date available download content users wishing cancel mobileme—thus immediately end services—could gain full refunds purchased within 45 days june 6 2011 partial refunds purchased 46 days however unclear whether refund policy applied icloud service launched fall 2011 mobileme like .mac itools closely integrated mobileme account extended functions many programs mostly within ilife suite notably idisk could mounted volume desktop furthermore possible mount public portion another user idisk mechanism one early ways receive free software part .mac possible queue files upload offline idisk though uploaded idisk mounted idisk commands located go menu finder additionally address book entries ical events to-do entries safari bookmarks keychains mail accounts mail rules mail signatures smart mailboxes could synced idisk allowing easy synchronization multiple computers iweb allowed users create web pages could uploaded idisk published iphoto could used one-click web-publishing photo albums ical could used publish calendars web also backup software could used make backups idisk local media prior .mac service iphoto imovie garageband itunes libraries could easily uploaded idisk subject various licensing agreements mobileme integrated various applications ios devices included ical syncing calendar address book syncing contacts mail syncing across devices safari bookmarks syncing across devices apple later introduced mobileme idisk app july 29 2009 mobileme gallery app january 14 2010 find iphone app june 18 2010 allowed mobile access find iphone feature initially available mobileme users later made free ios device users initially iphone ipod touch apps following updates made universal app compatible iphone ipod touch ipad august 2010 apple introduced feature allowed users stream music stored idisk background device subdirectory private subdomain public access points mobileme user individual account functions provided direct web access mobileme user account via links function directly see list private public original collection internet software services known icloud first called itools released january 5 2000 made available free charge mac users services offered itools included first availability mac.com email addresses could accessed email client e.g mail app icards free greeting card service ireview collection reviews popular web sites homepage free web page publishing service first version idisk online data storage system kidsafe directory family-friendly web sites itools primarily mac-only offering provided limited discussion board-based technical support however features itools accessible via non-mac platforms although mac required create account example modifying homepage content possible using web browser windows via linux although original version idisk used appleshare ip transport required eventually updated use webdav technology therefore opened access non-mac operating systems apple even offered application use windows xp costs rose particularly due idisk storage space wide demand mac.com email accounts increasing support needs itools renamed .mac july 17 2002 subscription-based suite services dedicated technical support team .mac offered several tools subscribers including upgraded versions homepage personal web hosting service idisk online disk storage service mac.com email service provider offering pop imap protocols icards online greeting card service new services offered .mac included backup personal backup solution allowed users archive data idisk cd dvd mcafee virex virus scanner given .mac subscribers june 15 2005 apple announced september 17 2002 100,000 people subscribed .mac since launch earlier year existing itools accounts transitioned .mac accounts free trial period ended september 30 2002 move generated mixed reaction among mac users believing .mac overpriced .mac occasionally received new features october 2006 apple launched update .mac mail service whose interface close mac os x mail new functionality built top ajax provided drag-and-drop live-updating three-way split view ability resize panels v10.5 leopard used .mac provide dynamic dns services back mac feature remote desktop service august 7 2007 apple ceo steve jobs announced new features .mac including new web gallery feature similar combination features flickr youtube .mac account came 10 gb storage space could divided email storage mac.com email address user idisk account preference allowed user decide much storage space allocate either service see fit users wanted additional storage capacity could buy total 30 gb higher annual fee storage space email idisk could used way user wanted subject terms .mac license agreement .mac also offered boxed version available stores online physical product box contained activation code entered registering renewing subscription initial speculation new service replace .mac came early june 2008 apple bought me.com domain name june 9 2008 apple announced .mac would replaced mobileme launched july 9 2008 mac.com taken offline 08:00 12:00 day mobileme service went live 20:00 02:00 pacific time mobileme taken offline short time later leaving customers redirected mobileme information page option log several hours infrequent service mobileme officially went live july 11 2008 several .mac features removed transition mobileme launch mobileme plagued various issues mobileme .mac successor initially criticized launch unstable syncing problems reports users unable access mail functions mobileme suspected related .mac mobileme switch-over free trial mobileme inadvertently charged australian european customers ’ credit cards leading apple issue refunds extend free trial four months problems switching .mac accounts issues apple created status news page revamped support page initial versions windows mobileme control panel allowed synchronization corporate outlook accounts mobileme mid-2008 update control panel removed ability synchronize outlook mobileme outlook using microsoft exchange server calendars contacts according apple support design bug fixed support synchronizing even standalone outlook tasks notes mobileme may 2011 fortune magazine reported summer 2008 mobileme launched mostly negative reviews apple ceo steve jobs summoned mobileme team meeting town hall auditorium 4 infinite loop asking mobileme supposed someone answered jobs reportedly shot back fuck n't internal email sent apple employees august 4 2008 jobs admitted mobileme launched hurriedly “ apple ’ standards ” wrote “ mistake launch mobileme time iphone 3g iphone 2.0 software app store ” august 18 2008 announced mobileme subscribers would offered 60-day extension addition one-month extension previously offered early 2011 onwards mobileme retail boxes began removed entirely sale apple stores stock slowly discontinued stores june 6 2011 users prevented subscribing renewing mobileme service via apple website june 6 2011 wwdc 2011 icloud release announced sometime fall 2011 entirely replacing mobileme service would discontinued however would continue run concurrently current mobileme subscribers june 30 2012 mobileme perceived public failings steve jobs anticipated skepticism claim icloud works asked rhetorically believe 're ones brought mobileme october 12 2011 alongside release ios 5 iphone 4s icloud released new users current mobileme subscribers able move icloud either immediately anytime june 30 2012 mobileme would permanently discontinued except limited download abilities addition mobileme email calendar services icloud syncs files across multiple devices promised wwdc 2011 apple began service fall 2011 giving every user either ios 5 mac os x lion 5 gb cloud data storage basic service free point usage additional paid-for tiers data storage also available me.com retained default email domain address new icloud users year later around fall 2012 apple started sign-up new users free icloud.com email addresses previous me.com users also able continue using email domain concurrently done previous service changes first step apple sent 30 days left emails existing users mobileme june 1 2012 followed 7 days left emails june 23 2012 advising users download photos files mobileme ends june 30 remember download gallery photos idisk files move iweb sites date previously advertised apple following announcement icloud year earlier main mobileme service discontinued june 30 2012 services moved icloud users expected moved new service already given year notice one exception mobileme gallery idisk services still limited downloading abilities remaining online portal showing banners mobileme ended either still download files limited time idisk page download photos gallery page complete shut-down mobileme occurred july 31 2012 mobileme closed banner showing homepage redirect link icloud ios apps gallery idisk also ceased operating june 30 2012 mobileme later removed system preferences os x release os x mountain lion july 25 2012
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Distributed computing architecture
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cubesat space protocol cubesat space protocol csp small network-layer delivery protocol designed cubesats idea developed group students aalborg university 2008 developed aausat3 cubesat mission launched 2013 protocol based 32-bit header containing network transport layer information implementation designed embedded systems 8-bit avr microprocessor 32-bit arm avr atmel implementation written c ported run freertos posix pthreads-based operating systems linux support mac os x microsoft windows available version 1.1 three-letter acronym csp adopted abbreviation space protocol first mac-layer driver written can-bus physical layer since extended include several technologies name therefore extended general cubesat space protocol without changing abbreviation protocol implementation actively maintained students aalborg university spin-off company gomspace source code available lgpl license hosted github cubesat space protocol enables distributed embedded systems deploy service-oriented network topology layering csp corresponds layers tcp/ip model implementation supports connection oriented transport protocol layer 4 router-core layer 3 several network-interfaces layer 1–2 service-oriented topology eases design satellite subsystems since communication bus interface subsystems means subsystem developer needs define service-contract set port-numbers system responding furthermore subsystem inter-dependencies reduced redundancy easily added adding multiple similar nodes communication bus key features include csp compile platforms recent version gcc compiler csp requires support c99 features inline functions designated initializers csp supports several physical layer technologies lgpl licensed source code contains implementation fragmenting interface drivers socketcan atmel at90can128 at91sam7a1 at91sam7a3 processors version 1.1 onwards csp also includes interfaces i2c rs-232 interfaces need implement function transmit packet insert received packets protocol stack csp_new_packet function csp successfully tested following physical layers port range divided three adjustable segments ports 0 7 used general services ping buffer status implemented csp service handler ports 8 47 used subsystem specific services remaining ports 48 63 ephemeral ports used outgoing connections bits 28 31 used marking packets hmac xtea encryption rdp header crc32 checksum
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Internet protocols
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arm cortex-a arm cortex-a group 32-bit 64-bit risc arm processor cores licensed arm holdings cores intended application use group consists 32-bit cores arm cortex-a5 arm cortex-a7 arm cortex-a8 arm cortex-a9 arm cortex-a12 arm cortex-a15 arm cortex-a17 mpcore arm cortex-a32 64-bit cores arm cortex-a35 arm cortex-a53 arm cortex-a55 arm cortex-a57 arm cortex-a72 arm cortex-a73 arm cortex-a75 arm cortex-a76 32-bit arm cortex-a cores except cortex-a32 implement armv7-a profile armv7 architecture main distinguishing feature armv7-a profile compared two profiles armv7-r profile implemented arm cortex-r cores armv7-m profile implemented arm cortex-m cores armv7-a profile includes memory management unit mmu many modern operating systems require mmu run 64-bit arm cortex-a cores well 32-bit arm cortex-a32 implement armv8-a profile armv8 architecture arm holdings neither manufactures sells cpu devices based designs rather licenses processor architecture interested parties arm offers variety licensing terms varying cost deliverables licensees arm provides integratable hardware description arm core well complete software development toolset right sell manufactured silicon containing arm cpu integrated device manufacturers idm receive arm processor ip synthesizable rtl written verilog form ability perform architectural level optimizations extensions allows manufacturer achieve custom design goals higher clock speed low power consumption instruction set extensions optimizations size debug support etc determine components included arm ic chip consult manufacturer datasheet related documentation cortex-a5 a7 a8 a9 a12 a15 a17 cores implement armv7-a architecture cortex-a32 a35 a53 a57 a72 a73 a75 a76 cores implement armv8-a architecture amount documentation arm chips daunting especially newcomers documentation microcontrollers past decades would easily inclusive single document chips evolved documentation grown total documentation especially hard grasp arm chips since consists documents ic manufacturer documents cpu core vendor arm holdings typical top-down documentation tree ic manufacturers usually additional documents including evaluation board user manuals application notes getting started development software software library documents errata
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Computer architecture
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rodovid rodovid free online collaborative family tree portal originally ukrainian project 2012 active communities 25 languages provides web service built using mediawiki rodovid engine software help store visualize family relationships rodovid founded september 2005 group developers genealogy enthusiasts kiev ukraine name comes ukrainian word rodovid meaning lineage genealogy 2015 rodovid 1,001,000 total records individuals across languages including 290,000 ukrainian russian making second largest free genealogy service online largest language english 2016 rodovid ranked 82 top 100 genealogy websites 2016 genealogyintime magazine experimented supporting imports gedcom files engine software proprietary discussions releasing openly supports layouts family trees optimised browsing printing claims generate trees thousands people seconds rodovid project data descriptions stored servers kiev available creative commons attribution license already public domain data periodically archived wikiteam project internet archive
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Databases
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getsimple cms getsimple cms free web content management system primary goal simple easy use based programming language php uses xml files store content flat file content management system contrast cms software tend use databases mysql getsimple cms created 2009 resident pittsburgh pa us web developer chris cagle still presides project senior developer claims created getsimple cms need cms powerful wordpress use easier since developers joined getsimple team active community contributes plug-ins translations themes getsimple cms primarily developed creation smaller websites however also suitable medium large websites thanks extendability platform via plug-ins themes target groups cms organizations companies individuals need small medium-sized websites according statistics w3tech getsimple cms used less 0.1 sites internet simple installation process copying files web server start installation routine allows immediate use software web hosts offer cms already pre-installed installed software expanded numerous plug-ins themes getsimple cms downloaded 120,000 times march 2013 magazine t3n assigns getsimple micro minimal-cms one praises simplicity yet possible extensibility plug-ins author article states theming concept getsimple belong intuitive ever seen british magazine computer active raises backup function simplicity cleanliness work surface well supplied templates produced content manager magazine dedicated cms detailed presentation took 2012 next typo3 wordpress comparison 15 open source cms hot scripts counted cms may 2010 ten easiest lightest weight scripts web design shack counts among 50 wordpress alternatives ranks eighth demo specialized installations page opensourcecms.com counted getsimple 30 common best-rated systems stand 2013 german-speaking community dedicated language english separate area official forum
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Internet protocols
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ws-coordination ws-coordination web services specification developed bea systems ibm microsoft accepted oasis web services transaction tc 1.2 version describes extensible framework providing protocols coordinate actions distributed applications coordination protocols used support number applications including need reach consistent agreement outcome distributed transactions framework defined specification enables application service create context needed propagate activity services register coordination protocols framework enables existing transaction processing workflow systems coordination hide proprietary protocols operate heterogeneous environment additionally ws-coordination describes definition structure context requirements propagating context cooperating services however specification n't enough coordinate transactions among web services provides coordination framework specifications like ws-atomic transaction ws-businessactivity needed purpose
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Web technology
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exactly c exactly c nxc high-level programming language lego mindstorms nxt designed john hansen 2006 nxc short exactly c based next byte codes assembly language nxc syntax like c. ide nxc bricx command center nxc compiler available mozilla public license sample code shown
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Programming language topics
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cloudike cloudike brandable file storage platform operated cloudike inc. headquartered san jose california platform provides cloud storage file synchronization contact synchronization personal cloud client software company data storage approach similar dropbox google drive apple icloud store user data provide access files smartphones laptops tablets etc main difference apart functionality end-users cloudike personal cloudike offers customization businesses cloudike enterprise brands widely known white-label cloudike started 2013 saas-platform grew multi-tier cloud solution used build white-label enterprise data storages oems mobile internet service providers platform modules enterprise data administration storage api integration billing systems cloudike enables building large-scale file storages based openstack swift amazon s3 storage systems compatible amazon s3 apis synchronize user files server cloudike provides desktop clients windows macos android ios devices cloudike offers mobile clients files contact lists accessed via web browser data updates synchronized computers mobile devices associated user accounts cloudike based set programmatic interfaces apis written python uses python frameworks django tornado create rest api message broker software rabbitmq mongodb build contact synchronization mechanism cloudike utilizes sabredav framework web-frontend part single page application based angularjs end-user features enterprise modules several cloud platforms provide white-label services similar cloudike list contains cloud storage platforms might directly indirectly compete cloudike
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Distributed computing architecture
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boyce–codd normal form boyce–codd normal form bcnf 3.5nf normal form used database normalization slightly stronger version third normal form 3nf bcnf developed 1975 raymond f. boyce edgar f. codd address certain types anomalies dealt 3nf originally defined relational schema bcnf redundancy based functional dependency removed although types redundancy may still exist relational schema r boyce–codd normal form every one dependencies x → least one following conditions hold rare cases 3nf table meet requirements bcnf 3nf table multiple overlapping candidate keys guaranteed bcnf depending functional dependencies 3nf table two overlapping candidate keys may may bcnf example 3nf table meet bcnf table superkeys note even though table start time end time attributes duplicate values still admit days two different bookings court 1 court 2 could start time end time reason start time end time considered table superkeys however candidate keys minimal superkeys relation e.g ⊂ candidate key recall 2nf prohibits partial functional dependencies non-prime attributes i.e. attribute occur candidate key see candidate keys 3nf prohibits transitive functional dependencies non-prime attributes candidate keys today court bookings table non-prime attributes attributes belong candidate key therefore table adheres 2nf 3nf table adhere bcnf dependency rate type → court determining attribute rate type court depends 1 neither candidate key superset candidate key 2 court subset rate type dependency rate type → court respected since rate type ever apply single court design amended meets bcnf candidate keys rate types table rate type court member flag candidate keys today bookings table court start time court end time tables bcnf rate type key rate types table one rate type associated two different courts impossible using rate type key rate types table anomaly affecting original table eliminated cases non-bcnf table decomposed tables satisfy bcnf preserve dependencies held original table beeri bernstein showed 1979 example set functional dependencies ab → c c → b represented bcnf schema consider following non-bcnf table whose functional dependencies follow ab → c c → b pattern person shop type combination table tells us shop type geographically nearest person home assume simplicity single shop one type candidate keys table three attributes prime attributes i.e belong candidate keys table 3nf table bcnf however shop type attribute functionally dependent non-superkey nearest shop violation bcnf means table subject anomalies example eagle eye might shop type changed optometrist fuller record retaining shop type optician davidson record would imply contradictory answers question eagle eye shop type holding shop shop type would seem preferable would prevent anomalies occurring revised design shop near person table candidate key person shop shop table candidate key shop unfortunately although design adheres bcnf unacceptable different grounds allows us record multiple shops type person words candidate keys guarantee functional dependency person shop type → shop respected design eliminates anomalies conform bcnf possible design introduces new normal form known elementary key normal form design consists original nearest shops table supplemented shop table described table structure generated bernstein schema generation algorithm actually eknf although enhancement 3nf recognized time algorithm designed referential integrity constraint defined effect shop type nearest shop first table must refer shop type shop second table data anomalies described previously prevented np-complete given database schema third normal form determine whether violates boyce-codd normal form chris date pointed definition know bcnf appeared paper ian heath 1971 date writes since definition predated boyce codd definition three years seems bcnf ought rights called heath normal form n't edgar f. codd released original paper relational model data large shared databanks june 1970 first time notion relational database published work including boyce-codd normal form method based relational model
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Databases
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cellular architecture cellular architecture type computer architecture prominent parallel computing cellular architectures relatively new ibm cell microprocessor first one reach market cellular architecture takes multi-core architecture design logical conclusion giving programmer ability run large numbers concurrent threads within single processor 'cell compute node containing thread units memory communication speed-up achieved exploiting thread-level parallelism inherent many applications cell cellular architecture containing 9 cores processor used playstation 3 another prominent cellular architecture cyclops64 massively parallel architecture currently development ibm cellular architectures follow low-level programming paradigm exposes programmer much underlying hardware allows programmer greatly optimize code platform time makes difficult develop software
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Computer architecture
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sixth normal form sixth normal form 6nf term relational database theory used two different ways christopher j date others defined sixth normal form normal form based extension relational algebra relational operators join generalized support natural treatment interval data sequences dates moments time instance temporal databases sixth normal form based generalized join follows relvar r table sixth normal form abbreviated 6nf satisfies nontrivial join dependencies — join dependency trivial least one projections possibly u_projections involved taken set attributes relvar table concerned date et al also given following definition relvar r sixth normal form 6nf every jd join dependency r trivial — jd trivial one components equal pertinent heading entirety relation 6nf also 5nf sixth normal form intended decompose relation variables irreducible components though may relatively unimportant non-temporal relation variables important dealing temporal variables interval data instance relation comprises supplier name status city may also want add temporal data time values valid e.g. historical data three values may vary independently different rates may instance wish trace history changes status review production costs may reveal change caused supplier changing city hence charged delivery discussion temporal aggregation sql see also zimanyi different approach see tsql2 authors used term sixth normal form differently synonym domain/key normal form dknf usage predates date et al work sixth normal form currently used data warehouses benefits outweigh drawbacks example using anchor modeling although using 6nf leads explosion tables modern databases prune tables select queries using process called 'table elimination required thus speed queries access several attributes order table 6nf comply 5nf first requires table satisfies trivial join dependencies let ’ take simple example table already 5nf users table every attribute non null primary key username users_table table 5nf join dependency implied unique candidate key table username specifically possible join dependencies username status username department 6nf version would look like users users_dept one table 5nf 6nf produces two tables following another example table 1 join dependencies table medic name occupation medic name practice years practice years type hence could see table 2nf due appearance transitive dependency following tables try bring 6nf table 2.1 table 2.2 table 2.3
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Databases
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fifth normal form fifth normal form 5nf also known project-join normal form pj/nf level database normalization designed reduce redundancy relational databases recording multi-valued facts isolating semantically related multiple relationships table said 5nf every non-trivial join dependency table implied candidate keys join dependency b … z r implied candidate key r b … z superkey r. fifth normal form first described ronald fagin 1979 conference paper normal forms relational database operators consider following example table predicate products type designated product type made brand designated brand available traveling salesman designated traveling salesman primary key composite three columns also note table 4nf since multivalued dependencies 2-part join dependencies table column candidate key superkey determinant two columns absence rules restricting valid possible combinations traveling salesman brand product type three-attribute table necessary order model situation correctly suppose however following rule applies traveling salesman certain brands certain product types repertoire brand b1 brand b2 repertoire product type p repertoire assuming brand b1 brand b2 make product type p traveling salesman must offer products product type p made brand b1 made brand b2 case possible split table three case impossible louis ferguson refuse offer vacuum cleaners made acme assuming acme makes vacuum cleaners sells anything else made acme lava lamp also sells vacuum cleaners made brand robusto note setup helps remove redundancy suppose jack schneider starts selling robusto products breadboxes vacuum cleaners previous setup would add two new entries one product type jack schneider robusto breadboxes jack schneider robusto vacuum cleaners new setup need add single entry jack schneider robusto brands traveling salesman rare situations 4nf table conform 5nf situations complex real-world constraint governing valid combinations attribute values 4nf table implicit structure table table normalized 5nf burden maintaining logical consistency data within table must carried partly application responsible insertions deletions updates heightened risk data within table become inconsistent contrast 5nf design excludes possibility inconsistencies table fifth normal form 5nf project-join normal form pjnf lossless decomposition number smaller tables case smaller tables decomposition candidate key table excluded
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Databases
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dependent type computer science logic dependent type type whose definition depends value overlapping feature type theory type systems intuitionistic type theory dependent types used encode logic quantifiers like exists functional programming languages like agda ats coq f* epigram idris dependent types may help reduce bugs enabling programmer assign types restrain set possible implementations two common examples dependent types dependent functions dependent pairs return type dependent function may depend value type one arguments instance function takes positive integer formula_1 may return array length formula_1 array length part type array note different polymorphism generic programming include type argument dependent pair may second value type depends first value sticking array example dependent pair may used pair array length type-safe way dependent types add complexity type system deciding equality dependent types program may require computations arbitrary values allowed dependent types deciding type equality may involve deciding whether two arbitrary programs produce result hence type checking may become undecidable dependent types created deepen connection programming logic 1934 haskell curry noticed types used typed lambda calculus combinatory logic counterpart followed pattern axioms propositional logic going every proof logic matching function term programming language one curry examples correspondence simply typed lambda calculus intuitionistic logic predicate logic extension propositional logic adding quantifiers howard de bruijn extended lambda calculus match powerful logic creating types dependent functions correspond dependent pairs correspond exists loosely speaking dependent types similar type indexed family sets formally given type formula_4 universe types formula_5 one may family types formula_6 assigns term formula_7 type formula_8 say type b varies function whose type return value varies argument i.e fixed codomain dependent function type function called dependent product type pi-type dependent function type example dependent function type typically written formula_9 formula_10 formula_6 constant function corresponding dependent product type equivalent ordinary function type formula_12 judgmentally equal formula_13 b depend x name 'pi-type comes idea may viewed cartesian product types pi-types also understood models universal quantifiers example write formula_14 n -tuples real numbers formula_15 would type function given natural number n returns tuple real numbers size n usual function space arises special case range type actually depend input e.g formula_16 type functions natural numbers real numbers written formula_17 typed lambda calculus dual dependent product type dependent pair type dependent sum type sigma-type confusingly dependent product type sigma-types also understood existential quantifiers continuing example universe types formula_5 type formula_4 family types formula_6 dependent pair type formula_22 dependent pair type captures idea ordered pair type second term dependent value first formula_23 formula_7 formula_25 b constant function dependent pair type becomes judgementally equal product type ordinary cartesian product formula_26 let formula_4 type let formula_6 curry–howard correspondence b interpreted logical predicate terms given formula_7 whether type b inhabited indicates whether satisfies predicate correspondence extended existential quantification dependent pairs proposition formula_30 true type formula_31 inhabited example formula_32 less equal formula_33 exists another natural number formula_34 k n logic statement codified existential quantification formula_35 proposition corresponds dependent pair type formula_36 proof statement less n pair contains positive number k difference n proof equality k n henk barendregt developed lambda cube means classifying type systems along three axes eight corners resulting cube-shaped diagram correspond type system simply typed lambda calculus least expressive corner calculus constructions expressive three axes cube correspond three different augmentations simply typed lambda calculus addition dependent types addition polymorphism addition higher kinded type constructors functions types types example lambda cube generalized pure type systems system formula_37 pure first order dependent types corresponding logical framework lf obtained generalising function space type simply typed lambda calculus dependent product type system formula_38 second order dependent types obtained formula_37 allowing quantification type constructors theory dependent product operator subsumes formula_40 operator simply typed lambda calculus formula_41 binder system f. higher order system formula_42 extends formula_38 four forms abstraction lambda cube functions terms terms types types terms types types terms system corresponds calculus constructions whose derivative calculus inductive constructions underlying system coq proof assistant curry–howard correspondence implies types constructed express arbitrarily complex mathematical properties user supply constructive proof type inhabited i.e. value type exists compiler check proof convert executable computer code computes value carrying construction proof checking feature makes dependently typed languages closely related proof assistants code-generation aspect provides powerful approach formal program verification proof-carrying code since code derived directly mechanically verified mathematical proof
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Programming language topics
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bitcasa bitcasa inc. american cloud storage company founded 2011 st. louis missouri company later based mountain view california shut 2017 bitcasa provided client software microsoft windows os x android web browsers ios client pending apple approval former product infinite drive provided centralized storage included unlimited capacity client-side encryption media streaming file versioning backups multi-platform mobile access 2013 bitcasa moved tiered storage model offering 1tb 99/year infinite 999/year october 2014 bitcasa announced discontinuation infinite drive 999/year users would get 10tb storage infinite drive users would required migrate one new pricing plans delete account may 2016 bitcasa discontinued offering cloud storage consumers alleging focusing business products company started idea finalist techcrunch disrupt conference september 2011 2012 tony lee recruited vice president engineering frank meehan joined company board directors june 2012 bitcasa closed 9 million investment investors included crunchfund pelion venture partners horizons ventures andreessen horowitz samsung ventures first round capital ceo brian taptich announced jan 2017 bitcasa acquired intel intel spokesperson later clarified intel acquired bitcasa bitcasa provided client software web browsers os x microsoft windows linux mobile app android windows versions include xp vista windows 7 windows 8 bitcasa products provide centralized streaming storage devices simultaneous real-time access files files uploaded one device instantly available devices bitcasa require file syncing devices centralized storage eliminates need duplicate files across devices wait files become synchronized company patent pending infinite storage algorithm designed reduce actual storage space identifying duplicate content providing encryption stored data according popular mechanics magazine bitcasa uses convergent encryption method whereby client data assigned anonymous identifier uploaded data already exists bitcasa servers popular song uploaded instead earmarked available download client protocol said reduce upload time bitcasa encryption method reportedly cloaks data still client computer blocks data sent enterprise-grade aes-256 encryption method data cloud storage according extremetech service gives users access ownership rights data review gizmodo australia bitcasa cloud service described winner pricier competitors supported mac pc android platforms users could access infinite drive mobile apps android windows rt browsers support offline viewing files app collects displays individual media types photos video music documents independently folder hierarchy stored video files streamed auto-transcoded based device bandwidth items may uploaded downloaded shared directly social media sites files size shared web link distributed via email text im initial server migration apps android ios browsers updated effectively rendering devices unusable service september 2011 article published extreme tech said bitcasa convergent encryption based system mostly safe risks associated november 19 2013 company announced infinite storage offering would increase price move sparked intense reaction users company forum even though existing users grandfathered original pricing plan reactions bloggers particularly critical announcement pricing plans change bitcasa blog commented heavily users post ensuing comments removed internet bitcasa bitcasa introduced interface developers october 23 2014 bitcasa announced would removing grandfathered 'infinite plans although company assured customers plans would continued long cancelled service company removed official blog post though still available wayback machine bitcasa backtracked due 'lack demand 'abuse company instead offered previous clients packages regular users pay 10/month 1tb 99 annually 99/month 10tb 999 annually company gave users 23 days migrate download data would deleted move criticized many users physically possible download rates provided bitcasa result system migration users data loss replaceable angry customers gave company bad feedback community forum became less active company offered yearly subscribers right cancel get prorated refund however disabled ability cancel accounts refused delete accounts support system november 13 2014 northern californian district judge william alsup granted temporary restraining order enjoining bitcasa deleting disabling access infinite plan subscribers data bitcasa filed response 18 november challenging legality tro apparent result restraining order bitcasa announced 5-day extension deadline email users november 16 email mention restraining order hearing set 10.00 19 november bitcasa 'won lawsuit february 2015 community forum shut april 7 2016 company switched free 5gb plan free trial tier users account prior april 7 would automatically start trial 60-day trial user changed paid plan account data deleted server april 21 2016 bitcasa announced would discontinue cloud storage service focus business products users may 20 2016 download data user data could deleted bitcasa shut consumer cloud storage end may 20 2016 offering products developers four months refund customers website bitcasa inaccessible
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Distributed computing architecture
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gustafson law computer architecture gustafson law gustafson–barsis law gives theoretical speedup latency execution task fixed execution time expected system whose resources improved named computer scientist john l. gustafson colleague edwin h. barsis presented article reevaluating amdahl law 1988 gustafson estimated speedup gained using n processors instead one task serial fraction benefit parallelism follows using different variables gustafson law formulated following way gustafson law addresses shortcomings amdahl law based assumption fixed problem size execution workload change respect improvement resources gustafson law instead proposes programmers tend set size problems fully exploit computing power becomes available resources improve therefore faster equipment available larger problems solved within time impact gustafson law shift research goals select reformulate problems solving larger problem amount time would possible way law redefines efficiency due possibility limitations imposed sequential part program may countered increasing total amount computation task executed system whose resources improved compared initial similar system split two parts example — computer program processes files disk part program may scan directory disk create list files internally memory another part program passes file separate thread processing part scans directory creates file list sped parallel computer part processes files execution workload whole task improvement resources system denoted formula_3 includes execution workload part benefit improvement resources execution workload one benefits fraction execution workload would benefit improvement resources denoted formula_4 fraction concerning part would benefit therefore execution part benefits improvement resources sped factor formula_6 improvement resources consequently execution workload part benefit remains theoretical execution workload formula_7 whole task improvement resources gustafson law gives theoretical speedup latency execution whole task fixed time formula_9 yields amdahl law presupposes computing requirements stay given increased processing power words analysis data take less time given computing power gustafson hand argues computing power cause data carefully fully analyzed pixel pixel unit unit rather larger scale would possible practical simulate impact nuclear detonation every building car contents including furniture structure strength etc calculation would taken time available provide answer increase computing power prompt researchers add data fully simulate variables giving accurate result amdahl law reveals limitation example ability multiple cores reduce time takes computer boot operating system ready use assuming boot process mostly parallel quadrupling computing power system took one minute load might reduce boot time fifteen seconds greater greater parallelization would eventually fail make bootup go faster part boot process inherently sequential gustafson law argues fourfold increase computing power would instead lead similar increase expectations system capable one-minute load time acceptable users starting point increase features functions system time taken boot operating system i.e one minute new system would include graphical user-friendly features problems fundamentally larger datasets example processing one data point per world citizen gets larger percent per year principal point gustafson law problems likely fruitful applications parallelism algorithms nonlinear runtimes may find hard take advantage parallelism exposed gustafson law snyder points n algorithm means double concurrency gives 26 increase problem size thus may possible occupy vast concurrency may bring little advantage original less concurrent solution—however practice still considerable improvements hill marty emphasize also methods speeding sequential execution still needed even multicore machines point locally inefficient methods globally efficient reduce sequential phase furthermore woo lee studied implication energy power future many-core processors based amdahl law showing asymmetric many-core processor achieve best possible energy efficiency activating optimal number cores given amount parallelism known prior execution
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Computer architecture
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enhanced mitigation experience toolkit enhanced mitigation experience toolkit emet freeware security toolkit microsoft windows developed microsoft provides unified interface enable fine-tune windows security features used extra layer defense malware attacks firewall antivirus software emet targeted mostly system administrators newest version supported windows user running windows 7 later windows server 2008 r2 later .net framework 4.5 installed older versions used windows xp features available version 4.1 last version support windows xp microsoft announced emet reach end life july 31 2018 successors emet processmitigations module —aka process mitigation management tool —and windows defender exploit guard available windows 10 windows server 2016
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Computer security
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univention corporate server univention corporate server ucs server operating system derived debian gnu/linux integrated management system central cross-platform administration servers services clients desktops users well virtualized computers operated ucs addition operation local virtual instances ucs also operated openstack-based microsoft azure-based amazon ec2-based cloud environments via integration open source software samba 4 univention also supports functions provided many companies microsoft active directory administration computers operated microsoft windows ucs-based components ucs-certified established third party products installed integrated via univention app center ucs provides app center applications runtime environment services operation including central consistent management apps docker containers also run ucs systems several apps available app center docker-based univention member open source business alliance supports creation open source business alliance open source software stacks impulse development ucs began 2002 lack standardised linux server operating system offering companies organisations alternative microsoft ’ domain concept proprietary directory service active directory comparable linux solutions e.g. suse red hat offer integrated cross-system user computer management system result corresponding solutions configured maintained individually important early driving forces development ucs initially oldenburgische landesbank department bremen senator education science product ready market launch end 2004 since addition new versions number software solutions based main product ucs also launched ucs predominantly employed german-speaking world companies public organisations wide range sectors fields among others regional government authority federal state brandenburg 2005 univention began market ucs also german-speaking countries today ucs used many european countries also outside europe example australia nigeria usa univention established subsidiary 2013 ucs open-source software proprietary developments univention gmbh included ucs published gnu gpl version 2.3 launch version 2.4 company switched gnu agpl also range software appliances based ucs e.g. groupware desktop service management fields since april 21 2015 ucs freely available companies form ucs core edition replaced previous „ free personal use license core edition fully featured version differs fee-based edition terms product liability support univention corporate server based linux distribution debian gnu/linux numerous open source applications integrated ucs example samba authentication service kerberos virtualization software kvm nagios monitoring servers core important unique selling point ucs central administration tool univention management console allows cross-system cross-location management infrastructures ucs uses directory service openldap save data identity system management administration tools operated via web-based applications command-line interfaces thanks integrated administration service ucs virtual machine manager uvmm administration tools also allow central administration virtualized servers clients hard drives cdrom dvd images well physical systems operated manufacturer goes great lengths guarantee possibilities integration ucs existing environments via use open standards supplied connectors way integrated tool active directory connection allows bidirectional synchronisation microsoft directory service active directory directory service used ucs openldap addition ucs offers various interfaces manufacturers application software enabling integrate applications ucs management system since ucs 3.1 ucs provides univention app center graphic management component installation deinstallation ucs components ucs-certified third-party appliances univention app center includes beside univention solutions example open source groupware solutions kopano open-xchange document management system agorum core slack alternative rocket.chat dropbox alternatives owncloud nextcloud collaboration solutions onlyoffice collabora
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Computer architecture
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wingify wingify software company based new delhi india products include vwo a/b testing conversion optimization platform pushcrew push notification service web mobile wingify founded 2010 paras chopra sparsh gupta office new delhi company bootstrapped 2017 annual revenue 18 million success products wingify bootstrap champ category economic times startup awards 2017 india owing success company forbes featured wingify founder paras chopra 30 30 list influential people india 2014 february 2018 wingify announced sparsh gupta company chief operating officer appointed new ceo paras chopra remaining chairman
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Web technology
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moore second law rock law moore second law named arthur rock gordon moore says cost semiconductor chip fabrication plant doubles every four years 2015 price already reached 14 billion us dollars rock law seen economic flip side moores first law – number transistors dense integrated circuit doubles every two years latter direct consequence ongoing growth capital-intensive semiconductor industry— innovative popular products mean profits meaning capital available invest ever higher levels large-scale integration turn leads creation even innovative products semiconductor industry always extremely capital-intensive ever-dropping manufacturing unit costs thus ultimate limits growth industry constrain maximum amount capital invested new products point rock law collide moore law suggested fabrication plant costs increased quickly predicted rock law – indeed plateauing late 1990s – also fabrication plant cost per transistor shown pronounced downward trend may relevant constraint moore law
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Computer architecture
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portable standard lisp portable standard lisp psl programming language dialect language lisp psl inspired predecessor standard lisp portable lisp compiler tail-recursive late binding dynamically bound developed researchers university utah 1980 released psl 3.1 development handed developers hewlett-packard 1982 released psl 3.3 portable standard lisp available kit containing screen editor compiler interpreter several hardware operating system computing platforms including motorola 68000 series decsystem-20s cray-1s vax many others today psl mainly developed available konrad-zuse-zentrum für informationstechnik berlin zib main modern use underlying language implementations reduce like older lisps first step psl compiles lisp code lap code another cross-platform language however older lisps mostly compiled lap directly assembly language architecture dependent intermediate psl compiles lap c code would run virtual machine language programs written portable c principle portable compiler written psl primitive dialect named system lisp syslisp ... experiment writing production-quality lisp lisp much possible minor amounts code written hand assembly language systems languages whole ensemble could bootstrap improvements compiler improved compiler later releases compatibility package common lisp sustained modern versions portable standard lisp fewer features lisps common lisp people found unpleasant use richard p. gabriel wrote popular essay lisp good news bad news win big third standard lisp portable standard lisp ran many machines people wanted use
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Programming language topics
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university tampere university tampere uta public university tampere finland merged tampere university technology create new tampere university 1 january 2019 university offered undergraduate postgraduate doctoral programmes 20,178 degree students 1,981 employees 2016 founded 1925 helsinki civic college 1930 onwards known school social sciences institution relocated tampere 1960 renamed university tampere 1966 2016 budget €184.6 million 59 government funding institution established 1925 civic college helsinki teaching public administration organisation management journalism inaugural intake 72 students 1930 total 195 students enrolled college name amended school social sciences similarly institution vocationally oriented bachelor degrees expanded municipal administration public law child protection civic education well master degree social sciences first faculty faculty social sciences established 1949 number students steadily increased 227 1940 661 1950 programmes offered school grew degrees social youth work librarianship economics well prison officer diploma first doctoral degree completed 1955 1956 city tampere school social sciences agreed relocating school tampere 1960 number students increased 933 school social sciences moved new päätalo main building designed toivo korhonen kalevantie 4 tampere faculty humanities faculty economics business administration established 1964 1965 respectively school social sciences renamed university tampere 1966 programme called tampere3 merge university tampere university technology tampere university applied sciences started spring 2014 merger approved parliament december 2017 came effect 1 january 2019 new foundation-based interdisciplinary higher education institution named tampere university proposed name tampere new university faced criticism total 14,712 degree students studied university tampere 2016 including 11,810 students bachelor master degree programmes 1,646 doctoral students likewise 2016 university received 17,482 applications 1,418 enrolled admission rate 8.1 hosted four centres excellence research mitochondrial disease russian studies 2016 2017 tuition fee approximately 10,000 euros charged general non-european union/european economic area citizens studying english-taught master degree programmes 50 100 cover scholarships available students exchange doctoral students exempt fees university ranked 201–250 times higher education world university rankings 2018 likewise ranked 551-600 qs world university rankings 2018 101-150 communication media studies category 2016 total budget university 184.6 million euros 108.8 million core funding government finland 67.49 million external endowments addition independent units finnish social science data archive fsd laboratory services language centre library university organized six faculties 1 january 2017 reorganization following people served rectors university tampere university tampere two campuses tampere main campus centre near tampere railway station kauppi campus next tampere university hospital main campus hosted faculties comprised päätalo pinni linna virta buildings faculty medicine life sciences laboratory services located arvo building kauppi campus päätalo building completed 1960 served university first premises tampere pinni complex completed gradually 1990s 2000s linna virta buildings ready use 2006 2009 respectively medicine-focused arvo building built two separate phases reached 2009 2016 floor area university facilities totaled 130,134 2016 instead dormitories campuses tampere student housing foundation rented apartments students around tampere
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Computer architecture
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sysjail sysjail defunct user-land virtualiser systems supporting systrace library version 1.0 limited openbsd netbsd miros original design inspired freebsd jail similar utility although part kernel freebsd sysjail developed released 2006 kristaps dzonsons aka johnson research assistant game theory stockholm school economics maikls deksters sysjail re-written scratch 2007 support emulated processes jails limited initially linux emulation project officially discontinued 3 march 2009 due flaws inherent syscall wrapper-based security architectures restrictions sysjail could evaded exploiting race conditions wrapper security checks kernel execution syscalls
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Computer security
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comparison database access orms manage database class represents row table named table
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Databases
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rwth asr rwth asr short rasr proprietary speech recognition toolkit toolkit includes newly developed speech recognition technology development automatic speech recognition systems developed human language technology pattern recognition group rwth aachen university rwth asr includes tools development acoustic models decoders well components speaker adaptation speaker adaptive training unsupervised training discriminative training word lattice processing software runs linux mac os x project homepage offers ready-to-use models research purposes tutorials comprehensive documentation toolkit published license called rwth asr license derived qpl license grants free usage including re-distribution modification non-commercial use unlike qpl permit commercial use
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Computational linguistics
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halloween problem computing halloween problem refers phenomenon databases update operation causes change physical location row potentially allowing row visited operation could even cause infinite loop cases updates continually place updated record ahead scan performing update operation potential database error first discovered chamberlin pat selinger morton astrahan 1976 halloween day working query supposed give ten percent raise every employee earned less 25,000 query would run successfully errors finished employees database earned least 25,000 kept giving raise reached level expectation query would iterate employee records salary less 25,000 precisely fact even updated records visible query execution engine continued match query criteria salary records matching multiple times time given 10 raise greater 25,000 name descriptive nature problem rather given due day discovered recounted chamberlin pat morton discovered problem halloween ... remember came office said ‘ chamberlin look make sure optimizer making plan processing update ’ use index based field updated going ’ happened friday said ‘ listen going able solve problem afternoon let ’ give name ’ call halloween problem ’ work next week. ’ turns called ever since
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Databases
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digital subscriber line access multiplexer digital subscriber line access multiplexer dslam often pronounced dee-slam network device often located telephone exchanges connects multiple customer digital subscriber line dsl interfaces high-speed digital communications channel using multiplexing techniques dslam equipment collects data many modem ports aggregates voice data traffic one complex composite signal via multiplexing depending device architecture setup dslam aggregates dsl lines asynchronous transfer mode atm frame relay and/or internet protocol network i.e. ip-dslam using packet transfer mode transmission convergence ptm-tc protocol stack aggregated traffic directed telco backbone switch via access network also called network service provider nsp 10 gbit/s data rates dslam acts like network switch since functionality layer 2 osi model therefore re-route traffic multiple ip networks isp devices end-user connection points dslam traffic switched broadband remote access server end-user traffic routed across isp network internet customer-premises equipment interfaces well dslam connected may take advantage enhanced telephone voice data line signaling features bandwidth monitoring compensation capabilities supports dslam may may located telephone exchange may also serve multiple data voice customers within neighborhood serving area interface sometimes conjunction digital loop carrier dslams also used hotels lodges residential neighborhoods businesses operating private telephone exchange addition data switch multiplexer dslam also large collection modems modem aggregation card communicates single subscriber dsl modem modem functionality integrated dslam instead done via external device like 20th-century voiceband modem like traditional voice-band modems dslam integrated dsl modems usually able probe line adjust electronically digitally compensate forward echoes bandwidth-limiting factors order move data maximum possible connection rate compensation capability also takes advantage better performance balanced line dsl connections providing capabilities lan segments longer physically similar unshielded twisted pair utp ethernet connections since balanced line type generally required hardware function correctly due nominal line impedance measured ohms comprising resistance inductance balanced lines somewhat lower utp thus supporting 'weaker signals however solid-state electronics required construct digital interfaces costly balanced pair cable higher attenuation higher frequencies therefore longer wire dslam subscriber slower maximum possible data rate due lower frequencies used limit total attenuation due higher number errors higher frequencies effectively lowering overall frequency/data rate following rough guide relation wire distance based 0.40 mm copper adsl2+ technology maximum data rate local conditions may vary especially beyond 2 km often necessitating closer dslam bring acceptable bandwidths customers connect dslam adsl modems dsl routers connected pstn network via typical unshielded twisted pair telephone lines dslam multiple aggregation cards card multiple ports customers lines connected typically single dslam aggregation card 24 ports number vary manufacturer common dslams housed telco-grade chassis supplied nominal 48 volts dc hence typical dslam setup may contain power converters dslam chassis aggregation cards cabling upstream links upstream trunk isp side many early dslams used atm—and approach standardized dsl forum—with gigabit ethernet support appearing sometime later today common upstream links dslams use gigabit ethernet multi-gigabit fiber optic links ip-dslam stands internet protocol digital subscriber line access multiplexer user traffic mostly ip based traditional 20th century dslams used asynchronous transfer mode atm technology connect upstream atm routers/switches devices extract ip traffic pass ip router ip network division work thought sensible dsl based atm could theoretically carry data ip atm stream contrast ip-dslam extracts ip traffic dslam passes ip router advantages ip-dslam traditional atm dslam merged equipment less expensive make operate offer richer set features
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Internet protocols
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location api java location api java compact generic java 2 api produces information device present physical location java applications api optionally supported mobile phone pda manufacturers minimum java platform required api cldc v1.1 location api developed java community process jsr 179 released september 2003 updated version 1.0.1 march 2006 nokia main author maintainer jsr openlapi lgpl implementation use emulator environments nokia reference implementation exist devices access gps device bluetooth location api designed work many different positioning methods generic interfaces lets application developers implement systems retrieve location data multiple sources based availability device advantages single means tracking including fail-over indoor/outdoor transparency choice speed accuracy trade-offs gps cellular positioning methods api supports location api support previously location service implementations provider specific aim api provide common api retrieving location information variety devices openlapi supports several back-ends along device specific wrappers since many providers choose implement optional jsr goal universality still happened developers often required create custom builds different devices location api available java applications blackberry windows mobile devices recent motorola sony ericsson devices nokia series 60 3rd edition devices
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Programming language topics
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gtunnel gtunnel windows application developed garden networks sets local http socks proxy server tunnels traffic server farm reaches intended destination gtunnel protects internet users privacy freedom speech ways gtunnel version 1.1 provides standard mode main working mode provides best data transfer performance connecting back-end servers directly skype mode tor mode go computers p2p network gtunnel also improved user interface features real-time traffic graphs gtunnel replaces earlier garden g2 client software becomes main client software garden networks gtunnel works linux wine support
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Internet protocols
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model-driven security model-driven security mds means applying model-driven approaches especially concepts behind model-driven software development security general concept model-driven security earliest forms around since late 1990s mostly university research first commercialized around 2002 also body later scientific research area continues day specific definition model-driven security specifically applies model-driven approaches automatically generate technical security implementations security requirements models particular model driven security mds tool supported process modelling security requirements high level abstraction using information sources available system produced stakeholders inputs expressed domain specific languages dsl transformed enforceable security rules little human intervention possible mds explicitly also includes run-time security management e.g entitlements/authorisations i.e run-time enforcement policy protected systems dynamic policy updates monitoring policy violations model-driven security also well-suited automated auditing reporting documenting analysis e.g compliance accreditation relationships models technical security implementations traceably defined model-transformations several industry analyst sources state mds significant impact information security infrastructure required become increasingly real-time automated adaptive changes organisation environment many information technology architectures today built support adaptive changes e.g service oriented architectures soa so-called platform-as-a-service mashups cloud computing information security infrastructure need support adaptivity agility term devopssec see devops used analysts equivalent model-driven security mds automates generation re-generation technical security enforcement generic models apart academic proof-of-concept developments commercially available full implementations model-driven security authorization management policy automation include objectsecurity openpmf earned listing gartner cool vendor report 2008 advocated number organizations e.g u.s. navy means make authorization policy management easier automated
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Computer security
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peerio peerio cross-platform end-to-end encrypted application provides secure messaging file sharing cloud file storage peerio available application ios android macos windows linux peerio legacy originally released 14 january 2015 replaced peerio 2 15 june 2017 messages user files stored peerio cloud protected end-to-end encryption meaning data encrypted way read third parties peerio service providers security provided single permanent key-password peerio called account key company peerio technologies inc. founded 2014 vincent drouin intent behind peerio provide security program easier use current pgp standard peerio allows users share encrypted messages files direct messages groups peerio calls rooms peerio rooms offered team-oriented group chat allowing administrative functionality add remove users group chat peerio allows users store encrypted files online offering limited cloud storage free optional paid upgrades peerio messages files persist logins hardware differing ephemeral encrypted messaging apps retain message file history logins different devices peerio supports application based multi-factor authentication peerio allows users share animated gifs peerio utilizes end-to-end encryption applied default message file data end-to-end encryption intended encrypt data way sender intended recipients able decrypt thus read data taken peerio privacy policy peerio utilizes nacl pronounced salt cryptographic framework uses following cryptographic primitives additionally peerio uses scrypt memory-hard key derivation blake2s used various hashing operations in-transit encryption peerio services use transport layer security tls best-practice cipher suite configuration including support perfect forward secrecy pfs view detailed up-to-date independent review peerio ’ tls configuration ssl labs prior peerio initial release software audited german security firm cure53 found non-security related bugs fixed prior applications release according peerio website application also audited march 2017 cure53 peerio partly open source publishes code publicly github peerio offers bug bounty offering cash rewards anyone reports security vulnerabilities first iteration peerio peerio legacy developed nadim kobeissi florencia herra-vega released 14 january 2015 closed 8 january 2018 peerio legacy free application available android ios windows macos linux google chrome extension offered end-to-end encryption enabled default encryption used minilock open-source security standard also developed kobeissi 15 june 2017 peerio 2 launched successor peerio legacy according company blog peerio 2 purported radical overhaul original application core technology claimed benefits comparison peerio legacy include increased speed support larger file transfers 7000gb re-designed user interface peerio also stated added focus towards businesses looking encrypted team collaboration software
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Computer security
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alphabasic alphabasic computer programming language created alpha microsystems 1976 language written alpha microsystems employees paul edelstein dick wilcox bob courier alphabasic shares much common basic languages offer fairly unusual features multi-user orientation ability control memory layout variables map statement calling external assembly language subroutines xcall statement language designed developers vertical market software packages compiler runtime system written motorola 68000 assembly language thus able run alpha microsystems hardware compiler emits interpreter code
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Programming language topics
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select unix select system call application programming interface api unix-like posix-compliant operating systems examining status file descriptors open input/output channels select system call similar poll facility introduced unix system v later operating systems however c10k problem select poll superseded likes kqueue epoll /dev/poll i/o completion ports c programming language select system call declared header file sys/select.h unistd.h following syntax codice_1 arguments may manipulated four utility macros fd_set fd_clr fd_zero fd_isset select returns total number bits set readfds writefds errorfds zero timeout expired -1 error sets file descriptor used select finite size depending operating system newer system call poll provides flexible solution
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Computer architecture
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iso 13490 iso/iec 13490 also known ecma-168 successor iso 9660 level 3 intended describe file system cd-rom cd-r. iso 13490 several improvements predecessor fully addresses filename posix attribute multibyte character issues handled iso 9660 also efficient format permits incremental recording permits iso 9660 format iso/iec 13490 format co-exist media also specifies use multisession properly derived frankfurt group formed 1990 many cd-rom cd-wo hardware media manufacturers cd-rom data publishers users cd-roms major computer companies proposal fully supports orange book media iso 13490 define rule operating systems read multiple-session iso 9660 volume cd-r instead looking volume descriptor offset 32,768 sector number 16 cd start disc would default behavior iso 9660 programs accessing disc start reading 16th sector first track latest session sector numbers form contiguous sequence starting first session continue added sessions gaps hence cd mastering program wants add single file cd-r iso 9660 volume append session containing least updated copy entire directory tree plus new file duplicated directory entries still reference data files previous session similar way file data updated even removed removal however virtual removed content appear directory shown user still physically present disc therefore recovered takes space cd become full even though appearing still unused space though originally intended multisession support apply mode 2 form 1 formatted discs cd writing software supported multisession writing mode 1 format discs since early disc drives supported multisession mode 1 discs many cases second following sessions would become unreachable drives older cd writing software nero burning rom would import previous session data inserted disc could thus write subsequent session disc computer written previous sessions previous session data saved writing software closed
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Computer file systems
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tcp-illinois tcp-illinois variant tcp congestion control protocol developed university illinois urbana–champaign especially targeted high-speed long-distance networks sender side modification standard tcp congestion control algorithm achieves higher average throughput standard tcp allocates network resource fairly standard tcp compatible standard tcp provides incentives tcp users switch tcp-illinois loss-delay based algorithm uses packet loss primary congestion signal determine direction window size change uses queuing delay secondary congestion signal adjust pace window size change similarly standard tcp tcp-illinois increases window size w formula_1 acknowledgment decreases formula_2 formula_3 loss event unlike standard tcp formula_4 formula_5 constants instead functions average queuing delay formula_6 formula_7 formula_8 decreasing formula_9 increasing numerous choices formula_8 formula_9 one class formula_12 formula_13 let formula_8 formula_9 continuous functions thus formula_16 formula_17 formula_18 suppose formula_19 maximum average queuing delay denote formula_20 also formula_21 conditions formula_22 specific choice demonstrated figure 1 tcp-illinois increases throughput much quickly tcp congestion far increases throughput slowly congestion imminent result window curve concave average throughput achieved much larger standard tcp see figure 2 also many desirable features like fairness compatibility standard tcp providing incentive tcp users switch robust inaccurate delay measurement
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Internet protocols
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delphish delphish software product protects user data free anti-phishing extension microsoft outlook outlook express integrated toolbar delphish enables user check suspicious e-mails author country origin detects hidden links informs user origin operator linked web sites analyzes entire e-mail delphish created developed team made better-known safersurf another piece computer security software nutzwerk internet technologies software company headquartered leipzig delphish provides various features delphish released 2007 positive reviews ghacks said use delphish first layer defense phishing make sure able analyze mails well computerwoche wrote although delphish all-inclusive package anti-phishing protection turns useful informative tool seccity commented user estimate danger link since obtains detailed information link actual target type popularity age domain owners etc online pc said delphish provides advantages automatic recognition raises user awareness safe responsible use e-mails
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Computer security
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freebsd ports freebsd ports collection package management system freebsd operating system providing easy consistent way installing software packages april 2018 31,679 ports available collection also adopted netbsd basis pkgsrc system ports collection uses makefiles arranged directory hierarchy software built installed uninstalled make command installing application little user intervention required issuing beginning command make install make install clean ports directory desired application cases software automatically downloaded internet patched configured necessary compiled installed registered package database new port needed dependencies applications libraries installed beforehand automatically ports already configured default options deemed generally appropriate users however configuration options called knobs sometimes changed installation using make config command brings text-based interface allows user select desired options historically port software package maintained individual port maintainer responsible ensuring currency port providing general support today many ports maintained special task forces sub-projects dedicated mailing list e.g kde freebsd.org java freebsd.org etc unmaintained ports assigned generic group ports freebsd.org general anyone may become port maintainer contributing favorite software collection one may also choose maintain existing port active maintainer precompiled binary ports called packages package created corresponding port make package command prebuilt packages also available download freebsd-hosted package repositories user install package passing package name pkg install command downloads appropriate package installed freebsd release version installs application including software dependencies may default packages downloaded main freebsd package repository pkg.freebsd.org freebsd maintains build farm called pointyhat cluster packages supported architectures major releases built build logs known errors ports built packages pointyhat cluster available database weekly builds logs also available mailing list archives precompiled packages separated categories architectures available packages separated several release directories one current production release built ports collection shipped release production release directories never updated also stable current directories several major release branches updated less weekly cases package created older version freebsd installed used newer system without difficulty since binary backward compatibility across major releases enabled default packaging system binary packages called codice_1 replaced package management system freebsd 10 jordan hubbard committed port make macros freebsd cvs repository august 21 1994 package install suite makefile committed year earlier august 26 1993 core ports framework first maintained hubbard along satoshi asami several years ports management team later formed handle task netbsd pkgsrc openbsd ports collection trace roots freebsd since release 3.6 dragonfly bsd project uses freebsd ports base dports ports collection john marino dragonfly bsd project created deltaports repository – collection patches files overlay modify freebsd ports order generate dports
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Operating systems
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knight lore knight lore 1984 action-adventure game known popularising isometric graphics video games game developed published ultimate play game written company founders chris tim stamper knight lore player character sabreman forty days collect objects throughout castle brew cure werewolf curse castle room depicted monochrome screen consists blocks climb obstacles avoid puzzles solve ultimate released knight lore third sabreman series despite completed first stamper brothers withheld release year position company advantageously anticipation game effect market knight lore novel image masking technique filmation let images appear pass atop behind without contents colliding created illusion depth priority computer natively support delaying knight lore release ultimate protected sales then-upcoming sabre wulf created another filmation game developers could copy style ultimate released original sabreman trilogy quick succession 1984 zx spectrum knight lore came last november ports followed bbc micro amstrad cpc msx family computer disk system 2008 unofficially ported atari 8-bit computers based bbc micro version game later included compilations including rare 2015 xbox one retrospective compilation rare replay knight lore regarded seminal work british gaming history included multiple lists top spectrum games critics considered technical solutions isometric 3d style harbinger future game design praised game controls atmosphere mystery noted difficult gameplay criticised sound occasional graphical slowdown knight lore best-selling game january 1985 named 1984 game year golden joystick awards popular computing weekly readers though first isometric 3d video game knight lore popularised format isometric flip-screen style fell fashion knight lore influence persisted computer role-playing games retrospective reviewers remember game first offer exploratory world rather flat surface consider controls outdated frustrating thirty years since release player sabreman bitten sabre wulf transforms werewolf nightfall 40 days collect items throughout melkhior wizard castle brew cure curse onscreen timer shows progression day night sabreman metamorphoses werewolf returning human form sunrise castle monsters attack sabreman werewolf game ends player completes potion finish task forty days game directions given poem included game cassette tape castle consists series 128 rooms displayed single non-scrolling screen sabreman must navigate 3d maze stone blocks room usually retrieve collectible object whilst avoiding spikes enemies kill contact player starts five lives loses one death running lives ends game stone blocks serve platforms player jump fall player weight move accord pushed enemies sabreman sabreman jumps higher werewolf form helps specific puzzles player often needs move blocks reach distant objects used platforms reach areas puzzles complete game player must return 14 sequential objects throughout castle wizard cauldron room end game player receives final score based remaining time amount quest completed ultimate play game represented co-founding brothers tim chris stamper uncommonly taciturn matters press marketing though provided details knight lore development crash magazine knight lore released third game sabreman series stamper brothers finished first withheld game year market reasons thought knight lore advancements—copyrighted filmation engine—would hurt sales then-upcoming sabre wulf used extra time prepare another filmation game alien 8 preempt sales would lost publishers would try copy technique sit everyone else far behind tim stamper recalled sabre wulf released commercial critical success 1984 alien 8 next two sabreman titles— underwurlde knight lore —followed close succession end year filmation knight lore graphical novelty lay images could render without overlapping filmation introduced masked sprites whereas earlier games used planar sprites overlapped without regard depth order chris stamper solution use image masking mask version image defines background subject matter different colours combining mask on-screen composite image mask background data ignored hole shape desired image sprite added background filled sprite details thus rooms knight lore drawn one sprite time masking method recent times contemporary images render layer priority set individual pixel level knight lore depicted monochrome changes rooms avoid attribute clash computing limitation wherein object colour interfered others close proximity ultimate released knight lore zx spectrum november 1984 press release announced game beginning new class adventure games pinnacle software development 48k spectrum standard cryptic company ultimate circulate screenshots game press materials cover art knight lore subsequently released bbc micro amstrad cpc msx later 1985 amstrad version upgraded monochromatic colouring two-colour foreground setup jaleco released versions knight lore msx later famicom disk system latter 1986 release barely resembled namesake ultimate asked shahid ahmad developed knight lore -inspired chimera 1985 develop knight lore port commodore 64 come fruition knight lore later appeared spectrum version 1986 compilation sold million ii 2015 xbox one compilation 30 ultimate rare titles rare replay computer game magazines lauded knight lore writing graphics first kind marked sea change contemporaries computer video games cvg wrote never seen graphics calibre lived ultimate hype peter sweasey home computing weekly left speechless predicted knight lore would change market crash said unlikely surpassed spectrum best game crash selected knight lore crash smash recommendation january 1985 issue knight lore best selling game united kingdom month popular computing weekly readers named knight lore 1984 arcade game overall game year knight lore also named cvg game year 1985 golden joystick awards event ultimate named developer programmer year knight lore atmosphere sinclair user described crepuscular world claustrophobic menace inspired many curious questions part adventurer contemporaneous 1985 reviews crash appreciated imaginative mystery game attempted answer sabreman turns werewolf preferred play collectible objects throughout castle sabreman werewolf transformation sequence particular annoyed cvg traumatised players according well played book academic close readings video games players empathised suffering sabreman game design gave impression castle far grander scale reality crash wrote game novel eight-way direction scheme suited 3d space crash compared knight lore stylistically 1984 avalon suggested former bolder visuals magazine preferred knight lore predecessor underwurlde one critic even considered former ultimate best game crash noted knight lore masking technique addressed issues flicker attribute clash sinclair user appreciated sabreman disappeared view passing behind blocks criticism reviewers considered knight lore sound weakest component though spectrum clash also identified sometimes cruel difficulty gameplay later rooms castle require pixel-perfect precision compounded anxiety running timer game animations would slow proportional degree onscreen action reviews amstrad release amtix noted colour additions monochromatic original wrote knight lore among amstrad best adventures one complaint graphical slowdown many elements moving onscreen amstrad action shared complaint nevertheless named knight lore among amstrad best three games—an improvement spectrum release par quality commodore 64 titles knight lore widely regarded seminal work british gaming history according kieron gillen rock paper shotgun knight lore second elite 1984 icon 1980s british computer game industry british magazine retro gamer described players first impressions knight lore unforgettable par experience playing space harrier 1985 wolfenstein 3d 1992 super mario 64 1996 first time retro gamer recalled knight lore striking isometric 3d visuals bold advance game graphics foretelling future british magazine edge described game graphics engine single greatest advance history video games retro gamer compared engine impact introduction sound film knight lore first use isometric graphics—earlier examples include zaxxon 1982 q*bert 1982 ant attack 1983 —but graphic style large in-game world popularised technique put ultimate filmation epicentre several video game clones inspired knight lore edge games struggled approximate isometric style internally visiting developer bo jangeborg devised solution result fairlight 1985 regarded another classic platform edge version filmation received branding worldmaker shahid ahmad said firebird chimera 1985 even closer knight lore ahmad shock admiration playing knight lore reportedly changed life convinced continue making games released chimera amstrad cpc atari 8-bit commodore 64 zx spectrum customising port processing limitations hardware 1986 many british video game publishers produced knight lore -style isometric games examples include sweevo world movie quazatron get dexter glider rider molecule man spindizzy bobby bearing many titles suffered slowdown issues knight lore due much on-screen activity ultimate released four filmation games alien 8 1985 rushed release developers opportunity react knight lore though retro gamer said rush noticeable alien 8 larger game world knight lore even puzzles alien 8 knight lore similar gameplay former set outer space updated filmation ii engine nightshade 1985 added colour scrolling graphics place flip-screen room changes however retro gamer regarded gameplay comparatively dull gunfright 1986 reported stampers last game also used filmation ii robust predecessor pentagram 1986 returned flip-screen rooms action-based gameplay included shooting enemies sold poorly last sabreman game meanwhile stamper brothers sought enter burgeoning console industry sold ultimate u.s. gold mid-1980s established rare develop nintendo console games ultimate last two isometric games lesser quality consumer interest genre endured isometric flip-screen trend continued britain several years apart fairlight sweevo world get dexter isometric flip-screen games included jon ritman knight lore -inspired batman 1986 head heels 1987 last ninja 1987 la abadía del crimen 1987 cadaver 1990 console games solstice 1990 landstalker 1992 players grew tired genre similar reiterations ritman games particular brought new ideas sandy white developed pre- knight lore isometric game ant attack impressed ultimate in-game balance gutsy design decisions developer great escape another isometric game considered knight lore rival title inspiration still spurred spend nine months making time stood still retro gamer wrote knight lore influence persisted 30 years later titles populous 1989 syndicate 1993 1994 civilization ii 1996 style also spread computer role-playing games like baldur gate diablo fallout though gamesradar matt cundy reported 2009 isometric perspective longer prominent topic game design 2014 chris scullion vice traced knight lore isometric influence sims 4 2014 diablo iii 2012 knight lore included multiple lists top spectrum games even top games platform inspired two fangames 1999 sequel 2010 3d remake development four years though isometric games existed previously retrospective review gillen rock paper shotgun recalled knight lore first game offer world physical depth exploration opposed simple mechanics arcade games jeremy signor usgamer agreed knight lore felt like world painting added game innovative use successive single-screen rooms flip-screen pre-dated legend zelda years gillen said game punishing style unforgiving gameplay high difficulty awkward controls become obsolete 30 years since release criticised knight lore enormously innovative incredibly atmospheric totally unplayable suggesting similar head heels 1987 aged much better peter parrish eurogamer found game frustrating though well-made dan whitehead publication appreciated 2015 rare replay compilation version knight lore emulated original choppy animations zx spectrum processor struggled render onscreen objects
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Computer architecture
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compaq presario 1200 compaq presario 1200 series line notebook computers produced 1998 2000 compaq originally noted amd processors light weight 12-inch lcd screens later models included shift intel processors changed features label compaq presario 1200 includes vast set model numbers revisions many totally compatible even though machines share general presario model number many original models presario 1200 series ran amd k6-2 processors quite adventurous move time amd much second place dominant market leader intel chips notable inclusion 3d-now technology enabling marked performance increases original k6 chips came variety speeds ranging 333 mhz 550 mhz however performance varied slightly models number presario 1200 series notebooks exist celeron pentium iii processors well primarily found later designs later models often noted silver display lid instead original black lid range came toshiba hdds optical media drives available 24x cd-roms 4x dvd-roms hard drives ranged 3.01 gb 10.0 gb ran slow 3300 rpm across range could due noise limitations series noted low noise output screens available 12.1 13.0 inch lcds yet screen housing varied model model 1245 1246 different screen housing 1200 1200xl came 13 inch screen 1200 also silver housing whereas models came black screens series notable banding white edges appear evident machine ages backlight sides clearly visible memory expansion available bottom units allowing 128mb additional sodimm memory added models came equipped floppy disk drive vga output pc card slot standard also came on-board jbl stereo speakers synaptics touchpads systems preinstalled windows 98 windows windows 2000 professional supplied quick restore disc returned system factory condition event change ownership wish reinstall os system failure priced £1200 1200 contained 500 mhz amd k6-2 processor lithium ion battery originally priced 1,699 1200-xl125 designated model number 12xl125 1200-xl300 designated model number 12xl325 one newer models 1200 series features 1246 generally mirrored 1200-xl325 notable differences change intel processor architecture physical differences include silver lid different display hinge configuration slightly rearranged motherboard layout changes render generation presario 1200 distinctly incompatible component level predecessors major differences hardware 1200-xl325 1200-xl405a designated model number 12xl405a another model using intel processor similar layout xl325 motherboard equipped socket-370 zif cpu socket uses via ple133 chipset comprising vt8601 north bridge vt82c686a south bridge graphics provided via trident cyberblade-i1 controller integrated vt8601 circuitry although similar hardware xl405a xl502a model number 12xl502a upgraded model based brother notorious inclusion minipci slot bottom presence slightly faster processor color case silver lid maintained rest case all-black firsts units model originally came ni-mh battery pack later ones came dependable li-ion one types available purchase obviously fitted 1200-series one interesting thing specific model support pentium iii processors 1ghz coppermine cores expense massive heat battery power draw increase 1200-xl302 model number 12xl302 equipped similar xl502a difference celeron processor 600 mhz askey modem minipci slot compaq presario 1230 manufactured 1998 mmx intel processor known 3d sound speakers priced rrp £1000 1245 came equipped next model 1245 1246 offered new processor bigger hdd cf card slot fold-down feet desktop operation aesthetically 1246 almost identical 1245 screens cases highly similar many components interchangeable 1245 lcd inverters processors housing addition aforementioned 1245 spec 1246 offered almost technically identical 1245 1260 borrowed 333 mhz amd k6-2 processor 64mb ram ati rage ii graphics chip compaq presario 1200 laptops often found damaged power jacks power jacks appear blown half due sort short others rip copper traces motherboard due stress placed power jack presario 1200 laptops typically four tiny copper rings embedded motherboard behind power jack used reattach slightly damaged power jack repair failing unit lcd power inverter cable runs hinge base screen susceptible damage given strain bending closing lid cable 6-strand ribbon variety therefore soldering impossible
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Computer architecture
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lguest lguest linux kernel x86 virtualization hypervisor introduced kernel version 2.6.23 released 9 october 2007 removed kernel version 4.14 november 2017 hypervisor operating-system-level virtualization system capable running unmodified 32-bit x86 linux kernels guest machines installation easy running modprobe lg followed tools/lguest/lguest create new guest lguest still installed kernel 4.14 later out-of-tree patches lguest maintained rusty russell
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Operating systems
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interrupt handler computer systems programming interrupt handler also known interrupt service routine isr special block code associated specific interrupt condition interrupt handlers initiated hardware interrupts software interrupt instructions software exceptions used implementing device drivers transitions protected modes operation system calls traditional form interrupt handler hardware interrupt handler hardware interrupts arise electrical conditions low-level protocols implemented digital logic usually dispatched via hard-coded table interrupt vectors asynchronously normal execution stream interrupt masking levels permit often using separate stack automatically entering different execution context privilege level duration interrupt handler execution general hardware interrupts handlers used handle high-priority conditions require interruption current code processor executing later found convenient software able trigger mechanism means software interrupt form synchronous interrupt rather using hard-coded interrupt dispatch table hardware level software interrupts often implemented operating system level form callback function interrupt handlers multitude functions vary based triggered interrupt speed interrupt handler completes task example pressing key computer keyboard moving mouse triggers interrupts call interrupt handlers read key mouse position copy associated information computer memory interrupt handler low-level counterpart event handlers however interrupt handlers unusual execution context many harsh constraints time space intrinsically asynchronous nature makes notoriously difficult debug standard practice reproducible test cases generally n't exist thus demanding specialized skillset—an important subset system programming—of software engineers engage hardware interrupt layer unlike event handlers interrupt handlers expected set interrupt flags appropriate values part core functionality even cpu supports nested interrupts handler often reached interrupts globally masked cpu hardware operation architecture interrupt handler would normally save smallest amount context necessary reset global interrupt disable flag first opportunity permit higher priority interrupts interrupt current handler also important interrupt handler quell current interrupt source method often toggling flag bit kind peripheral register current interrupt n't immediately repeated handler exit resulting infinite loop exiting interrupt handler interrupt system exactly right state every eventuality sometimes arduous exacting task mishandling source many serious bugs kind halt system completely bugs sometimes intermittent mishandled edge case occurring weeks months continuous operation formal validation interrupt handlers tremendously difficult testing typically identifies frequent failure modes thus subtle intermittent bugs interrupt handlers often ship end customers modern operating system upon entry execution context hardware interrupt handler subtle reasons performance handler typically initiated memory execution context running process special connection interrupt essentially usurping running context—process time accounting often accrue time spent handling interrupts interrupted process however unlike interrupted process interrupt usually elevated hard-coded cpu mechanism privilege level high enough access hardware resources directly low-level microcontroller chip might lack protection modes memory management unit mmu chips execution context interrupt handler essentially interrupted program typically runs small stack fixed size memory resources traditionally extremely scant low end nested interrupts often provided exacerbates stack usage primary constraint interrupt handler programming endeavour exceed available stack worst-case condition requiring programmer reason globally stack space requirement every implemented interrupt handler application task allocated stack space exceeded condition known stack overflow normally detected hardware chips class stack exceeded another writable memory area handler typically work expected application fail later sometimes much later due handler side effect memory corruption stack exceeded non-writable protected memory area failure usually occur inside handler generally easier case later debug writable case one implement sentinel stack guard—a fixed value right beyond end legal stack whose value overwritten never system operates correctly common regularly observe corruption stack guard kind watch dog mechanism catch majority stack overflow conditions point time close offending operation multitasking system thread execution typically stack special system stack provided interrupts interrupts consume stack space whatever thread execution interrupted designs usually contain mmu user stacks usually configured stack overflow trapped mmu either system error debugging remap memory extend space available memory resources level microcontroller typically far less constrained stacks allocated generous safety margin systems supporting high thread counts better hardware interrupt mechanism switches stack special system stack none thread stacks need account worst-case nested interrupt usage tiny cpus far back 8-bit motorola 6809 1978 provided separate system user stack pointers many reasons highly desired interrupt handler execute briefly possible highly discouraged forbidden hardware interrupt invoke potentially blocking system calls system multiple execution cores considerations reentrancy also paramount system provides hardware dma concurrency issues arise even single cpu core uncommon mid-tier microcontroller lack protection levels mmu still provide dma engine many channels scenario many interrupts typically triggered dma engine associated interrupt handler expected tread carefully modern practice evolved divide hardware interrupt handlers front-half back-half elements front-half first level receives initial interrupt context running process minimal work restore hardware less urgent condition emptying full receive buffer marks back-half second level execution near future appropriate scheduling priority invoked back-half operates process context fewer restrictions completes handler logical operation conveying newly received data operating system data queue several operating systemslinux unix macos microsoft windows z/os desqview operating systems used pastinterrupt handlers divided two parts first-level interrupt handler flih second-level interrupt handlers slih flihs also known hard interrupt handlers fast interrupt handlers slihs also known slow/soft interrupt handlers deferred procedure calls windows flih implements minimum platform-specific interrupt handling similar interrupt routines response interrupt context switch code interrupt loaded executed job flih quickly service interrupt record platform-specific critical information available time interrupt schedule execution slih long-lived interrupt handling flihs cause jitter process execution flihs also mask interrupts reducing jitter important real-time operating systems since must maintain guarantee execution specific code complete within agreed amount time reduce jitter reduce potential losing data masked interrupts programmers attempt minimize execution time flih moving much possible slih speed modern computers flihs may implement device platform-dependent handling use slih platform-independent long-lived handling flihs service hardware typically mask associated interrupt keep masked case may complete execution unusual flih unmasks associated interrupt completes called reentrant interrupt handler reentrant interrupt handlers might cause stack overflow multiple preemptions interrupt vector usually avoided priority interrupt system flih also briefly masks interrupts equal lesser priority slih completes long interrupt processing tasks similarly process slihs either dedicated kernel thread handler executed pool kernel worker threads threads sit run queue operating system processor time available perform processing interrupt slihs may long-lived execution time thus typically scheduled similarly threads processes linux flihs called upper half slihs called lower half bottom half different naming used unix-like systems part bottom half
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Computer architecture
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access linux platform access linux platform alp discontinued open-source software based operating system referred next-generation version palm os mobile devices developed marketed access co. tokyo japan platform included execution environments java classic palm os gtk+-based native linux applications alp demonstrated devices variety conferences including 3gsm linuxworld guadec open source mobile alp first announced february 2006 initial versions platform software development kits officially released february 2007 coordinated effort access esteemo nec ntt docomo panasonic use platform basis shared platform implementing revised version i.mode mobile oriented applications platform moap l application programming interfaces apis conforming specifications limo foundation first smartphone use alp edelweiss emblaze mobile scheduled mid-2009 however shelved release first else renamed monolith smartphone developed sharp corporation cooperation emblaze mobile seven partners scheduled 2009 never released officially cancelled june 2010 result platform never launched independently devices longer referenced access website user interface designed similar general goals earlier palm os releases aim preserving zen palm design philosophy centered making applications simple possible aspects interface included task-based orientation rather file/document orientation commonly found desktop systems appearance platform intended highly customizable provide differentiation specific devices contexts last releases went much modern look gesture support longer close palm os similarly maemo nokia internet tablet framework alp based components drawn gnome project including gtk+ gstreamer frameworks variety core components drawn mainstream open source projects including bluez matchbox cramfs others components licensed gnu general public license gpl gnu lesser general public license lgpl open source licenses meaning alp free open environment software level several components alp released mozilla public license hiker project components addressed issues application life-cycle intertask communication exchange use structured data security time event-based notifications areas common development applications mobile devices alp presented standard apis common operations defined standards portable operating system interface posix linux standard base lsb however neither standard addresses telephony device customizing messaging several topics several frameworks apis defined access applications alp could developed linux-native code c c++ legacy palm os applications run garnet vm emulation environment java execution environments supported via development launchpad used application manager part hiker framework alp sdk used eclipse-based integrated development environment ide added plug-ins predecessor palm os development environment compilers used embedded application binary interface eabi enabled arm versions standard gnu compiler collection gcc tool chain alp used combination user-space policy-based security framework kernel-space linux security module implement fine-grained access controls components alp security implementation released part hiker framework controls based signatures certificates unsigned applications allowed access predefined set safe apis
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Operating systems
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spacewire spacewire spacecraft communication network based part ieee 1355 standard communications coordinated european space agency esa collaboration international space agencies including nasa jaxa rka within spacewire network nodes connected low-cost low-latency full-duplex point-to-point serial links packet switching wormhole routing routers spacewire covers two physical data-link seven layers osi model communications spacewire modulation data formats generally follow data strobe encoding differential ended signaling ds-de part ieee std 1355-1995 spacewire utilizes asynchronous communication allows speeds 2 mbit/s 400 mbit/s initial signalling rate 10mbit/s ds-de well-favored describes modulation bit formats routing flow control error detection hardware little need software spacewire also low error rates deterministic system behavior relatively simple digital electronics spacewire replaced old pecl differential drivers physical layer ieee 1355 ds-de low-voltage differential signaling lvds spacewire also proposes use space-qualified 9-pin connectors spacewire ieee 1355 ds-de allows wider set speeds data transmission new features automatic failover fail-over features let data find alternate routes spacecraft multiple data buses made fault-tolerant spacewire also allows propagation time interrupts spacewire links eliminating need separate time discretes transferred character starts parity bit data-control flag bit data-control flag 0-bit 8-bit lsb character follows otherwise one control codes including end packet eop network data frames look follows one address bytes used routing addresses either physical ones 0-32 logical ones difference physical addresses deleted frame header routing used hop-based routing based path specified frame logical addresses may deleted well depending router configuration hardware devices may connected either directly via spacewire router former case usually pairs devices used guarantee fail-safe operation however handled software spacewire router usually crossbar switch-type device operating wormhole switching mode also may limit speed communication lowest common speed routing decisions based programmed routing table initial incoming frame contents spacewire used worldwide use began primarily esa projects currently used nasa jaxa rka many organizations companies nasa projects using include james webb space telescope swift burst alert telescope lunar reconnaissance orbiter lcross geostationary operational environmental satellite goes-r scan testbed previously known communications navigation networking reconfigurable testbed connect also selected united states department defense operationally responsive space spacewire initiatives coordinated several space agencies frame ccsds order extend communication model network transport layers osi model spacewire supports highly fault-tolerant networks systems one reason popularity esa draft specification place protocol id following protocol id assigned ecss-e-st-50-11 commercial providers spacewire equipment spacewire ip cores articles
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Computer architecture
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diana intermediate language diana descriptive intermediate attributed notation ada intermediate language used represent semantics ada program originally designed interface front end syntactic analysis middle semantic analysis compiler one hand back end code generation optimization also used internal representation language tools diana also used pl/sql based ada diana abstract data type concrete implementations defined using idl specification language diana descends tcol aida earlier representations ada programs ada-0 subset ada karlsruhe 1980 first using aida later aida got replaced diana full karlsruhe ada compilation system used diana well idl external representation marshalling middle-end code generating back-end
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Programming language topics
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adminer adminer formerly known phpminadmin tool managing content mysql databases since version 2 also postgresql ms sql sqlite oracle databases adminer distributed apache license gpl v2 form single php file around 470 kib size author jakub vrána started develop tool light-weight alternative phpmyadmin july 2007 adminer got attention 2008 made cca finals sourceforge also first webhosting providers started include adminer mysql managing tool portfolio services 2012 adminer got coverage linux.com second time project priorities according author order safety user-friendliness performance functionality size small single file result compilation minification source codes
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Databases
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knight tyme knight tyme computer game released zx spectrum amstrad cpc commodore 64 msx compatibles 1986 published mastertronic part mastertronic added dimension label two versions zx spectrum release published full version 128k spectrum published first cut-down version 48k spectrum removed music graphics locations published later programmed david jones third game magic knight series in-game music written david whittaker c64 version rob hubbard spectrum amstrad versions graphics ray owen rescued friend gimbal self-inflicted white-out spell magic knight finds transported far future aboard starship uss pisces magic knight must find way back time help tyme guardians apprehended paradox police board u.s.s pisces magic knight first recognized crew ship must create id card receives template derby iv ship main computer getting id completed takes command ship first arriving starbase 1 refuel ship refueling magic knight collects pieces golden sundial monopole retreat outpost returning ship pieces sundial discovers time machine appeared inside uss pisces take back time gameplay similar knight tyme predecessor spellbound game wide range commands carried-out using windimation system whereby text commands carried-out choosing options command windows importance watching magic knight energy level keeping harm rather different time around whilst spellbound required player vigilant health needed player occasionally avoid flying objects could sap strength knight tyme much focused puzzle-solving aspect although still death rooms spellbound reason regarded true graphic adventure gameworld features large number characters hero interact time around however responsible welfare help quest belong time magic knight found displaced person time around knight tyme also involves space travel magic knight commandeering uss pisces using journey various planets star systems planets communicated beamed-down via uss pisces transporter system magic knight also needs keep note ship fuel runs starship stranded means end game refuelling take place many planets uss pisces visits one magic knight game stormbringer released 1987
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Computer architecture
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numachine numachine nu machine early microprocessor-based computer workstation designed interface local area networks developed late 1970s mit laboratory computer science lcs professor steve ward research group concert western digital project included development trix unix operating system variant numachine first developed commercially western digital bought texas instruments 1983 texas instruments dropped numachine development 1985 favor ti explorer main legacy bus architecture called nubus later adopted apple computer macintosh ii next influenced design pci bus trix operating system used gnu project first attempt operating system kernel
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Computer architecture
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wolfram mathematica wolfram mathematica usually termed mathematica modern technical computing system spanning areas technical computing including neural networks machine learning image processing geometry data science visualizations others system used many technical scientific engineering mathematical computing fields conceived stephen wolfram developed wolfram research champaign illinois wolfram language programming language used mathematica features wolfram mathematica include wolfram mathematica split two parts kernel front end kernel interprets expressions wolfram language code returns result expressions front end designed theodore gray 1988 provides gui allows creation editing notebook documents containing program code prettyprinting formatted text together results including typeset mathematics graphics gui components tables sounds content formatting generated algorithmically edited interactively standard word processing capabilities supported including real-time multi-lingual spell-checking documents structured using hierarchy cells allow outlining sectioning document support automatic numbering index creation documents presented slideshow environment presentations notebooks contents represented mathematica expressions created modified analyzed mathematica programs converted formats front end includes development tools debugger input completion automatic syntax highlighting among alternative front ends wolfram workbench eclipse based integrated development environment ide introduced 2006 provides project-based code development tools mathematica including revision management debugging profiling testing plugin intellij idea based ides work wolfram language code addition syntax highlighting analyse auto-complete local variables defined functions mathematica kernel also includes command line front end interfaces include jmath based gnu readline wolframscript ref
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Programming language topics
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run queue modern computers many processes run active processes placed array called run queue runqueue run queue may contain priority values process used scheduler determine process run next ensure program fair share resources one run time period quantum paused placed back run queue program stopped let another run program highest priority run queue allowed execute processes also removed run queue ask sleep waiting resource become available terminated linux operating system prior kernel 2.6.23 cpu system given run queue maintains active expired array processes array contains 140 one priority level pointers doubly linked lists turn reference processes given priority scheduler selects next process active array highest priority process quantum expires placed expired array priority active array contains processes scheduler swaps active expired arrays hence name 1 scheduler unix linux sar command used check run queue vmstat unix linux command also used determine number processes queued run waiting run appear r column two models run queues one assigns run queue physical processor one run queue system
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Computer architecture
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hp converged systems hp convergedsystem portfolio system-based products hewlett-packard hp integrates preconfigured components systems virtualization cloud computing big data collaboration converged management client virtualization composed servers storage networking integrated software services systems designed address cost complexity data center operations maintenance pulling components together single resource pool easier manage faster deploy previously would take three six months time order get system running reportedly takes 20 days hp convergedsystem hp convergedsystem uses common converged infrastructure architecture common foundation used hp server storage networking products hp converged infrastructure pools resources shared across different applications managed standardized management platform security software convergence server storage networking help user organizations save investment equipment maintenance management hp converged systems includes hp convergedsystem virtualization developing managing virtualized environments hp cloudsystem building managing cloud computing services across private public hybrid clouds hp convergedsystem big data loading analyzing managing vast quantities data hp convergedsystem collaboration configuration deployment microsoft unified communications software hp oneview converged infrastructure management hp convergedsystem client virtualization running virtual desktop infrastructure hp cloudsystem integrated cloud infrastructure delivering private public hybrid cloud services integrates hp cloud software hp servers storage networking technologies single system hp oneview converged infrastructure management product provides unified interface lets users automate formerly labor-intensive manual data center management maintenance tasks part software-defined data center hp convergedsystem virtualization consists series integrated server storage networking infrastructures offer scalability modular virtualization systems support 50 1,000 virtual machines hp convergedsystem 300 designed support 50 300 virtual machines comes configured hp proliant servers hp convergedsystem 700 designed larger enterprise installations 100 1,000 virtual machines comes configured hp bladesystem servers models customers choose vmware microsoft virtualization environments customers 700 model also install virtualization software models managed single console reported hp convergedsystem virtualization performs twice fast costs 25 percent less competing systems hp cloudsystem used enterprises service providers build manage private public hybrid cloud services system includes consumer-style user interface streamlined management tools based hp converged infrastructure hp cloudsystem modular infrastructure hp cloud service automation software cloudsystem integrates servers storage networking security management automate application infrastructure lifecycle service delivery via private hybrid clouds hp cloudsystem component hp converged cloud combines software cloud services unified set packages single unified architecture hp cloudsystem built hp cloud os features openstack technology enables users choose multiple hypervisors operating systems including microsoft vmware hp cloudsystem automatically shift workloads external clouds busy periods based pre-defined business policies supported public clouds include arsys sfr well amazon web services microsoft windows azure function commonly known cloud bursting hp cloudsystem lifecycle management tools automate process application provisioning customization configuration patch management retirement hp cloudsystem foundation features core components additional management capabilities simplified installation included hp cloudsystem enterprise hp convergedsystem big data provides workload-specific single-purpose systems support tasks performance critical data analytics data warehousing business applications software applications pre-integrated designed integrated hardware networking storage components hp convergedsystem 300 vertica designed businesses run hp vertica data analytics solution system works cloudera hortonworks mapr versions apache hadoop reported system operate 50 1,000 times faster competitors ’ data warehouse offerings hp convergedsystem 300 microsoft analytics platform system aps includes sql server parallel data warehouse pdw configured hdinsight hadoop nodes possible run polybase queries sql server pdw cloudera apache hortonworks hdp nodes hp convergedsystem 500 sap hana operates sap hana in-memory data management platform data analytics data warehousing reported system process data analytics twice fast competing systems sap hana hp convergedsystem 500 sap hana includes convergedsystem 500 hardware hp serviceguard sap hana data management tool protects unscheduled downtime providing capability automatic failover hp convergedsystem 500 sap hana enables users run data analytics enterprise resource planning erp workload-based system reported data analytics processes used take days weeks run accessed real-time hp convergedsystem 900 sap hana designed manage analyze large varied data sets reported hp convergedsystem 900 sap hana capable supplying 12 terabytes data one memory pool hp convergedsystem collaboration integrates hardware software services provide unified communications specific platforms pre-supplied workload configurations include hp collaboration solutions microsoft sharepoint server include hp sharepoint business decision business intelligence combines hp proliant gen8 servers sharepoint 2013 sql server ’ power view reported system takes less hour install launch hp convergedsystems solutions microsoft exchange server designed users deploy business email system modular simplified manner hp converged systems solutions microsoft lync server streamlines deployment microsoft lync communications voice instant messaging video includes reference architecture small medium enterprises hp oneview converged infrastructure management enables data center administrators perform automated lifecycle management hp servers part software-defined data center unlike legacy converged infrastructure management software focuses managing devices hp oneview designed help administrators enable tasks administrators view resources relationships visual map use representational state transfer rest application programming interface api automate system management tasks hp oneview interface modeled consumer applications efficiently manage hp bladesystem hp proliant generation 7 8 servers support hp moonshot arm servers planned reported hp oneview ’ deep knowledge servers hp virtual connect virtualization technology administrators deploy 16-node computer cluster 12 times faster could using manual operations administrators also use hp oneview provision maintain firmware across hp bladesystem enclosures servers virtual connect modules well manage virtual lan vlan network edge hp oneview plug-in vmware vcenter virtualization console enables administrators work directly vcenter console operations vmware vsphere hosts clusters managed automated reducing number steps takes carry tasks like setting new cluster hp convergedsystem 100 hosted desktops works software-defined hp moonshot m700 microserver systems includes software hardware services provide users environment running virtual desktops user gets dedicated cpu gpu removes need hypervisor according published reports moonshot server consumes 63 percent less power competing systems lower total cost ownership 44 percent compared standard desktop computer systems built joint effort amd citrix system reported provide graphics six times faster competing products client virtualization also provides way users securely access business applications data mobile devices
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Distributed computing architecture
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r programming language r programming language free software environment statistical computing graphics supported r foundation statistical computing r language widely used among statisticians data miners developing statistical software data analysis polls data mining surveys studies scholarly literature databases show substantial increases popularity r ranks 20th tiobe index measure popularity programming languages gnu package source code r software environment written primarily c fortran r freely available gnu general public license pre-compiled binary versions provided various operating systems although r command line interface several graphical user interfaces rstudio integrated development environment r implementation programming language combined lexical scoping semantics inspired scheme created john chambers 1976 bell labs important differences much code written runs unaltered r created ross ihaka robert gentleman university auckland new zealand currently developed r development core team chambers member r named partly first names first two r authors partly play name s. project conceived 1992 initial version released 1995 stable beta version 2000 r libraries implement wide variety statistical graphical techniques including linear nonlinear modelling classical statistical tests time-series analysis classification clustering others r easily extensible functions extensions r community noted active contributions terms packages many r standard functions written r makes easy users follow algorithmic choices made computationally intensive tasks c c++ fortran code linked called run time advanced users write c c++ java .net python code manipulate r objects directly r highly extensible use user-submitted packages specific functions specific areas study due heritage r stronger object-oriented programming facilities statistical computing languages extending r also eased lexical scoping rules another strength r static graphics produce publication-quality graphs including mathematical symbols dynamic interactive graphics available additional packages r rd latex-like documentation format used supply comprehensive documentation online number formats hard copy r interpreted language users typically access command-line interpreter user types codice_1 r command prompt presses enter computer replies 4 shown calculation interpreted sum two single-element vectors resulting single-element vector prefix codice_2 indicates list elements following line starts first element vector feature useful output extends multiple lines like similar languages apl matlab r supports matrix arithmetic r data structures include vectors matrices arrays data frames similar tables relational database lists arrays stored column-major order r extensible object system includes objects among others regression models time-series geo-spatial coordinates scalar data type never data structure r. instead scalar represented vector length one many features r derive scheme r uses s-expressions represent data code functions first-class manipulated way data objects facilitating meta-programming allow multiple dispatch variables r lexically scoped dynamically typed function arguments passed value lazy -- say evaluated used function called r supports procedural programming functions functions object-oriented programming generic functions generic function acts differently depending classes arguments passed words generic function dispatches function method specific class object example r generic codice_3 function print almost every class object r simple codice_4 syntax although used mainly statisticians practitioners requiring environment statistical computation software development r also operate general matrix calculation toolbox – performance benchmarks comparable gnu octave matlab capabilities r extended user-created packages allow specialised statistical techniques graphical devices import/export capabilities reporting tools rmarkdown knitr sweave etc packages developed primarily r sometimes java c c++ fortran r packaging system also used researchers create compendia organise research data code report files systematic way sharing public archiving core set packages included installation r 15,000 additional packages available comprehensive r archive network cran bioconductor omegahat github repositories task views page subject list cran website lists wide range tasks fields finance genetics high performance computing machine learning medical imaging social sciences spatial statistics r applied packages available r also identified fda suitable interpreting data clinical research r package resources include crantastic community site rating reviewing cran packages r-forge central platform collaborative development r packages r-related software projects r-forge also hosts many unpublished beta packages development versions cran packages bioconductor project provides r packages analysis genomic data includes object-oriented data-handling analysis tools data affymetrix cdna microarray next-generation high-throughput sequencing methods list changes r releases maintained various news files cran highlights listed several major releases specialized integrated development environment ide r rstudio similar development interface r tools visual studio generic ides like eclipse also offer features work r. graphical user interfaces point-and-click approach include rattle gui r commander rkward common editors varying levels support r include emacs emacs speaks statistics vim nvim-r plugin neovim nvim-r plugin kate lyx notepad++ visual studio code winedt tinn-r. r functionality accessible several scripting languages python perl ruby f julia interfaces high-level programming languages like java .net c available well main r implementation written r c fortran several implementations aimed improving speed increasing extensibility closely related implementation pqr pretty quick r radford m. neal improved memory management support automatic multithreading renjin fastr java implementations r use java virtual machine cxxr rho riposte implementations r c++ renjin riposte pqr attempt improve performance using multiple processor cores form deferred evaluation alternative implementations experimental incomplete relatively users compared main implementation maintained r development core team tibco built runtime engine called terr part spotfire microsoft r open fully compatible r distribution modifications multi-threaded computations r vibrant active local communities worldwide users network share ideas learn growing number r events bringing users together conferences e.g user whyr conectar satrdays meetups well r-ladies groups promote gender diversity official annual gathering r users called user first event user 2004 may 2004 vienna austria skipping 2005 user conference held annually usually alternating locations europe north america subsequent conferences included future conferences planned follows r journal open access refereed journal r project statistical computing features short medium length articles use development r including packages programming tips cran news foundation news r comparable popular commercial statistical packages sas spss stata r available users charge free software license january 2009 new york times ran article charting growth r reasons popularity among data scientists threat poses commercial statistical packages sas june 2017 data scientist robert muenchen published in-depth comparison r software packages popularity data science software although r open-source project supported community developing companies strive provide commercial support and/or extensions customers section gives examples companies 2007 richard schultz martin schultz steve weston kirk mettler founded revolution analytics provide commercial support revolution r distribution r also includes components developed company major additional components include parallelr r productivity environment ide revoscaler big data analysis revodeployr web services framework ability reading writing data sas file format revolution analytics also offer distribution r designed comply established iq/oq/pq criteria enables clients pharmaceutical sector validate installation revolution r. 2015 microsoft corporation completed acquisition revolution analytics since integrated r programming language sql server 2016 sql server 2017 power bi azure sql database azure cortana intelligence microsoft r server visual studio 2017 october 2011 oracle announced big data appliance integrates r apache hadoop oracle linux nosql database exadata hardware oracle r enterprise became one two components oracle advanced analytics option alongside oracle data mining ibm offers support in-hadoop execution r provides programming model massively parallel in-database analytics r. tibco offers runtime-version r part spotfire mango offers validation package r validr make compliant drug approval agencies like fda agencies allow use statistical software submissions software validated either vendor sponsor following examples illustrate basic syntax language use command-line interface r generally preferred assignment operator arrow made two characters codice_5 although codice_6 usually used instead one r ’ strengths ease creating new functions objects function body remain local function data type may returned example user-created function short r code calculating mandelbrot set first 20 iterations equation z z c plotted different complex constants c example demonstrates
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Programming language topics
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automated certificate management environment automatic certificate management environment acme protocol communications protocol automating interactions certificate authorities users web servers allowing automated deployment public key infrastructure low cost designed internet security research group isrg let encrypt service protocol based passing json-formatted messages https published internet standard rfc 8555 chartered ietf working group isrg provides free open-source reference implementations acme certbot python-based implementation server certificate management software using acme protocol boulder certificate authority implementation written go december 2015 web server caddy gained native support automatic certificate issuance renewal using acme protocol since spun go library called certmagic october 2017 let encrypt announced similar built-in functionality module apache httpd since large number client options appeared api v1 released april 12 2016 supports issuing certificates single domains example.com cluster.example.com let encrypt suggests users migrate v2 soon possible support v1 planned deprecated many acme clients already support v2 ahead release api v2 released march 13 2018 pushed back several times acme v2 backwards compatible v1 version 2 supports wildcard domains *.example.com allowing many subdomains trusted ssl e.g nowiki https //cluster01.example.com /nowiki nowiki https //cluster02.example.com /nowiki nowiki https //example.com /nowiki private networks single domain using single shared wildcard certificate major new requirement v2 requests wildcard certificates require modification domain name service txt record verifying control domain changes acme v2 protocol since v1 include
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Computer security
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defendermx defendermx commercial linux based email security solution company founded 2002 company headquarters located washington dc usa company develops gateway hosted solutions built linux defendermx originally developed 2001 bains digital technologies fsl bains digital merged defendermx product merged barricademx plus line products fsl revived defendermx name next generation products based open source haraka project fsl major contributor defendermx uses following open source projects technologies
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Computer security
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block contention database management systems block contention data contention refers multiple processes instances competing access index data block time general caused frequent index table scans frequent updates concurrent statement executions two instances may also lead contention subsequently busy waiting process without lock situations goal spread queries greater number blocks avoid concentrating single one
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Databases
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matthias felleisen matthias felleisen german-american computer science professor author grew germany immigrated us 21 years old felleisen currently trustee professor khoury college computer sciences northeastern university boston massachusetts past taught rice university receiving phd indiana university direction daniel p. friedman felleisen interests include programming languages including software tools program design design recipe software contracts many 1990s felleisen launched plt teachscheme programbydesign eventually giving rise bootstrap project goal teaching program-design principles beginners explore use scheme produce large systems part effort authored design programs mit press 2001 findler flatt krishnamurthi dissertation felleisen developed small-step operational semantics higher-order functional imperative extensions state control part semantics engineering plt redex derived dissertation well-known application proof type safety worked phd student andrew wright control delimiters basis delimited continuations introduced felleisen 1988 since used large number domains particularly defining new control operators see queinnec survey a-normal form anf intermediate representation programs functional compilers introduced sabry felleisen 1992 simpler alternative continuation-passing style cps felleisen gave keynote addresses 2011 technical symposium computer science education 2010 international conference functional programming 2004 european conference object-oriented programming 2001 symposium principles programming languages several conferences workshops computer science 2006 inducted fellow association computing machinery 2009 received karl v. karlstrom outstanding educator award acm 2010 received sigcse award outstanding contribution computer science education acm 2012 received acm sigplan programming languages achievement award significant lasting contribution field programming languages including small-step operational semantics control state mixin classes mixin modules fully abstract semantics sequential pcf web programming techniques higher-order contracts blame static typing dynamic languages felleisen co-author
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Programming language topics
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appian corporation appian corporation cloud computing company currently headquartered tysons corner virginia part dulles technology corridor appian sells platform service building enterprise software applications competes low-code development business process management case management markets appian named 2018 washington d.c. area top workplace washington post appian founded 1999 matthew calkins co-founders michael beckley marc wilson robert kramer 2001 appian developed army knowledge online time regarded “ world largest intranet 2004 appian released appian enterprise first business process management suite bpms software platform 2014 appian received 37.5 million secondary investments new enterprise associates 2016 appian ’ software platform evolved include broader aspects application development focus low-code development may 25 2017 appian became publicly-traded company trading symbol appn nasdaq global exchange 2018 appian announced move headquarters tysons virginia
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Distributed computing architecture
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dynamite bowl general concept five players play 30 bowling lanes available simulating concept bowling league players change lane positioning determine strong throw even make ball go various curves even straight ball pins player character either male female options bowling ball weights ranging
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Computer architecture
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paging computer operating systems paging memory management scheme computer stores retrieves data secondary storage use main memory scheme operating system retrieves data secondary storage same-size blocks called pages paging important part virtual memory implementations modern operating systems using secondary storage let programs exceed size available physical memory simplicity main memory called ram acronym random-access memory secondary storage called disk shorthand hard disk drive concepts depend whether terms apply literally specific computer system ferranti introduced paging atlas first mass market memory pages concepts computer architecture regardless whether page moved ram disk example pdp-8 7 instruction bits comprised memory address selected one 128 2 words zone memory called page use term rare 1960s swapping early virtual memory technique entire program would swapped rolled ram disk another one would swapped rolled swapped-out program would current execution would suspended ram use another program program might include multiple overlays occupy memory different times overlays method paging ram disk merely minimizing program use ram subsequent architectures used memory segmentation individual program segments became units exchanged disk ram segment program entire code segment data segment sometimes large data structures segments contiguous resident ram requiring additional computation movement remedy fragmentation invention page table let processor operate arbitrary pages anywhere ram seemingly contiguous logical address space pages became units exchanged disk ram process tries reference page currently present ram processor treats invalid memory reference page fault transfers control program operating system operating system must page frames use operating system must select page frame reuse page program needs evicted page frame dynamically allocated program hold data program modified since read ram words become dirty must written disk freed program later references evicted page another page fault occurs page must read back ram method operating system uses select page frame reuse page replacement algorithm important efficiency operating system predicts page frame least likely needed soon often least recently used lru algorithm algorithm based program working set increase responsiveness paging systems may predict pages needed soon preemptively loading ram program references completing initialization programs operate small number code data pages compared total memory program requires pages frequently accessed called working set working set small percentage system total number pages virtual memory systems work efficiently insignificant amount computing spent resolving page faults working set grows resolving page faults remains manageable growth reaches critical point faults go dramatically time spent resolving overwhelms time spent computing program written condition referred thrashing thrashing occurs program works huge data structures large working set causes continual page faults drastically slow system satisfying page faults may require freeing pages soon re-read disk thrashing also used contexts virtual memory systems example describe cache issues computing silly window syndrome networking worst case might occur vax processors single movl crossing page boundary could source operand using displacement deferred addressing mode longword containing operand address crosses page boundary destination operand using displacement deferred addressing mode longword containing operand address crosses page boundary source destination could cross page boundaries single instruction references ten pages ram cause page fault fault occurs operating system needs go extensive memory management routines perhaps causing multiple i/os might including writing process pages disk reading pages active process disk operating system could allocate ten pages program remedying page fault would discard another page instruction needs restart instruction would fault decrease excessive paging resolve thrashing problems user increase number pages available per program either running fewer programs concurrently increasing amount ram computer multi-programming multi-user environment many users may execute program written code data separate pages minimize use ram users share single copy program process page table set pages address code point single shared copy pages address data point different physical pages process different programs might also use libraries save space one copy shared library loaded physical memory programs use library virtual addresses map pages contain library code data programs want modify library code use copy-on-write memory allocated needed shared memory efficient way communication programs programs share pages memory write read exchange data first computer support paging supercomputer atlas jointly developed ferranti university manchester plessey 1963 machine associative content-addressable memory one entry 512 word page supervisor handled non-equivalence interruptions managed transfer pages core drum order provide one-level store programs paging feature microsoft windows since windows 3.0 1990 windows 3.x creates hidden file named 386spart.par win386.swp use swap file generally found root directory may appear elsewhere typically windows directory size depends much swap space system setting selected user control panel → enhanced virtual memory user moves deletes file blue screen appear next time windows started error message permanent swap file corrupt user prompted choose whether delete file whether exists windows 95 windows 98 windows use similar file settings located control panel → system → performance tab → virtual memory windows automatically sets size page file start 1.5× size physical memory expand 3× physical memory necessary user runs memory-intensive applications system low physical memory preferable manually set sizes value higher default file used paging windows nt family pagefile.sys default location page file root directory partition windows installed windows configured use free space available drives pagefiles required however boot partition i.e drive containing windows directory pagefile system configured write either kernel full memory dumps blue screen death windows uses paging file temporary storage memory dump system rebooted windows copies memory dump pagefile separate file frees space used pagefile default configuration windows pagefile allowed expand beyond initial allocation necessary happens gradually become heavily fragmented potentially cause performance problems common advice given avoid set single locked pagefile size windows expand however pagefile expands filled default configuration 150 total amount physical memory thus total demand pagefile-backed virtual memory must exceed 250 computer physical memory pagefile expand fragmentation pagefile occurs expands temporary soon expanded regions longer use next reboot sooner additional disk space allocations freed pagefile back original state locking pagefile size problematic windows application requests memory total size physical memory pagefile leading failed requests allocate memory may cause applications system processes fail also pagefile rarely read written sequential order performance advantage completely sequential page file minimal however large pagefile generally allows use memory-heavy applications penalties beside using disk space fragmented pagefile may issue fragmentation variable size page file time create number fragmented blocks drive causing files become fragmented reason fixed-size contiguous pagefile better providing size allocated large enough accommodate needs applications required disk space may easily allocated systems recent specifications i.e system 3 gb memory 6 gb fixed-size pagefile 750 gb disk drive system 6 gb memory 16 gb fixed-size pagefile 2 tb disk space examples system using 0.8 disk space pagefile pre-extended maximum defragmenting page file also occasionally recommended improve performance windows system chronically using much memory total physical memory view ignores fact aside temporary results expansion pagefile become fragmented time general performance concerns related pagefile access much effectively dealt adding physical memory unix systems unix-like operating systems use term swap describe act moving memory pages ram disk region disk pages stored systems common dedicate entire partition hard disk swapping partitions called swap partitions many systems entire hard drive dedicated swapping separate data drive containing swap partition hard drive dedicated swapping called swap drive scratch drive scratch disk systems support swapping swap partition others also support swapping files linux kernel supports virtually unlimited number swap backends devices files also supports assignment backend priorities kernel needs swap pages physical memory uses highest-priority backend available free space multiple swap backends assigned priority used round-robin fashion somewhat similar raid 0 storage layouts providing improved performance long underlying devices efficiently accessed parallel end-user perspective swap files versions 2.6.x later linux kernel virtually fast swap partitions limitation swap files contiguously allocated underlying file systems increase performance swap files kernel keeps map placed underlying devices accesses directly thus bypassing cache avoiding filesystem overhead regardless red hat recommends swap partitions used residing hdds rotational magnetic media devices one benefit using swap partitions ability place contiguous hdd areas provide higher data throughput faster seek time however administrative flexibility swap files outweigh certain advantages swap partitions example swap file placed mounted file system set desired size added changed needed swap partitions flexible enlarged without using partitioning volume management tools introduce various complexities potential downtimes swappiness linux kernel parameter controls relative weight given swapping runtime memory opposed dropping pages system page cache whenever memory allocation request met free memory swappiness set values 0 100 inclusive low value causes kernel prefer evict pages page cache higher value causes kernel prefer swap cold memory pages default value codice_1 setting higher increase overall throughput particularly disk io risk occasional high latency cold pages need swapped back setting lower even 0 may provide consistently low latency certainly default values work well workloads desktops interactive systems adequate ram expected task may want lower setting batch processing less interactive systems may want increase system memory highly insufficient current tasks large portion memory activity goes slow swap system become practically unable execute task even cpu idle every process waiting swap system considered swap death swap death happen due incorrectly configured memory overcommitment original description swapping death problem relates x server code data used x server respond keystroke main memory user enters keystroke server take one page faults requiring pages read swap keystroke processed slowing response pages n't remain memory faulted handle next keystroke making system practically unresponsive even actually executing tasks normally macos uses multiple swap files default apple-recommended installation places root partition though possible place instead separate partition device amigaos 4.0 introduced new system allocating ram defragmenting physical memory still uses flat shared address space defragmented based slab allocation method paging memory allows swapping paging implemented amigaos 4.1 may lock system physical memory used swap memory could activated deactivated moment allowing user choose use physical ram backing store virtual memory operating system typically many orders magnitude slower ram additionally using mechanical storage devices introduces delay several milliseconds hard disk therefore desirable reduce eliminate swapping practical operating systems offer settings influence kernel decisions many unix-like operating systems example aix linux solaris allow using multiple storage devices swap space parallel increase performance older virtual memory operating systems space swap backing store reserved programs allocate memory runtime data operating system vendors typically issue guidelines much swap space allocated paging one way allowing size addresses used process process virtual address space logical address space different amount main memory actually installed particular computer physical address space systems size process virtual address space much larger available main memory example computer true n -bit addressing may 2 addressable units ram installed example 32-bit x86 processor 4 gb without physical address extension pae case processor able address ram installed however even case paging used create virtual memory 4 gb instance many programs may running concurrently together may require 4 gb ram paging system makes efficient decisions memory relegate secondary storage leading best use installed ram although processor example address ram beyond 4 gb operating system may provide services programs envision larger memory files grow beyond limit installed ram operating system lets program manipulate data file arbitrarily using paging bring parts file ram necessary computers main memory larger virtual address space process magic-1 pdp-11 machines systems using 32-bit x86 processors physical address extension nullifies significant advantage virtual memory since single process use main memory amount virtual address space systems often use paging techniques obtain secondary benefits size cumulative total virtual address spaces still limited amount secondary storage available
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Operating systems
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mysqli mysqli extension mysql improved relational database driver used php scripting language provide interface mysql databases three main api options considering connecting mysql database server php code consists core optional extensions core functionality php mysql-related extensions mysqli extension mysql extension implemented using php extension framework extension typically exposes api php developer allow facilities used programmatically however extensions use php extension framework expose api php developer pdo mysql driver extension example expose api php developer provides interface pdo layer mysqli improved version older php mysql driver offering various benefits authors php scripting language recommend using mysqli dealing mysql server versions 4.1.3 newer takes advantage new functionality mysqli extension provides various benefits respect predecessor prominent according php website mysqli extension features dual interface supports procedural object-oriented programming paradigms users migrating old mysql extension may prefer procedural interface procedural interface similar old mysql extension many cases function names differ prefix mysqli functions take connection handle first argument whereas matching functions old mysql interface took optional last argument example easy migration old mysql extension mysql server supports use different transport layers connections connections use tcp/ip unix domain sockets windows named pipes hostname codice_1 special meaning bound use unix domain sockets possible open tcp/ip connection using hostname codice_1 must use codice_3 instead example special meaning localhost output hr statements executed mysqli_query mysqli_real_query mysqli_multi_query functions mysqli_query function common combines executing statement buffered fetch result set one call calling mysqli_query identical calling mysqli_real_query followed mysqli_store_result example connecting mysql buffered result sets statement execution results retrieved buffered client read row row client-side result set buffering allows server free resources associated statement results early possible generally speaking clients slow consuming result sets therefore recommended use buffered result sets mysqli_query combines statement execution result set buffering php applications navigate freely buffered results navigation fast result sets held client memory please keep mind often easier scale client scale server example navigation buffered results example output unbuffered result sets client memory short resource freeing server resources early possible keep server load low needed unbuffered results used scrolling unbuffered results possible rows read example navigation unbuffered results result set values data types mysqli_query mysqli_real_query mysqli_multi_query functions used execute non-prepared statements level mysql client server protocol command com_query text protocol used statement execution text protocol mysql server converts data result sets strings sending conversion done regardless sql result set column data type mysql client libraries receive column values strings client-side casting done convert columns back native types instead values provided php strings example text protocol returns strings default example output possible convert integer float columns back php numbers setting mysqli_opt_int_and_float_native connection option using mysqlnd library set mysqlnd library check result set meta data column types convert numeric sql columns php numbers php data type value range allows way example sql int columns returned integers example native data types mysqlnd connection option example output mysql database supports prepared statements prepared statement parameterized statement used execute statement repeatedly high efficiency basic workflow prepared statement execution consists two stages prepare execute prepare stage statement template sent database server server performs syntax check initializes server internal resources later use mysql server supports using anonymous positional placeholder see example mysql database supports stored procedures stored procedure subroutine stored database catalog applications call execute stored procedure call sql statement used execute stored procedure parameter stored procedures inout parameters depending mysql version mysqli interface special notion different kinds parameters parameter input parameters provided call statement please make sure values escaped correctly see examples mysql optionally allows multiple statements one statement string sending multiple statements reduces client-server round trips requires special handling multiple statements multi queries must executed mysqli_multi_query individual statements statement string separated semicolon result sets returned executed statements must fetched mysql server allows statements return result sets statements return result sets one multiple statement see examples mysql server supports transactions depending storage engine used since mysql 5.5 default storage engine innodb innodb full acid transaction support transactions either controlled using sql api calls recommended use api calls enabling disabling auto commit mode committing rolling back transactions examples mysql result set contains metadata metadata describes columns found result set metadata sent mysql accessible mysqli interface extension performs negligible changes information receives differences mysql server versions aligned meta data access mysqli_result interface view persistent connection support introduced php 5.3 mysqli extension support already present pdo mysql ext/mysql idea behind persistent connections connection client process database reused client process rather created destroyed multiple times reduces overhead creating fresh connections every time one required unused connections cached ready reused unlike mysql extension mysqli provide separate function opening persistent connections open persistent connection must prepend p hostname connecting problem persistent connections left unpredictable states clients example table lock might activated client terminates unexpectedly new client process reusing persistent connection get connection cleanup would need done new client process could make good use persistent connection increasing burden programmer persistent connection mysqli extension however provides built-in cleanup handling code cleanup carried mysqli includes ensures persistent connections clean state return connection pool client process uses mysqli extension cleanup automatically calling c-api function mysql_change_user automatic cleanup feature advantages disadvantages though advantage developer longer needs worry adding cleanup code called automatically however disadvantage code could potentially little slower code perform cleanup needs run time connection returned connection pool possible switch automatic cleanup code compiling php mysqli_no_change_user_on_pconnect defined
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Databases
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engineered software inc engineered software inc. software publisher engineering products company based lacey washington founded 1982 company develops hydraulic analysis software specialized piping system design based mainly darcy-weisbach equation centrifugal pump selection using pump affinity rules industries served segments includes aerospace defense chemical processing engineering design consulting food beverage oil petrochemical mining metals pharmaceutical power generation pulp paper wastewater collection treatment education business segments software including saas industrial training publications technical support company one leading manufacturers windows web-based pump selection software products division split 2002 operates brand pump-flo solutions company best known consumer public manufacturer pipe-flo software pipe-flo program proprietary file extension .pipe opened programs including viewer type program uses .psv extension 2008 engineered software inc. expanded engineering products include training courses publications sold brand name fluid fundamentals training 2006 engineered software inc. entered four-year agreement crane valve north america known crane company publish technical paper number 410 tp410 crane agreed allow engineered software provide flow fluids premium software crane manual crane fluid handling later partnered engineered software rewrite crane tp410 2009 company still holds contract crane fluid handling market sell produce guide crane co. flow fluids brand 2007 company became member educational non-profit pump systems matter™ engineered software ceo ray hardee p.e. recognized 2008 hydraulic institute hi contributions hydraulic institute/pump systems matter committee led publication optimizing pumping systems guidebook ops company ceo also member committee wrote standard asme ea-2-2009 energy assessment pumping systems author piping system fundamentals complete guide gaining clear picture piping system
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Distributed computing architecture
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media gateway control protocol media gateway control protocol mgcp signaling call control communications protocol used voice ip voip telecommunication systems implements media gateway control protocol architecture controlling media gateways internet protocol ip networks connected public switched telephone network pstn protocol successor simple gateway control protocol sgcp developed bellcore cisco internet protocol device control ipdc methodology mgcp reflects structure pstn power network residing call control center softswitch analogous central office telephone network endpoints low-intelligence devices mostly executing control commands call agent media gateway controller softswitch providing result indications response protocol represents decomposition voip models h.323 session initiation protocol sip endpoint devices call higher levels signaling intelligence mgcp text-based protocol consisting commands responses uses session description protocol sdp specifying negotiating media streams transmitted call session real-time transport protocol rtp framing media streams media gateway control protocol architecture methodologies programming interfaces described rfc 2805 mgcp master-slave protocol media gateways mgs controlled call control agent softswitch controller called media gateway controller mgc call agent ca network protocol control specific port media gateway facilitates centralized gateway administration provides scalable ip telephony solutions distributed system composed least one call agent one usually multiple media gateways performs conversion media signals circuit-switched packet-switched networks least one signaling gateway sg connected pstn mgcp presents call control architecture limited intelligence edge endpoints media gateways intelligence core controllers mgcp model assumes call agents synchronize send coherent commands responses gateways control call agent uses mgcp request event notifications reports status configuration data media gateway well specify connection parameters activation signals toward pstn telephony interface softswitch typically used conjunction signaling gateways access signalling system 7 ss7 functionality example call agent use mgcp control signaling gateway rather sigtran protocols used backhaul signaling signaling gateway call agents typically media gateway may configured list call agents may accept control commands principle event notifications may sent different call agents endpoint gateway according instructions received call agents setting notifiedentity parameter practice however usually desirable endpoints gateway controlled call agent call agents available provide redundancy event primary call agent fails loses contact media gateway event failure backup call agent responsibility reconfigure media gateway reports backup call agent gateway may audited determine controlling call agent query may used resolve conflicts case multiple call agents mgcp assumes maintain knowledge device state among failover features take account planned unplanned outages mgcp recognizes three essential elements communication media gateway controller call agent media gateway endpoint connections entities media gateway may host multiple endpoints endpoint able engage multiple connections multiple connections endpoints support calling features call waiting three-way calling mgcp text-based protocol using command response model commands responses encoded messages structured formatted whitespace characters space horizontal tab carriage return linefeed colon full stop messages transmitted using user datagram protocol udp media gateways use port number 2427 call agents use 2727 default message sequence command request response known transaction identified numerical transaction identifier exchanged transaction protocol specification defines nine standard commands distinguished four-letter command verb auep aucx crcx dlcx epcf mdcx ntfy rqnt rsip responses begin three-digit numerical response code identifies outcome result transaction two verbs used call agent query state endpoint associated connections three verbs used call agent manage connection media gateway endpoint one verb used call agent request notification events occurring endpoint apply signals connected pstn network link connected telephony endpoint e.g. telephone one verb used endpoint indicate call agent detected event call agent previously requested notification rqnt command one verb used call agent modify coding characteristics expected line side endpoint one verb used endpoint indicate call agent process restarting another implementation media gateway control protocol architecture h.248/megaco protocol collaboration internet engineering task force rfc 3525 international telecommunication union recommendation h.248.1 protocols follow guidelines overlying media gateway control protocol architecture described rfc 2805 however protocols incompatible due differences protocol syntax underlying connection model
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Internet protocols
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sse2 sse2 streaming simd extensions 2 one intel simd single instruction multiple data processor supplementary instruction sets first introduced intel initial version pentium 4 2000 extends earlier sse instruction set intended fully replace mmx intel extended sse2 create sse3 2004 sse2 added 144 new instructions sse 70 instructions competing chip-maker amd added support sse2 introduction opteron athlon 64 ranges amd64 64-bit cpus 2003 sse2 instructions implement integer vector operations also found mmx instead mmx registers use xmm registers wider allow significant performance improvements specialized applications another advantage replacing mmx sse2 avoiding mode switching penalty issuing x87 instructions present mmx sharing register space x87 fpu sse2 also complements floating-point vector operations sse instruction set adding support double precision data type sse2 extensions include set cache control instructions intended primarily minimize cache pollution processing infinite streams information sophisticated complement numeric format conversion instructions amd implementation sse2 amd64 x86-64 platform includes additional eight registers doubling total number 16 xmm0 xmm15 additional registers visible running 64-bit mode intel adopted additional registers part support x86-64 architecture intel parlance intel 64 2004 fpu x87 instructions provide higher precision calculating intermediate results 80 bits precision default minimise roundoff error numerically unstable algorithms see ieee 754 design rationale references therein however x87 fpu scalar unit whereas sse2 process small vector operands parallel codes designed x87 ported lower precision double precision sse2 floating point certain combinations math operations input datasets result measurable numerical deviation issue reproducible scientific computations e.g calculation results must compared results generated different machine architecture related issue historically language standards compilers inconsistent handling x87 80-bit registers implementing double extended precision variables compared double single precision formats implemented sse2 rounding extended precision intermediate values double precision variables fully defined dependent implementation details registers spilled memory sse2 extends mmx instructions operate xmm registers therefore possible convert existing mmx code sse2 equivalent since sse2 register twice long mmx register loop counters memory access may need changed accommodate however 8 byte loads stores xmm available strictly required although one sse2 instruction operate twice much data mmx instruction performance might increase significantly two major reasons accessing sse2 data memory aligned 16-byte boundary incur significant penalty throughput sse2 instructions older x86 implementations half mmx instructions intel addressed first problem adding instruction sse3 reduce overhead accessing unaligned data improving overall performance misaligned loads last problem widening execution engine core microarchitecture core 2 duo later products since mmx x87 register files alias one another using mmx prevent x87 instructions working desired mmx used programmer must use emms instruction c _mm_empty restore operation x87 register file operating systems x87 used much may still used critical areas like pow extra precision needed cases corrupt floating-point state caused failure emit emms may go undetected millions instructions ultimately causing floating-point routine fail returning nan since problem locally apparent mmx code finding correcting bug time consuming sse2 problem usually provides much better throughput provides registers 64-bit code preferred nearly vectorization work first introduced 2000 sse2 supported software development tools example use sse2 microsoft visual studio project programmer either manually write inline-assembly import object-code external source later visual c++ processor pack added sse2 support visual c++ masm intel c++ compiler automatically generate sse4 ssse3 sse3 sse2 sse code without use hand-coded assembly since gcc 3 gcc automatically generate sse/sse2 scalar code target supports instructions automatic vectorization sse/sse2 added since gcc 4 sun studio compiler suite also generate sse2 instructions compiler flag -xvector=simd used since microsoft visual c++ 2012 compiler option generate sse2 instructions turned default sse2 extension ia-32 architecture based x86 instruction set therefore x86 processors include sse2 amd64 architecture supports ia-32 compatibility mode includes sse2 specification also doubles number xmm registers allowing better performance sse2 also requirement installing windows 8 later microsoft office 2013 later enhance reliability third-party apps drivers running windows 8 following ia-32 cpus support sse2 following ia-32 cpus released sse2 developed implement
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Computer architecture
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first-generation programming language first generation programming language 1gl grouping programming languages machine level languages used program first-generation computers originally translator used compile assemble first-generation language first-generation programming instructions entered front panel switches computer system instructions 1gl made binary numbers represented 1s 0s makes language suitable understanding machine far difficult interpret learn human programmer main advantage programming 1gl code run fast efficiently precisely instructions executed directly central processing unit cpu one main disadvantages programming low level language error occurs code easy fix first generation languages much adapted specific computer cpu code portability therefore significantly reduced comparison higher level languages modern day programmers still occasionally use machine level code especially programming lower level functions system drivers interfaces firmware hardware devices modern tools native-code compilers used produce machine level higher-level language 1 nwankwogu s.e 2016 programming languages history
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Programming language topics
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comparison javascript charting libraries different javascript charting libraries available comparison features available
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Programming language topics
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openstego openstego open source steganography tools developed samir vaidya released gnu general public license version 2 gplv2 tools detect data hidden openstego
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Computer security
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multicloud multicloud use multiple cloud computing storage services single heterogeneous architecture also known polynimbus cloud strategy also refers distribution cloud assets software applications etc across several cloud-hosting environments typical multicloud architecture utilizing two public clouds well multiple private clouds multicloud environment aims eliminate reliance single cloud provider differs hybrid cloud refers multiple cloud services rather multiple deployment modes public private legacy also multicloud environment synchronization different vendors essential complete computation process unlike parallel computing distributed computing environments example enterprise may concurrently use separate cloud providers infrastructure iaas software saas services use multiple infrastructure iaas providers latter case may use different infrastructure providers different workloads deploy single workload load balanced across multiple providers active-active deploy single workload one provider backup another active-passive number reasons deploying multicloud architecture including reducing reliance single vendor cost-efficiencies increasing flexibility choice adherence local policies require certain data physically present within area/country geographical distribution processing requests physically closer cloud unit turn reduces latency mitigating disasters similar use best-of-breed applications multiple developers personal computer rather defaults offered operating system vendor recognition fact one provider everything everyone various issues also present multicloud environment security governance complicated moving parts may create resiliency issues selection right cloud products services also present challenge users may suffer paradox choice
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Distributed computing architecture
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mod wsgi mod_wsgi apache http server module graham dumpleton provides wsgi compliant interface hosting python based web applications apache version 4.5.3 mod_wsgi supports python 2 3 starting 2.6 3.2 alternative mod_python cgi fastcgi solutions python-web integration first available 2007 later versions mod_wsgi may installed one two ways original way apache module commonly used many languages v4 'mod_wsgi express method also supported installed python module using setup.py pip without needing manual intervention apache configuration method simplifies installation python developers familiar python apache also advantages virtualization creates local environment without affecting system settings requiring root access install
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Web technology
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event condition action event condition action eca short-cut referring structure active rules event driven architecture active database systems rule traditionally consisted three parts structure used early research active databases started use term eca current state art eca rule engines use many variations rule structure also features considered early research introduced strategies event selection event part memory-based rule engine condition could tests local data actions could updates object attributes database system condition could simply query database result set null passed action part changes database either case actions could also calls external programs remote procedures note database usage updates database regarded internal events consequence execution action part active rule match event part another active rule thus triggering equivalent memory-based rule engine would invoke external method caused external event trigger another eca rule eca rules also used rule engines use variants rete algorithm rule processing
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Databases
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aleste story aleste concerns manmade supercomputer dia 51 infected hybrid virus spreading like wildfire eventually leading dia 51 eliminate human race yuri ray girlfriend gets injured dia assault raymond waizen reason world get rid dia 51 aleste fighter game originally released master system february 1988 version released outside japan power strike us release mail-only limited edition european release normal retail package msx2 version released july year featuring two new stages lowered difficulty series cutscenes version game released phones square enix presumably based msx2 version msx2 version rereleased nintendo wii virtual console service japan along aleste 2 also rereleased now-defunct woomb service aleste followed several sequels also number similar games various aleste entries based example gunhed would inspire super aleste finally known around 1993 various employees left compile joined raizing made similar games
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Computer architecture
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robert bruce findler robert bruce findler colloquially known robby american computer scientist currently professor electrical engineering computer science northwestern university also member plt group responsible creation maintenance drracket addition drracket findler contributed numerous components racket supervises web-based software library called planet findler also leading team member programbydesign project findler received phd rice university direction matthias felleisen dissertation linguistics software contracts popularly known design contract work software contracts provides careful accounting blame thereby helping programmers quickly home faulty part software system addition drracket software contracts findler focuses design implementation workbench semantics engineers workbench called redex tool specifying executing reduction semantics programming language used programming language researchers us europe recently sun fortress research team used redex specify explore key parts language findler served semantics editor revised^6 report scheme programming language phd student jacob matthews developed redex model core semantics included appendix report appendix plays role standard ml formal specification milner tofte harper macqueen executable thus visualize individual examples
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Programming language topics
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