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blazor blazor web ui framework based c razor html runs browser via webassembly blazor designed simplify task building single-page applications run browser enables web developers write .net-based web apps run client-side web browsers using open web standards blazor released apache 2 open source license part .net core 3.0 code written c visualbasic.net compiled normal .net assemblies downloaded run web browser using webassembly based .net runtime runtime compiled webassembly .net assemblies created user code interpreted runtime current implementation rather slow ahead time compiler may added later development stage
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Operating systems
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ipoe internet protocol ethernet ipoe method delivering ip payload ethernet-based access network access network using bridged ethernet asynchronous transfer mode atm without using pppoe directly encapsulates ip datagrams ethernet frames using standard encapsulation use ipoe addresses disadvantage ppp unsuited multicast delivery multiple users typically ipoe uses dynamic host configuration protocol extensible authentication protocol provide functionality pppoe less robust manner
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Internet protocols
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microsoft adcenter analytics microsoft adcenter analytics codenamed gatineau microsoft web analytics solution 2006 microsoft acquired deepmetrix corporation used analytics technology deliver adcenter analytics competed google analytics tied microsoft adcenter way google tied google analytics google adwords led complaints webmasters due five dollar fee sign compared lack cost use google analytics features included march 2009 microsoft announced adcenter analytics would discontinued existing accounts would operational till end 2009
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Web technology
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tim-100 tim-100 ptt teller microcomputer developed mihajlo pupin institute serbia 1985 ref.lit 1 based intel microprocessors types 80x86 vlsi circuitry ram capacity max.8mb external memory floppy disks 5.25 3.50 inch ref.literature 2 3 4 multiuser multitasking operating system real-time nrt also tranos developed ptt office fig.4 tim designers m.p.institute-belgrade wikimedia
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Computer architecture
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macintosh classic ii macintosh classic ii also sold performa 200 personal computer designed manufactured sold apple computer inc. october 1991 september 1993 like macintosh se/30 replaces classic ii powered 16 mhz motorola 68030 cpu 40 80 mb hard disk contrast predecessor limited 16-bit data bus se/30 32-bit data bus 10 mb memory ceiling slower data bus resulted classic ii 30 slower se/30 classic ii shares case earlier classic architecturally similar macintosh lc use custom ics identical used lc enabled classic ii lower component count older macs unlike lc se/30 classic ii internal processor direct slot making first slotless desktop macintosh since macintosh plus classic ii one three machines apple repackaged macintosh performa brand introduced september 1992 called performa 200 sold specifications original classic ii addition speaker grille left side enhanced sound number changes packaged software included ease desktop alternative aimed provide simpler user interface standard macintosh finder exact software included tended vary one retailer next initially offered retail price 1,250 usd classic ii last black-and-white compact macintosh last desktop macintosh include external floppy disk drive port apple discontinued support classic ii january 1 2001 processor 16 mhz 15.6672 mhz motorola 68030 32-bit internally 16-bit bus optional motorola 68882 fpu ram 2 mb expandable 10 mb using two 100 ns 30-pin simms display 9 b w screen 512 x 342 pixels audio 8-bit mono 22khz hard drive 40 80 mb floppy 1.4 mb double sided addressing 24-bit 32-bit battery 3.6 v lithium expansion connectors rear panel include adb port keyboard mouse two mini-din-8 rs-422 serial ports db-25 scsi db-19 external floppy drive two 3.5 mm minijack audio sockets audio headphone classic ii 50-pin internal expansion slot intended either fpu co-processor additional rom socket designed used purpose suitable use general expansion slot apple never produced expansion card kind slot although least one third-party fpu available fastmath classic ii applied engineering sonnet offered synchronous 16mhz asynchronous 50mhz 68882 fpu 2016 group hobbyists 68k mac liberation army forums produced expansion card sockets fpu bootable rewriteable rom
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Computer architecture
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data architect data architect practitioner data architecture data management discipline concerned designing creating deploying managing organization data architecture data architects define data stored consumed integrated managed different data entities systems well applications using processing data way closely allied business architecture considered one four domains enterprise architecture according data management body knowledge data architect “ provides standard common business vocabulary expresses strategic data requirements outlines high level integrated designs meet requirements aligns enterprise strategy related business architecture. ” according open group architecture framework togaf data architect expected set data architecture principles create models data enable implementation intended business architecture create diagrams showing key data entities create inventory data needed implement architecture vision bob lambert describes necessary skills data architect follows
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Computer security
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sound blaster live sound blaster live pci add-on sound card creative technology limited pcs moving isa pci allowed card dispense onboard memory storing digital samples computer main memory accessing real time bus allowed much wider selection longer playing samples also included higher quality sound output levels quadrophonic output new midi synthesizer 64 sampled voices live introduced august 1998 variations design remained creative primary sound card line 2000s sound blaster live august 1998 saw introduction emu10k1 audio processor manufactured 0.35µm 3-metal-layer cmos process 2.44 million transistor asic rated 1000 mips emu10k1 featured hardware acceleration directsound eax 1.0 2.0 environmental audio extensions along high-quality 64-voice midi sample-based synthesizer integrated fx8010 dsp chip real-time digital audio effects major design change predecessor emu8000 emu10k1 used system memory accessed pci bus wavetable samples rather using expensive on-board memory possible point systems equipped far ram previously pci offered far faster efficient data transfer old isa bus integrated fx8010 32-bit programmable processor 1 kilobyte instruction memory provided real-time postprocessing effects reverb flanging chorus capability let users select pre-defined listening environment control-panel application concert hall theater headphones etc also provided hardware-acceleration eax creative environmental audio technology effect algorithms created development system integrated microsoft developer studio effects written language similar c compiled native fx8010 object code compiler fxasm sound blaster live featured higher audio quality previous sound blasters processed sound digitally every stage greater chip integration reduced analog signal losses older larger cards unfortunately digital processing brought limitations dsp internal fixed sample rate 48 khz standard ac'97 clock meaning emu10k1 always captured external audio-sources 48 khz performed sample-rate conversion 48 khz waveform output requested target rate 44.1 khz 32 khz rate-conversion step introduced intermodulation distortion downsampled output however rate-conversion applied audio signal passed effects engine sb/live great difficulty resampling audio-cd source material 44.1 khz without introducing audible distortion creative addressed concern recommending audio-recording performed exclusively 48 khz use third-party software handle desired sample-rate conversion avoid using emu10k1 sample-rate conversion sound blaster live supported multi-speaker output initially 4-speaker setup software referred 4.1 setup meaning 4 satellites subwoofer case subwoofer separate output 5.1 higher audio instead low-pass filter crossover within speaker system removes high midrange frequencies sound card output subwoofer games see 4.1 speaker system quadraphonic directsound offers subwoofer output configuration limited creative sound cards aureal ensoniq philips manufacturers made cards use four-speaker output fashion later versions live usually called live 5.1 offered 5.1-channel support adds center-channel speaker lfe subwoofer output useful movie watching dolby digital 5.1 decoded live implemented dos legacy support via ensoniq audiopci dos tsr program creative acquired ensoniq 1998 part deal made use highly-compatible isa sound card emulator newer cards fact live uses .ecw ensoniq concert wavetable files wavetable emulation dos program enables support many standards sound blaster 16 general midi adlib opl3 among others sound blaster live first sound card creative u hear recording input channel supported windows drivers additional software needed utilize analog stereo audio signal came main line directed input way one could mix available inputs midi synth one stereo signal using u hear 5.1 sound sound would downmixed stereo first creative recorder utility included sound card specifically designed take advantage u hear feature making simple matter capture streaming sound source even programs deliberately avoid providing means saving digital sounds thus freeing non-technical users complexities patching inputs outputs various software modules original sb live low noise floor time however critical design flaw limited application quadraphonic audio two s/p-dif channels provided stereo pair differed digital analog reconstruction since ac'97 chip provided internal 48 khz dac creative chose implement two identical dac pipelines front-speaker audio pair subjected different reconstruction amplification regime rear channel evidenced differently valued pull-up resistors filter-capacitors area forward ac'97 chip specifications ac'97 use different amplifier op-amps rear channel serviced separate arguably better philips uda1334 dac yet op-amp used boost signal output levels noticeably different frequency response envelope normalized front channel leaving thin quiet rear channel make matters worse rear channel op-amp inverting variety without treated leaving rear speakers phase front requiring switchover problems encountered using gold editions daughterboard 4-speaker digital-output tendency ac'97 chip fail used input source medium-impedance musical instruments removed use front channels altogether although chip could sourced cheaper ac'97 compatible products soldered place nevertheless simply redirecting front signal rear output sb live long time favorite trick computer audio enthusiasts want better sound minimum money despite problems original sb live still used well s/p-dif input/output midi input/output device network-connected digital audio workstation environments live live value original releases live family live value also known live 1024 identical full live exception color-coded plastic connectors instead gold include extended digital i/o card one version live value ct4830 deleted digital audio input edge card marked cd_spdif interface chip used digital audio original sound blaster live proprietary 9-pin mini-din connector digital output creative referred mini din connector allowed use microphone digital speakers time done value base models subsequent creative sound cards share single port s/pdif digital in/output microphone connectivity mini-din connection included subsequent sound blaster product however owners speaker systems use digital input may buy adapter creative card supported windows vista unless running 5.1 surround sound setting outside party released free drivers sound card http //kxproject.com/ drivers offer control dsp details original live including gold edition marketing strategy design faults see sound blaster live original released 1999 includes live drive ir released 2000 live added outputs center channel speaker lfe subwoofer channel card marketed sound blaster live full capabilities retail versions live used different audio chip emu10k1 emu10k1x noticeably smaller fewer pins chip accelerate directsound hardware eax sale board dell created controversy obviously marketed inferior cheaper product card identified part number sb0200/0203 later improved model emu10k1 chip restored hardware eax/directsound/directsound3d acceleration currently windows drivers available download creative website filename dell driver install pack 2_10 languages recommended recording done 48 khz sampling rate issue hardware down-sampling sound blaster live 24-bit sb0410 actually member sound blaster live family lacked emu10k1/10k2 processor stripped version audigy value snr 100 db software based eax advanced resolution dvd-audio playback dolby digital 5.1 dolby digital ex 6.1 playback proof linux operating systems using alsa sound system module used sound blaster live 24-bit snd-ca0106 module used sound blaster live snd-emu10k1 professional version made e-mu owned creative developed emu10k1 chip featured creative live products professional features included effects higher quality front-mounted drive bay panel headphone output dual mic/line inputs physical level control knobs digital coax in/out pci card drive bay mixer db precision phantom power microphones 12v asio mixer presets internal mixer rerouting 64 midi channels 32mb system ram usage sf2 gigabyte expandable winxp future expandability extra multi-out card also featured line line analogue inputs outputs balanced ¼ /6.3mm trs jacks
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Computer architecture
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sound blaster audigy sound blaster audigy product line sound cards creative technology flagship model audigy family used emu10k2 audio dsp improved version sb-live emu10k1 value/se editions built less-expensive audio controller audigy family available pcs pci pci express slot usb port audigy cards equipped emu10k2 ca0100 chip could process 4 eax environments simultaneously on-chip dsp native eax 3.0 advanced hd support supported stereo 5.1-channel output audio processor could mix 64 directsound3d sound channels hardware live 32 channels creative labs advertised audigy 24-bit sound card controversial marketing claim product support end-to-end playback 24-bit/96 khz audio streams audigy live shared similar architectural limitation audio transport dma engine fixed 16-bit sample precision 48 khz despite 24-bit/96 khz high-resolution dacs audigy dsp could process 16-bit/48 khz audio sources fact immediately obvious creative literature difficult ascertain even upon examination audigy spec sheets resulting class-action settlement creative later awarded us customers 35 discount creative products maximum discount 65 aside lack end-to-end path 24-bit audio dolby digital ac-3 dts passthrough s/pdif digital issues never resolved audigy card supports professional asio 1 driver interface natively making possible obtain low latencies virtual studio technology vst instruments versions audigy featured external break box connectors s/pdif midi ieee 1394 analog optical signals asio break box features attempt tap home studio market mainstream product variant sb0160 uses full emu10k2 chip ca0100 chip result quite similar feature set missing firewire port audigy se sb0570 audigy value sb0570 stripped models less expensive ca0106 audio-controller place emu10k2 ca0106 se/value limited software-based eax 3.0 upgraded software-based eax 4.0 driver update advanced resolution dvd-audio playback dolby digital 5.1 dolby digital ex 6.1 playback cards one mic line aux sources may unmuted time audigy se audigy value carry sb0570 model number possible card sold different markets different names perhaps cards sold one name later changed possible could even slightly different cards se low-profile pci card audigy family still many unsold units online retailers unlike audigy cards sound quality wavetable 64-voice synthesizer audio path analog-digital converter adc 24 bit 96 khz digital-analog converter dac 24 bit 96 khz recording 16‥24 bit 8 11.025 16 22.05 24 32 44.1 48 96 khz digital path s/pdif 24 bit 44.1 48 96 khz sound channels analog 2.1 4.1 5.1 6.1 7.1 creative multi speaker surround cmss means audigy se 7.1 cards upmix mono stereo sources 7.1 channels digital 2.1 sound blaster audigy ls sb0310 similar audigy se supports neither hardware acceleration firewire sound blaster audigy platinum ex sb0090 similar audigy es supported external break box instead standard internal version came firewire port introduced models vx sb0060 low-profile pci card audigy family suggestion readers model number listed number cards sound blaster live 5.1 series typo sound blaster audigy 2 sb0240 september 2002 featured updated emu10k2 processor called ca0102 gain access ca0151 separate chip collectively ca0102 ca0151 sometimes referred emu10k2.5 ca0102 chip alone version emu10k2 address biggest shortcoming original audigy revised dma engine allowed end-to-end high-resolution 24-bit audio playback 96 khz 6.1 channel recording 192 khz stereo however high-resolution audio achieved bypassing dsp decoded directly ca0151 chip also known p16v take advantage creative substituted ca0102 old ca0100 used audigy 1 using dsp high-resolution audiostreams resulted audigy characteristic downsampling dsp native-rate 48 khz mixing audio sources use windows vista 7 mitigate dsp sample rate conversion issue setting card 16-bit/48 khz resamples audio using much superior 32-bit float windows audio stack sending card unclear whether works use cases e.g openal audigy 2 supported 6.1 speakers improved signal-to-noise ratio snr audigy 106 vs. 100 decibels audio output supplied ac'97 codec front outputs i²s rear also featured built-in dolby digital 5.1 ex decoding improved dvd play-back ieee-1394 firewire connector present modifications except value audigy 2 3d audio capabilities received boost compared predecessors creative created eax 4.0 advanced hd standard coincide audigy 2 release chip process 64 directsound3d audio channels hardware also native support free open source openal audio api sound blaster audigy 2 zs sb0350 revision audigy 2 slightly improved signal-to-noise ratio 108 vs. 106 db dts-es extended surround dvd playback audigy 2 zs supports 7.1 speakers via 4-pole mini-jacks although used non-conventional pin side r/l line 2/3 respectively widespread card audigy series unofficial drivers 32 64-bit editions windows 10 8.x 7 vista sp2 xp sp3 available irix drivers sound blaster audigy 2 zs installed sgi fuel series workstations also cardbus version zs use notebook computers testing chain external loopback line-out1 line-in3 br sampling mode 24-bit 96 khz br measured values testing chain external loopback line-out1 line-in3 br sampling mode 24-bit 96 khz br measured values sound blaster audigy 2 zs notebook sb0530 cardbus version audigy 2 zs released fall 2004 notebook market nearly capabilities pci edition far smaller form factor reductions capability included somewhat limited midi capability compared pci version loss firewire first gaming-oriented sound hardware add-on board notebooks offered full hardware acceleration 3d audio along high-fidelity audio output quality card struggled compatibility due quality issues cardbus host chipsets many notebooks time problem also suffered companies products echo digital audio corporation indigo sound blaster audigy 2 zs video editor sb0480 external usb soundcard combined audio playback accelerated video editing 4-port usb 2.0 hub one solution featured accelerated video encoding dominofx video processing technologies audio system provided thx certified sound 24-bit eax advanced hd 5.1 7.1 surround video capture device hardware-accelerated encoding complex format real-time rather using cpu results good quality video even basic systems device used software uses standard directshow vfw interface limitation supplied software capture video must used prevents use device conjunction video camera webcam standard webcam interfaces use directshow creative made free vidcap application available website allows quick easy capture output devices captured files imported video editor application dvd authoring program sound blaster audigy 2 value sb0400 somewhat stripped version audigy 2 zs uses emu10k2.5 chip ca0108 integrate ca0102 ca0151 single piece silicon value version snr 106 db ieee-1394 firewire connector dts-es 6.1 playback however fully hardware accelerated directsound eax 4 sold cheaper companion expensive zs sound blaster audigy 2 se sb0570 similar audigy se live 24-bit edition hardware dsp part audio chip puts far load host system cpu card physically smaller audigy 2 cards designed entry-level budget sound card suggestion readers knowledge cards searched internet could find evidence retail boxes labeled audigy 2 se see numerous boxes labeled audigy se audigy value containing cards carrying sb0570 model number audigy 2 se n't seem likely would model number others unless card sold different part world different name perhaps card name changed time though could slightly different card exists somewhere sound blaster audigy 2 nx sb0300 external usb soundcard supporting 24 bit playback dsp chip also known sound blaster audigy advanced mb sb060 similar audigy 2 se software supports eax 3.0 supports 64-channel software wavetable directsound acceleration without hardware accelerated wavetable synthesis dac rated 95 db signal-to-noise ratio available integrated option dell inspiron studio xps notebooks note creative hardware necessary device entirely software solution adaptable various dacs sound blaster audigy 4 sb0610 uses ca10300 ca0108 unleaded counterpart dsp instead advanced ca10200 ca0102 unleaded counterpart external hub firewire port gold connectors board layout similar audigy 2 value snr rated 106 db sound blaster audigy 4 pro sb0380 improves sound blaster audigy 2 zs improving snr 113 db features much core technology audigy 2 zs uses ca0102 newer model uses ca10200 unleaded instead new external i/o hub superior dacs offering higher digital-to-analog audio conversion quality also allows simultaneous recording six audio channels 96 khz/24-bit still supports maximum 7.1 audio channels 96 khz/24bit stereo output 192 khz/24bit 7.1 mode supported windows xp well 6.1 speaker mode supported windows 7 windows vista sound blaster audigy 4 se sb0610vp sound blaster audigy 4 pro without remote control however uses audio dsp functionally capable audigy 2 4 series audigy 2 se features full hardware acceleration directsound eax sound blaster audigy rx sb1550 released september 2013 uses e-mu ca10300 audigy 4 dedicated 600-ohm headphone amplifier one toslink optical output pci express ×1 interface supported via plx technology bridge controller sound blaster audigy fx sb1570 released september 2013 hda card uses alc898 chip realtek includes 600-ohm amplifier sound blaster audigy fx control panel eax studio software independent line-in microphone inputs half-height expansion card pci express ×1 interface alternate independent wdm driver windows developed provide user-control emu10k1 emu10k2 chips found many audigy-branded cards kx project driver supports mixing numerous different effects real time hardware emu10k1 emu10k2 chips developed eugene gavrilov driver longer maintained regular basis original authors source code freed gplv2 license continues get contributions time time user daniel_k daniel kawakami creative forums maintenance updates keep compatibility latest version windows implements several non public fixes available creative forums blog latest version based creative audigy rx driver older audigy cards benefits drawbacks compared latest official drivers bring back cmss2 deprecated creative vista/7 openal quality reported differ significantly drivers support eax combination openal windows 10 1903 update drivers stopped working install sound soundcard neither creative audio console see card solution install latest driver audigy rx manually via *inf rest package creative programs left daniel_k package
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Computer architecture
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arm cortex-a76 arm cortex-a76 microarchitecture implementing armv8.2-a 64-bit instruction set designed arm holdings austin design centre cortex-a76 frontend 4-wide decode out-of-order superscalar design backend 8 execution ports pipeline depth 13 stages execution latencies 11 stages cortex-a76 serves successor cortex-a73 cortex-a75 though based clean sheet design core supports unprivileged 32-bit applications privileged applications must utilize 64-bit armv8-a isa also supports load acquire ldapr instructions armv8.3-a dot product instructions armv8.4-a pstate speculative store bypass safe ssbs bit speculation barriers csdb ssbb pssbb instructions armv8.5-a arm announced 25 35 increases integer floating point performance respectively memory bandwidth increased 90 relative a75 according arm a76 expected offer twice performance a73 targeted beyond mobile workloads performance targeted laptop class including windows 10 devices competitive intel kaby lake cortex-a76 support arm dynamiq technology expected used high-performance cores used combination cortex-a55 power-efficient cores cortex-a76 available sip core licensees design makes suitable integration sip cores e.g gpu display controller dsp image processor etc one die constituting system chip soc arm also collaborated qualcomm semi-custom version cortex-a76 used within high-end kryo 495 snapdragon 8cx /kryo 485 snapdragon 855 855 plus also mid-range kryo 460 snapdragon 675 kryo 470 snapdragon 730 cpus one modifications qualcomm made increasing reorder buffer increase out-of-order window size
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Computer architecture
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economic social data service economic social data service esds national data archiving dissemination service founded january 2003 funded jointly economic social research council esrc jisc july 2012 esrc announced become partner uk data service established october 1 2012 esds provides access support wide range key economic social data uk collection covers quantitative qualitative data span many different disciplines themes esds service distributed service based collaboration four key centres expertise uk data archive institute social economic research iser based university essex manchester information associated services mimas cathie marsh centre census survey research ccsr located university manchester centres work collaboration acquire process preserve disseminate wide range data across social sciences esds also provides enhanced user support training secondary use data research learning teaching communities uk data archive responsible overall direction management esds within esds four specialist data services provide value-added support follows study descriptions online documentation including questionnaires datasets accessed online free charge without registering access data requires registration uses federated access management shibboleth user authentication registered users also download explore/analyse online large growing number datasets
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Databases
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sound blaster 16 sound blaster 16 series sound cards creative technology add-on boards pcs isa pci slot sound blaster 16 june 1992 successor sound blaster pro introduced 16-bit digital audio sampling sound blaster line sound blaster 16 also added expansion-header add-on midi-daughterboards sample-based synthesis capabilities complying general midi standard socket optional digital signal processor dubbed advanced signal processor later creative signal processor asp later csp mpu-401 compatible uart communication external midi-devices sound blaster 16 retained pro opl-3 support fm synthesis mostly compatible software written older sound blaster sound blaster pro sound cards sb16 mpu-401 emulation limited uart dumb mode sufficient midi software daughterboard wave blaster roland scb-7 roland scb-55 yamaha db50xg yamaha db60xg installed sound blaster wave blaster behaved like standard midi device accessible mpu-401 compatible midi software asp csp chip added new features sound blaster line hardware-assisted speech synthesis textassist software qsound audio spatialization technology digital pcm wave playback pcm audio compression decompression software needed written leverage unique abilities yet offered capabilities lacked compelling applications result chip generally ignored market sound blaster 16 featured widely used tea2025 amplifier ic configuration creative chosen would allow approximately 700 milliwatts 0.7 watts per channel used standard pair unpowered 4-ohm multi-media speakers later models typically ones vibra chips used also then-widely used tda1517 amplifier ic setting onboard jumper user could select line-level output bypassing on-board amplifier amplified-output sound blaster 16 hugely popular creative audio revenue grew us 40 million per year nearly us 1 billion following launch sound blaster 16 related products rich sorkin general manager global business time responsible product planning product management marketing oem sales due popularity wide support sound blaster 16 emulated variety virtualization and/or emulation programs dosbox qemu bochs vmware virtualbox varying degrees faithfulness compatibility early intel pcs built ibm pc/at typically included support one ata interface controlled two ata devices computer needs grew became common system need 1 ata interface development cd-rom many computers could support since devices one channel already used sound blaster 16 boards ct2940 example provided additional ide interface computers spare ata-ports cdrom though additional drive interface typically supported one device rather two typically supported cd rom drives usually could support additional hard drives proprietary cd-rom standards also supported several sound blaster 16 cards mitsumi ct2700 philips/lmsi ct1780 example sound blaster 16 cards came panasonic matsushita interface resembles ide 40pin connector sound blaster scsi controller sb 16 scsi-2 ct1770 ct1779 designed use high end scsi based cd-rom drives controller on-board firmware boot bios start os scsi hard drive normally meant scsi device id-0 id-1 used well computer scsi hard drive required scsi controller settings scsi controller sb card selected sb scsi-2 interface conflict main scsi controller sound blaster 16 cards feature connectors cd-audio input necessity since operating systems cd-rom drives time support streaming cd-audio digitally main interface cd-audio input could also daisy-chained another sound generating device mpeg decoder tv tuner card majority sound blaster 16 cards feature either discrete yamaha ymf262 opl-3 fm synthesizer ct1747 chip synthesizer integrated post-1995 cards notably ct2910 feature fully compatible ymf289 fm synthesis chip instead starting late 1995 creative utilized cost-reduced software-compatible replacement opl-3 fm support termed cqm synthesis however synthesis far entirely faithful opl-3 chips producing considerable distortion along high-pitched 'squeaking 'ringing artifacts fm-synthesized music sound effects boards utilizing cqm synthesis feature ct1978 chip may cqm integrated case vibra16c/x-based boards following model numbers assigned sound blaster 16 note various pcbs model number shipped different configuration regarding cd-rom interfaces sockets presence/absence asp/csp chip following models typically equipped asp/csp socket ct1740 ct1750 ct1770 ct1790 ct2230 ct2740 ct2950 ct2290 sound blaster easy 16 ct2750 sold asp/csp chip parallel cd-rom port 1 audio sound blaster vibra 16 released cost-reduced integrated sound blaster 16 chipset targeting oems entry-level mid-range markets variants support plug play microsoft windows operating systems lacked separate bass treble control asp/csp socket models even lacked wave blaster connector came equipped connector several different revisions vibra chipset exist following model numbers assigned sound blaster vibra 16 note various pcbs model number shipped different configuration regarding cd-rom interfaces sockets even among models variations exist example oem-specific cards made without tea2025/tda1517 amplifier reduce costs sound blaster 16 waveffects released 1997 cheaper simpler redesign sound blaster 16 came creative wavesynth also bundled sound blaster awe64 gold physical modeling software synthesizer developed seer systems led dave smith based sondius waveguide technology developed stanford ccrma waveffects line also supports cqm synthesis adlib/opl compatibility following model numbers assigned sound blaster 16 waveffects 1998 creative technology acquired ensoniq subsequently released sound blaster 16 pci sound blaster 16 pci based ensoniq audiopci technology therefore unrelated isa sound blaster 16 sound blaster 16 vibra sound blaster 16 waveffects dedicated hardware adlib/opl support instead using ensoniq sample-synthesis engine simulate though simulation considered inaccurate compared original opl chips fortunately general midi compatible games following model numbers assigned sound blaster 16 pci many sound blaster 16s well 20 years old many cards suffer symptoms related aging capacitors ranging muffled distorted output cards failing function properly addition regard headphone amplifier design boards creative fully adhere datasheets recommendations component values potentially impacting amplified output sound quality users found replacing capacitors fresh ones recommended values noticeably improved amplified line-level audio quality addition restoring proper operation large number sound blaster 16 cards flawed digital sound processor board causes various issues midi daughtercards attached wave blaster header problems include stuck notes incorrect notes various flaws midi playback particular sound blaster 16 cards affected carry dsp versions 4.11 4.12 4.13 dsp versions 4.16 later older dsp versions 4.05 suffer bug workaround flaw occurs operating systems since issue hardware level dsp version checked running diagnose utility dos looking dsp chip sound card version number printed ct1740a chip usually near ct1745a mixer chip computer gaming world 1993 stated impressed quality digital audio sound blaster 16 16 asp reporting pops extra noise incomplete sound blaster compatibility magazine instead recommended almost foolproof sound blaster pro original sound blaster
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Computer architecture
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memory-scraping malware memory-scraping malware ram scrapping malware malware scans memory digital devices notably point-of-sale pos systems collect sensitive personal information credit card numbers personal identification numbers pin purpose exploitation magnetic stripe payment cards hold three different data trackstrack 1 track 2 track 3 pos ram scrapers created implement use expression matches gain access collect track 1 track 2 card data ram process memory ram scrapers use luhn algorithm check validity card data exfiltration
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Computer security
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macintosh quadra 800 macintosh quadra 800 also sold bundled server software apple workgroup server 80 personal computer part apple computer quadra series macintosh computers introduced february 1993 alongside first macintosh centris models first totally new quadra model since original quadras 700 900 950 positioned 950 previous midrange quadra 700 discontinued shortly 800 introduction debuting half price 950 800 featured motorola 68040 33 mhz processor 950 additional interleaved ram running 70ns well enhanced video system scsi bus enabled outperform 950 however tower case smaller much less accessible giving reputation one apple worst cases time quadra 800 later joined multimedia-focused quadra 840av quadra 800 discontinued march 1994 favor powerpc-based power macintosh 8100 8100 successor power macintosh 8500 used quadra 800 case european version power macintosh 7200 marketed power macintosh 8200 taller highly-modified variant case also used power macintosh 9500 case apple introduced new mini-tower case design quadra 800 subsequently used quadra 840av power macintosh 8100 8200 8500 infoworld review quadra 800 described case design follows apple recommends take machine authorized dealer install additional memory ’ wonder — procedure fraught difficulties although bad previous compact models se order access simm slots need detach logic board ’ plastic holders easily broken flip board access slots boards machine need remove try put back together may find internal scsi connections come loose video logic board 512 kb on-board vram sufficient provide 256-color 8-bit support monitors 16 inches size two vram simm slots provide ability upgrade 1 mb vram allows 32,768 color 16-bit resolutions quadra 800 capable operating 24-bit color regardless much vram installed whether external video card used david pogue described apple deliberately crippling machine enhance attractiveness quadra 900 950 models cd-rom configurations included applecd 300i 2x cd-rom quadra 800 one first macintoshes shipped bootable cd-rom configurations include external scsi port two adb two serial ports 3 nubus slots processor direct slot mono audio stereo audio inclusion aaui ethernet port varied region newly-introduced apple desktop bus mouse ii included configurations introduced february 10 1993 introduced march 22 1993
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Computer architecture
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principal computer security principal computer security entity authenticated computer system network referred security principal java microsoft literature principals individual people computers services computational entities processes threads group things need identified authenticated assigned rights privileges resources network principal typically associated identifier security identifier allows referenced identification assignment properties permissions
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Computer security
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tablespace tablespace storage location actual data underlying database objects kept provides layer abstraction physical logical data serves allocate storage dbms managed segments database segment database object occupies physical space table data indexes created tablespace referred name creating database segments tablespaces specify database storage locations logical database structure database schema instance different objects schema may different underlying tablespaces similarly tablespace may service segments one schema sometimes used specify schema form bond logical physical data using tablespaces administrator also control disk layout installation common use tablespaces optimize performance example heavily used index placed fast ssd hand database table contains archived data rarely accessed could stored less expensive slower magnetic hard drive common tablespaces store data filesystem file single file must part single tablespace database management systems allow tablespaces configured directly operating-system device entries called raw devices providing better performance avoiding os filesystem overheads oracle stores data logically tablespaces physically datafiles associated corresponding tablespace
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Databases
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content delivery network content delivery network content distribution network cdn geographically distributed network proxy servers data centers goal provide high availability high performance distributing service spatially relative end-users cdns serve large portion internet content today including web objects text graphics scripts downloadable objects media files software documents applications e-commerce portals live streaming media on-demand streaming media social media sites cdns layer internet ecosystem content owners media companies e-commerce vendors pay cdn operators deliver content end users turn cdn pays isps carriers network operators hosting servers data centers cdn umbrella term spanning different types content delivery services video streaming software downloads web mobile content acceleration licensed/managed cdn transparent caching services measure cdn performance load balancing multi cdn switching analytics cloud intelligence cdn vendors may cross industries like security ddos protection web application firewalls waf wan optimization cdn nodes usually deployed multiple locations often multiple backbones benefits include reducing bandwidth costs improving page load times increasing global availability content number nodes servers making cdn varies depending architecture reaching thousands nodes tens thousands servers many remote points presence pops others build global network small number geographical pops requests content typically algorithmically directed nodes optimal way optimizing performance locations best serving content user may chosen may measured choosing locations fewest hops lowest number network seconds away requesting client highest availability terms server performance current historical optimize delivery across local networks optimizing cost locations least expensive may chosen instead optimal scenario two goals tend align edge servers close end-user edge network may advantage performance cost cdn providers provide services varying defined set pops depending coverage desired united states international global asia-pacific etc sets pops called edges edge nodes edge networks would closest edge cdn assets end user cdn edge network grows outward origins acquisitions via purchase peering exchange co-locations facilities bandwidth servers cdn providers profit either direct fees paid content providers using network profit user analytics tracking data collected scripts loaded onto customer websites inside browser origin services pointed potential privacy intrusion purpose behavioral targeting solutions created restore single-origin serving caching resources cdn networks serving javascript also targeted way inject malicious content pages using sub-resource integrity mechanism created response ensure page loads script whose content known constrained hash referenced website author internet designed according end-to-end principle principle keeps core network relatively simple moves intelligence much possible network end-points hosts clients result core network specialized simplified optimized forward data packets content delivery networks augment end-to-end transport network distributing variety intelligent applications employing techniques designed optimize content delivery resulting tightly integrated overlay uses web caching server-load balancing request routing content services techniques briefly described web caches store popular content servers greatest demand content requested shared network appliances reduce bandwidth requirements reduce server load improve client response times content stored cache web caches populated based requests users pull caching based preloaded content disseminated content servers push caching server-load balancing uses one techniques including service-based global load balancing hardware-based i.e layer 4–7 switches also known web switch content switch multilayer switch share traffic among number servers web caches switch assigned single virtual ip address traffic arriving switch directed one real web servers attached switch advantage balancing load increasing total capacity improving scalability providing increased reliability redistributing load failed web server providing server health checks content cluster service node formed using layer 4–7 switch balance load across number servers number web caches within network request routing directs client requests content source best able serve request may involve directing client request service node closest client one capacity variety algorithms used route request include global server load balancing dns-based request routing dynamic metafile generation html rewriting anycasting proximity—choosing closest service node—is estimated using variety techniques including reactive probing proactive probing connection monitoring cdns use variety methods content delivery including limited manual asset copying active web caches global hardware load balancers several protocol suites designed provide access wide variety content services distributed throughout content network internet content adaptation protocol icap developed late 1990s provide open standard connecting application servers recently defined robust solution provided open pluggable edge services opes protocol architecture defines opes service applications reside opes processor executed remotely callout server edge side includes esi small markup language edge level dynamic web content assembly fairly common websites generated content could changing content like catalogs forums personalization creates problem caching systems overcome problem group companies created esi peer-to-peer p2p content-delivery networks clients provide resources well use means unlike client-server systems content centric networks actually perform better users begin access content especially protocols bittorrent require users share property one major advantages using p2p networks makes setup running costs small original content distributor content owners satisfied options costs commercial cdn service create cdn called private cdn private cdn consists pops points presence serving content owner pops caching servers reverse proxies application delivery controllers simple two caching servers large enough serve petabytes content large content distribution networks may even build set private network distribute copies content across cache locations private networks usually used conjunction public networks backup option case capacity private network enough failure leads capacity reduction since content distributed across many locations variety multicasting techniques may used reduce bandwidth consumption private networks also proposed select multicast trees according network load conditions efficiently utilize available network capacity rapid growth streaming video traffic uses large capital expenditures broadband providers order meet demand retain subscribers delivering sufficiently good quality experience address telecommunications service providers tsps begun launch content delivery networks means lessen demands network backbone reduce infrastructure investments networks video content transmitted telco cdns advantages traditional cdns last mile deliver content closer end user cached deep networks deep caching minimizes distance video data travels general internet delivers quickly reliably telco cdns also built-in cost advantage since traditional cdns must lease bandwidth build operator margin cost model addition operating content delivery infrastructure telco operators better control utilization resources content management operations performed cdns usually applied without limited information network e.g. topology utilization etc telco-operators interact business relationships pose number challenges telco-operators limited sphere actions face impact operations utilization resources contrast deployment telco-cdns allow operators implement content management operations enables better control utilization resources provide better quality service experience end users june 2011 streamingmedia.com reported group tsps founded operator carrier exchange ocx interconnect networks compete directly large traditional cdns like akamai limelight networks extensive pops worldwide way telcos building federated cdn offering interesting content provider willing deliver content aggregated audience federation likely near future telco cdn federations created grow enrollment new telcos joining federation bringing network presence internet subscriber bases existing ones august 2011 global consortium leading internet service providers led google announced official implementation edns-client-subnet ietf internet-draft intended accurately localize dns resolution responses initiative involves limited number leading dns cdn service providers edns-client-subnet edns0 option recursive dns servers cdns utilize ip address requesting client subnet resolving dns requests cdn relies ip address dns resolver instead client resolving dns requests incorrectly geo-locate client client using google anycast addresses dns resolver create latency problems initially google 8.8.8.8 dns addresses geo-located california potentially far location requesting client google public dns servers available worldwide generally speaking internet service providers provide content delivery network
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Distributed computing architecture
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sound blaster awe64 sound blaster advanced wave effects 64 isa sound card creative technology add-on board pcs card launched november 1996 sound blaster awe64 significantly smaller predecessor sound blaster awe32 offers similar feature set also notable improvements awe64 support greater polyphony awe32 unfortunately additional voices achieved via software-based processing system cpu technology called waveguide synthesizes instrument sounds rather using stored instrument patches like hardware voices demands processing power host system also equal quality available soundfonts inability adjust synthesis parameters unlike hardware portion awe64 also limited waveguide function usefulness another improvement comes better on-board circuitry increases signal-to-noise ratio overall signal quality compared frequently quite noisy awe32 sound blaster 16 boards improvement notable awe64 gold superior gold plated rca connector outputs improvement also comes increased integration components awe64 compared predecessors increased integration means board simpler trace routing components reduced decreasing amount noise-inducing signal travel also made possible reduce size awe64 board noticeably compared awe32 sound blaster awe32 boards allowed sample ram expansion installation 30-pin fast-page dram simms simms commodity items time awe32 awe64 used many applications including plain system ram creative control sale awe64 creative moved proprietary ram expansion modules manufactured sold memory boards priced rather high limited production also made quite difficult expand awe64 ram capacity since awe64 left production awe64 end basically revision awe32 quality components output improved cost manufacturing lessened functionality hardware nearly identical boards based around awe32 e-mu 8000 sample-based synthesis chipset e-mu effects processor creative audio dsp codec digital sound playback awe64 came two versions initially standard version later re-branded value 512kb ram gold version 4mb ram high quality 20-bit dac separate spdif output earlier revision standard value versions card ie model ct4500 all-black jacks later revision model ct4520 ac ’ 97 color coded jacks third version arrived later designed around pci bus offers features original isa awe64 pci interface built around even integrated asic made board even compact thus cheaper build unfortunately card time issue compatibility older legacy dos applications accessing pci audio cards ideally addressed creative created motherboard port called sb-link assisted pci bus working software looked legacy i/o resources isa sound cards without motherboard port card incompatible dos software awe64 pci later followed awe64d variant pci awe64 developed oems offered feature support awe64 cards including dos support issues awe64d quite compatible awe64 pci drivers however use separate driver packages awe64 mark ii also designed prototype boards drivers made card added 4 speaker surround sound games hardware dolby digital decoder six extra phono plugs sub center left rear right rear digital digital pass-through extra dolby decoder chips placed second board connected main board via ribbon cable project dropped favor sound blaster live cards due high expense solution aging isa interface response creative move towards proprietary memory module jeff briden created adapter board plugged awe64 allowed user install normal 30-pin simms awe-simm available several years starting 1998 longer available 1998 beijing luck star power machines co ltd. designed adapter board named simmconn could plugged awe64 allowed install single 72-pin simm module adapter came two variants simmconn value designed awe64 awe64 value simmconn gold designed awe64 gold although adapters longer ordered design manufacturing files remain available download personal non-commercial use
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Computer architecture
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goaccess goaccess open-source web analytics application unix-like operating systems text-based web application user interface provide real-time analytics continuously monitoring web server logs https //geekflare.com/monitor-analyze-access-logs-goaccess/
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Web technology
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sound blaster awe32 sound blaster awe32 isa sound card creative technology expansion board pcs part sound blaster family products sound blaster awe32 introduced march 1994 near full-length isa sound card measuring 14 inches 356 mm length due number features included awe32 digital audio section basically entire sound blaster 16 compatible creative earlier sound blaster 2.0 minus c/ms audio chips specifications included 16-bit 44.1 khz ad/da conversion real-time on-board compression decompression yamaha opl3 fm synthesizer chip however compatibility always perfect situations various bugs could arise games many sound blaster awe32 cards codecs supported bass treble gain adjustments creative included mixer software many variants revisions awe32 however numerous variations audio chipset amplifier selection design supported features example sound blaster awe32 boards utilize vibra chip bass treble adjustments sound blaster awe32 included two distinct audio sections one creative digital audio section audio codec optional csp/asp chip socket second e-mu midi synthesizer section synthesizer section consisted emu8000 synthesizer effects processor chip 1 mib emu8011 sample rom variable amount ram none sb32 512 kib awe32 ram expandable 28 mib cards chips comprised powerful flexible sample-based synthesis system based e-mu high-end sampler systems e-mu emulator iii e-mu proteus effects processor generated various effects i.e reverb chorus environments midi output similar later eax standard live newer cards also add effects output yamaha opl-3 fm synthesis awe32 first sampler support e-mu soundfont standard allowed users build custom sound sets using samples samples included rom card sold software building custom soundfonts creative subsequent cards sound blaster pci64/128 series support soundfonts initial release creative promoted emu8000 waveguide physical modelling synthesis engine due ability work delay lines option used mostly effect engine chorus flanging effects actual physical modeling instruments popular awe although support exists soundfont format awe32 n't use mpu-401 port access emu8000—creative decided expose emu8000 registers directly three sets non-standard ports interpret midi commands software host cpu gravis ultrasound software designers write special awe32 support programs support older software awe32 featured opl-3 fm synthesis came aweutil program attempted provide gm/mt-32/gs redirection native awe hardware however aweutil n't compatible programs motherboards due use non-maskable interrupt feature omitted disabled many clone boards used lot precious dos conventional memory also game used dos 32-bit protected mode non-dpmi compliant dos extender mpu-401 emulation would function emu8000 would used unless directly supported software affect creative wave blaster daughterboard header awe32 usage windows simplified fact windows 3.1x drivers made opl3 emu8000 appear like another midi peripheral midi interfaces sound blaster awe32 value another value-oriented offering lacked simm slots asp processor featured 512kb onboard ram empty asp chip socket also awe32 panasonic/sony/mitsumi cd-rom interface support proprietary non-atapi cd-rom drives wave blaster header two 30-pin simm slots increase sample memory later sound blaster awe32 revisions replaced proprietary cd-rom interfaces atapi interface sound blaster awe32 supported 28 mb additional simm memory maximum 32 mb could added sound blaster awe32 synthesizer could address 4mb emu8000 address space reserved sample rom following model numbers assigned sound blaster awe32 sound blaster 32 sb32 value-oriented offering creative announced june 6 1995 designed fit awe32 value lineup sb32 lacked onboard ram wave blaster header csp socket boards also used vibra integrated audio chips lacked adjustments bass treble gain sb32 midi capabilities awe32 30-pin simm ram expansion capability board also fully compatible awe32 option software used windows drivers sb32 outfitted 30-pin simms sampler section performed identically awe32 opl-3 support varied among models ct3930 came yamaha ymf262 opl-3 fm synthesis chip whereas models feature cqm synthesis either integrated vibra chip via external ct1978 chip majority sound blaster 32 cards used tda1517 amplifiers sound blaster 32 pnp onboard 512kb ram sold awe32 oem dell computers following model numbers assigned sound blaster 32
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Computer architecture
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robert slade robert michael slade also known robert m. slade rob slade canadian information security consultant researcher instructor author robert slade guide computer viruses software forensics dictionary information security co-author viruses revealed slade author thousands technical book reviews today published techbooks mailing list risks digest archived internet review project expert computer viruses malware also mr. slade mr. slade lists slade married gloria j. slade edits much work editor slade book reviews grandchildren appear field every review 2008 rob grandpa ryan trevor devon hannah holds bachelor degree university british columbia master computer information science education university oregon diploma christian studies regent college slade became one small number researchers called world experts malware fred cohen named slade early work organizing computer viruses software bbses book reviews mr. slade lists slade one fewer thirty people worldwide credited contributions final version virus-l faq usenet group comp.virus virus-l mailing list public group record computer virus issues 1988 1995 1996 maintained antiviral software evaluation faq quick reference users seeking antivirus software vendor contacts list contributor well least three group computer virus faqs web came prominence written two books viruses sole author robert slade guide computer viruses first published 1994 2nd edition 1996 co-wrote viruses revealed david harley urs gattiker 2001 slade advanced field computer forensics antivirus research found intentions identity virus authors discovered program code created first course ever offered forensic programming book software forensics published 2004 chapter subject print information security management handbook fifth edition today slade consultant businesses government—among client list fortune 500 companies government canada—as well educational institutions created curricula taught courses simon fraser university macdonald dettwiler university phoenix slade creates seminars local federal international training groups senior instructor isc ² develops courses information security quality assurance qa seek certification slade one world approximately 60,000 cissps certification used private industry well least united states government defense slade moved online security glossary 2006 book dictionary information security virus bulletin remarked unusual collection five forewords many acknowledged experts willing contribute says something author standing field —the forewords written fred cohen jack holleran peter g. neumann harold tipton gene spafford dictionary considered dependable baseline definitions citable common source slade surveyed literature field shared knowledge internet review project published book reviews perhaps widely known reviews works gave first priority information security reviews often critical—to project faq question n't like books slade replied may cruel fair
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Computer security
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opencable application platform opencable application platform ocap operating system layer designed consumer electronics connect cable television system java-based middleware portion platform unlike operating systems personal computer cable company controls ocap programs run consumer machine designed cablelabs cable networks north america ocap programs intended interactive services ecommerce online banking electronic program guides digital video recording cable companies required ocap part cablecard 2.0 specification proposal controversial approved federal communications commission cable companies stated two-way communications third party devices networks require support ocap consumer electronics association groups argue ocap intended block features compete cable company provided services consumers entitled add delete otherwise control programs personal computers january 8 2008 cablelabs announced tru2way brand opencable platform including ocap application platform ocap java based software/middleware portion opencable initiative ocap based globally executable mhp gem -standard defined cablelabs ocap based gem lot common multimedia home platform mhp -standard defined dvb project present two versions ocap standard exist
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Operating systems
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real server real server relational database management system rdbms built top sqlite database engine real server evolved sqliteserver originally developed sqlabs 2004 may 2005 real software inc. creator realbasic purchased source code copyrights sqliteserver invested development 2007/2008 first version real sql server released new version released april 2009 renamed real server september 2010 sqlabs repurchased server intellectual properties new major release development sqlabs team real server used following
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Databases
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bobcat microarchitecture amd bobcat family 14h microarchitecture created amd amd apus aimed low-power/low-cost market revealed speech amd executive vice-president henri richard computex 2007 put production q1 2011 one major supporters executive vice-president mario a. rivas felt difficult compete x86 market single core optimized 10–100 w range actively promoted development simpler core target range 1–10 w. addition believed core could migrate hand-held space power consumption reduced less 1 w. bobcat cores used together gpu cores accelerated processing units apus fusion brand simplified architecture diagram released amd analyst day november 2009 similar concept earlier amd research 2003 detailing specifications advantages extending x86 everywhere bobcat x86 cpu core design since completed implemented amd apu processor products tdp 18 w less core targeted low-power markets like netbooks/nettops ultra-portable laptops consumer electronics embedded market since launch bobcat-based cpus also used oems larger laptops architecture specifics february 2013 amd detailed plans successor bobcat codenamed jaguar january 2011 amd introduced several processors implemented bobcat core core following amd accelerated processors e-series c-series standard parts g-series embedded parts
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Computer architecture
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sunwah linux rays linux previously sun wah linux chinese debian-based linux distribution sunwah linux debian-based distribution first chinese linux distribution receive linux standard base lsb certification system architecture designed hong kong programming developed nanjing distribution sponsored sunwah group hong kong jiangsu provincial government china sunwah pearl linux abbreviated swp technology training entity group providing research assistance testing training support distribution swp joint establishment hong kong polytechnic university sunwah group 2005 sunwah linux installed 140,000 pcs primary secondary schools china april 2006 sunwah linux best linux desktop application award linuxworld conference expo boston according albert chung presented distribution judges competition fierce proud chinese linux desktop distribution recognized industry experts judges
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Operating systems
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apache mahout apache mahout project apache software foundation produce free implementations distributed otherwise scalable machine learning algorithms focused primarily areas collaborative filtering clustering classification many implementations use apache hadoop platform mahout also provides java libraries common maths operations focused linear algebra statistics primitive java collections mahout work progress number implemented algorithms grown quickly various algorithms still missing mahout core algorithms clustering classification batch based collaborative filtering implemented top apache hadoop using map/reduce paradigm restrict contributions hadoop-based implementations contributions run single node non-hadoop cluster also welcomed example 'taste collaborative-filtering recommender component mahout originally separate project run stand-alone without hadoop starting release 0.10.0 project shifted focus building backend-independent programming environment code named samsara environment consists algebraic backend-independent optimizer algebraic scala dsl unifying in-memory distributed algebraic operators supported algebraic platforms apache spark h2o apache flink support mapreduce algorithms started gradually phased 2014
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Distributed computing architecture
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trusted path trusted path trusted channel mechanism provides confidence user communicating user intended communicate ensuring attackers ca n't intercept modify whatever information communicated term initially introduced orange book security architecture concept implemented technical safeguards suitable particular environment risk profile common criteria european union electronic signature standards trusted path trusted channel describe techniques prevent interception tampering sensitive data passes various system components one popular techniques password stealing microsoft windows login spoofing based programs simulated operating system login prompt users try log fake login program capture user passwords later use safeguard windows nt introduced ctrl-alt-del sequence secure attention key escape third party programs invoke system login prompt similar problem arises case websites requiring authentication user expected enter credentials without actually knowing website spoofed https mitigates attack first authenticating server user using trust anchor certification path validation algorithm displaying login form
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Computer security
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dave resurrector dave resurrector so-called resurrector bot responded attempts canceling message usenet newsgroup news.admin.net-abuse re-posting message written chris lewis bot notable one first escalations spam arms race
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Computer security
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gmer gmer software tool written polish researcher przemysław gmerek detecting removing rootkits runs microsoft windows support windows nt 2000 xp vista 7 8 10 version 2.0.18327 full support windows x64 added time first release 2004 introduced innovative rootkit detection techniques quickly gained popularity effectiveness incorporated antivirus tools including avast antivirus sdfix several months 2006 2007 tool website target heavy ddos attacks attempting block downloads
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Computer security
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amplitude-shift keying amplitude-shift keying ask form amplitude modulation represents digital data variations amplitude carrier wave ask system binary symbol 1 represented transmitting fixed-amplitude carrier wave fixed frequency bit duration seconds signal value 1 carrier signal transmitted otherwise signal value 0 transmitted digital modulation scheme uses finite number distinct signals represent digital data ask uses finite number amplitudes assigned unique pattern binary digits usually amplitude encodes equal number bits pattern bits forms symbol represented particular amplitude demodulator designed specifically symbol-set used modulator determines amplitude received signal maps back symbol represents thus recovering original data frequency phase carrier kept constant like ask also linear sensitive atmospheric noise distortions propagation conditions different routes pstn etc ask modulation demodulation processes relatively inexpensive ask technique also commonly used transmit digital data optical fiber led transmitters binary 1 represented short pulse light binary 0 absence light laser transmitters normally fixed bias current causes device emit low light level low level represents binary 0 higher-amplitude lightwave represents binary 1 simplest common form ask operates switch using presence carrier wave indicate binary one absence indicate binary zero type modulation called on-off keying ook used radio frequencies transmit morse code referred continuous wave operation sophisticated encoding schemes developed represent data groups using additional amplitude levels instance four-level encoding scheme represent two bits shift amplitude eight-level scheme represent three bits forms amplitude-shift keying require high signal-to-noise ratio recovery nature much signal transmitted reduced power ask system divided three blocks first one represents transmitter second one linear model effects channel third one shows structure receiver following notation used different symbols represented different voltages maximum allowed value voltage possible values range −a given difference one voltage considering picture symbols v n generated randomly source impulse generator creates impulses area v n impulses sent filter ht sent channel words symbol different carrier wave sent relative amplitude transmitter signal expressed form receiver filtering hr signal use notation indicates convolution two signals a/d conversion signal z k expressed form relationship second term represents symbol extracted others unwanted first one effect noise third one due intersymbol interference filters chosen g satisfy nyquist isi criterion intersymbol interference value sum zero transmission affected noise probability density function error given size modelled gaussian function mean value relative sent value variance given formula_9 spectral density noise within band hr f continuous fourier transform impulse response filter hr f probability making error given example formula_11 conditional probability making error given symbol v0 sent formula_12 probability sending symbol v0 probability sending symbol represent probability density functions plot possible value voltage transmitted get picture like particular case formula_14 shown probability making error single symbol sent area gaussian function falling functions symbols shown cyan one call formula_15 area one side gaussian sum areas formula_16 total probability making error expressed form calculate value formula_15 order move origin reference wherever want area function change situation like one shown following picture matter gaussian function considering area want calculate value looking given following integral formula_20 complementary error function putting results together probability make error formula_21 formula easily understand probability make error decreases maximum amplitude transmitted signal amplification system becomes greater hand increases number levels power noise becomes greater relationship valid intersymbol interference i.e formula_22 nyquist function
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Computer security
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dm-cache dm-cache component specifically target linux kernel device mapper framework mapping block devices onto higher-level virtual block devices allows one fast storage devices flash-based solid-state drives ssds act cache one slower storage devices hard disk drives hdds effectively creates hybrid volumes provides secondary storage performance improvements design dm-cache requires three physical storage devices creation single hybrid volume dm-cache uses storage devices separately store actual data cache data required metadata configurable operating modes cache policies latter form separate modules determine way data caching actually performed dm-cache licensed terms gnu general public license gpl joe thornber heinz mauelshagen mike snitzer primary developers dm-cache uses solid-state drives ssds additional level indirection accessing hard disk drives hdds improving overall performance using fast flash-based ssds caches slower mechanical hdds based rotational magnetic media result costly speed ssds becomes combined storage capacity offered slower less expensive hdds moreover case storage area networks sans used cloud environments shared storage systems virtual machines dm-cache also improve overall performance reduce load sans providing data caching using client-side local storage dm-cache implemented component linux kernel device mapper volume management framework allows various mappings created physical virtual block devices way mapping devices created determines virtual blocks translated underlying physical blocks specific translation types referred targets acting mapping target dm-cache makes possible ssd-based caching part created virtual block device configurable operating modes cache policies determine dm-cache works internally operating mode selects way data kept sync hdd ssd cache policy selectable separate modules implement policies provides algorithm determining blocks promoted moved hdd ssd demoted moved ssd hdd cleaned etc configured use multiqueue mq stochastic multiqueue smq cache policy latter default dm-cache uses ssds store data associated performed random reads writes capitalizing near-zero seek times ssds avoiding i/o operations typical hdd performance bottlenecks data associated sequential reads writes cached ssds avoiding undesirable cache invalidation operations performance-wise beneficial sequential i/o operations suitable hdds due mechanical nature caching sequential i/o also helps extending lifetime ssds used caches another dm-cache project similar goals announced eric van hensbergen ming zhao 2006 result internship work ibm later joe thornber heinz mauelshagen mike snitzer provided implementation concept resulted inclusion dm-cache linux kernel dm-cache merged linux kernel mainline kernel version 3.9 released april 28 2013 dm-cache creating mapped virtual block device acts hybrid volume requires three physical storage devices internally dm-cache references origin devices number fixed-size blocks size blocks equaling size caching extent configurable creation hybrid volume size caching extent must range 32 kb 1 gb must multiple 32 kb typically size caching extent 256 1024 kb choice caching extents bigger disk sectors acts compromise size metadata possibility wasting cache space small caching extents increases size metadata metadata device kernel memory large caching extents increases amount wasted cache space due caching whole extents even case high hit rates parts operating modes supported dm-cache write-back default write-through pass-through write-back operating mode writes cached blocks go cache device blocks origin device marked dirty metadata write-through operating mode write requests returned completed data reaches origin cache devices clean blocks becoming marked dirty pass-through operating mode reads performed directly origin device avoiding cache writes go directly origin device cache write hits also cause invalidation cached blocks pass-through mode allows hybrid volume activated state cache device known consistent origin device rate data migration dm-cache performs directions i.e. data promotions demotions throttled configured speed regular i/o origin cache devices preserved decommissioning hybrid volume shrinking cache device requires use cleaner policy effectively flushes blocks marked metadata dirty cache device origin device version 4.2 linux kernel following three cache policies distributed linux kernel mainline dm-cache default uses stochastic multiqueue policy
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Operating systems
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vex prefix vex prefix vector extensions vex coding scheme comprising extension x86 x86-64 instruction set architecture microprocessors intel amd others vex coding scheme allows definition new instructions extension modification previously existing instruction codes serves following purposes vex prefix replaces commonly used instruction prefix bytes escape codes many cases number prefix bytes escape bytes replaced number bytes vex prefix total length vex-encoded instruction length legacy instruction code cases vex-encoded version longer shorter legacy code 32-bit mode vex encoded instructions access first 8 ymm/xmm registers encodings registers would interpreted legacy lds les instructions supported 64-bit mode two-byte vex prefix contains following components three-byte vex prefix additionally contains vex coding scheme uses code prefix consisting two three bytes added existing new instruction codes x86 architecture instructions memory operand may use modr/m byte specifies addressing mode byte three bit fields base-plus-index scale-plus-index forms 32-bit addressing encoded r/m=100 mod 11 require another addressing byte sib byte following fields use 64-bit addressing additional registers present x86-64 architecture rex prefix introduced provides additional space encoding addressing modes bit-field w expands operand size 64 bits r expands reg b expands r/m reg depending opcode format used x b expand index base sib byte however rex prefix encoded quite inefficiently wasting half 8 bits vex prefix provides compact representation rex prefix well various prefixes expand addressing mode register enumeration operand size width vex prefix initial-byte values c4h c5h opcodes lds les instructions instructions supported 64-bit mode resolve ambiguity 32-bit mode vex specification exploits fact legal lds les modrm byte form 11xxxxxx would specify register operand various bit-fields vex prefix second byte inverted ensure byte always form 32-bit mode instructions need three operands extra suffix byte specifying one two additional register operands instructions coded vex prefix five operands one operands memory operand one operands immediate constant 4 8 bits remaining operands registers avx instruction set first instruction set extension use vex coding scheme avx instructions four operands avx instruction set allows vex prefix applied instructions using simd xmm registers however vex coding scheme space applying vex prefix instructions well future instruction sets legacy simd instructions vex prefix added equivalent instructions without vex prefix following differences instructions use whole 256-bit ymm register mixed non-vex instructions leave upper half register unchanged reasons efficiency
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Computer architecture
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fdm group fdm group international professional services company headquartered london united kingdom offices leeds glasgow brighton new york city toronto reston frankfurt hong kong singapore australia china composed mostly university graduates returners work ex-military personnel 'trained fdm group academies working consultants one fdm group ’ clients primarily financial institutions banks around world listed london stock exchange constituent ftse 250 index company founded brighton rod flavell julian jacqueline divett 1991 company focused recruitment acquiring mountfield software 1995 1998 name changed fdm group reflect acquisition company began hiring training placing consultants on-site clients april 2005 fdm group floated alternative investment market raising £3m net company 2010 company completed management buyout bring company private june 2014 fdm flotation time valued £308m london stock exchange fdm group remains publicly traded london stock exchange today 2015 company opened new offices city centres leeds glasgow fdm group ’ model involves recruiting recent university graduates returners work ex-forces turn consultants clients individuals go 6–14 weeks paid training one fdm group ’ academy facilities signing two-year contract company work consultant consultants employees work site clients include mostly banking finance industry fdm group women initiative focused hiring inspiring women pursue jobs stem fields part efforts sponsored 2013 2014 2015 2016 everywoman technology awards london fdm group also ex-forces initiative began new york academy veterans initiative partnered british forces resettlement services signed ministry defence armed forces corporate covenant well us army memorandum agreement army pays programme new york fdm group sponsored wall street rocks charity concert marched veterans day parade support cause helping veterans find jobs fdm group two academies located united states one academy new york opened 2011 located 14 wall street new york new york 10005 2016 fdm group opened training center virginia located 1805 library street reston va 20190 february 2016 class action lawsuit filed united states district court southern new york grace park fdm group holdings plc fdm group inc. alleging state wage violations us fair labor standards act flsa march 2017 united states district court southern new york found favor fdm group motion dismissal finding fdm group correctly classified academy trainees non-employees therefore entitled compensation court also found termination fee stipulated training agreement signed park 30,000 constitute kickback park failed provide sufficient details regarding unpaid work april 2017 park filed appeal 2nd circuit court appeals park v. fdm group inc. case number 17-1030
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Web technology
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lumension security lumension security inc. part software company ivanti lumension products include endpoint management security software providing endpoint protection vulnerability management data protection application whitelisting encryption usb security risk management lumension largely focused providing security organizations businesses 2017 lumension part merger landesk heat software create new software company called ivanti lumension founded high tech software 1991 company rebranded patchlink corporation 1999 adopted lumension name 2007 2015 frontrange lumension combined create heat software 2017 heat landesk combined create ivanti lumension products traditionally competed endpoint management security industry sophos mcafee kaspersky lab symantec trend micro among others
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Computer security
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ike nassi isaac robert ike nassi born 1949 brooklyn new york currently ceo tidalscale inc. campbell ca adjunct professor computer science university california santa cruz formerly executive vice president chief scientist sap ag practice lead sap research technology infrastructure practice focused guiding sap technology infrastructure vision direction execution group also responsible sap sponsored academic research program probably best known creating ben shneiderman highly influential nassi–shneiderman diagram notation also helped design ada programming language prior work tidalscale sap nassi helped start three companies firetide infogear technology encore computer co-founded wireless mesh company firetide served executive vice president chief technology officer cto chairman board nassi cto head product operations infogear prior acquisition cisco systems helped start encore computer pioneer symmetric multiprocessors forerunner today multicore processors addition start-up experience nassi held executive position cisco systems following acquisition infogear technology joined apple inc. run new advanced technology group research lab cambridge near mit work dylan programming language intended apple newton become vp development tools california become senior vice president software launch mklinux become corporate officer served boards taligent opendoc foundation also held executive senior management roles visual technology tewkesbury digital equipment corporation softech nassi serves active member board trustees computer history museum mountain view california formerly served board anita borg institute women technology member industry advisory board ieee computer society member advisory boards northwestern university stony brook university peking university visiting scholar stanford university u.c berkeley recently visiting scientist mit nassi holds several patents certificate distinguished service department defense work design ada programming language member defense advanced research projects agency information systems technology group testified congress emerging telecommunications act 1991 nassi holds memberships ieee acm earned bachelor degree mathematics master degree doctorate computer science stony brook university new york
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Programming language topics
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shell script shell script computer program designed run unix shell command-line interpreter various dialects shell scripts considered scripting languages typical operations performed shell scripts include file manipulation program execution printing text script sets environment runs program necessary cleanup logging etc called wrapper term also used generally mean automated mode running operating system shell specific operating systems called things batch files msdos-win95 stream os/2 command procedures vms shell scripts windows nt stream third-party derivatives like 4nt—article cmd.exe mainframe operating systems associated number terms typical unix/linux/posix-compliant installation includes kornshell codice_1 several possible versions ksh88 korn shell '93 others oldest shell still common use bourne shell codice_2 unix systems invariably also include c shell codice_3 bash codice_4 remote shell codice_5 secure shell codice_6 ssl telnet connections shell main component tcl/tk installation usually called codice_7 wish gui-based tcl/tk shell c tcl shells syntax quite similar said programming languages korn shells bash developments bourne shell based algol language elements number others added well hand various shells plus tools like awk sed grep basic lisp c forth contributed perl programming language shells available machine available download and/or purchase include almquist shell codice_8 powershell codice_9 z shell codice_10 particularly common enhanced kornshell tenex c shell codice_11 perl-like shell codice_12 related programs shells based python ruby c java perl pascal rexx c various forms also widely available another somewhat common shell osh whose manual page states enhanced backward-compatible port standard command interpreter sixth edition unix windows-unix interoperability software mks toolkit cygwin uwin interix others make shells unix programming available windows systems providing functionality way signals inter-process communication system calls apis hamilton c shell windows shell similar unix c shell microsoft distributes windows services unix use nt-based operating systems particular posix environmental subsystem shell script provide convenient variation system command special environment settings command options post-processing apply automatically way allows new script still act fully normal unix command one example would create version ls command list files giving shorter command name l would normally saved user bin directory /home/ username /bin/l default set command options pre-supplied first line shebang indicates interpreter execute rest script second line makes listing options file format indicators columns files none omitted size blocks lc_collate=c sets default collation order fold upper lower case together intermix dotfiles normal filenames side effect ignoring punctuation names dotfiles usually shown option like -a used causes parameters given l pass parameters ls normal options syntax known ls still used user could simply use l commonly used short listing another example shell script could used shortcut would print list files directories within given directory case shell script would start normal starting line /bin/sh following script executes command clear clears terminal text going next line following line provides main function script ls -al command lists files directories directory script run ls command attributes could changed reflect needs user note implementation clear command try using clr command instead shell scripts allow several commands would entered manually command-line interface executed automatically without wait user trigger stage sequence example directory three c source code files rather manually running four commands required build final program one could instead create c shell script named build kept directory would compile automatically script would allow user save file edited pause editor run ./build create updated program test return editor since 1980s however scripts type replaced utilities like make specialized building programs simple batch jobs unusual isolated tasks using shell loops tests variables provides much flexibility users bash unix shell script convert jpeg images png images image names provided command-line—possibly via wildcards—instead listed within script created file typically saved file like /home/ username /bin/jpg2png jpg2png command run entire directory full jpeg images /home/ username /bin/jpg2png *.jpg key feature shell scripts invocation interpreters handled core operating system feature rather user shell able execute scripts shell language script interpreter directive handled correctly run shell limitations early bourne shell handling scripts shell scripts set executed os modern shell script footing system commands rather many system commands actually shell scripts generally scripts since interpreted shell instead perl python language extends returning exit codes like system utilities indicate success failure allows called components larger programs regardless larger tools implemented like standard system commands shell scripts classically omit kind filename extension unless intended read running shell special mechanism purpose sh ’ codice_13 csh ’ source many modern shells also supply various features usually found sophisticated general-purpose programming languages control-flow constructs variables comments arrays subroutines sorts features available possible write reasonably sophisticated applications shell scripts however still limited fact shell languages little support data typing systems classes threading complex math common full language features also generally much slower compiled code interpreted languages written speed performance goal standard unix tools sed awk provide extra capabilities shell programming perl also embedded shell scripts scripting languages like tcl perl tcl come graphics toolkits well many powerful scripting languages introduced tasks large complex comfortably handled ordinary shell scripts advantages script desirable development overhead full-blown compiled programming language would disadvantageous specifics separates scripting languages high-level programming languages frequent source debate generally speaking scripting language one requires interpreter shell scripts often serve initial stage software development often subject conversion later different underlying implementation commonly converted perl python c. interpreter directive allows implementation detail fully hidden inside script rather exposed filename extension provides seamless reimplementation different languages impact end users files .sh file extension usually shell script kind shell scripts filename extension perhaps biggest advantage writing shell script commands syntax exactly directly entered command-line programmer switch totally different syntax would script written different language compiled language used often writing shell script much quicker writing equivalent code programming languages many advantages include easy program file selection quick start interactive debugging shell script used provide sequencing decision-making linkage around existing programs moderately sized scripts absence compilation step advantage interpretive running makes easy write debugging code script re-run detect fix bugs non-expert users use scripting tailor behavior programs shell scripting provides limited scope multiprocessing hand shell scripting prone costly errors inadvertent typing errors rm -rf instead intended rm -rf */ folklore unix community single extra space converts command one deletes everything sub-directories one deletes everything—and also tries delete everything root directory similar problems transform cp mv dangerous weapons misuse redirect delete contents file made problematic fact many unix commands differ name one letter cp cd dd df etc another significant disadvantage slow execution speed need launch new process almost every shell command executed script job accomplished setting pipeline efficient filter commands perform work slowdown mitigated complex script typically several orders magnitude slower conventional compiled program performs equivalent task also compatibility problems different platforms larry wall creator perl famously wrote easier port shell shell script similarly complex scripts run limitations shell scripting language limits make difficult write quality code extensions various shells ameliorate problems original shell language make problems worse many disadvantages using script languages caused design flaws within language syntax implementation necessarily imposed use text-based command-line number shells use shell programming languages even full-fledged languages like scsh uses scheme interoperability software cygwin mks toolkit interix available microsoft windows services unix hamilton c shell uwin unix windows others allow unix shell programs run machines running windows nt successors loss functionality ms-dos-windows 95 branch well earlier mks toolkit versions os/2 least three dcl implementations windows type operating systems—in addition xlnt multiple-use scripting language package used command shell windows script host cgi programming—are available systems well mac os x subsequent unix-like well addition aforementioned tools posix os/2 functionality used corresponding environmental subsystems windows nt operating system series windows 2000 well third 16-bit subsystem often called ms-dos subsystem uses command.com provided operating systems run aforementioned ms-dos batch files console alternatives 4dos 4os2 freedos peter norton ndos 4nt take command add functionality windows nt-style cmd.exe ms-dos/windows 95 batch files run command.com os/2 cmd.exe 4nt respectively similar shells enhance integrated windows script host comes three pre-installed engines vbscript jscript vba numerous third-party engines added rexx perl python ruby tcl pre-defined functions 4nt related programs pc dos quite similar ms-dos whilst dr dos different earlier versions windows nt able run contemporary versions 4os2 os/2 subsystem scripting languages definition able extended example ms-dos/windows 95/98 windows nt type systems allows shell/batch programs call tools like kixtart qbasic various basic rexx perl python implementations windows script host installed engines unix posix-compliant systems awk sed used extend string numeric processing ability shell scripts tcl perl rexx python graphics toolkits used code functions procedures shell scripts pose speed bottleneck c fortran assembly language c much faster still add functionality available shell language sockets connectivity functions heavy-duty text processing working numbers calling script abilities self-writing self-modifying code techniques like recursion direct memory access various types sorting difficult impossible main script visual basic applications vbscript used control communicate things spreadsheets databases scriptable programs types telecommunications software development tools graphics tools software accessed component object model
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Programming language topics
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universal windows platform apps universal windows platforms uwp apps formerly windows store apps metro-style apps applications used across compatible microsoft windows devices including personal computers pcs tablets smartphones xbox one microsoft hololens internet things uwp software primarily purchased downloaded via microsoft store starting windows 10 windows uses windows app refer uwp apps app installed microsoft store formerly windows store trusted windows store app computer programs running desktop computer desktop apps terms universal windows platform uwp uwp app appear microsoft documentation developers microsoft started retrospectively use windows runtime app refer precursors uwp app unambiguous name windows software first became available name metro-style apps windows store opened 2012 marketed windows 8 windows 8.x metro-style apps run window instead either occupy entire screen snapped one side case occupy entire height screen part width title bar system menu window borders control buttons command interfaces like scroll bars usually hidden first menus located settings charm metro-style apps use ui controls windows 8.x typically follow windows 8.x ui guidelines horizontal scrolling inclusion edge-uis like app bar response criticism customers windows 8.1 title bar present hidden unless users move mouse cursor top screen hamburger menu button title bar gives access charms users point entry metro-style apps windows store enterprises operating windows domain infrastructure may enter contract microsoft allows sideload line-of-business metro-style apps circumventing windows store also major web browser vendors google mozilla foundation selectively exempted rule allowed circumvent microsoft guidelines windows store run metro-style version user chooses make product default web browser metro-style apps third-party apps run windows rt traditional third-party apps run operating system windows 8 computer programs identified static computer icons windows taskbar responsible representing every app window run metro-style apps however identified tiles show icon also dynamic contents addition windows 8 windows 8.1 rtm shown windows taskbar run dedicated app switcher left side screen windows 8.1 update restored taskbar icons metro-style apps set limit many copies desktop apps run simultaneously example one user may run many copies programs notepad paint firefox system resources support desktop apps windows media player designed allow single instance enforced operating system however windows 8 one copy metro-style apps may run given time invoking app brings running instance front true multi-instancing apps available windows 10 version 1803 released may 2018 windows 10 brings significant changes uwp apps look work uwp apps look depends app uwp apps built specifically windows 10 typically distinct look feel use new ui controls look different previous versions windows exception apps use custom ui especially case video games apps designed windows 8.x look significantly different designed windows 10 uwp apps also look almost identical traditional desktop apps using legacy ui controls windows versions dating back windows 95 legacy desktop apps converted uwp apps distributed using appx file format windows 10 uwp apps even designed windows 8.x run floating windows users use windows taskbar task view switch uwp apps desktop apps windows 10 also introduced continuum tablet mode mode default disabled desktop computers enabled tablet computers desktop users switch manually tablet mode apps may resizable windows visible title bars tablet mode enabled resizable apps use windowing system similar metro-style apps windows 8.x forced either occupy whole screen snapped one side uwp apps windows 10 open multiple windows microsoft edge calculator photos examples apps allow windows 10 v1803 released may 2018 added true multi-instancing capabilities multiple independent copies uwp app run uwp apps downloaded windows store sideloaded another device sideloading requirements reduced significantly windows 8.x 10 app must still signed trusted digital certificate chains root certificate metro-style apps suspended closed suspended apps terminated automatically needed windows app manager dynamic tiles background components contracts interfaces interacting apps may require app activated user starts six years invoking arbitrary metro-style app uwp app command line supported feature first introduced insider build 16226 windows 10 released 21 june 2017 traditionally windows software developed using windows api software access api arbitrary restrictions developers free choose programming language development tools metro-style apps however developed using windows runtime winrt calling forbidden api disqualifies app appearing windows store every app using winrt metro-style app limited subset winrt available desktop apps metro-style apps developed using microsoft development tools according allen bauer chief scientist embarcadero technologies apis every computer program must call microsoft forbidden except call comes microsoft visual c++ runtime apps developed work intrinsically smartphones personal computers video game consoles hololens called universal apps accomplished using universal app api first introduced windows 8.1 windows phone 8.1 visual studio 2013 update 2 could used develop apps windows 10 introduced universal windows platform uwp 10 developing universal apps apps take advantage platform developed visual studio 2015 later older metro-style apps windows 8.1 windows phone 8.1 universal 8.1 need modifications migrate platform uwp distinct windows runtime rather extension universal apps longer indicate written specific os manifest instead target one device families e.g desktop mobile xbox internet things iot react capabilities become available device universal app may run small mobile phone tablet provide suitable experience universal app running mobile phone may start behaving way would tablet phone connected monitor suitable docking station appx file format used distribute install apps windows 8.x 10 windows phone 8.1 windows 10 mobile xbox one hololens windows 10 iot core unlike legacy desktop apps appx installation system allowed uwp apps replaces xap file format windows phone 8.1 attempt unify distribution apps windows phone windows 8 appx files compatible windows phone 8.1 later versions windows 8 later versions windows phone 8.x marketplace allows users download appx files sd card install manually contrast sideloading prohibited windows 8.x unless user developers license business domain traditionally windows software power use change ecosystem however wanted windows user account rights user account control antivirus software attempt keep ability check notify user app tries use malicious purposes metro-style apps however sandboxed permanently change windows ecosystem need permission access hardware devices webcam microphone file system access restricted user folders documents microsoft moderates programs may remove windows store discovered security privacy issues
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Operating systems
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comparison relational database management systems following tables compare general technical information number relational database management systems please see individual products articles information unless otherwise specified footnotes comparisons based stable versions without add-ons extensions external programs style= width:16em maintainer first public release date latest stable version latest release date license public issues list style= text-align left 4d 4th dimension style= text-align left adabas style= text-align left adaptive server enterprise style= text-align left advantage database server ads style= text-align left altibase style= text-align left apache derby style= text-align left clustrixdb style= text-align left cubrid style= text-align left datacom style= text-align left db2 style= text-align left empress embedded database style= text-align left exasolution style= text-align left filemaker style= text-align left firebird style= text-align left gpudb style= text-align left hsqldb style= text-align left h2 style= text-align left informix dynamic server style= text-align left ingres style= text-align left interbase style= text-align left linter sql rdbms style= text-align left luciddb style= text-align left mariadb style= text-align left maxdb style= text-align left microsoft access jet style= text-align left microsoft visual foxpro style= text-align left microsoft sql server style= text-align left microsoft sql server compact embedded database style= text-align left mimer sql style= text-align left monetdb style= text-align left msql style= text-align left mysql style= text-align left memsql style= text-align left nexusdb style= text-align left hp nonstop sql style= text-align left nuodb style= text-align left omnis studio style= text-align left openbase sql style= text-align left openedge style= text-align left openlink virtuoso style= text-align left oracle db style= text-align left oracle rdb style= text-align left paradox style= text-align left percona server mysql style= text-align left pervasive psql style= text-align left polyhedra dbms style= text-align left postgresql style= text-align left style= text-align left raima database manager style= text-align left rdm server style= text-align left sap hana style= text-align left soliddb style= text-align left sql anywhere style= text-align left sqlbase style= text-align left sqlite style= text-align left sqream db style= text-align left superbase style= text-align left teradata style= text-align left tibero style= text-align left tidb
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Databases
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bitly bitly url shortening service link management platform company bitly inc. established 2008 privately held based new york city bitly shortens 600 million links per month use social networking sms email bitly makes money charging access aggregate data created result many people using shortened urls 2017 spectrum equity acquired majority stake bitly 64 million august 2018 bitly shortened 37.5 billion urls bitly url shortening service became popular twitter became default url shortening service website may 6 2009 subsequently replaced twitter t.co service company behind bitly launched similar service online videos determine videos popular web company offers paid solution called bitly enterprise provides advanced branding features audience intel omnichannel campaign tracking companies use custom domains generate shortened links example new york times uses codice_1 pepsi uses codice_2 allows company push brand awareness services twitter use bitly engine generate shortened urls track marketing metrics bitly enterprise also advanced analytics features uses bitly data provide advanced social insight tools companies brands company uses http 301 redirects links shortcuts intended permanent changed created urls shortened bitly service use codice_3 domain generic domain service offers information short bitly url codice_4 available codice_5 url plus sign appended example codice_6 allows users see check long url visiting starting october 12 2010 users could automatically generate qr codes scanned mobile qr code reader automatically directed users shortened links later removed may 29 2012 bitly announced bitmarks new search feature enhanced public profiles iphone app codice_7 country code top-level domain cctld libya 2011 bit.ly address set redirect bitly.com .ly tld controlled libyan government previously removed one domain deemed incompatible muslim law shortened url generated bitly also accessed replacing domain one following
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Web technology
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little implementation language lil little implementation language system programming language early days unix history pdp-11 machines written p. j. plauger bell labs lil attempted fill gap assemblers machine-independent system implementation languages c programming language basically adding structured programming pdp-11 assembly language lil resembled pl360 c-like flow control syntax lil compiler lc part fifth edition unix 1974 dropped sixth edition unix 1975 plauger left bell labs year plauger explains lil abandoned bell labs favor c
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Programming language topics
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spyware spyware software aims gather information person organization sometimes without knowledge may send information another entity without consumer consent asserts control device without consumer knowledge may send information another entity consumer consent cookies spyware mostly classified four types adware system monitors tracking cookies trojans examples notorious types include digital rights management capabilities phone home keyloggers rootkits web beacons spyware mostly used stealing information storing internet users movements web serving pop-up ads internet users whenever spyware used malicious purposes presence typically hidden user difficult detect spyware keyloggers may installed owner shared corporate public computer intentionally order monitor users term spyware suggests software monitors user computing functions spyware extend beyond simple monitoring spyware collect almost type data including personal information like internet surfing habits user logins bank credit account information spyware also interfere user control computer installing additional software redirecting web browsers spyware change computer settings result slow internet connection speeds un-authorized changes browser settings changes software settings sometimes spyware included along genuine software may come malicious website may added intentional functionality genuine software see paragraph facebook response emergence spyware small industry sprung dealing anti-spyware software running anti-spyware software become widely recognized element computer security practices especially computers running microsoft windows number jurisdictions passed anti-spyware laws usually target software surreptitiously installed control user computer german-speaking countries spyware used made government called govware computer experts common parlance regierungstrojaner literally government trojan govware typically trojan horse software used intercept communications target computer countries like switzerland germany legal framework governing use software us term policeware used similar purposes use term spyware eventually declined practice tracking users pushed ever mainstream major websites data mining companies generally break known laws compel users tracked fraudulent practices per se default settings created users language terms-of-service agreements one documented example cbs/cnet news reported march 7 2011 wall street journal analysis revealing practice facebook websites tracking users browsing activity linked identity far beyond users visits activity within facebook site report stated works go facebook log spend time ... move without logging let say next site go new york times buttons without clicking reported back facebook twitter went also identity within accounts let say moved something like site depression one also tweet button google widget report back went wsj analysis researched brian kennish founder disconnect inc. spyware necessarily spread way virus worm infected systems generally attempt transmit copy software computers instead spyware installs system deceiving user exploiting software vulnerabilities spyware installed without knowledge using deceptive tactics spyware may try deceive users bundling desirable software common tactics using trojan horse spy gadgets look like normal devices turn something else usb keylogger devices actually connected device memory units capable recording stroke made keyboard spyware authors infect system security holes web browser software user navigates web page controlled spyware author page contains code attacks browser forces download installation spyware installation spyware frequently involves internet explorer popularity history security issues made frequent target deep integration windows environment make susceptible attack windows operating system internet explorer also serves point attachment spyware form browser helper objects modify browser behavior spyware rarely operates alone computer affected machine usually multiple infections users frequently notice unwanted behavior degradation system performance spyware infestation create significant unwanted cpu activity disk usage network traffic stability issues applications freezing failure boot system-wide crashes also common spyware interferes networking software commonly causes difficulty connecting internet infections spyware even evident users assume situations performance issues relate faulty hardware windows installation problems another malware infection owners badly infected systems resort contacting technical support experts even buying new computer existing system become slow badly infected systems may require clean reinstallation software order return full functionality moreover types spyware disable software firewalls antivirus software and/or reduce browser security settings opens system opportunistic infections spyware disables even removes competing spyware programs grounds spyware-related annoyances increase likelihood users take action remove programs keyloggers sometimes part malware packages downloaded onto computers without owners knowledge keylogger software freely available internet others commercial private applications keyloggers allow keyboard keystrokes captured also often capable collecting screen captures computer typical windows user administrative privileges mostly convenience program user runs unrestricted access system operating systems windows users able follow principle least privilege use non-administrator accounts alternatively reduce privileges specific vulnerable internet-facing processes internet explorer since windows vista default computer administrator runs everything limited user privileges program requires administrative privileges user account control pop-up prompt user allow deny action improves design used previous versions windows spyware threat evolved number techniques emerged counteract include programs designed remove block spyware well various user practices reduce chance getting spyware system nonetheless spyware remains costly problem large number pieces spyware infected windows computer remedy may involve backing user data fully reinstalling operating system instance spyware completely removed symantec microsoft pc tools many programmers commercial firms released products dedicated remove block spyware programs pc tools spyware doctor lavasoft ad-aware se patrick kolla spybot search destroy rapidly gained popularity tools remove cases intercept spyware programs december 16 2004 microsoft acquired giant antispyware software rebranding windows antispyware beta releasing free download genuine windows xp windows 2003 users 2006 renamed windows defender major anti-virus firms symantec pc tools mcafee sophos also added anti-spyware features existing anti-virus products early anti-virus firms expressed reluctance add anti-spyware functions citing lawsuits brought spyware authors authors web sites programs described products spyware however recent versions major firms home business anti-virus products include anti-spyware functions albeit treated differently viruses symantec anti-virus instance categorizes spyware programs extended threats offers real-time protection threats anti-spyware programs combat spyware two ways programs inspect contents windows registry operating system files installed programs remove files entries match list known spyware real-time protection spyware works identically real-time anti-virus protection software scans disk files download time blocks activity components known represent spyware cases may also intercept attempts install start-up items modify browser settings earlier versions anti-spyware programs focused chiefly detection removal javacool software spywareblaster one first offer real-time protection blocked installation activex-based spyware like anti-virus software many anti-spyware/adware tools require frequently updated database threats new spyware programs released anti-spyware developers discover evaluate adding list known spyware allows software detect remove new spyware result anti-spyware software limited usefulness without regular updates updates may installed automatically manually popular generic spyware removal tool used requires certain degree expertise hijackthis scans certain areas windows os spyware often resides presents list items delete manually items legitimate windows files/registry entries advised less knowledgeable subject post hijackthis log numerous antispyware sites let experts decide delete spyware program blocked manages get installed may resist attempts terminate uninstall programs work pairs anti-spyware scanner user terminates one running process one respawns killed program likewise spyware detect attempts remove registry keys immediately add usually booting infected computer safe mode allows anti-spyware program better chance removing persistent spyware killing process tree may also work detect spyware computer users found several practices useful addition installing anti-spyware programs many users installed web browser internet explorer mozilla firefox google chrome though browser completely safe internet explorer greater risk spyware infection due large user base well vulnerabilities activex three major browsers close equivalent comes security isps—particularly colleges universities—have taken different approach blocking spyware use network firewalls web proxies block access web sites known install spyware march 31 2005 cornell university information technology department released report detailing behavior one particular piece proxy-based spyware marketscore steps university took intercept many educational institutions taken similar steps individual users also install firewalls variety companies monitor flow information going networked computer provide protection spyware malware users install large hosts file prevents user computer connecting known spyware-related web addresses spyware may get installed via certain shareware programs offered download downloading programs reputable sources provide protection source attack individual users use cellphone computer physical electric switch isolated electronic switch disconnects microphone camera without bypass keep disconnected position use limits information spyware collect policy recommended nist guidelines managing security mobile devices 2013 spyware vendors notably 180 solutions written new york times dubbed stealware spyware researcher ben edelman terms affiliate fraud form click fraud stealware diverts payment affiliate marketing revenues legitimate affiliate spyware vendor spyware attacks affiliate networks places spyware operator affiliate tag user activity – replacing tag one spyware operator party gains user choices thwarted legitimate affiliate loses revenue networks reputations injured vendors harmed pay affiliate revenues affiliate party contract affiliate fraud violation terms service affiliate marketing networks result spyware operators 180 solutions terminated affiliate networks including linkshare sharesale mobile devices also vulnerable chargeware manipulates users illegitimate mobile charges one case spyware closely associated identity theft august 2005 researchers security software firm sunbelt software suspected creators common coolwebsearch spyware used transmit chat sessions user names passwords bank information etc however turned actually sophisticated criminal little trojan independent cws case currently investigation fbi federal trade commission estimates 27.3 million americans victims identity theft financial losses identity theft totaled nearly 48 billion businesses financial institutions least 5 billion out-of-pocket expenses individuals copy-protection technologies borrowed spyware 2005 sony bmg music entertainment found using rootkits xcp digital rights management technology like spyware difficult detect uninstall poorly written efforts remove could rendered computers unable function texas attorney general greg abbott filed suit three separate class-action suits filed sony bmg later provided workaround website help users remove beginning april 25 2006 microsoft windows genuine advantage notifications application installed windows pcs critical security update main purpose deliberately uninstallable application ensure copy windows machine lawfully purchased installed also installs software accused phoning home daily basis like spyware removed removewga tool spyware used monitor electronic activities partners intimate relationships least one software package loverspy specifically marketed purpose depending local laws regarding communal/marital property observing partner online activity without consent may illegal author loverspy several users product indicted california 2005 charges wiretapping various computer crimes anti-spyware programs often report web advertisers http cookies small text files track browsing activity spyware always inherently malicious many users object third parties using space personal computers business purposes many anti-spyware programs offer remove common spyware programs illustrate diversity behaviors found attacks note computer viruses researchers give names spyware programs may used creators programs may grouped families based shared program code common behaviors following money apparent financial business connections instance number spyware programs distributed claria collectively known gator likewise programs frequently installed together may described parts spyware package even function separately first recorded use term spyware occurred october 16 1995 usenet post poked fun microsoft business model spyware first denoted software meant espionage purposes however early 2000 founder zone labs gregor freund used term press release zonealarm personal firewall later 2000 parent using zonealarm alerted fact reader rabbit educational software marketed children mattel toy company surreptitiously sending data back mattel since spyware taken present sense according 2005 study aol national cyber-security alliance 61 percent surveyed users computers infected form spyware 92 percent surveyed users spyware reported know presence 91 percent reported given permission installation spyware spyware become one preeminent security threats computer systems running microsoft windows operating systems computers internet explorer ie primary browser particularly vulnerable attacks ie widely used tight integration windows allows spyware access crucial parts operating system internet explorer 6 sp2 released part windows xp service pack 2 browser would automatically display installation window activex component website wanted install combination user ignorance changes assumption internet explorer activex components benign helped spread spyware significantly many spyware components would also make use exploits javascript internet explorer windows install without user knowledge permission windows registry contains multiple sections modification key values allows software executed automatically operating system boots spyware exploit design circumvent attempts removal spyware typically link location registry allows execution running spyware periodically check links removed automatically restored ensures spyware execute operating system booted even registry links removed malicious programmers released large number rogue fake anti-spyware programs widely distributed web banner ads warn users computers infected spyware directing purchase programs actually remove spyware—or else may add spyware proliferation fake spoofed antivirus products bill antispyware troublesome users may receive popups prompting install protect computer fact add spyware software called rogue software recommended users install freeware claiming anti-spyware unless verified legitimate known offenders include fake antivirus products constitute 15 percent malware january 26 2006 microsoft washington state attorney general filed suit secure computer spyware cleaner product unauthorized access computer illegal computer crime laws u.s. computer fraud abuse act u.k. computer misuse act similar laws countries since owners computers infected spyware generally claim never authorized installation prima facie reading would suggest promulgation spyware would count criminal act law enforcement often pursued authors malware particularly viruses however spyware developers prosecuted many operate openly strictly legitimate businesses though faced lawsuits spyware producers argue contrary users claims users fact give consent installations spyware comes bundled shareware applications may described legalese text end-user license agreement eula many users habitually ignore purported contracts spyware companies claria say demonstrate users consented despite ubiquity eulas agreements single click taken consent entire text relatively little caselaw resulted use established common law jurisdictions type agreement binding contract certain circumstances however mean every agreement contract every term one enforceable jurisdictions including u.s. states iowa washington passed laws criminalizing forms spyware laws make illegal anyone owner operator computer install software alters web-browser settings monitors keystrokes disables computer-security software united states lawmakers introduced bill 2005 entitled internet spyware prevention act would imprison creators spyware us federal trade commission sued internet marketing organizations unfairness doctrine make stop infecting consumers pcs spyware one case seismic entertainment productions ftc accused defendants developing program seized control pcs nationwide infected spyware malicious software bombarded barrage pop-up advertising seismic clients exposed pcs security risks caused malfunction seismic offered sell victims antispyware program fix computers stop popups problems seismic caused november 21 2006 settlement entered federal court 1.75 million judgment imposed one case 1.86 million another defendants insolvent second case brought cyberspy software llc ftc charged cyberspy marketed sold remotespy keylogger spyware clients would secretly monitor unsuspecting consumers computers according ftc cyberspy touted remotespy 100 undetectable way spy anyone anywhere ftc obtained temporary order prohibiting defendants selling software disconnecting internet servers collect store provide access information software gathered case still preliminary stages complaint filed electronic privacy information center epic brought remotespy software ftc attention administrative fine first kind europe issued independent authority posts telecommunications opta netherlands applied fines total value euro 1,000,000 infecting 22 million computers spyware concerned called dollarrevenue law articles violated art 4.1 decision universal service providers interests end users fines issued based art 15.4 taken together art 15.10 dutch telecommunications law former new york state attorney general former governor new york eliot spitzer pursued spyware companies fraudulent installation software suit brought 2005 spitzer california firm intermix media inc. ended settling agreeing pay us 7.5 million stop distributing spyware hijacking web advertisements also led litigation june 2002 number large web publishers sued claria replacing advertisements settled court courts yet decide whether advertisers held liable spyware displays ads many cases companies whose advertisements appear spyware pop-ups directly business spyware firm rather contracted advertising agency turn contracts online subcontractor gets paid number impressions appearances advertisement major firms dell computer mercedes-benz sacked advertising agencies run ads spyware litigation gone ways since spyware become common pejorative makers filed libel defamation actions products described 2003 gator known claria filed suit website pc pitstop describing program spyware pc pitstop settled agreeing use word spyware continues describe harm caused gator/claria software result anti-spyware anti-virus companies also used terms potentially unwanted programs greyware denote products 2010 webcamgate case plaintiffs charged two suburban philadelphia high schools secretly spied students surreptitiously remotely activating webcams embedded school-issued laptops students using home therefore infringed privacy rights school loaded student computer lanrev remote activation tracking software included now-discontinued thefttrack thefttrack enabled default software program allowed school district elect activate choose thefttrack surveillance options school wanted enable thefttrack allowed school district employees secretly remotely activate webcam embedded student laptop laptop screen allowed school officials secretly take photos webcam whatever front line sight send photos school server lanrev software disabled webcams uses e.g students unable use photo booth video chat students mistakenly believed webcams work addition webcam surveillance thefttrack allowed school officials take screenshots send school server addition lanrev allowed school officials take snapshots instant messages web browsing music playlists written compositions schools admitted secretly snapping 66,000 webshots screenshots including webcam shots students bedrooms
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Computer security
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nexus nexus smartphone co-developed google samsung manufactured samsung electronics release 2010 first smartphone use android 2.3 gingerbread operating system first android device support near field communication nfc hardware software fourth time google worked manufacturer produce phone previous google g1 mytouch nexus one three htc following nexus next android developer phone galaxy nexus released following year google current generation nexus phones nexus 6p huawei nexus 5x lg electronics nexus first commercial smartphone certified nasa fly space shuttle used international space station part spheres experiment nexus demonstrated google ceo eric schmidt 15 november 2010 web 2.0 summit google officially announced phone blog 6 december 2010 phone became available purchase 16 december united states 22 december united kingdom super amoled version phone gt-i9020 based samsung galaxy hardware principal hardware differences absence support sd card addition near field chip alternate sc-lcd super clear lcd version phone gt-i9023 meant european non-uk market may 2011 sprint introduced nexus us unlike gsm version sprint nexus runs wimax network uses cdma instead gsm also march 2011 vodafone released white version phone web store uk united kingdom nexus sold carphone warehouse available vodafone o2 t-mobile 3 orange networks france available sfr bouygues telecom india samsung officially announced sale unlocked version super lcd screen i9023 support gsm-based carriers throughout country canada nexus became available carriers april 2011 two versions one telus bell rogers 3g frequencies 850/1900/2100 mhz wind/mobilicity/vidéotron using 3g frequencies 900/1700/2100 australia nexus became available black white available vodafone virtual provider crazy john nexus samsung exynos 3110 processor processor combines 45 nm 1 ghz arm cortex a8 based cpu core powervr sgx 540 gpu cpu core code-named hummingbird co-developed samsung intrinsity gpu designed imagination technologies supports opengl es 1.1/2.0 capable 20 million triangles per second nexus first device use slightly curved glass touchscreen described google contour display super amoled 800 x 480 wvga pentile matrix display manufactured samsung markets outside canada us uk super lcd supplied instead phone shipped android 2.3 gingerbread first device ship updated os 19 december 2011 google released android 4.0 ice cream sandwich nexus s. automatic update suspended allegedly due poor battery performance umts/gsm variants among first receive android 4.0.4 march 2012 nexus 4g aka samsung sph-d720 i9020a m200 taking longer gsm variant received android 4.0.4 update several devices samsung galaxy ii receive updates variants 27 june 2012 google i/o conference announced nexus would one first devices receive upgrade android 4.1 jelly bean along motorola xoom galaxy nexus began 26 july 2012 october 2012 jelly bean 4.1.2 ota update released last official os released devices 13 november 2012 announced nexus would updated android 4.2 jelly bean still supported independent developers though android 4.2.2-based well 4.3- 4.4- 5.1- 6.0-based alternative software installed see nexus sim locked unlockable bootloader allowing users install custom roms joshua topolsky writing engadget review praised devices hardware software concluding truth really best android device available right review register gave nexus 85 rating summarized cool innovative device eye snatch apple ’ smartphone crown anandtech review praised display nfc tag reader android gingerbread operating system noted lack 720p video recording hspa+ baseband external storage support techradar review praised nexus fixing gps problems experienced samsung galaxy good news looking upgrade samsung galaxy – gps issues resolved actually get signal problem cnet review enthusiastic display operating system performance cnet noted lack 720p video recording hdmi output external sd card memory support cnet also noted rather fragile feel phone lack led notifications new features nexus one
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Computer architecture
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gobolinux gobolinux open source operating system whose prominent feature reorganization traditional linux file system rather following filesystem hierarchy standard like unix-like systems program gobolinux system subdirectory tree files including settings specific program may found thus program foo specific files libraries codice_1 corresponding version program hand example commonly known gcc compiler suite version 8.1.0 would reside directory codice_2 according gobolinux developers results cleaner system gobolinux hierarchy represents radical departure filesystem hierarchy traditionally employed unix-like operating systems specific types files stored together common standard subdirectories codice_3 executables codice_4 configuration files package managers used keep track file belongs program gobolinux files program placed respective program dedicated subdirectory makers gobolinux said filesystem package manager gobolinux package system uses filesystem package database said produce straightforward less cluttered directory tree gobolinux uses symlinks optional kernel module called gobohide achieve maintaining full compatibility traditional linux filesystem hierarchy creators gobolinux stated design modernisms removal distinctions similar traditional directories locations executables codice_3 codice_6 codice_7 gobolinux designers claimed results shell scripts breaking less often linux distributions change introduced gobolinux 2003 adopted distributions much later fedora merged /bin /usr/bin 2012 debian enabled /usr merge default 2016 gobolinux also allows user different versions program installed concurrently even run concurrently furthermore claimed package management index could never become unsynchronized filesystem references nonexistent files simply become broken links thus become inactive gobolinux filesystem changes also allow innovations entirely new boot system use system v bsd style init systems design gobolinux influenced earlier systems nextstep atheos beos adopted original filesystem structures still maintaining considerable degree compatibility unix root gobolinux tree six directories programs users system files mount depot contents described compile program downloads unpacks compiles source code tarballs installs resulting executable code single command codice_25 using simple compilation scripts known recipes compile system somewhat similar gentoo portage system based freebsd ports collection however portage made traditional filesystem hierarchy compatible filesystem hierarchy standard compile extends capability gobolinux distinctive filesystem hierarchy area package management thus gobolinux filesystem serves naturally kind package manager database compile program introduced gobolinux version 011 discussions porting gentoo portage system gobolinux developing port sourceforge.net project name goboportage compile features included gobolinux hierarchy files grouped functional categories index-like structure using symbolic links rooted codice_12 executables accessible codice_27 libraries accessible codice_28 eliminates many traditional distinctions filesystem hierarchy standard distinction made non-essential files stored codice_29 essential emergency files stored directly subdirectories root directory gobolinux developers maintained although distinctions useful longer necessary gobolinux schema symbolic links relating usual unix directories gobolinux tree therefore one find directories codice_4 codice_31 codice_6 expected places symbolic links point functional equivalent codice_12 tree thus traditionally crucial path names codice_34 codice_35 resolved correctly compatibility directories concealed view using custom kernel modification called gobohide implements support hidden files linux used aesthetic reasons thus optional feature gobolinux uses initialization procedure unlike linux distributions use bsd system v procedure codice_36 files command entire boot procedure codice_37 codice_38 run system boot shutdown respectively additionally possible define runlevel scripts specify different ways system may initialized example codice_39 single-user codice_40 multi-user codice_41 boot graphic mode controlled boot loader menu codice_42 file separates site-specific settings rest scripts application-specific tasks found codice_43 called boot scripts releases numbered using octal base system according authors scheme chosen keeps typical leading zero present many free software version numbers since leading zero often indicates number octal play version numbers race happened among linux distributions around 1999 read decimal numbers using octal numbers causes deterministic version bump eight releases version 013 gobolinux made point releases order avoid implication releases stable others tradition broken version 014.01 update 014 focused bug fixes gobolinux currently developed x86-64 officially made i686 release 015 one point incomplete port i386 made ports also made embedded architectures arm superh tasks achieved bootstrap tool developed especially automate making ports lwn.net reviewed gobolinux 010 2004 linux.com wrote review gobolinux 013 jesse smith distrowatch weekly reviewed gobolinux 015 smith also reviewed gobolinux 016
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Operating systems
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continuation-passing style functional programming continuation-passing style cps style programming control passed explicitly form continuation contrasted direct style usual style programming gerald jay sussman guy l. steele jr. coined phrase ai memo 349 1975 sets first version scheme programming language john c. reynolds gives detailed account numerous discoveries continuations function written continuation-passing style takes extra argument explicit continuation i.e function one argument cps function computed result value returns calling continuation function value argument means invoking cps function calling function required supply procedure invoked subroutine return value expressing code form makes number things explicit implicit direct style include procedure returns become apparent calls continuation intermediate values given names order argument evaluation made explicit tail calls simply call procedure continuation unmodified passed caller programs automatically transformed direct style cps functional logic compilers often use cps intermediate representation compiler imperative procedural programming language would use static single assignment form ssa ssa formally equivalent subset cps excluding non-local control flow occur cps used intermediate representation functional compilers also use a-normal form anf languages requiring eager evaluation rather 'thunks described examples cps cps used frequently compilers programmers local global style cps procedure takes extra argument representing done result function calculating along restrictive style prohibiting variety constructs usually available used expose semantics programs making easier analyze style also makes easy express unusual control structures like catch/throw non-local transfers control key cps remember every function takes extra argument continuation b every argument function call must either variable lambda expression complex expression effect turning expressions inside-out innermost parts expression must evaluated first cps explicitizes order evaluation well control flow examples code direct style corresponding cps appear examples written scheme programming language convention continuation function represented parameter named codice_1 note cps versions primitives used like codice_2 codice_3 cps direct style make examples work scheme system would need write cps versions primitives instance codice_3 defined order call procedure written cps procedure written direct style necessary provide continuation receive result computed cps procedure example assuming cps-style primitives provided might call codice_5 variety compilers way primitive functions provided cps used simplest convention however sometimes boolean primitives provided take two thunks called two possible cases codice_6 call inside codice_7 definition would written instead codice_8 similarly sometimes codice_9 primitive included cps instead function codice_10 provided takes three arguments boolean condition two thunks corresponding two arms conditional translations shown show cps global transformation direct-style factorial takes might expected single argument cps factorial takes two argument continuation function calling cps-ed function must either provide new continuation pass calls cps-ed function non-cps function use implicit continuations thus ensure total absence function stack entire program must cps section write function codice_11 calculates hypotenuse using pythagorean theorem traditional implementation codice_11 function looks like transform traditional function cps one need change signature function get another argument function type return type depends function first calculate square codice_13 function pass lambda function continuation accept square first argument reach result calculations get result function pass codice_14 function final argument returns value passed unchanged codice_15 mtl library shipped ghc compiler control.monad.cont module module provides cont type implements monad useful functions following snippet shows codice_13 function using cont type syntax become cleaner type allows us use function codice_17 type codice_18 function one argument function type function argument accepts function discards computations going call example let break execution codice_11 function least one arguments negative returning zero programming continuations also useful caller want wait callee completes example user-interface ui programming routine set dialog box fields pass along continuation function ui framework call returns right away allowing application code continue user interacts dialog box user presses ok button framework calls continuation function updated fields although style coding uses continuations full cps similar idea used function must run different thread different processor framework execute called function worker thread call continuation function original thread worker results java using swing ui framework using java 8 lambda notation code shortens codice_20 keyword might skipped every call cps tail call continuation explicitly passed using cps without tail call optimization tco cause constructed continuation potentially grow recursion also call stack usually undesirable used interesting ways—see chicken scheme compiler cps tco eliminate concept implicit function return combined use eliminate need run-time stack several compilers interpreters functional programming languages use ability novel ways continuation passing style used implement continuations control flow operators functional language feature first-class continuations first-class functions tail-call optimization without tail-call optimization techniques trampolining i.e using loop iteratively invokes thunk-returning functions used without first-class functions even possible convert tail calls gotos loop writing code cps impossible often error-prone various translations usually defined one- two-pass conversions pure lambda calculus convert direct style expressions cps expressions writing trampolined style however extremely difficult used usually target sort transformation compilation functions using one continuation defined capture various control flow paradigms example scheme note cps transform conceptually yoneda embedding also similar embedding lambda calculus π-calculus outside computer science cps general interest alternative conventional method composing simple expressions complex expressions example within linguistic semantics chris barker collaborators suggested specifying denotations sentences using cps might explain certain phenomena natural language mathematics curry–howard isomorphism computer programs mathematical proofs relates continuation-passing style translation variation double-negation embeddings classical logic intuitionistic constructive logic unlike regular double-negation translation maps atomic propositions p p → ⊥ → ⊥ continuation passing style replaces ⊥ type final expression accordingly result obtained passing identity function continuation cps-style expression example classical logic relates manipulating continuation programs directly scheme call-with-current-continuation control operator observation due tim griffin using closely related c control operator
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Programming language topics
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ws-metadataexchange ws-metadataexchange web services protocol specification published bea systems ibm microsoft sap ws-metadataexchange part ws-federation roadmap designed work conjunction ws-addressing wsdl ws-policy allow retrieval metadata web services endpoint uses soap message request metadata goes beyond basic technique appending wsdl service name url
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Web technology
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libranet libranet operating system based debian gnu/linux last version april 25 2005 released libranet 3.0 cost 90 us dollars new users 65 existing libranet users previous version libranet 2.8.1 became free download development libranet discontinued name comes libra computer systems company owned founder fact libra.com taken first release libranet 1999 linux distributions time difficult install considered either programmers wanted low cost server libranet attempted put sell distribution easy install meant desktop use corel likewise attempted corel linux abandoned refocused software windows mac os x operating systems libranet however continued developed recognition linux distribution good desktop users corel sold rights linux operating system xandros later released offering linux desktop 1999 2003 linux distributions comparable desktop usability libranet also priced similarly began change however 2004 linux whole advanced many distributions reasonably easy install relatively user-friendly desktop distributions mepis competitive far less expensive others knoppix offered cost libranet attempted carve niche user-friendly linux distro extensive support termed running support desktop distros compatible debian release time woody support offered truly extensive jon danzig founder would often personally answer people inquiries helped make people chosen libranet even loyal however release debian sarge 2005 along emergence ubuntu debian based distro offered cost option purchase support libranet received less attention debian revamped installer making easier use good reason use debian-based distribution debian installer user friendly libranet released version 3.0 received good reviews market changed desktop distributions various commercial vendors released free versions distributions suse released opensuse red hat released fedora whereas libranet sold distribution gave free extensive support many distributors chose give away distribution sell support and/or sell proprietary software enhancements jon danzig founder libranet died june 1 2005 son tal taken leadership development team stated would stop maintaining libranet daniel de kok remaining employee went become developer centos many users interested seeing libranet libranet adminmenu software continued available operating system setup configuration tool unique also contained user-friendly kernel compiling tool team including daniel de kok proposed opensource libranet release openlibranet 3.1 failing obtain definitive permission plan tal danzig owner plan dropped
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Operating systems
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erp security erp security wide range measures aimed protecting enterprise resource planning erp systems illicit access ensuring accessibility integrity system data erp system computer software serves unify information intended manage company including production supply chain management financial management human resource management customer relationship management enterprise performance management etc common erp systems sap oracle e-business suite microsoft dynamics erp system integrates business processes enabling procurement payment transport human resources management product management financial planning erp system stores confidential information isaca recommends regularly conduct comprehensive assessment erp system security checking erp servers software vulnerabilities configuration errors segregation duties conflicts compliance relevant standards recommendations recommendations vendors erp systems process transactions implement procedures ensure users different access privileges hundreds authorization objects sap permitting users perform actions system case 200 users company approximately 800,000 100*2*20*200 ways customize security settings erp systems growth complexity possibility errors segregation duties conflicts increases vendors fix vulnerabilities regular basis since hackers monitor business applications find exploit security issues sap releases patches monthly patch tuesday oracle issues security fixes every quarter oracle critical patch update business applications becoming exposed internet migrate cloud erp cybersecurity survey revealed organizations running erp systems lack awareness actions taken towards erp security isaca states shortage staff members trained erp security security services superficial understanding risks threats associated erp systems consequently security vulnerabilities complicate undertakings detecting subsequent fixing erp security audit done manually various tools erp packages provide means system security auditing manual auditing complex time-consuming process increases possibility making mistake system includes thousands parameters fine settings including segregation duties transactions tables security parameters set every single system erp system settings customized according customers requirements security issues occur erp systems different levels traffic interception modification 2011 sensepost specialists analyzed diag protocol used sap erp system transferring data client sap server two utilities published allowed intercept decrypt modify client-server requests containing critical information made attacks possible including man-in-the-middle attack second utility operates like proxy created identify new vulnerabilities allowed modifying requests coming client server sap erp system possible perform administering functions via telnet protocol encrypts passwords vulnerabilities encryption authentication protocols vulnerabilities protocols e.g rfc sap erp oracle net oracle e-business suite rfc protocol used remote function call connect two systems tcp/ip sap erp rfc call function enables calling running functional module located system abap language used writing business applications sap functions make rfc calls several critical vulnerabilities found sap rfc library versions 6.x 7.x os software vulnerabilities weak os passwords insecure os settings erp systems transfer functionality web applications level lot vulnerabilities erp systems rbac role-based access control model applied users perform transactions gain access business objects model decision grant access user made based functions users roles roles multitude transactions user group users performs company transaction procedure transforming system data helps perform transaction role number corresponding users one multiple roles roles hierarchical roles implemented system transactions corresponding role rarely change administrator needs add delete users roles administrator provides new user membership one roles employees leave organization administrator removes roles segregation separation duties also known sod concept according user make transaction without users e.g user add new supplier write cheque pay supplier risk fraud much lower sod implemented rbac mechanisms notion mutually exclusive roles introduced instance pay supplier one user initiates payment procedure another accepts case initiating payment accepting mutually exclusive roles segregation duties either static dynamic static sod ssod user belong two mutually exclusive roles dynamic sod dsod user perform within one transaction advantages ssod simple dsod flexible segregation duties explained sod matrix x matrixes describe system roles two roles mutually exclusive flag interception corresponding rows columns erp security scanner software intended search vulnerabilities erp systems scanner analyzes configurations erp system searches misconfigurations access control encryption conflicts insecure components checks updates scanner checks system parameters compliance manufacturer recommendations auditing procedures erp security scanners produce reports vulnerabilities listed according criticality examples scanners
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Computer security
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cannon algorithm computer science cannon algorithm distributed algorithm matrix multiplication two-dimensional meshes first described 1969 lynn elliot cannon especially suitable computers laid n × n mesh cannon algorithm works well homogeneous 2d grids extending heterogeneous 2d grids shown difficult main advantage algorithm storage requirements remain constant independent number processors scalable universal matrix multiplication algorithm summa practical algorithm requires less workspace overcomes need square 2d grid used scalapack plapack elemental libraries multiplying two n×n matrices b need n ×n processing nodes p arranged 2d grid initially p responsible b need select k every iteration every processor element pe processors n't access data computing formula_1 therefore processors row column must begin summation different indexes example pe 0,0 calculates formula_2 first step pe 0,1 chooses formula_3 first selection k j mod n pe j satisfies constraint first step first step distribute input matrices processors based previous rule next iterations choose new k k 1 mod n every processor way every processor continue accessing different values matrices needed data always neighbour processors pe j needs formula_4 pe j 1 mod n formula_5 pe 1 mod n j next step means formula_4 passed cyclically left also formula_5 cyclically upwards results multiplications summed usual n steps processor calculated formula_1 sum thus searched formula_9 initial distribution processor data next step stored intermediate result previous sum formula_10 formula_11 means three matrices need stored memory evenly distributed across processors practice much fewer processors matrix elements replace matrix elements submatrices every processor processes values scalar multiplication addition become sequential matrix multiplication addition width height submatrices formula_12 runtime algorithm formula_13 formula_14 time initial distribution matrices first step formula_15 calculation intermediate results formula_16 formula_17 stands time takes establish connection transmission byte respectively disadvantage algorithm many connection setups small message sizes would better able transmit data message
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Distributed computing architecture
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dartmouth algol 30 dartmouth algol 30 1960s-era implementation firstly algol 58 programming language algol 60 lgp-30 dartmouth college hence name since limited size lgp-30 precluded full implementation algol 60 certain features arrays called value arrays strings variable array bounds recursion omitted implementers include parameters called name using thunks integer labels dubbed work algol 30 since lgp-30 project emerged small group undergraduate students well equipped perform work development computer languages instance one student stephen j. garland discovered compound statements blocks could included samelson bauer scanning algorithm simple fact published years later algol 30 system suffered one defect hindered wide use student-oriented language two-pass system intermediate code similar relocatable binary punched onto paper tape compilations could batched delays presenting source code tape final execution great allow widespread student use clear load-and-go system needed thus born scalp self contained algol processor
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Programming language topics
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virtual health library virtual health library vhl biblioteca virtual en salud bvs institution employs world wide web improve access reliable locally relevant information health health sciences health-professionals researchers academics educators decision makers general public bvses organized auspices pan-american health organization world health organization vhl on-line digital library common space convergence cooperative work producers intermediaries users information healthcare science built developed latin american caribbean center health sciences information also known bireme 1998 vhl promotes development network sources scientific technical information universal access internet bireme envisioned vhl new model management information knowledge includes cooperation convergence institutions systems networks initiatives producers intermediaries users operation networks local national regional international information sources favoring open universal access today every country latin america caribbean regions participates either directly indirectly cooperative products services offered vhl includes 1,000 institutions 30 countries vhl simulated virtual space internet formed collection network health information sources region users different levels locations interact navigate space one many information sources regardless information sources generated updated stored operated internet producers integrators intermediaries decentralized manner following common methodologies integration vhl vhl organizes information structure integrates interconnects literature databases directories experts events institutions catalogue information resources available internet collections full texts highlight scielo scientific electronic library online collection scientific journals selective information dissemination services information sources support education decision-making news discussion lists support virtual communities space vhl therefore dynamic decentralized network information sources based possible retrieve extract information knowledge support health decision-making processes virtual health library visualized distributed base scientific technical health knowledge saved organized stored electronic format countries region universally accessible internet compatible international databases bvs web sites individual countries
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Databases
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multicast source discovery protocol multicast source discovery protocol msdp protocol independent multicast pim family multicast routing protocol defined experimental rfc 3618 despite becoming ipv4 de facto standard inter-domain multicast development protocol stopped 2006 decided authors proceed making proposed standard msdp interconnects multiple ipv4 pim sparse-mode pim-sm domains enables pim-sm rendezvous point rp redundancy inter-domain multicasting rfc 4611 msdp uses tcp transport protocol multicast tree needs rp rps peers directly msdp peers messages contain sender source address multicast group address g rp domain receives message determines listeners group listeners exist triggers pim join source domain towards data source peering relationship one msdp peer listens new tcp connections well-known port 639 msdp deliberately unspecified ipv6 number reasons including protocols source-specific multicast ssm bi-directional multicast ipv6 embedded rendezvous points would mean less requirement msdp
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Internet protocols
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secd machine secd machine highly influential see landin contribution virtual machine abstract machine intended target functional programming language compilers letters stand stack environment control dump internal registers machine registers stack control dump point realisations stacks environment points realisation associative array machine first specifically designed evaluate lambda calculus expressions originally described peter j. landin mechanical evaluation expressions 1964 description published landin fairly abstract left many implementation choices open like operational semantics hence secd machine often presented detailed form peter henderson lispkit lisp compiler distributed since 1980 since used target several experimental compilers 1989 researchers university calgary worked hardware implementation machine d. a. turner 2012 points revised report algol 60 naur 1963 specifies procedure call copying rule avoids variable capture systematic change identifiers method works algol 60 implementation functional programming language functions first-class citizens free variable call stack might dereferenced error turner notes landin solved secd machine function represented closure heap instead evaluation expression begins expression loaded element control codice_1 environment codice_2 stack codice_3 dump codice_4 begin empty evaluation codice_1 converted reverse polish notation rpn codice_6 apply operator example expression codice_7 single list element changed list codice_8 evaluation codice_1 proceeds similarly rpn expressions first item codice_1 value pushed onto stack codice_3 exactly item identifier value pushed onto stack binding identifier current environment codice_2 item abstraction closure constructed preserve bindings free variables codice_2 closure pushed onto stack item codice_6 two values popped stack application done first applied second result application value pushed onto stack application abstraction value however result lambda calculus expression may application rather value pushed onto stack case current contents codice_3 codice_2 codice_1 pushed onto dump codice_4 stack triples codice_3 reinitialised empty codice_1 reinitialised application result codice_2 containing environment free variables expression augmented binding resulted application evaluation proceeds completed evaluation indicated codice_1 empty case result stack codice_3 last saved evaluation state codice_4 popped result completed evaluation pushed onto stack contents restored codice_4 evaluation restored state continues codice_1 codice_4 empty overall evaluation completed result stack codice_3 secd machine stack-based functions take arguments stack arguments built-in instructions encoded immediately instruction stream like internal data-structures stack list codice_3 register pointing list head beginning due list structure stack need continuous block memory stack space available long single free memory cell even cells used garbage collection may yield additional free memory obviously specific implementations secd structure implement stack canonical stack structure improving overall efficiency virtual machine provided strict bound put dimension stack codice_1 register points head code instruction list evaluated instruction executed codice_1 pointed next instruction list—it similar instruction pointer program counter conventional machines except subsequent instructions always specified execution default contained subsequent memory locations case conventional machines current variable environment managed codice_2 register points list lists individual list represents one environment level parameters current function head list variables free current function bound surrounding function elements codice_2 dump whose head codice_4 register points used temporary storage values registers example function calls likened return stack machines memory organization secd machine similar model used functional language interpreters number memory cells hold either atom simple value example 13 represent empty non-empty list latter case cell holds two pointers cells one representing first element representing list except first element two pointers traditionally named car cdr respectively—but modern terms head tail often used instead different types values cell hold distinguished tag often different types atoms integers strings etc distinguished well list holding numbers 1 2 3 usually written codice_35 might represented follows memory cells 3 5 belong list cells distributed randomly memory cell 2 head list points cell 1 holds first element value list containing 2 3 beginning cell 6 cell 6 points cell holding 2 cell 7 represents list containing 3 pointing cell 8 containing value 3 pointing empty list nil cdr secd machine cell 0 always implicitly represents empty list special tag value needed signal empty list everything needing simply point cell 0 principle cdr list cell must point another list convention car cdr point atoms yield pair usually written like codice_36 number additional instructions basic functions like car cdr list construction integer addition i/o etc exist take necessary parameters stack
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Programming language topics
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canadian police information centre canadian police information centre cpic cipc central police database canada law enforcement agencies access information number matters canada national law enforcement networking computer system ensuring officers across country access information approximately 3 million files generated year responsibility originating agency ensure data integrity file cpic approved use treasury board canada became operational 1972 maintained royal canadian mounted police rcmp central registry located rcmp headquarters ottawa ontario canada cpic interfaced united states national crime information center national law enforcement telecommunications system information shared example wandering persons registry information shared across border order government agency access cpic must agree abide rules set cpic reference manual approved cpic advisory committee composed 26 senior police officers municipal provincial police forces ontario police commission rcmp non-policing agencies must also enter memorandum understanding rcmp may audited time time compliance cpic broken four data banks investigative identification intelligence ancillary contain information local municipal provincial police services canada well federal law enforcement agencies canada border services agency military police maintain local records addition cpic records local records maintained contact police variety reasons may may contain information would entered cpic system cpic agencies subject audit 4-year cycle records added cpic system must satisfy stringent entry criteria every record must valid accurate complete nature compliant input rules province british columbia mandated law police forces share platform known prime-bc ontario local records kept systems known either niche versadex depending municipalities choice implementation quebec system used called crpq centre de reseignement des policiers du québec rcmp runs similar system called pros police reporting occurrence system provinces providing contract policing well federal policing 2011 toronto-based psychiatric patient advocate office announced received numerous complaints people denied entry united states names american department homeland security watchlist names provided canadian police information centre available american law enforcement authorities according wikileaks
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Databases
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encfs encfs free lgpl fuse-based cryptographic filesystem transparently encrypts files using arbitrary directory storage encrypted files two directories involved mounting encfs filesystem source directory mountpoint file mountpoint specific file source directory corresponds file mountpoint provides unencrypted view one source directory filenames encrypted source directory files encrypted using volume key stored either within outside encrypted source directory password used decrypt key encfs offers several advantages disk encryption software simply file stored individually encrypted file elsewhere host directory tree encfs available multiple platforms whereas ecryptfs tied linux kernel encfs implements bitrot detection top underlying filesystem encfs volumes occupy fixed size — encrypted directories grow shrink files added removed mountpoint encfs encrypted directory located normal file server via nfs sshfs etc mirrored backed efficiently normal file-system tools rsync possible directories mountpoint exist different physical devices filesystem mounted one sub-directories source directory backup utilities back files changed source directory file synchronisation cloud storage corruption data isolated corruption filedata local single file data corruption filesystem corrected reliable filesystem repair utility like fsck whole-disk encryption systems lack one attributes since file modifications shine underlying file system various optimizations operating system still possible unlike full-disk encryption example passing information released space trim improve performance ssd drives also supported dm-crypt files accessed random example skip middle large encrypted video without decrypting whole file drawbacks using encfs mounted encfs directories share features restrictions filesystem containing source directory due encryption filenames encrypted files produced encfs longer original filenames therefore filenames whose length close maximum supported filesystem stored encfs since exceed length limit encryption filesystems limit filenames 255 bytes case encfs supports filenames 190 bytes anyone access source directory able see many files encrypted filesystem permissions approximate size last time accessed modified though file names file data encrypted paid security audit conducted february 2014 revealed several potential vulnerabilities concludes announcement encfs 1.8 included several underlying design changes acknowledging security concerns raised previous audit however certain concerns still remain regarding vulnerabilities creating new encfs volume several different options available customize filesystem suit various needs encfs uses whatever ciphers able locate various encryption libraries system blowfish aes typically available cipher key length keysize selected ciphers support variable key lengths file encrypted blocks option controls size blocks time single byte read entire block contained must decrypted likewise write block must decrypted altered re-encrypted default block size 1024 sufficient purposes filenames source directory plain encrypted block stream mode block mode obscures filename length somewhat stream mode keeps short possible might save space source directory filesystem depending filesystem manages directory tree enabled initialization vector filename encryption derived file parent directories causing two files name — different directories — different encrypted filenames directory renamed files directories contained therein need encrypted filenames re-encrypted expensive operation option disabled heavily populated directories renamed often enabled file encrypted random 8-byte initialization vector stored within encrypted file source directory option disabled file encrypted initialization vector make volume key easier break enabling option makes filesystem secure cost additional 8 bytes per file causes file data initialization vector derived filename initialization vector chain data encrypted differently given different filename directory consequently renaming file mode enabled requires either file random initialization vector offset change filename initialization vector chain data re-encoded authors encfs chosen former route considerably faster especially large files makes encoding depend full pathname renaming moving means reencoding hardlinks supported stores checksum encrypted block causing corruption modification encrypted files detected encfs checksum blockmacbytes 8 bytes optionally 8 additional bytes random data blockmacrandbytes added block prevent two blocks unencrypted data checksum option creates large amount cpu overhead block checksum must calculated data read verify integrity written update checksum encfs supports somewhat primitive form secondary volumes single source directory offering different files given different passwords encfs unable decrypt file volume key ignored encfs forced ignore invalid password entry volume key decode differently hence files encrypted decrypted different key present two different encrypted volumes given different passwords however possible two filenames two different secondary volumes encrypted filename case file overwritten new file created note refers encrypted filenames unencrypted filenames danger averted creating one directory per secondary volume storing files visible directory secondary volume mounted also password changed volume key re-encoded new password cause secondary filesystems vanish volume key longer incorrectly decode key given secondary password primary password changed back secondary filesystems become available encfs author support technique
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Computer file systems
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interface builder interface builder software development application apple macos operating system part xcode formerly project builder apple developer developer toolset interface builder allows cocoa carbon developers create interfaces applications using graphical user interface resulting interface stored .nib file short next interface builder recently .xib file interface builder descended nextstep development software name version interface builder also used development openstep software similar tool called gorm exists gnustep march 27 2008 specialized iphone version interface builder allowing interface construction iphone applications released iphone sdk beta 2 interface builder intentionally developed separate application allow interaction designers design interfaces without use code-oriented ide xcode 4 apple integrated functionality directly xcode interface builder first made appearance 1986 written lisp experlisp product expertelligence invented developed jean-marie hullot using object-oriented features experlisp deeply integrated macintosh toolbox denison bollay took jean-marie hullot next later year demonstrate steve jobs jobs immediately recognized value started incorporating nextstep 1988 part nextstep 0.8 first commercial application allowed interface objects buttons menus windows placed interface using mouse one notable early use interface builder development first worldwideweb web browser tim berners-lee cern made using next workstation interface builder provides palettes collections user interface objects objective-c swift developer user interface objects contain items like text fields data tables sliders pop-up menus interface builder palettes completely extensible meaning developer develop new objects add palettes interface builder build interface developer simply drags interface objects palette onto window menu actions messages objects emit connected targets application code outlets pointers declared application code connected specific objects way initialization done runtime improving performance streamlining development process interface builder standalone application interface designers could ship nib files developers would drop projects interface builder saves application interface bundle contains interface objects relationships used application objects archived process also known serialization marshalling contexts either xml file next-style property list file .nib extension upon running application proper nib objects unarchived connected binary owning application awakened unlike almost gui designer systems generate code construct ui notable exceptions glade embarcadero technologies delphi c++builder stream ui objects similarly nibs often referred freeze dried contain archived objects ready run interface builder version 3 new file format extension .xib added functionally identical .nib except stored flat file making suitable storage revision control systems processing tools diff
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Operating systems
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dup system call unix-like operating systems dup short duplicate dup2 system calls create copy given file descriptor new descriptor actually behave like copy like alias old one dup dup2 calls standardized posix specification former allocates first available descriptor like open behaves alternative way duplicate file descriptor unspecified place fcntl system call codice_1 command latter places copy newfd newfd open closed first unix shells use dup2 input/output redirection along codice_2 tool unix pipes rely following example uses codice_2 codice_4 order connect two separate processes program1 program2 using unix pipes
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Computer architecture
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port state control port state control psc inspection regime countries inspect foreign-registered ships port flag state take action ships compliance inspectors called psc officers required investigate compliance requirements international conventions solas marpol stcw mlc inspections involve checking vessel manned operated compliance applicable international law verifying competency ship master officers ship condition equipment 1978 number european countries agreed hague memorandum audit labour conditions board vessels whether accordance rules ilo amoco cadiz sank year decided also audit safety pollution practices end 1982 fourteen european countries agreed paris memorandum understanding port state control paris mou establish port state control nowadays 26 european countries canada signatories paris mou psc reaction failure flag states especially flag convenience states — delegated survey certification responsibilities classification societies modeled paris mou several regional mous signed including tokyo mou pacific ocean acuerdo latino acuerdo de viña del mar south central america caribbean mou mediterranean mou indian ocean mou abuja mou west central atlantic africa black sea mou riyadh mou persian gulf port state control psc makes inspection ships port taken port state control officer psco annual report paris mou reported total 74,713 deficiencies recorded port state control inspections 2007 deficiencies resulted 1,250 detentions year detention ship last course action psco would take upon finding deficiencies aboard vessel courses action psco may impose ship deficiencies order ascending gravity
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Databases
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transcriber transcriber tool transcription annotation speech signals linguistic research supports multiple hierarchical layers segmentation named entity annotation speaker lists topic lists overlapping speakers two views sound pressure waveform different resolutions may viewed simultaneously various character encodings including unicode supported annotations transcriber may exported xml oasis cover pages publishes open dtd used transcriber transcriber written tcl/tk snack audio library therefore available major platforms distributed gnu general public license transcriber superseded transcriberag
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Computational linguistics
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nokia e52/e55 nokia e52 nokia e55 smartphones nokia business-oriented eseries range run symbian os v9.3 s60 3rd edition fp1 e55 announced 16 february 2009 whilst e52 announced later 6 may 2009 physically functionally identical except e55 'half-qwerty keyboard whereas e52 revision traditional t9 keypad available black black aluminum metal grey aluminium white aluminium gold came 1gb microsd memory card supports microsd cards 32gb memory also 60 mb free user memory e52 successor nokia successful e51 model latest firmware version v091.004 released june 2 2012 e52 e55 9.9 mm thickness slim time feature mostly metallic bodies nokia called e55 world thinnest smartphone 0.1 mm thinner nokia e71 e55 model unique 'compact qwerty keyboard featuring two letters qwerty order single key observed 5.5 watt-hour 1500 mah 3.7 v battery easily last 27 days practical use considerably higher phones class made nokia manufacturers wifi bluetooth used built-in voip client active battery last 24 hours
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Operating systems
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cnk operating system compute node kernel cnk node level operating system ibm blue gene series supercomputers compute nodes blue gene family supercomputers run compute node kernel cnk lightweight kernel runs node supports one application running one user node maximize operating efficiency design cnk kept simple minimal implemented 5,000 lines c++ code physical memory statically mapped cnk neither needs provides scheduling context switching given point runs one application one user allowing virtual memory multi-tasking design cnk aimed devote many cycles possible application processing cnk even implement file input/output i/o compute node delegates dedicated i/o nodes i/o nodes blue gene supercomputers run different operating system i/o node kernel ink ink based modified linux kernel
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Operating systems
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dynamic application security testing dynamic application security testing dast tool program communicates web application web front-end order identify potential security vulnerabilities web application architectural weaknesses performs black-box test unlike static application security testing tools dast tools access source code therefore detect vulnerabilities actually performing attacks dast tools allow sophisticated scans detecting vulnerabilities minimal user interactions configured host name crawling parameters authentication credentials tools attempt detect vulnerabilities query strings headers fragments verbs get/post/put dom injection customers benefit convenience applications tacitly taking risk private information stored web applications compromised hacker attacks insider leaks according privacy rights clearinghouse 18 million customer records compromised 2012 due insufficient security controls corporate data web applications dast tools facilitate automated review web application expressed purpose discovering security vulnerabilities required comply various regulatory requirements web application scanners look wide variety vulnerabilities input/output validation e.g cross-site scripting sql injection specific application problems server configuration mistakes copyrighted report published march 2012 security vendor cenzic common application vulnerabilities recently tested applications include commercial scanners category web-assessment tools need bought specific price usually quite high scanners include free features need bought full access tool power open-source scanners another class free nature best category since source code open user gets know happening unlike commercial scanners security researcher shay chen previously compiled exhaustive list commercial open-source web application security scanners list also highlights scanners performed benchmarking tests wavsep wavsep platform publicly available used evaluate various aspects web application scanners technology support performance accuracy coverage result consistency tools detect vulnerabilities finalized release candidate versions prior shipping scanners simulate malicious user attacking probing identifying results part expected result set dynamic testing tool web scanners language dependent web application scanner able scan engine-driven web applications attackers use tools tools find vulnerability attackers scanning dast tool data may overwritten malicious payloads injected subject site sites scanned production like non-production environment ensure accurate results protecting data production environment tool implementing dynamic testing method cover 100 source code application application penetration tester look coverage web application attack surface know tool configured correctly able understand web application tool implement variants attacks given vulnerability tools generally predefined list attacks generate attack payloads depending tested web application tools also quite limited understanding behavior applications dynamic content javascript flash report 2012 found top application technologies overlooked web application scanners includes json jquery rest google webtoolkit ajax applications flash remoting amf html5 well mobile apps web services using json rest xml-rpc soap technologies used web services complex workflows shopping cart xsrf/csrf tokens also listed
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Computer security
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sql sql s-q-l sequel structured query language domain-specific language used programming designed managing data held relational database management system rdbms stream processing relational data stream management system rdsms particularly useful handling structured data relations different entities/variables data sql offers two main advantages older read/write apis like isam vsam first introduced concept accessing many records one single command second eliminates need specify reach record e.g without index originally based upon relational algebra tuple relational calculus sql consists many types statements may informally classed sublanguages commonly data query language dql data definition language ddl data control language dcl data manipulation language dml scope sql includes data query data manipulation insert update delete data definition schema creation modification data access control although sql often described great extent declarative language 4gl also includes procedural elements sql one first commercial languages edgar f. codd relational model model described influential 1970 paper relational model data large shared data banks despite entirely adhering relational model described codd became widely used database language sql became standard american national standards institute ansi 1986 international organization standardization iso 1987 since standard revised include larger set features despite existence standards sql code completely portable among different database systems without adjustments sql initially developed ibm donald d. chamberlin raymond f. boyce learning relational model ted codd early 1970s version initially called sequel structured english query language designed manipulate retrieve data stored ibm original quasi-relational database management system system r group ibm san jose research laboratory developed 1970s chamberlin boyce first attempt relational database language square difficult use due subscript notation moving san jose research laboratory 1973 began work sequel acronym sequel later changed sql sequel trademark uk-based hawker siddeley dynamics engineering limited company testing sql customer test sites determine usefulness practicality system ibm began developing commercial products based system r prototype including system/38 sql/ds db2 commercially available 1979 1981 1983 respectively late 1970s relational software inc. oracle corporation saw potential concepts described codd chamberlin boyce developed sql-based rdbms aspirations selling u.s. navy central intelligence agency u.s. government agencies june 1979 relational software inc. introduced first commercially available implementation sql oracle v2 version2 vax computers 1986 ansi iso standard groups officially adopted standard database language sql language definition new versions standard published 1989 1992 1996 1999 2003 2006 2008 2011 recently 2016 sql deviates several ways theoretical foundation relational model tuple calculus model table set tuples sql tables query results lists rows row may occur multiple times order rows employed queries e.g limit clause critics argue sql replaced language strictly returns original foundation example see third manifesto however known proof exists uniqueness added sql least variation sql words quite possible sql fixed least improved regard industry may switch completely different query language obtain uniqueness debate remains open /math sql language subdivided several language elements including sql designed specific purpose query data contained relational database sql set-based declarative programming language imperative programming language like c basic however extensions standard sql add procedural programming language functionality control-of-flow constructs include addition standard sql/psm extensions proprietary sql extensions procedural object-oriented programmability available many sql platforms via dbms integration languages sql standard defines sql/jrt extensions sql routines types java programming language support java code sql databases sql server 2005 uses sqlclr sql server common language runtime host managed .net assemblies database prior versions sql server restricted unmanaged extended stored procedures primarily written c. postgresql lets users write functions wide variety languages—including perl python tcl javascript pl/v8 c. sql implementations incompatible vendors necessarily completely follow standards particular date time syntax string concatenation codice_1s comparison case sensitivity vary vendor vendor particular exceptions postgresql mimer sql strive standards compliance though postgresql adhere standard folding unquoted names done folding unquoted names lower case postgresql incompatible sql standard says unquoted names folded upper case thus codice_2 equivalent codice_3 codice_4 according standard popular implementations sql commonly omit support basic features standard sql codice_5 codice_6 data types obvious examples incidentally popular commercial proprietary sql dbmss oracle whose codice_5 behaves codice_8 lacks codice_6 type ms sql server 2008 version result sql code rarely ported database systems without modifications several reasons lack portability database systems sql adopted standard american national standards institute ansi 1986 sql-86 international organization standardization iso 1987 maintained iso/iec jtc 1 information technology subcommittee sc 32 data management interchange standard commonly denoted pattern iso/iec 9075-n yyyy part n title shortcut iso/iec 9075 iso/iec 9075 complemented iso/iec 13249 sql multimedia application packages sql/mm defines sql based interfaces packages widely spread applications like video audio spatial data 1996 national institute standards technology nist data management standards program certified sql dbms compliance sql standard vendors self-certify compliance products original standard declared official pronunciation sql initialism ess cue el regardless many english-speaking database professionals including donald chamberlin use acronym-like pronunciation sequel mirroring language pre-release development name sequel sql standard gone number revisions interested parties may purchase sql standards documents iso iec ansi draft sql:2008 freely available zip archive sql standard divided ten parts iso/iec 9075 complemented iso/iec 13249 sql multimedia application packages closely related separate standard developed committee defines interfaces packages based sql aim unified access typical database applications like text pictures data mining spatial data iso/iec 9075 also accompanied series technical reports published iso/iec tr 19075 8 parts technical reports explain justification usage features sql giving examples appropriate technical reports non-normative discrepancy 9075 text 9075 holds currently available 19075 technical reports distinction made alternatives sql language alternatives relational model proposed relational alternatives sql language see navigational database nosql alternatives relational model distributed relational database architecture drda designed work group within ibm period 1988 1994 drda enables network connected relational databases cooperate fulfill sql requests interactive user program issue sql statements local rdb receive tables data status indicators reply remote rdbs sql statements also compiled stored remote rdbs packages invoked package name important efficient operation application programs issue complex high-frequency queries especially important tables accessed located remote systems messages protocols structural components drda defined distributed data management architecture chamberlin 2012 paper discusses four historical criticisms sql early specifications support major features primary keys result sets could named sub-queries defined added 1992 sql controversial null three-value logic predicates evaluated nulls return logical value unknown rather true false features outer-join depend nulls null equivalent space null represents data row another popular criticism allows duplicate rows making integration languages python whose data types might make difficult accurately represent data difficult terms parsing absence modularity avoided declaring unique constraint one fields identifies uniquely row table constraint could also become primary key table similar sense object-relational impedance mismatch mismatch declarative sql language procedural languages sql typically embedded iso/iec information technology task force publishes publicly available standards including sql technical corrigenda corrections technical reports discussion documents published sql -- part 1 framework sql/framework formal sql standards available iso ansi fee informative use opposed strict standards compliance late drafts often suffice
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Databases
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windows image acquisition windows image acquisition wia sometimes also called windows imaging architecture proprietary microsoft driver model application programming interface api microsoft windows later windows operating systems enables graphics software communicate imaging hardware scanners digital cameras digital video equipment first introduced 2000 part windows continues standard imaging device api model successive windows versions implemented on-demand service windows xp later windows operating systems wia significant superset support digital still imaging drivers provided still image architecture sti windows 98 whereas sti provided low-level interface basic transfers data device well invocation image scan process windows machine external device wia provides framework device present unique capabilities operating system applications invoke features according microsoft wia drivers made user interface ui component driver core component loaded two different process spaces ui application space driver core wia service space certain scanners support wia 2002 microsoft released windows image acquisition automation library tool provides access wia functionality programming languages scripting environments support ole automation windows xp wia runs localsystem context security ramifications running service localsystem whereby buggy driver malicious person would unrestricted access system wia service windows server 2003 windows vista operates localservice context result compatibility issues using driver designed windows xp windows xp support added automatic document feeder scanners scroll-feed scanners without preview capabilities multi-page tiff generation wia video snapshot filter driver introduced allows still frames captured video stream windows vista introduced windows image acquisition 2.0 windows vista also wia automation library built-in wia2 supports push scanning multi-image scanning push scanning allows initiating scans adjusting scanning parameters directly scanner control panel multi-image scanning allows one scan several images save directly separate files however video content support removed wia windows vista
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Operating systems
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queued telecommunications access method queued telecommunications access method qtam ibm system/360 communications access method incorporating built-in queuing qtam alternative lower level basic telecommunications access method btam access method qtam announced ibm 1965 part os/360 dos/360 aimed inquiry data collection announced also supported remote job entry rje applications called job processing dropped 1968 originally qtam supported ibm 1030 data collection system ibm 1050 data communications system ibm 1060 data communications system 83b2 selective calling stations western union plan 115a outstations teletype model 33 35 teletypewriters 1968 terminal support expanded include ibm 2260 display complex ibm 2740 communications terminal qtam devices attached system/360 multiplexor channel ibm 2701 data adapter ibm 2702 transmission control 1968 support ibm 2703 transmission control unit added qtam succeeded tcam provided roughly similar facilities supported dos qtam consists message control program mcp zero message processing programs mpp mcp handles communications terminals identifies input messages starts mpps process required similar concept much later internet service daemon inetd unix systems mcp assembled user installation set macros supplied ibm macros define lines terminals comprising system datasets required procedures used process received transmitted messages mpps incorporating logic process various messages supplied installation use standard os/360 data management macros codice_1 codice_2 codice_3 codice_4 pl/i includes codice_5 file declaration attribute allow mpps written high-level language
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Operating systems
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network based application recognition network based application recognition nbar mechanism used cisco routers switches recognize dataflow inspecting packets sent networking equipment uses nbar deep packet inspection packets dataflow determine traffic category flow belongs used conjunction features may program internal application-specific integrated circuits asics handle flow appropriately categorization may done open systems interconnection osi layer 4 info packet content signaling new applications made difficult purpose cling kind tagging nbar approach useful dealing malicious software using known ports fake priority traffic well non-standard applications using dynamic ports nbar also known osi layer 7 categorization cisco routers nbar mainly used quality service security purposes
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Computer security
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deep packet inspection deep packet inspection dpi type data processing inspects detail data sent computer network usually takes action blocking re-routing logging accordingly deep packet inspection often used ensure data correct format check malicious code eavesdropping internet censorship among purposes multiple headers ip packets network equipment needs use first ip header normal operation use second header tcp udp normally considered shallow packet inspection usually called stateful packet inspection despite definition multiple ways acquire packets deep packet inspection using port mirroring sometimes called span port common way well optical splitter deep packet inspection filtering enables advanced network management user service security functions well internet data mining eavesdropping internet censorship although dpi used internet management many years advocates net neutrality fear technique may used anticompetitively reduce openness internet dpi used wide range applications so-called enterprise level corporations larger institutions telecommunications service providers governments dpi combines functionality intrusion detection system ids intrusion prevention system ips traditional stateful firewall combination makes possible detect certain attacks neither ids/ips stateful firewall catch stateful firewalls able see beginning end packet flow catch events would bounds particular application idss able detect intrusions little capability blocking attack dpis used prevent attacks viruses worms wire speeds specifically dpi effective buffer overflow attacks denial-of-service attacks dos sophisticated intrusions small percentage worms fit within single packet dpi-enabled devices ability look layer 2 beyond layer 3 osi model cases dpi invoked look layer 2-7 osi model includes headers data protocol structures well payload message dpi functionality invoked device looks takes action based information beyond layer 3 osi model dpi identify classify traffic based signature database includes information extracted data part packet allowing finer control classification based header information end points utilize encryption obfuscation techniques evade dpi actions many cases classified packet may redirected marked/tagged see quality service blocked rate limited course reported reporting agent network way http errors different classifications may identified forwarded analysis many dpi devices identify packet flows rather packet-by-packet analysis allowing control actions based accumulated flow information initially security enterprise level perimeter discipline dominant philosophy keeping unauthorized users shielding authorized users outside world frequently used tool accomplishing stateful firewall permit fine-grained control access outside world pre-defined destinations internal network well permitting access back hosts request outside world made previously vulnerabilities exist network layers however visible stateful firewall also increase use laptops enterprise makes difficult prevent threats viruses worms spyware penetrating corporate network many users connect laptop less-secure networks home broadband connections wireless networks public locations firewalls also distinguish permitted forbidden uses legitimately-accessed applications dpi enables administrators security officials set policies enforce layers including application user layer help combat threats deep packet inspection able detect kinds buffer overflow attacks dpi may used enterprise data leak prevention dlp e-mail user tries send protected file user may given information get proper clearance send file addition using dpi secure internal networks internet service providers also apply public networks provided customers common uses dpi isps lawful intercept policy definition enforcement targeted advertising quality service offering tiered services copyright enforcement service providers required almost governments worldwide enable lawful intercept capabilities decades ago legacy telephone environment met creating traffic access point tap using intercepting proxy server connects government surveillance equipment acquisition component functionality may provided many ways including dpi dpi-enabled products li calea-compliant used – directed court order – access user datastream service providers obligated service-level agreement customers provide certain level service time enforce acceptable use policy may make use dpi implement certain policies cover copyright infringements illegal materials unfair use bandwidth countries isps required perform filtering depending country laws dpi allows service providers readily know packets information receiving online—from e-mail websites sharing music video software downloads policies defined allow disallow connection ip address certain protocols even heuristics identify certain application behavior isps route traffic customers able monitor web-browsing habits detailed way allowing gain information customers interests used companies specializing targeted advertising least 100,000 united states customers tracked way many 10 u.s. customers tracked way technology providers include nebuad front porch phorm u.s. isps monitoring customers include knology wide open west addition united kingdom isp british telecom admitted testing solutions phorm without customers knowledge consent dpi used net neutrality applications peer-to-peer p2p traffic present increasing problems broadband service providers typically p2p traffic used applications file sharing may kind files i.e documents music videos applications due frequently large size media files transferred p2p drives increasing traffic loads requiring additional network capacity service providers say minority users generate large quantities p2p traffic degrade performance majority broadband subscribers using applications e-mail web browsing use less bandwidth poor network performance increases customer dissatisfaction leads decline service revenues dpi allows operators oversell available bandwidth ensuring equitable bandwidth distribution users preventing network congestion additionally higher priority allocated voip video conferencing call requires low latency versus web browsing approach service providers use dynamically allocate bandwidth according traffic passing networks mobile broadband service providers use dpi means implement tiered service plans differentiate walled garden services value added all-you-can-eat one-size-fits-all data services able charge walled garden per application per service all-you-can-eat rather one-size-fits-all package operator tailor offering individual subscriber increase average revenue per user arpu policy created per user user group dpi system turn enforces policy allowing user access different services applications isps sometimes requested copyright owners required courts official policy help enforce copyrights 2006 one denmark largest isps tele2 given court injunction told must block customers accessing pirate bay launching point bittorrent instead prosecuting file sharers one time international federation phonographic industry ifpi big four record labels emi sony bmg universal music warner music begun suing isps eircom enough protecting copyrights ifpi wants isps filter traffic remove illicitly uploaded downloaded copyrighted material network despite european directive 2000/31/ec clearly stating isps may put general obligation monitor information transmit directive 2002/58/ec granting european citizens right privacy communications motion picture association america mpaa enforces movie copyrights taken position federal communications commission fcc network neutrality could hurt anti-piracy techniques deep packet inspection forms filtering dpi allows isps gather statistical information use patterns user group instance might interest whether users 2 mbit connection use network dissimilar manner users 5 mbit connection access trend data also helps network planning addition using dpi security networks governments north america europe asia use dpi various purposes surveillance censorship many programs classified fcc adopts internet calea requirements fcc pursuant mandate u.s. congress line policies countries worldwide required telecommunication providers including internet services capable supporting execution court order provide real-time communication forensics specified users 2006 fcc adopted new title 47 subpart z rules requiring internet access providers meet requirements dpi one platforms essential meeting requirement deployed purpose throughout u.s national security agency nsa cooperation inc. used deep packet inspection make internet traffic surveillance sorting forwarding intelligent dpi used find packets carrying e-mail voice internet protocol voip telephone call traffic associated ’ common backbone split two fibers dividing signal 50 percent signal strength went output fiber one output fibers diverted secure room carried communications ’ switching equipment secure room contained narus traffic analyzers logic servers narus states devices capable real-time data collection recording data consideration capture 10 gigabits per second certain traffic selected sent dedicated line central location analysis according affidavit expert witness j. scott marcus former senior advisor internet technology us federal communications commission diverted traffic represented substantially ’ peering traffic san francisco bay area thus designers ... configuration made attempt terms location position fiber split exclude data sources primarily domestic data narus semantic traffic analyzer software runs ibm dell linux servers using dpi sorts ip traffic 10gbit/s pick specific messages based targeted e-mail address ip address case voip telephone number president george w. bush attorney general alberto r. gonzales asserted believe president authority order secret intercepts telephone e-mail exchanges people inside united states contacts abroad without obtaining fisa warrant defense information systems agency developed sensor platform uses deep packet inspection chinese government uses deep packet inspection monitor censor network traffic content claims harmful chinese citizens state interests material includes pornography information religion political dissent chinese network isps use dpi see sensitive keyword going network connection cut people within china often find blocked accessing web sites containing content related taiwanese tibetan independence falun gong dalai lama tiananmen square protests massacre 1989 political parties oppose ruling communist party variety anti-communist movements materials signed dpi sensitive keywords already china previously blocked voip traffic country many available voip applications function china voice traffic skype unaffected although text messages subject dpi messages containing sensitive material curse-words simply delivered notification provided either participant conversation china also blocks visual media sites youtube.com various photography blogging sites iranian government purchased system reportedly deep packet inspection 2008 nokia siemens networks nsn joint venture siemens ag german conglomerate nokia corp. finnish cell telephone company nsn nokia solutions networks according report wall street journal june 2009 quoting nsn spokesperson ben roome according unnamed experts cited article system enables authorities block communication monitor gather information individuals well alter disinformation purposes system purchased telecommunication infrastructure co. part iranian government telecom monopoly according journal nsn provided equipment iran last year internationally recognized concept 'lawful intercept said mr. roome relates intercepting data purposes combating terrorism child pornography drug trafficking criminal activities carried online capability telecom companies said ... monitoring center nokia siemens networks sold iran described company brochure allowing 'the monitoring interception types voice data communication networks joint venture exited business included monitoring equipment called 'intelligence solution end march selling perusa partners fund 1 lp munich-based investment firm mr. roome said said company determined longer part core business nsn system followed purchases iran secure computing corp. earlier decade questions raised reporting reliability journal report david isenberg independent washington d.c.-based analyst cato institute adjunct scholar specifically saying mr. roome denying quotes attributed isenberg also similar complaints one journal reporters earlier story nsn issued following denial nsn provided deep packet inspection web censorship internet filtering capability iran concurrent article new york times said nsn sale covered spate news reports april 2009 including washington times reviewed censorship internet media country mention dpi according walid al-saqaf developer internet censorship circumventor alkasir iran using deep packet inspection february 2012 bringing internet speeds entire country near standstill briefly eliminated access tools tor alkasir dpi yet mandated russia federal law №139 enforces blocking websites russian internet blacklist using ip filtering force isps analyzing data part packets yet isps still use different dpi solutions implement blacklisting 2019 governmental agency roskomnadzor planning nationwide rollout dpi pilot project one country regions estimated cost 20 billion roubles us 300m human rights activists consider deep packet inspection contrary article 23 constitution russian federation though legal process prove refute never taken place city state reportedly employs deep packet inspection internet traffic state reportedly employs deep packet inspection internet traffic analyze block unallowed transit incumbent malaysian government headed barisan nasional said using dpi political opponent run-up 13th general elections held 5 may 2013 purpose dpi instance block and/or hinder access selected websites e.g facebook accounts blogs news portals since 2015 egypt reportedly started join list constantly denied egyptian national telecom regulatory authority ntra officials however came news country decided block encrypted messaging app signal announced application developer april 2017 voip applications including facetime facebook messenger viber whatsapp calls skype blocked country people organizations concerned privacy network neutrality find inspection content layers internet protocol offensive saying example 'net built open access non-discrimination packets critics network neutrality rules meanwhile call solution search problem say net neutrality rules would reduce incentives upgrade networks launch next-generation network services deep packet inspection considered many undermine infrastructure internet increased use https privacy tunneling using vpns effectiveness dpi coming question response many web application firewalls offer https inspection decrypt https traffic analyse waf either terminate encryption connection waf client browser uses plain http re-encrypt data using https certificate must distributed clients beforehand techniques used https ssl inspection also known https ssl interception used man-in-the-middle mitm attacks works like done tls-terminated connection https long firewall product modify truststore ssl-client traditionally mantra served isp well operate layer 4 osi model simply deciding packets go routing comparably easy handle securely traditional model still allows isp accomplish required tasks safely restricting bandwidth depending amount bandwidth used layer 4 rather per protocol application type layer 7 strong often ignored argument isp action layer 4 osi model provides known security community 'stepping stones platforms conduct man middle attacks problem exacerbated isp often choosing cheaper hardware poor security track records difficult arguably impossible secure task deep packet inspection openbsd packet filter specifically avoids dpi reason done securely confidence means dpi dependent security services talktalk former homesafe implementation actually trading security protectable often already protectable effective ways cost decreased security users also far less possibility mitigating risk homesafe service particular opt blocking dpi opted even business users ndpi fork opendpi eol developers ntop open source version non-obfuscated protocols pace another engine includes obfuscated encrypted protocols types associated skype encrypted bittorrent opendpi longer maintained opendpi-fork named ndpi created actively maintained extended new protocols including skype webex citrix many others l7-filter classifier linux netfilter identifies packets based application layer data classify packets kazaa http jabber citrix bittorrent ftp gnucleus edonkey2000 others classifies streaming mailing p2p voip protocols gaming applications hippie hi-performance protocol identification engine open source project developed linux kernel module developed josh ballard supports dpi well firewall functionality spid statistical protocol identification project based statistical analysis network flows identify application traffic spid algorithm detect application layer protocol layer 7 analysing flow packet sizes etc payload statistics byte values etc pcap files proof concept application currently supports approximately 15 application/protocols edonkey obfuscation traffic skype udp tcp bittorrent imap irc msn others tstat tcp statistic analysis tool provides insight traffic patterns gives details statistics numerous applications protocols libprotoident introduces lightweight packet inspection lpi examines first four bytes payload direction allows minimize privacy concerns decreasing disk space needed store packet traces necessary classification libprotoident supports 200 different protocols classification based combined approach using payload pattern matching payload size port numbers ip matching french company called amesys designed sold intrusive massive internet monitoring system eagle muammar gaddafi comprehensive comparison various network traffic classifiers depend deep packet inspection pace opendpi 4 different configurations l7-filter ndpi libprotoident cisco nbar shown independent comparison popular dpi tools traffic classification greater emphasis placed deep packet inspection comes light rejection sopa pipa bills many current dpi methods slow costly especially high bandwidth applications efficient methods dpi developed specialized routers able perform dpi routers armed dictionary programs help identify purposes behind lan internet traffic routing cisco systems second iteration dpi enabled routers announcement cisco isr g2 router
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Computer security
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database virtualization database virtualization decoupling database layer lies storage application layers within application stack virtualization database layer enables shift away physical toward logical virtual virtualization enables compute storage resources pooled allocated demand enables sharing single server resources multi-tenancy well pooling server resources single logical database cluster cases database virtualization provides increased flexibility granular efficient allocation pooled resources scalable computing act partitioning data stores database grows use several decades two primary ways data partitioned inside legacy data management systems virtual partitioning logical data abstracted physical data autonomously creating managing large numbers data partitions 100s 1000s autonomously maintained resources required manage partitions minimal kind massive partitioning results “ shared-data ” “ shared-nothing ” architectures allow scalability multiple data partitions cross-partition querying transaction processing without full partition scanning partitioning database sources consumers fundamental concept greater numbers database sources inserting horizontal data virtualization layer sources consumers helps address complexity rick van der lans author multiple books sql relational databases defined data virtualization process offering data consumers data access interface hides technical aspects stored data location storage structure api access language storage technology
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Databases
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espruino espruino open-source javascript interpreter microcontrollers designed devices small amounts ram low 8kb espruino created gordon williams 2012 attempt make microcontroller development truly multiplatform though initially open-source espruino firmware offered free download stm32 microcontrollers made open-source 2013 successful kickstarter campaign development board running software since original espruino board number new official development boards including small usb thumb-drive-sized espruino pico wifi-equipped espruino wifi puck.js built-in bluetooth pixl.js built-in lc display arduino shield compatibility addition official boards espruino runs approximately 40 types development boards including esp8266 large body reference material espruino including 100 tutorials well book making things smart contains selection hardware projects created espruino-based microcontrollers first official development board original espruino later boards available variety form factors original espruino followed espruino pico espruino wifi puck.js pixl.js breakout board featuring mdbt42q bluetooth le module used puck.js pixl.js also available espruino programs written using javascript espruino ide available web-based app google chrome app native windows application also alternative methods programming espruino boards using terminal programs example windows users program boards putty espruino open source different parts licensed follows
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Programming language topics
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polymorphic engine polymorphic engine sometimes called mutation engine mutating engine computer program used transform program subsequent version consists different code yet operates functionality example 3+1 6-2 achieve result yet use completely different code polymorphic engines typically work either encrypting code obfuscating code latter may involve encryption polymorphic engines used almost exclusively computer viruses shellcodes malware main purpose make hard virus scanners security software detect identify body malware traditional fixed signatures usually used first polymorphic engine called mte short mutation engine written 1992 virus author called 'dark avenger polymorphic packer type polymorphic engine polymorphic packer software tool rolls several kinds malware single package e-mail attachment ability make signature mutate time difficult detect remove
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Computer security
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prevayler prevayler open-source bsd system-prevalence layer java transparently persists plain old java objects in-ram database backed snapshots system via object serialization loaded system crash restore state changes data happen via transaction operations objects made serializable classes prevayler development started klaus wuestefeld read operations three four orders magnitude faster prevayler compared traditional database systems since objects always ram in-process prevayler requires enough ram keep entire system state
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Operating systems
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network block device operating systems network block device device node whose content provided remote machine typically network block devices used access storage device physically reside local machine remote one example local machine access hard disk drive attached another computer technically network block device realized three components server part client part network client machine device node kernel driver controls device whenever program tries access device kernel driver forwards request client part fully implemented kernel done help userspace program server machine data resides physically server machine requests client handled userspace program network block device servers typically implemented userspace program running general-purpose computer function specific network block device servers reside userspace process process communicates client via conventional sockets accesses storage via conventional file system interface network block device client module available unix-like operating systems including linux bitrig since server userspace program potentially run every unix-like platform example nbd server part ported solaris
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Operating systems
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frederica darema frederica darema greek american physicist proposed spmd programming model 1984 dynamic data driven application systems dddas 2000 elected ieee fellow 2004 darema received bs degree school physics mathematics university athens greece ms ph d. degrees theoretical nuclear physics illinois institute technology university california davis respectively attended fulbright scholar distinguished scholar physics research associate positions university pittsburgh brookhaven national laboratory received aps industrial fellowship became technical staff member nuclear sciences department schlumberger doll research subsequently 1982 joined ibm thomas j. watson research center research staff member computer sciences department later-on established became manager research group ibm research parallel applications dr. darema national science foundation since 1994 managed new generation software dynamic data driven application systems programs 1996-1998 completed two-year assignment darpa air force office scientific research
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Programming language topics
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chuck yeager advanced flight trainer chuck yeager advanced flight trainer 1987 computer aircraft simulation game produced electronic arts originally released chuck yeager advanced flight simulator due legal dispute microsoft usage flight simulator name title pulled shelves later re-released chuck yeager advanced flight trainer many copies original title sold pulled shelves chuck yeager served technical consultant game likeness voice prominently used game allows player test pilot 14 different airplanes including bell x-1 yeager piloted become first man exceed mach 1 game embellished yeager laconic commentary user crashes one plane yeager remarks really screwed pooch one asides chuck yeager advanced flight trainer includes 11 real aircraft three experimental aircraft designed developers fictional experimental aircraft named people worked game game big hit ea selling 100,000 copies december 1987 sales surpassed 250,000 copies november 1989 game reviewers hartley patricia lesser complimented game role computers column dragon 126 1987 stating much game going quite time another flight simulator offer much performance buck reviewers gave pc/ms-dos version game 4 5 stars lessers reviewed macintosh version game 1988 dragon 140 role computers column giving version 4 stars well compute criticized blocky graphics sound noted simple graphics resulted high frame rate concluded chuck yeager differed games simulating flying high-performance experimental aircraft 1994 survey wargames computer gaming world gave title one-plus stars five stating replaced chuck yeager air combat game followed 1989 chuck yeager advanced flight trainer 2.0 1991 chuck yeager air combat
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Computer architecture
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trustix trustix secure linux linux distribution intended use servers focused security stability hardened secure os meaning non-essential services binaries installed unix staples like sendmail replaced programs like postfix trustix originally produced trustix company established late 1997 entrepreneurs usa norway company went bankrupt 2003 comodo group bought assets november 2003 shortly thereafter comodo announced end free version trustix secure linux long thereafter comodo changed minds free version reappeared late 2005 series budget cuts resulted many developers laid early 2006 members original trustix team left company trustix secure linux continues maintained small team developers india late 2007 comodo announced discontinue distribution updates direct support trustix secure linux effective december 31 2007
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Operating systems
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parkerian hexad parkerian hexad set six elements information security proposed donn b. parker 1998 parkerian hexad adds three additional attributes three classic security attributes cia triad confidentiality integrity availability parkerian hexad attributes following attributes information atomic broken constituents non-overlapping refer unique aspects information information security breach described affecting one fundamental attributes information confidentiality refers limits get kind information example executives concerned protecting enterprise strategic plans competitors individuals concerned unauthorized access financial records integrity refers correct consistent intended state information unauthorized modification data whether deliberate accidental breach data integrity example data stored disk expected stable – supposed changed random problems disk controller similarly application programs supposed record information correctly introduce deviations intended values donn parker definition information integrity comes dictionaries integrity means information whole sound unimpared necessarily correct means nothing missing information complete intended good order author statement comes close saying information correct ... state information may incorrect authentic integrity correct authentic lacking integrity availability means timely access information example disk crash denial-of-service attacks cause breach availability delay exceeds expected service levels system described breach availability authenticity refers veracity claim origin authorship information example one method verifying authorship hand written document compare handwriting characteristics document sampling others already verified electronic information digital signature could used verify authorship digital document using public-key cryptography could also used verify integrity document possession control suppose thief steal sealed envelope containing bank debit card personal identification number even thief open envelope reasonable victim concerned thief could time situation illustrates loss control possession information involve breach confidentiality utility means usefulness example suppose someone encrypted data disk prevent unauthorized access undetected modifications – lost decryption key would breach utility data would confidential controlled integral authentic available – would n't useful form similarly conversion salary data one currency inappropriate currency would breach utility would storage data format inappropriate specific computer architecture e.g. ebcdic instead ascii 9-track magnetic tape instead dvd-rom tabular representation data substituted graph could described breach utility substitution made difficult interpret data utility often confused availability breaches described examples may also require time work around change data format presentation however concept usefulness distinct availability
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Computer security
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pagerduty pagerduty cloud computing company produces saas incident response platform departments 2018 company raised 170 million venture funding recognized forbes cloud 100 well usa today list top small mid-sized companies diversity 2018 pagerduty headquartered san francisco operations toronto ontario atlanta united kingdom australia platform designed alert clients disruptions outages machine learning automation software operates standalone service integrated existing systems company works 10,000 clients including airbnb ibm instacart lululemon uber william hill australia company founded 2009 toronto ontario university waterloo graduates alex solomon andrew miklas baskar puvanathasan company incubated combinator pagerduty raised seed funding round 1.9 million 2010 followed series round raised 10.7 million january 2013 july 2016 former ceo keynote systems jennifer tejada named ceo pagerduty later year company held first pagerduty summit industry conference encourage digital innovation pagerduty summit held san francisco 2017 2018 2016 pagerduty received silver stevie award female executive year computer services computer software category following year company gold new product service year award software service management solution silver award customer service department year computer services pagerduty announced funding round april 2017 led accel 43.8 million round included existing investors andreessen horowitz bessemer venture partners baseline ventures harrison metal september 2018 pagerduty raised 90 million round led t. rowe price associates wellington management june 2018 pagerduty launched event intelligence product designed analyze incoming digital signals human responses communicate incident response suggestions operators new incidents occur industry conference september 2018 company also launched pagerduty visibility pagerduty analytics march 2019 pagerduty filed s-1 sec anticipation ipo april 2019 pagerduty went public new york stock exchange
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Distributed computing architecture
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windows terminal windows terminal terminal emulator windows 10 written microsoft includes support command prompt powershell wsl ssh initial source code release github preview release first published microsoft store june 21 2019
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Operating systems
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geoplexing geoplexing computer science term relating duplication computer storage applications within server farm geographically diverse locations purpose fault tolerance name comes contraction geographical multiplex geoplex server clusters duplicated one geographically separate sites geoplexes active-active clusters used tandem active-passive one clusters kept hot spare data applications shared either via cloning partitioning cloning server cluster handles one applications applications data cloned servers geoplex load balancer distributes requests cloned servers partitioning hardware applications duplicated geoplex application data divided servers requests routed correct server
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Computer architecture
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steelman language requirements steelman language requirements set requirements high-level general-purpose programming language meet created united states department defense department defense common high order language program 1978 predecessors document called order strawman woodenman tinman ironman requirements focused needs embedded computer applications emphasised reliability maintainability efficiency notably included exception handling facilities run-time checking parallel computing concluded existing language met criteria sufficient extent contest called create language would closer fulfilling design contest became ada programming language resulting language followed steelman requirements closely though exactly ada 95 revision language went beyond steelman requirements targeting general-purpose systems addition embedded ones adding features supporting object-oriented programming
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Programming language topics
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messenger plus messenger plus formerly known messenger plus live commonly abbreviated msgplus plus incorrectly msn plus add-on windows live messenger skype software provides additional functionality microsoft instant messaging client windows live messenger adding controls main interface controls affect messenger behaviour appearance often additional dialog boxes add-on first released may 2001 name messenger plus extension msn messenger windows messenger later changed name messenger plus release new windows live messenger client messenger plus live chosen 2011 name changed back messenger plus become one widely used add-ons microsoft im clients citing 62 million users february 2010 volunteers messenger plus community around world develop skins scripts submission database website software messenger plus generally expands features windows live messenger 2009 9.0 2011. notable features include messenger plus available 22 languages messenger plus originally created 2001 cyril paciullo better known pseudonym patchou born france currently resides canada started developing plus hobby next day job developer soon maintaining messenger plus software became full-time job q4 2009 paciullo announced longer full control product messenger plus owned yuna software limited q1 2011 paciullo officially declared left company chapter professional life closed financial details names people behind new company disclosed yuna software offices several places world office montreal also known kimahri software development team continued develop messenger plus developing messenger plus became full-time job form revenue added keep software free formerly software came bundled optional adware software developed circle development ltd. august 17 2005 messenger plus website contained petition microsoft anti-spyware division regarding windows defender known microsoft antispyware time detection messenger plus executable spyware subsequent warning messenger plus would attempt install spyware runtime post-installation rather setup program contained installer threat detected petition 401,683 signatures 10,137 pages long total sent redmond september 20 2005 stating messenger plus labeled threat september 23 2005 3 days petition mailed redmond canada microsoft released new definitions windows defender fixed false threat detection affecting messenger plus executable together detection improvements recent versions windows defender also stopped detecting messenger plus installer potentially dangerous software review websites criticized user agreement stating 'sponsorship agreement authorized installation optional adware software misleading looked like standard eula available english user get option install 'sponsor program however even slightly unorthodoxly since messenger plus 3.60 released september 27 2005 setup includes separate sponsor license agreement addition traditional eula agreements also translated several languages separate adware uninstallation program provided circle development ltd. appears users attempt uninstall sponsor program messenger plus early 2010 messenger plus versions 4.84 later longer contain sponsor program circle development ltd. yuna software currently uses conventional methods messenger plus bundles optional toolbar custom search page custom home page branded messenger plus network yuna software also launched sites 2010 affiliated messenger plus including plus games plus sports plus image plus network links old website earlier messenger plus versions caused sites mcafee siteadvisor warn website www.msgpluslive.net linked adware adware-lop/swizzor however siteadvisor tested current website www.msgplus.net found downloads free adware spyware potentially unwanted programs sites already found site safe example norton safe web found issues site stating 0 computer threats 0 identity threats 0 annoyance factors february 2013 yuna software released new installer messenger plus required user install least one bundled options order install software note may longer requirement recent updates appear require bundled options installed confirmed clean install coincide newly branded windows live messenger 2006 new versions messenger plus called messenger plus live rebuilt ground included new user interface design intended blend user interface windows live messenger since 2011 versions 5.0 later called messenger plus messenger plus 5 completely compatible windows live messenger 2011 latest version messenger plus longer supports messenger version older 2009 older messenger plus versions longer officially supported however last version messenger plus version 3.63 renamed messenger plus live still available download official website version supports msn messenger windows messenger 4.7 5 6 7 additionally last version messenger plus live version 4.90.392 name changed back also still available official website version supports windows live messenger 8.0 14.0 2009 messenger plus skype released english january 12 2012 adware adds video audio recording capabilities skype conversations lets users send flash animations users subsequent version messenger plus skype 1.2 released march 28 2012 introduced 16 additional languages video voice transformation effects ring tones version 1.5 released june 18 2012 included ability stream movies overlay images video conversations viewable skype-enabled devices including mobile phones tablets version 1.8 followed march 3 2013 release developed microsoft announcement discontinuing windows live messenger service integrated custom sounds united messenger plus windows live messenger/skype sound archive also introduced new default design add-on messenger plus skype application skype adds video audio recording capabilities skype notable features include skype announced intention discontinue desktop api used messenger plus skype note date happen originally december 2013 unknown skype tries come new methods support small subset desktop api functionality currently information available yuna website mentions plans handle desktop api discontinued skype point future version 3.0.0.180 messenger plus skype available automatic download around january 15 2014 built january 8th 2014 updated components december 2013 first version year feature seem mentioned anywhere sends ad messenger plus chat message random contacts feature makes less extension unusable second version year 3.0.0.185 released february 2014 feature mentioned turned apparently messenger plus still supported noted despite fact yuna software website gives impression software longer active development due following factors noted forums longer accessible public may even exist links redirect back yuna website archive forums exist hosted third party
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Internet protocols
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monaco typeface monaco monospaced sans-serif typeface designed susan kare kris holmes ships os x already present previous versions mac operating system characters distinct difficult confuse 0 figure zero uppercase 1 figure one vertical bar uppercase l lowercase l unique feature font high curvature parentheses well width square brackets result empty pair parentheses square brackets strongly resemble circle square respectively monaco released least three forms original bitmap monospace font still appears roms even new world macs still available recent macos releases size 9 disabled antialiasing second outline form loosely similar lucida mono created truetype font system 6 7 standard font used sizes briefly third known mpw since designed used macintosh programmer workshop ide essentially straight conversion bitmap font outline font addition disambiguation features added truetype monaco original monaco 9 point bitmap font designed compact macintosh window displayed full screen terminal emulator program would result standard text user interface display 80 columns 25 lines august 2009 release mac os x 10.6 snow leopard menlo introduced default monospaced font instead monaco terminal xcode however monaco remains part os x. monaco default font current python idle used mac running os x el capitan
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Operating systems
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ipfire ipfire hardened open source linux distribution primarily performs router firewall standalone firewall system web-based management console configuration ipfire originally started fork ipcop rewritten basis linux scratch since version 2 supports installation add-ons add server services extended soho server april 2015 project became member open invention network basic requirements least 1ghz cpu 1gb ram 4gb hard drive two network cards needed connect ethernet network dsl lte wi-fi wlan supported according hardware required computing power run ipfire depends area application commonly x86 systems used arm devices raspberry pi banana pi supported ipfire used virtual environments kvm vmware xen qemu etc. basic setup ipfire happens guided dialogue console administration takes place web-based management interface add-ons additional features project regularly updated development team maintain security developed stateful packet inspection spi firewall ipfire separates network different segments based security risk organised colours normal clients connected lan represented green internet represented red optional dmz represented orange optional wireless network represented blue traffic flow segments unless specifically permitted firewall rule ipfire package management system called pakfire allows install system updates keep security date additional software packages customisation different usage scenarios needs linux system customised concrete purpose firewall design modular making functionalities extensible plugins base comes following features
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Computer security
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chung kwei algorithm chung kwei spam filtering algorithm based teiresias algorithm finding coding genes within bulk dna
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Computer security
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syntactic sugar computer science syntactic sugar syntax within programming language designed make things easier read express makes language sweeter human use things expressed clearly concisely alternative style may prefer example many programming languages provide special syntax referencing updating array elements abstractly array reference procedure two arguments array subscript vector could expressed codice_1 instead many languages provide syntax codice_2 similarly array element update procedure three arguments example codice_3 many languages provide syntax codice_4 construct language called syntactic sugar removed language without effect language functionality expressive power remain language processors including compilers static analyzers often expand sugared constructs fundamental constructs processing process sometimes called desugaring term syntactic sugar coined peter j. landin 1964 describe surface syntax simple algol-like programming language defined semantically terms applicative expressions lambda calculus centered lexically replacing λ later programming languages clu ml scheme extended term refer syntax within language could defined terms language core essential constructs convenient higher-level features could desugared decomposed subset fact usual mathematical practice building primitives building landin distinction essential language constructs syntactic sugar 1991 matthias felleisen proposed codification expressive power align widely held beliefs literature defined expressive mean without language constructs question program would completely reorganized programmers feel syntax usability features either unimportant outright frivolous notably special syntactic forms make language less uniform specification complex may cause problems programs become large complex view particularly widespread lisp community lisp simple regular syntax surface syntax easily modified example alan perlis quipped epigrams programming reference bracket-delimited languages syntactic sugar causes cancer semi-colons metaphor extended coining term syntactic salt indicates feature designed make harder write bad code specifically syntactic salt hoop programmers must jump prove know going rather express program action example java pascal assigning float value variable declared int without additional syntax explicitly stating intention result compile error c c++ automatically truncate floats assigned int however syntax semantics c hiding inherited class member compiler warning issued unless codice_29 keyword used specify hiding intentional avoid potential bugs owing similarity switch statement syntax c c++ c requires codice_30 non-empty codice_31 label codice_32 unless codice_33 codice_34 codice_35 used even though allow implicit fall-through using codice_33 specifying subsequent label produces c/c++-like fall-through syntactic salt may defeat purpose making code unreadable thus worsen quality – extreme cases essential part code may shorter overhead introduced satisfy language requirements alternative syntactic salt generating compiler warnings high probability code result mistake – practice common modern c/c++ compilers extensions syntactic saccharin syntactic syrup meaning gratuitous syntax make programming easier
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Programming language topics
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sunos sunos unix-branded operating system developed sun microsystems workstation server computer systems sunos name usually used refer versions 1.0 4.1.4 based bsd versions 5.0 later based unix system v release 4 marketed brand name solaris sunos 1 supported sun-2 series systems including sun-1 systems upgraded sun-2 68010 cpu boards sunos 2 supported sun-2 sun-3 68020 series systems sunos 4 supported sun-2 release 4.0.3 sun-3 4.1.1 sun386i 4.0 4.0.1 4.0.2 sun-4 sparc architectures although sunos 4 intended first release fully support sun new sparc processor also sunos 3.2 release preliminary support sun-4 systems sunos 4.1.2 introduced support sun first sun4m-architecture multiprocessor machines sparcserver 600mp series since single lock kernel one cpu time could execute kernel last release sunos 4 4.1.4 solaris 1.1.2 1994 sun4 sun4c sun4m architectures supported 4.1.4 sun4d supported sun continued ship sunos 4.1.3 4.1.4 december 27 1998 supported september 30 2003 1987 corporation sun announced collaborating project merge popular unix flavors market time bsd including many features unique sunos system v xenix would become system v release 4 svr4 september 4 1991 sun announced next major os release would switch bsd-derived source base one based svr4 although internal designation release would sunos 5 point sun began using marketing name solaris justification new overbrand encompassed sunos also openwindows desktop environment open network computing onc functionality even though new svr4-based os expected ship volume following year sun immediately began using new solaris name refer currently shipping sunos 4 release also including openwindows thus sunos 4.1.1 rebranded solaris 1.0 sunos 5.0 would considered part solaris 2.0 sunos 4.1 x micro versions continued released 1994 also given solaris 1 x equivalent name practice often still referred customers even sun personnel sunos release names matching version numbers straightforward today sunos 5 universally known solaris although sunos name still visible within os startup banner output uname command man page footers among places matching sunos 5.x release corresponding solaris marketing name simple solaris release name includes corresponding sunos 5 minor version number example solaris 2.4 incorporated sunos 5.4 one small twist solaris 2.6 2 dropped solaris name sunos minor number appears latest solaris release named solaris 11 incorporates sunos 5.11 gui environments bundled earlier versions sunos included suntools later sunview news 1989 sun released openwindows open look-compliant x11-based environment also supported sunview news applications became default sunos gui sunos 4.1.1
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Operating systems
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sans institute sans institute officially escal institute advanced technologies private u.s. for-profit company founded 1989 specializes information security cybersecurity training selling certificates topics available training include cyber network defenses penetration testing incident response digital forensics audit information security courses developed consensus process involving administrators security managers information security professionals courses cover security fundamentals technical aspects information security institute recognized training programs certification programs sans stands sysadmin audit network security sans institute sponsors internet storm center internet monitoring system staffed global community security practitioners sans reading room research archive information security policy research documents sans one founding organizations center internet security sans offers news analysis twitter feeds e-mail newsletters additionally weekly news vulnerability digest available subscribers originally organized 1989 sans training events functioned like traditional technical conferences showcasing technical presentations mid-1990s sans offered events combined training tradeshows beginning 2006 sans offered asynchronous online training sans ondemand virtual synchronous classroom format sans vlive free webcasts email newsletters risk newsbites ouch developed conjunction security vendors actual content behind sans training courses training events remain vendor-agnostic vendors pay offer official sans course although teach sans hosted event via sponsorship 1999 sans institute formed global information assurance certification giac independent entity grants certifications information security topics developed operates netwars suite interactive learning tools simulating scenarios cyberattacks netwars use us air force us army majority sans faculty sans employees industry professionals respected experts field information security faculty organized six different levels mentors community certified instructors principal instructors senior instructors fellows sans established sans technology institute accredited college based sans training giac certifications november 21 2013 sans technology institute granted regional accreditation middle states commission higher education sans technology institute focuses exclusively cybersecurity offering master science degree program information security engineering msise five post-baccalaureate certificate programs penetration testing ethical hacking incident response industrial control systems cyber defense operations cybersecurity engineering core upper-division undergraduate certificate program applied cybersecurity sans continues offer free security content via sans technology institute leadership lab it/security related leadership information
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Computer security
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ibm advanced program-to-program communication computing advanced program program communication appc protocol computer programs use communicate network appc application layer osi model enables communications programs different computers portables workstations midrange host computers appc defined vtam lu 6.2 logical unit type 6.2 appc developed 1982 component ibm systems network architecture sna several apis developed programming languages cobol pl/i c rexx appc software available many different ibm non-ibm operating systems either part operating system separate software package appc serves translator application programs network application computer passes information appc software appc translates information passes network interface lan adapter card information travels across network another computer appc software receives information network interface appc translates information back original format passes corresponding partner application appc mainly used ibm installations running operating systems z/os formerly mvs os/390 z/vm formerly vm/cms z/tpf ibm formerly os/400 os/2 aix z/vse formerly dos/vse microsoft also includes sna support microsoft host integration server major ibm software products also include support appc including cics db2 cim websphere mq unlike tcp/ip communication partners always possess clear role one always server others always client appc peer-to-peer protocol communication partners appc equal every application server client equally role number parallel sessions partners negotiated cnos sessions change number session special log mode e.g ibm 'snasvcmg transmission data made 'data sessions log modes determined detail vtam administrator e.g length data blocks coding etc.. also apparent architects appc could used provide operating system services remote computers separate architecture group formed use appc enable programs one computer transparently use data management services remote computers use appc session created used client-server fashion conversational communications manager distributed data management architecture ddm message formats protocols defined accessing managing record-oriented files stream-oriented files relational databases base architecture distributed relational database architecture drda services variety ddm drda products implemented ibm vendors increasing prevalence tcp/ip appc declined although many ibm systems translators enterprise extender rfc 2353 allow sending appc-formatted traffic ip networks appc confused similarly named appn advanced peer-to-peer networking appc manages communication programs operating application presentation layers contrast appn manages communication machines including routing operates transport network layers
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Internet protocols
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data diffusion machine data diffusion machine historical virtual shared memory architecture data free migrate machine shared memory machines convenient programming scale beyond tens processors data diffusion machine ddm overcomes problem providing virtual memory abstraction top distributed memory machine ddm appears user conventional shared memory machine implemented using distributed memory architecture data diffusion machines active research late 1980s early 1990s research ceased since
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Distributed computing architecture
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cpu core voltage cpu core voltage v power supply voltage supplied cpu digital circuit gpu device containing processing core amount power cpu uses thus amount heat dissipates product voltage current draws modern cpus cmos circuits current almost proportional clock speed cpu drawing almost current clock cycles see however subthreshold leakage order help conserve power manage heat many laptop desktop processors power management feature allows software usually operating system adjust clock speed core voltage dynamically often voltage regulator module converts 5v 12 v voltage whatever cpu core voltage required cpu trend towards lower core voltages conserve power presents cmos designer challenge cmos voltages go ground supply voltage source gate drain terminals fets supply voltage zero voltage across mosfet formula formula_1 says current formula_2 supplied fet proportional gate-source voltage reduced threshold voltage formula_3 dependent geometrical shape fet channel gate physical properties especially capacitance order reduce formula_3 necessary order reduce supply voltage increase current one must increase capacitance load driven fact another fet gate current needed drive proportional capacitance thus requires designer keep low trend towards lower supply voltage therefore works goal high clock speed improvements photolithography reduction threshold voltage allow improve another note formula shown long channel mosfets area mosfets halving every 18-24 months moore law distance two terminals mosfet switch called channel length becoming smaller smaller changes nature relationship terminal voltages current processor overclocked clock speed increased cost system stability withstand higher clocks core voltage often needs increased cost power consumption heat dissipation known overvolting overvolting generally involves running processor specifications may damage shorten cpu life dual-voltage cpu uses split-rail design allow lower voltages used processor core external input/output i/o voltages remain 3.3 volts backwards compatibility single-voltage cpu uses single power voltage throughout chip supplying i/o power internal power 2002 microprocessor market statistics cpus single-voltage cpus cpus pentium mmx single-voltage cpus dual-voltage cpus introduced performance gain increasing clock speeds finer semiconductor fabrication processes resulted excess heat generation power supply concerns especially regarding laptop computers using voltage regulator external i/o voltage levels would transformed lower voltages order reduce power usage resulting less heat produced ability operate higher frequencies vrt feature older intel p5 pentium processors typically intended use mobile environment refers splitting core voltage supply i/o voltage vrt processor 3.3 v i/o 2.9 v core voltage save power compared typical pentium processor i/o core voltage 3.3v pentium mmx later processors adopted so-called split rail power supply
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Computer architecture
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driver vehicle licensing agency driver vehicle licensing agency dvla organisation uk government responsible maintaining database drivers great britain database vehicles entire united kingdom counterpart drivers northern ireland driver vehicle agency dva agency issues driving licences organises collection vehicle excise duty also known road tax road fund licence sells personalised registrations dvla executive agency department transport dft current chief executive agency julie lennard dvla based swansea wales prominent 16-storey building clase offices swansea vale previously known driver vehicle licensing centre dvlc agency previously network 39 offices around great britain known local office network users could attend apply licences transact business throughout course 2013 local offices gradually closed closed december 2013 agency work consequently fully centralised swansea majority users transact remotely post transactions phone dvla introduced electronic vehicle licensing evl 2004 allowing customers pay vehicle excise duty online telephone however customers still option tax vehicles via post office seven-year contract enabling post office continue process car tax applications agreed november 2012 option three-year extension originally vehicle registration responsibility borough county councils throughout great britain system created motor car act 1903 licensing system centralised 1965 administered driver vehicle licensing centre dvlc swansea 1990 dvlc renamed driver vehicle licensing agency dvla becoming executive agency department transport civilian vehicles used germany members british forces germany families registered dvla behalf ministry defence official diplomatic consular vehicles registered dvla behalf foreign commonwealth office vehicle register held dvla used many ways example dvla identify untaxed vehicles outside agencies identify keepers cars entering central london paid congestion charge exceed speed limits road speed cameras matching cars keepers utilising dvla database current dvla vehicle register built eds £5 million contract signed 1996 planned implementation date october 1998 though actual implementation delayed year uses client–server architecture uses vehicle identification number rather registration plate primary key track vehicles eliminating possibility multiple registrations single vehicle vehicle identity check vic introduced help reduce vehicle crime intended deter criminals disguising stolen cars identity written scrapped vehicles however scheme later scrapped october 2014 insurance company writes car registration document v5 logbook surrendered destroyed insurance company notify dvla vehicle written notification set vic marker vehicle record dvla database dvla database records used commercial vehicle check companies offer comprehensive individual car check prospective purchasers however accuracy data held remains continuing problem anyone request information database purport cause need fee £2.50 database drivers developed late 1980s holds details 42 million driving licence holders uk used produce driving licences assist bodies driving standards agency police courts enforcement legislation concerning driving entitlements road safety dvla revealed december 2012 temporarily banned 294 public bodies including local councils police forces using access database correctly 2006 2012 38 bodies banned permanently period 2002 2015 estimated dvla spent £500 million information technology ibm staff dvla predominantly female whereas parts department transport predominantly male starting salaries £12,500 november 2007 public accounts committee report criticised amazingly high levels sick leave among staff dvla employees took average three weeks per year sick leave report said overall sickness leave dft seven agencies averaged 10.4 working days per full-time employee 2005 calculated costing taxpayers £24 million sick leave rates department four agencies average—at dvla dsa together employ 50 dft staff—they significantly higher committee chairman edward leigh said surprising agencies could function adequately 2008 dvla staff went one-day strike pay inequality arguing receive similar salaries employees department transport recent level sickness absence 2012/13 6.7 days 2006 120,000 130,000 vehicle registration certificates went missing bbc investigation 2010 found vehicles worth £13 million stolen using documents 18 months preceding investigation around ten cars found week forged log books police said would decades recovered 7 february 2007 letter bomb sent dvla swansea injured four people suspected part group letter bombs sent organisations deal administration motoring charges offences capita central london targeted days earlier miles cooper aged 27 school caretaker arrested 19 february 2007 charged 22 february dvla since installed x-ray machines post opening areas reduce effectiveness attacks december 2007 revealed sending surveys 1,215 drivers dvla sent confidential details wrong owners error occurred sending routine surveys discovered members public contacted dvla notify error 2009 bbc watchdog reported entitlements specifically entitlement drive motorcycle lost reissued driving licences 2005 programme highlighted drivers lost entitlements drive heavy goods vehicles similar way 2010 revealed dvla sold drivers details database certain private parking enforcement companies run individuals criminal records dvla sells details companies £2.50 found agency sold business fined weeks unfair business practices dvla uses advertising warn drivers pay road tax cars may crushed despite bill rights 1689 section 12 states 'all fines forfeitures conviction illegal void uk legal persons equality law dvla therefore stands equal private citizens court law seeking civil penalty sorn 'fine so-called dvla right sue car owners civil court practice dvla illegally usurps judicial procedure bypasses presumption innocence levies fine £40 £80 without regard extenuating circumstances illness documents lost post etc sorn scheme never debated parliament also 'daft pointless legislation motorists ... asked confirm dvla already know acknowledgment lost post might need proof 've confirmed 've confirmed already know ... dvla makes mistake claims car owners responsible clamping vehicles explicitly outlawed scotland may english law constitute common law offence 'holding property ransom according peter oborne fines levied dvla grossly disproportionate represent justice part unofficial supplementary tax-gathering system dvla handled 12,775 complaints year 2015/16 failed resolve 14.9 first contact overall complaints year 6.5 dvla 'customer service excellence standard retained details provided measured customer satisfaction levels varied 76 97 four categories surveyed vehicle registration driver licence renewal vehicle taxation driver medical transactions data provided respect complaints sorn scheme fines levied dvlc swansea regularly referred british political sitcom yes minister bernard woolley regularly threatened reassignment episode big brother jim hacker scheduled give address
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Databases
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security obscurity security obscurity security obscurity reliance security engineering design implementation secrecy main method providing security system component security experts rejected view far back 1851 advise obscurity never security mechanism early opponent security obscurity locksmith alfred charles hobbs 1851 demonstrated public state-of-the-art locks could picked response concerns exposing security flaws design locks could make vulnerable criminals said rogues keen profession know already much teach scant formal literature issue security obscurity books security engineering cite kerckhoffs doctrine 1883 cite anything example discussion secrecy openness nuclear command control benefits reducing likelihood accidental war considered outweigh possible benefits secrecy modern reincarnation kerckhoffs doctrine first put forward nineteenth century security system depend key design remaining obscure field legal academia peter swire written trade-off notion security obscurity illusion military notion loose lips sink ships well competition affects incentives disclose principle security obscurity generally accepted cryptographic work days essentially well-informed cryptographers employed national intelligence agencies national security agency cryptographers often work universities researchers publish many even results publicly test others designs private industry results often controlled patents copyrights secrecy argument lost former popularity example pgp whose source code publicly available anyone generally regarded military-grade cryptosystem conflicting stories origin term fans mit incompatible timesharing system say coined opposition multics users hall security far issue within culture term referred self-mockingly poor coverage documentation obscurity many commands attitude time tourist figured make trouble 'd generally got urge make felt part community one instance deliberate security obscurity noted command allow patching running system altmode altmode control-r echoed ^d typing alt alt control-d set flag would prevent patching system even user later got right security obscurity alone discouraged recommended standards bodies national institute standards technology nist united states sometimes recommends practice system security depend secrecy implementation components technique stands contrast security design open security although many real-world projects include elements strategies knowledge system built differs concealment camouflage efficacy obscurity operations security depends whether obscurity lives top good security practices used alone used independent layer obscurity considered valid security tool recent years security obscurity gained support methodology cybersecurity moving target defense cyber deception nist cyber resiliency framework 800-160 volume 2 recommends usage security obscurity complementary part resilient secure computing environment research firm forrester recommends usage environment concealment protect messages advanced persistent threats
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Computer security
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rtxc quadros rtxc quadros real time operating system rtos written mainly c programming language mainly intended use embedded systems rtxc rtos originally developed barrett associates 1970s currently maintained quadros systems inc. houston texas rtxc quadros comes tracing tool give insight runtime dynamics timing rtxcview
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Operating systems
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text ip text ip toip means providing real-time text rtt service operates ip-based networks complements voice ip voip video ip real-time text streaming text transmitted produced allowing text used conversationally real-time text defined itu-t multimedia recommendation f.700 2.1.2.1 real-time text designed conversational use people interactively converse achieve particular user requirements specified delay character character loss rate see f.700 annex a.3 real-time text ip used toip designed around itu-t t.140 real-time text presentation layer protocol defined h.32x multimedia services t.140 allows real-time editing text e.g using 'backspace retyping t.140 based iso 10646-1 character set used ip text specifications uses utf-8 format transport toip uses real-time transport protocol rtp voip video-over-ip text encoded according ietf rfc 4103 rtp payload text conversation rfc 4103 supports optional forward error correction scheme based redundant transmission using rfc 2198 results low end-to-end packet loss across ip transmission links moderately high packet loss improve efficiency text buffered 0.3 – 0.5 seconds sent whilst still meeting delay requirements rtp usually transported user datagram protocol udp however 2.5g mobile networks supported transmission control protocol tcp consistently support udp implementations toip mobile networks use tcp internally 3g mobile networks support udp protocol stack toip medium fast typing 30 characters per second results two kilobit per second traffic load including overheads rfc4103 maximum level redundancy rtp udp ip control toip sessions defined using standard session initiation protocol sip rfc 3261 session description protocol sdp rfc 4566 protocols see ietf rfc 5194 framework real-time text ip using session initiation protocol sip ietf rfc 4504 sip telephony device requirements configuration section 2.9 information next generation networking ngns concept developed telecommunication service providers suppliers aims create true multi-service network based ip technology toip specified inclusion 3gpp ip multimedia subsystem ims 3gpp ts 26.114 v2.0.0 ims multimedia telephony media handling interaction ims used implement ngns many fixed mobile networks support toip considered multimedia emergency public-safety answering point psaps europe usa ecrit ietf working group defines toip one form access emergency services toip provide 'low impact solution meeting national regulatory requirements provide 'equivalent service telephone service people hearing speech impairments typical terminal fixed line access home computer supports multimedia communications voice video real-time text ip see external links information toip equipment software telecommunications device deaf tdd ttys also called textphone minicoms designed transport real-time text pstn tdds use range modem technologies text-over-ip designed replacement tdds using ip-based networks also use mainstream voice call users less service restrictions compared tdds designed used mainstream service used standard computers mobile terminals proper alerting systems incoming calls need included well user interfaces hardware software meet needs deaf people people hearing speech impairments best achieved input end-users development stages interworking tdds toip implemented using gateways t-meeting omnitor trace r rnid center voiceriver annies rfc 5194 framework real-time text ip using session initiation protocol sip provides overview interworking issues work proposed ietf sipping work group detailed interworking based range call scenarios
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Internet protocols
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find device find device application service provided google remotely trace locate android devices phones tablets watches using map find device uses map locate trace exert location android device located location available allow users remotely locate android device linked google account
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Operating systems
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internet watch foundation internet watch foundation iwf registered charity based cambridgeshire england states remit minimise availability online sexual abuse content specifically child sexual abuse images videos hosted anywhere world non-photographic child sexual abuse images hosted uk content inciting racial hatred removed iwf remit police website set purpose april 2011 iwf used also take reports criminally obscene adult content hosted uk removed iwf ’ remit 2017 part function iwf says supply partners accurate current url list enable blocking child sexual abuse content excellent responsive national hotline reporting service receiving reports public addition receiving referrals public agents also proactively search open web deep web identify child sexual abuse images videos ask service providers take websites containing images block fall outside uk jurisdiction found open web traces content hosted geographically either directly issues notice hosting company remove imagery hosted uk works network hotlines police around world follow country ’ process removing imagery 99 child sexual abuse images found iwf hosted outside uk instance whilst work remove imagery takes place iwf places web address url list partners block content 2010 office government commerce ogc required procurement specifications provision internet-related services government agencies public bodies require internet service provider isp block access sites iwf list iwf operates informal partnerships police government public internet companies across world originally formed police suspected child pornography online iwf remit later expanded cover criminally obscene material iwf takes strong stance term ‘ child pornography ’ website cites “ use term child sexual abuse reflect gravity images videos deal child pornography child porn kiddie porn acceptable descriptions child consent abuse ” iwf incorporated charity limited guarantee largely funded voluntary contributions uk communications service providers including isps mobile phone operators internet trade associations search engines hardware manufacturers software providers also currently receives funding european union comprising one third uk safer internet centre iwf governed board trustees consists independent chair six non-industry representatives three industry representatives plus one co-opted independent representative specialism human rights board monitors reviews iwf remit strategy policy budget enable iwf achieve objectives iwf operate offices vision park near cambridge criticized ineffective quango deserve charity status producing excessive numbers false positives secrecy proceedings poor technical implementations policies degraded response time whole uk internet iwf succeeded reducing child sexual abuse imagery hosted uk 18 1996 0.04 2018 1996 metropolitan police told internet service providers association ispa content carried newsgroups made available illegal considered isps involved publishers material therefore breaking law august 1996 chief inspector stephen french metropolitan police clubs vice unit sent open letter ispa requesting ban access list 132 newsgroups many deemed contain pornographic images explicit text list arranged first section consisted unambiguously titled paedophile newsgroups continued kinds groups police wanted restrict access including alt.binaries.pictures.erotica.cheerleaders alt.binaries.pictures.erotic.centerfolds although action taken place without prior debate parliament elsewhere police appeared best create simply enforce law acting entirely initiative alan travis home affairs editor newspaper guardian explained book bound gagged ian taylor conservative science industry minister time underlined explicit threat isps stop carrying newsgroups question police would act company provided users pornographic violent material taylor went make clear would calls legislation regulate aspects internet unless service providers seen wholeheartedly embrace responsible self-regulation isp demon internet regarded police request unacceptable censorship however attitude annoyed ispa chairman shez hamill said following tabloid-style exposé demon internet appeared observer newspaper alleged clive feather director demon provides paedophiles access thousands photographs children sexually abused summer autumn 1996 uk police made known planning raid isp aim launching test case regarding publication obscene material internet direct result campaign threats pressure establishment internet watch foundation initially known safety net foundation september 1996 facilitated department trade industry dti discussions held certain isps metropolitan police home office body called safety net foundation formed dawe charitable trust resulted r3 safety net agreement r3 referred triple approach rating reporting responsibility september 1996 agreement made ispa linx safety net foundation subsequently renamed internet watch foundation agreement set requirements associated isps regarding identifiability traceability internet users isps cooperate iwf identify providers illegal content facilitate easier traceability demon internet driving force behind iwf creation one employees clive feather became iwf first chair funding board solicitor mark stephens first chair iwf policy board policy board developed codes guidance operational oversight hotline reporting content funding board made industry representatives chair policy board provided wherewithal iwf day day activities set required policy board 3 years operation iwf reviewed dti home office consultants kpmg denton hall report delivered october 1999 resulted number changes made role structure organisation relaunched early 2000 endorsed government dti played facilitating role creation according dti spokesman time patricia hewitt minister e-commerce said internet watch foundation plays vital role combating criminal material net counter accusations iwf biased favour isps new independent chairman appointed roger darlington former head research communication workers union iwf website offers web-based government-endorsed method reporting suspect online content remains operation united kingdom acts relevant authority accordance memorandum understanding mou concerning section 46 sexual offences act 2003 meaning analysts prosecuted looking illegal content course duties reports submitted anonymously according iwf mou potentially illegal content hosted uk iwf work relevant service provider british police agency content ‘ taken ’ assist necessary offender responsible distributing offending content detected potentially illegal content includes however almost whole iwf site concerned suspected images child sexual abuse little mention criminally obscene material also within remit images judged iwf using uk law images child sexual abuse blocked government claimed would also handling images adult extreme pornography became illegal people uk possess 26 january 2009 longer part iwf ’ remit since 2017 iwf includes extreme pornography example criminally obscene content meaning report material hosted uk uploaded someone uk regarding blocking sites categories remit go far refer sites hosted uk appropriate authorities iwf states works partnership uk government departments home office dcms influence initiatives programmes developed combat online abuse funded european union online industry includes internet service providers mobile operators manufacturers content service providers telecommunications filtering companies search providers financial sector well blue-chip organisations support iwf corporate social responsibility reasons hotline reporting system organisation helps isps combat abuse services notice take service alerting potentially illegal content within remit systems simultaneously invites police investigate publisher iwf connections virtual global taskforce serious organised crime agency child exploitation online protection centre susie hargreaves appointed ceo september 2011 andrew puddephatt appointed chair january 2018 senior leadership team iwf comprises iwf passes notifications suspected child sexual abuse images videos inhope network hotlines across world whenever content traced inhope country inhope hotline iwf works relevant police body country previously iwf passed notifications suspected child pornography hosted non-uk servers uk national criminal intelligence service turn forwards interpol relevant foreign police authority works serious organised crime agency instead iwf however pass notifications types potentially illegal content hosted outside uk iwf compiles maintains list urls individual webpages child sexual abuse content called iwf url list previously referred child abuse image content list caic list whole website included list whole domain dedicated distribution child sexual abuse images says every url list depicts indecent images children advertisements links content publicly available website list typically contains 500 800 urls one time updated twice day ensure entries still live since iwf began proactively searching child sexual abuse imagery since introduction crawler technology list typically contains 5,000 12,000 urls every day daily ‘ churn ’ content added list removed list appropriate offending uk urls listed taken quickly urls elsewhere listed removed list applied isps 95 commercial internet customers uk according iwf website blocking applies potentially criminal urls related child sexual abuse content publicly available websites distribution images channels peer-to-peer matter police partners iwf plans extend type content included list staff 13 trained analysts responsible work iwf ’ 2018 annual report says average 376 new urls added list daily 2004 2006 bt group introduced cleanfeed technology used 80 internet service providers bt spokesman jon carter described cleanfeed function block access illegal web sites listed internet watch foundation described essentially server hosting filter checked requested urls web sites iwf list returning error message web site found positive matches 2006 home office minister alan campbell pledged isps would block access child abuse websites end 2007 middle 2006 government reported 90 domestic broadband connections either currently blocking plans end year target 100 coverage set end 2007 however middle 2008 stood 95 february 2009 government said looking ways cover final 5 interview march 2009 home office spokesperson mistakenly thought iwf deleted illegal content n't look content rate although iwf blacklist causes content censored even content found illegal court law iwf director communications sarah robertson claimed 8 december 2008 iwf opposed censorship legal content case iwf blacklisting cover art hosted wikipedia days prior claimed “ iwf found image illegal ” despite body legal jurisdiction march 2009 home office spokesperson said isps pressured sign iwf blacklist order block child pornography websites said alternative using iwf blacklist zen internet previously refused use iwf blacklist citing concerns effectiveness however quietly joined foundation september 2009 still maintaining concerns 2009 blacklist said contain 450 urls 2009 study researcher richard clayton university cambridge found quarter specific pages otherwise legitimate free file hosting services among rapidshare megaupload sendspace zshare listing pages confidential blacklist pages would cause accesses sites hosting referred iwf potentially causing unintended interference discussed 2018 iwf url list contained 100,682 unique urls r v walker sometimes called girls scream aloud obscenity trial first prosecution written material section 2 1 obscene publications act nearly two decades involved prosecution darryn walker posting story entitled girls scream aloud internet erotic story site 2008 story fictional written account describing kidnap rape murder pop group girls aloud reported iwf passed information scotland yard ’ obscene publications unit trial prosecution claimed story could easily accessed young fans girls aloud however defence demonstrated could located specifically searching material result case abandoned defendant cleared charges 5 december 2008 iwf system started blacklisting wikipedia article covering scorpions 1976 album virgin killer appeared article users major isps including bt vodafone virgin media/tesco.net be/o2 easynet/uk online/sky broadband plusnet demon talktalk opal telecom unable access filtered content although controversial album image still available internet shopping sites physical shops image reported iwf reader iwf determined could seen potentially illegal iwf estimated block affected 95 british residential users iwf since rescinded block issuing following statement additionally many uk internet users unable edit wikipedia pages unless registered logged wikipedia reported due single blacklisted article causing wikipedia traffic isps using system routed transparent proxy server wikipedia distinguishes unlogged-in users ip address interpreted unlogged-in users particular isp single user editing massively proxy address triggered wikipedia anti-abuse mechanism blocking 14 january 2009 uk users reported 85 billion pages internet archive wayback machine blocked although iwf policy block individual offending webpages whole domains according iwf chief executive peter robbins due technical hitch internet archive web site contained urls iwf blacklist requests sent demon internet carried particular header clashed internet archive internal mechanism convert web links serving archived versions web pages actual blocked url caused incident never became publicly known many isps implement iwf filtering using transparent proxy server unconnected iwf quoting plusnet ip address matches server used host one websites iwf list request diverted proxy server hosting server blacklisted problem due requesting page server also hosts listed page iwf lists internet companies voluntarily committed block access child sexual abuse web pages companies may use transparent proxies techniques using transparent proxy unintended side effect quite independent iwf filtering appearing websites connected originating proxy ip instead user real ip sites detect user ip adjust behaviour accordingly example trying download files file distribution website restricts free-of-charge usage enforcing delay typically 30 minutes downloads attempt download interpreted originating isp proxy rather user consequence user isp downloaded file site last half-hour likely large isp download allowed unintended consequence isp use proxy servers iwf filtering file sharing sites distribute files types example linux distribution files large use proxy servers also reported caused problem editing wikipedia blocking actual offending web page reported iwf filtering criticised interfering legitimate internet activity ineffective anyone intending access objectionable content one carefully argued discussion opposing things child pornography terrorism points filtering side effects discussed section would stop access material images child sexual abuse would stop email ftp https p2p usenet irc many ways access content simple encryption systems never stop best drives underground harder assess track february 2009 yorkshire-based software developer lodged formal complaint regarding iwf status charity charity commission pointed regulating worst internet really charitable purpose iwf existed mainly serve interests isps subscribing rather public iwf spokesperson said iwf attained charitable status 2004 order subject robust governance requirements higher levels scrutiny accountability charity law alongside company law brings iwf listed fakecharities.org directory so-called charities receive substantial funding either uk eu governments also termed quango critics implying poor management lack accountability iwf publishes details inspections audits website includes hotline audit every two years independent experts quality assurance inspections inhope hotline umbrella body iso27001 compliance human rights audit organisation carried lord ken macdonald 2014 following iwf blacklisting wikipedia article organisation operating habits came scrutiny j.r. raphael pc world stated incident raised serious free-speech issues alarming one non-governmental organisation ultimately acting morality police 95 uk internet users frank fisher guardian criticized iwf secretiveness lack legal authority among things noted blacklist could contain anything visitor blocked address may know browsing censored government believes self-regulatory system best solution metropolitan police also believe working isps rather trying force via legislation way forward iwf list urls considered host objectionable material distinct actual confidential blacklist pages available isps isps obliged subscribe self-appointed self-regulated internet watchdog views user-submitted content compiles list websites deems contain illegal images questions raised regarding legality viewing content would normally constitute criminal offence iwf memorandum understanding crown prosecution service association chief police officers – npcc “ clarify position professionally involved management operation use electronic communications networks services may face jeopardy criminal offences reassured protection acting combat creation distribution images child abuse ” iwf criticized blacklisting legal content telling websites blocked circumstances owner blocked webpage might even know offending content site means content would still readily available anyone outside uk internet companies deploy services across world implement iwf url list help prevent people stumbling across child sexual abuse imagery blocking methodology implemented company taking list iwf ’ good practice blocking guide recommends companies use splash page people know page blocked view rather simply delivering “ page found ” message lord ken macdonald carried human rights audit addressing iwf ’ members agm 26 november 2013 lord macdonald said “ deeply impressed ” quality staff “ commitment attention freedom expression privacy rights ” historically blacklisting sites may concealed generic http 404 page found message rather explanation content censored exact method censorship determined implementing isp bt example return http 404 pages whereas demon return message stating page censored time wikipedia blocking performance issues accessing site uk reported october 2014 users sky broadband reported slow intermittent performance image host imgur clicking image would typically result site appearing accessing via https causes images load normally bypasses proxy used sites blacklisted content aside iwf url list iwf developed many services may taken internet companies help stop spread child sexual abuse imagery online
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Computer security
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minio minio cloud storage server compatible amazon s3 released apache license v2 object store minio store unstructured data photos videos log files backups container images maximum size object 5tb main developer minio cloud storage stack minio inc silicon valley-based technology startup founded anand babu periasamy garima kapoor harshavardhana november 2014 source code hosted github 17,000 stars august 2019 contributions project accepted via github implementation pull requests minio server designed light enough bundled along application stack similar redis default server single instance single backing disk erasure code mode available server configured use four drives erasure code subsystem also attempts automatically detect correct data degradation minio server distributed mode allows operators pool multiple drives local remote single object storage server setup distributed mode resilient node failures provide increased data protection minio server hardware agnostic works variety physical virtual/container environments allows run containers running commodity servers local disks still enterprise-level data safety scalability minio server installed physical virtual machines launched docker containers deployed container orchestration platforms like kubernetes mesosphere docker swarm minio client codice_1 provides alternative standard unix commands e.g codice_2 codice_3 codice_4 codice_5 codice_6 etc adding support amazon s3-compatible cloud storage services aws signature v2 v4 minio client supported linux mac windows platforms minio client sdk provides simple api access amazon s3-compatible object storage server language bindings available go java python javascript haskell languages hosted .net framework
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Distributed computing architecture
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sony bmg copy protection rootkit scandal scandal erupted 2005 regarding sony bmg implementation deceptive illegal harmful copy protection measures 22 million cds inserted computer cds installed one two pieces software provided form digital rights management drm modifying operating system interfere cd copying neither program could easily uninstalled created vulnerabilities exploited unrelated malware sony claims unintentional one programs installed even user refused end-user license agreement eula would still phone home reports user private listening habits mentioned eula contained code several pieces copylefted free software apparent infringement copyright configured operating system hide software existence leading programs classified rootkits sony bmg initially denied rootkits harmful released one programs uninstaller un-hid program installed additional software could easily removed collected email address user introduced security vulnerabilities following public outcry government investigations class-action lawsuits 2005 2006 sony bmg partially addressed scandal consumer settlements recall 10 affected cds suspension cd copy protection efforts early 2007 august 2000 statements sony pictures entertainment us senior vp steve heckler foreshadowed events late 2005 heckler told attendees americas conference information systems industry take whatever steps needs protect protect revenue streams ... lose revenue stream matter ... sony going take aggressive steps stop develop technology transcends individual user firewall napster source – block cable company block phone company block isp firewall pc ... strategies aggressively pursued simply much stake europe bmg created minor scandal 2001 released natalie imbruglia second album white lilies island without warning labels stating cd copy protection cds eventually replaced bmg sony released copy-protected versions certain releases certain markets late 2001 late 2002 report indicated bmg cds sold europe would form copy protection two pieces copy-protection software issue 2005–2007 scandal included 22 million cds marketed sony bmg record company formed 2004 merger sony bmg recorded music divisions two million cds spanning 52 titles contained first 4 internet f4i extended copy protection xcp installed microsoft windows systems user accepted eula made mention software remaining 20 million cds spanning 50 titles contained sunncomm mediamax cd-3 installed either microsoft windows mac os x systems user presented eula regardless whether user accepted however mac os x prompted user confirmation software attempted modify os whereas computers running windows scandal erupted october 31 2005 winternals later acquired microsoft corporation researcher mark russinovich posted blog detailed description technical analysis f4i xcp software ascertained recently installed computer sony bmg music cd russinovich compared software rootkit due surreptitious installation efforts hide existence noted eula mention software asserted emphatically software illegitimate digital rights management gone far anti-virus firm f-secure concurred although software n't directly malicious used rootkit hiding techniques exactly used malicious software hide drm software cause many similar false alarms av software detect rootkits ... thus inappropriate commercial software use techniques public pressure symantec anti-virus vendors included detection rootkit products well microsoft announced would include detection removal capabilities security patches russinovich discovered numerous problems xcp soon russinovich first post several trojans worms exploiting xcp security holes people even used vulnerabilities cheat online games sony bmg quickly released software remove rootkit component xcp affected microsoft windows computers russinovich analyzed utility reported blog exacerbated security problems raised concerns privacy russinovich noted removal program merely unmasked hidden files installed rootkit actually remove rootkit also reported installed additional software could uninstalled order download uninstaller found necessary provide e-mail address sony bmg privacy policy implied added various bulk e-mail lists install activex control containing backdoor methods marked safe scripting thus prone exploits november 18 2005 sony bmg provided new improved removal tool remove rootkit component xcp affected microsoft windows computers november 15 2005 vnunet.com announced sony bmg backing copy-protection software recalling unsold cds stores offering consumers exchange cds versions lacking software electronic frontier foundation compiled partial list cds xcp sony bmg quoted maintaining security risks associated anti-piracy technology despite numerous virus malware reports november 16 2005 us-cert part united states department homeland security issued advisory xcp drm said xcp uses rootkit technology hide certain files computer user technique security threat computer users also said one uninstallation options provided sony bmg introduces vulnerabilities system us-cert advised install software sources expect contain software audio cd sony bmg announced instructed retailers remove unsold music discs containing software shelves estimated internet security expert dan kaminsky xcp use 500,000 networks cds xcp technology identified letters xcp printed back cover jewel case cd according sonybmg xcp faq november 18 2005 reuters reported sony bmg would exchange affected insecure cds new unprotected disks well unprotected mp3 files information swap found sony bmg swap program website part swap program consumers mail xcp-protected cds sony bmg sent unprotected disc via return mail november 29 new york attorney general eliot spitzer found investigators despite recall november 15 sony bmg cds xcp still sale new york city music retail outlets spitzer said unacceptable three weeks serious vulnerability revealed cds still shelves busiest shopping days year strongly urge retailers heed warnings issued products pull distribution immediately ship back sony next day massachusetts attorney general tom reilly issued statement saying sony bmg cds xcp still available boston despite sony bmg recall november 15 attorney general reilly advised consumers purchase sony bmg cds xcp said conducting investigation sony bmg may 11 2006 sony bmg website offered consumers link class action settlement information regarding xcp mediamax content protection online claim filing links software updates/uninstallers deadline submitting claim june 30 2007 april 2 2008 sony bmg website finally offered consumers explanation list affected cds november 21 2005 texas attorney general greg abbott sued sony bmg texas first state united states bring legal action sony bmg response rootkit suit also first filed state ’ 2005 spyware law alleged company surreptitiously installed spyware millions compact music discs cds consumers inserted computers play cds compromise systems december 21 2005 abbott added new allegations lawsuit sony-bmg regarding mediamax new allegations claimed mediamax violated state spyware deceptive trade practices laws mediamax software would installed computer even user declined license agreement would authorize installation abbott stated keep discovering additional methods sony used deceive texas consumers thought simply buying music thousands texans potential victims deceptive game sony played consumers purposes addition violations consumer protection computer spyware act 2005 allowed civil penalties 100,000 violation law alleged violations added updated lawsuit december 21 2005 carried maximum penalties 20,000 per violation sony lost battle abbott pay 750,000 legal fees texas accept customer returns affected cds place conspicuous detailed notice homepage make keyword buys alert consumers advertising google yahoo msn pay 150 per damaged computer much sony bmg also agree would make claim legal settlement way constitutes approval court class action suits filed sony bmg new york california december 30 2005 new york times reported sony bmg reached tentative settlement lawsuits proposing two ways compensating consumers purchased affected recordings according proposed settlement purchased xcp cd paid 7.50 per purchased recording given opportunity download free album able download three additional albums limited list recordings give cash incentive district judge naomi reice buchwald entered order tentatively approving settlement january 6 2006 settlement designed compensate whose computers infected otherwise damaged damages addressed class action able opt settlement pursue litigation fairness hearing held may 22 2006 9:15 daniel patrick moynihan united states courthouse southern district new york claims submitted december 31 2006 class members wished excluded settlement must filed may 1 2006 remained settlement could attend fairness hearing expense speak behalf represented attorney italy alcei association similar eff also reported rootkit financial police asking investigation various computer crime allegations along technical analysis rootkit us department justice doj made comment whether would take criminal action sony however stewart baker department homeland security publicly admonished sony stating intellectual property—it computer november 21 eff announced also pursuing lawsuit xcp sunncomm mediamax drm technology eff lawsuit also involves issues concerning sony bmg end user license agreement reported december 24 2005 then-florida attorney general charlie crist investigating sony bmg spyware january 30 2007 u.s. federal trade commission ftc announced settlement sony bmg charges cd copy protection violated federal law—section 5 federal trade commission act 15 usc 45 —by engaging unfair deceptive business practices settlement requires sony bmg reimburse consumers 150 repair damage resulted directly attempts remove software installed without consent settlement also requires provide clear prominent disclosure packaging future cds limits copying restrictions use playback devices ban company installing content protection software without obtaining consumers ’ authorization ftc chairwoman deborah platt majoras added installations secret software create security risks intrusive unlawful consumers computers belong companies must adequately disclose unexpected limitations customer use products consumers make informed decisions regarding whether purchase install content researchers found sony bmg makers xcp also apparently infringed copyright failing adhere licensing requirements various pieces free open-source software whose code used program including lame mp3 encoder mpglib faac id3lib mpg123 vlc media player january 2006 developers lame posted open letter stating expected appropriate action sony bmg developers plans investigate take action apparent violation lame source code license russinovich report discussed popular blogs almost immediately following release npr one first major news outlets report scandal november 4 2005 thomas hesse sony bmg global digital business president told reporter neda ulaby people think n't even know rootkit care november 7 2005 article vnunet.com summarised russinovich findings urged consumers avoid buying sony bmg music cds time following day boston globe classified software spyware computer associates etrust security management unit vp steve curry confirmed communicates personal information consumers computers sony bmg namely cd played user ip address methods used software avoid detection likened used data thieves november 8 2005 computer associates decided classify sony bmg software spyware provide tools removal speaking sony bmg suspending use xcp independent researcher mark russinovich said step taken immediately first virus made use sony bmg stealth technology make malicious files invisible user anti-virus programs surfaced november 10 2005 one day later yahoo news announced sony bmg suspended distribution controversial technology according zdnet news latest risk uninstaller program distributed sunncomm technologies company provides copy protection sony bmg releases uninstall program obeys commands sent allowing others take control pcs uninstaller used december 6 2005 sony bmg said 5.7 million cds spanning 27 titles shipped mediamax 5 software company announced availability new software patch prevent potential security breach consumers computers sony bmg australia released press release indicating sony bmg titles manufactured australia copy protection
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Computer security
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wizardry ii knight diamonds wizardry ii knight diamonds originally known wizardry knight diamonds second scenario second game wizardry series role-playing video games published 1982 sir-tech game begins city llylgamyn siege llylgamyn rulers killed city hope recovery staff gnilda obtainable trading mystic knight diamonds armor legendary knight diamonds fend invaders game functions virtually identically first scenario player guiding party six adventurers 6 level dungeon original version required players import characters first game whilst later versions include pregenerated party ability create new characters game intended played successfully completed first game difficulty level intended characters least level 13 training area means lower level characters go baptism fire mechanical differences include ability save game dungeon rather forcing characters exit dungeon return training grounds spells increasing power noted message dungeon unlike first scenario half levels purpose plot-wise could skipped player wished exploration levels knight diamonds necessary complete game six levels piece knight armor somewhere level pieces must collected order finish game furthermore unlike first scenario elevators used skip levels teleportation spells fail party attempts use teleport level yet reached via stairs softline 1982 praised knight diamonds variety monsters liked level dungeon quests magazine concluded one wonder amazing duo greenberg woodhead next scenario computer gaming world 1991 1993 called wizardry ii disappointingly weak follow-up criticizing small size noting first game necessary play magazine concluded best hard-core fan philip l. wing reviewed knight diamonds space gamer 76 wing commented recommend scenario interesting challenging adventure higher-level wizardry characters knight diamonds named best adventure game home computer 1982 origins game fair defeating ultima ii among nominees also received certificate merit category 1984 best computer adventure 5th annual arkie awards
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Computer architecture
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web beacon web beacon also called web bug tracking bug tag web tag page tag tracking pixel pixel tag 1×1 gif clear gif one various techniques used web pages email unobtrusively usually invisibly allow checking user accessed content web beacons typically used third parties monitor activity users website purpose web analytics page tagging also used email tracking implemented using javascript may called javascript tags using beacons companies organizations track online behavior web users first companies tracking mainly advertisers web analytics companies later social media sites also started use tracking techniques instance use buttons act tracking beacons work progress standardize interface web developers use create web beacons web beacon number techniques used track visiting web page also used see email read forwarded web page copied another website first web beacons small digital image files embedded web page email image could small single pixel could color background completely transparent thus name “ tracking pixel ” user opens page email image embedded might see image web browser email reader would automatically download image requiring user ’ computer send request host company ’ server source image stored request would provide identifying information computer allowing host keep track user basic technique developed sorts elements used beacons currently include visible elements graphics banners buttons also non-pictorial html elements frame style script input link embed object etc. email web page identifying information provided user computer typically includes ip address time request made type web browser email reader made request existence cookies previously sent host server host server store information associate session identifier tracking token uniquely marks interaction use framing added new level versatility web beacons framing allows web pages refer content images buttons html elements located servers rather hosting content directly server user sees email web page user ’ email reader web browser prepares referred content display send request third-party server ask send referred content part request user computer supply identifying information third-party server protocol allows companies embed beacons content directly operate use beacons tracking purposes beacons embedded email web page images buttons html elements hosted different server website embedded third-party server requests identifying information sent instance case advertisement displayed image web page image file would reside page ’ host server server belonging advertising company user opens page user computer request download advertisement page ’ server referred advertiser server request download image advertiser server request require user computer supply identifying information advertiser means third-party site advertiser gather information visitors main site news site social media site even users clicking advertisement moreover given beacons embedded visible advertisements embedded completely invisible elements third party gather information even user completely unaware third party ’ existence company identify particular user company track user behavior across multiple interactions different websites web servers example consider company owns network websites company could store images one particular server store contents web pages variety servers instance server could specific given website could even located different city company could use web beacons count recognize individual users visit different websites rather gathering statistics managing cookies server independently company analyze data together track behavior individual users across different websites assembling profile user navigates different environments web beacons embedded emails greater privacy implications beacons embedded web pages use embedded beacon sender email even third party record sort information advertiser website namely time email read ip address computer used read email ip address proxy server reader went type software used read email existence cookies previously sent way sender third party gather detailed information particular recipient reads email every subsequent time email message displayed information also sent sender third party return-receipt-to rrt email headers also trigger sending information may seen another form web beacon web beacons used email marketers spammers phishers verify email read using system send similar emails large number addresses check ones valid valid case means address actually use email made past spam filters content email actually viewed extent kind email tracking prevented configuring email reader software avoid accessing remote images examples email software able include gmail yahoo hushmail spamcop/horde webmail clients mozilla thunderbird opera pegasus mail incredimail apple mail later versions microsoft outlook kmail mail readers however since beacons embedded email non-pictorial elements email need contain image advertisement anything else related identity monitoring party makes detection emails difficult one way neutralize email tracking disconnect internet downloading email reading downloaded messages note assumes one using email reader resides one ’ computer downloads emails email server one ’ computer case messages containing beacons able trigger requests beacons host servers tracking prevented one would delete messages suspected containing beacons risk beacons activate computer reconnected internet way completely avoid email tracking beacons use text-based email reader pine mutt graphical email reader purely text-based html capabilities mulberry email readers interpret html display images users subject tracking email web beacons plain-text email messages contain web beacons contents interpreted display characters instead embedded html code opening messages initiate communication email readers offer option disable html every message thus rendering messages plain text prevent tracking beacons working recently many email readers web-based email services moved towards loading images opening hypertext email comes unknown sender suspected spam email user must explicitly choose load images course beacons embedded non-pictorial elements hypertext email web beacons also filtered server level never reach end user mailscanner example gateway software neutralize email tracking beacons users particular server beacon api application programming interface candidate recommendation world wide web consortium standards organization web standardized set protocols designed allow web developers track activity users without slowing website response times sending tracking information back beacon host server user navigated away webpage use beacon api allows tracking without interfering delaying navigation away site invisible end-user support beacon api introduced mozilla firefox browser february 2014 google chrome browser november 2014
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Web technology
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list router firmware projects list software created maintained people manufacturer product extent support testing particular hardware varies project project notable custom-firmware projects wireless routers many run various brands linksys asus netgear etc software distributions routers 5 gb storage 1 gb ram
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Operating systems
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semantic web semantic web extension world wide web standards world wide web consortium w3c standards promote common data formats exchange protocols web fundamentally resource description framework rdf according w3c semantic web provides common framework allows data shared reused across application enterprise community boundaries semantic web therefore regarded integrator across different content information applications systems term coined tim berners-lee web data data web processed machines—that one much meaning machine-readable critics questioned feasibility proponents argue applications library information science industry biology human sciences research already proven validity original concept berners-lee originally expressed vision semantic web follows 2001 scientific american article berners-lee hendler lassila described expected evolution existing web semantic web 2006 berners-lee colleagues stated simple idea…remains largely unrealized 2013 four million web domains contained semantic web markup following example text 'paul schuster born dresden website annotated connecting person place birth following html-fragment shows small graph described rdfa-syntax using schema.org vocabulary wikidata id div vocab= http //schema.org/ typeof= person /div example defines following five triples shown turtle syntax triple represents one edge resulting graph first element triple subject name node edge starts second element predicate type edge last third element object either name node edge ends literal value e.g text number etc. triples result graph shown given figure one advantages using uniform resource identifiers uris dereferenced using http protocol according so-called linked open data principles dereferenced uri result document offers data given uri example uris edges nodes e.g nowiki http //schema.org/person /nowiki nowiki http //schema.org/birthplace /nowiki nowiki http //www.wikidata.org/entity/q1731 /nowiki dereferenced result rdf graphs describing uri e.g dresden city germany person sense uri fictional second graph shows previous example enriched triples documents result dereferencing nowiki http //schema.org/person /nowiki green edge nowiki http //www.wikidata.org/entity/q1731 /nowiki blue edges additionally edges given involved documents explicitly edges automatically inferred triple original rdfa fragment triple document nowiki http //schema.org/person /nowiki green edge figure allow infer following triple given owl semantics red dashed line second figure concept semantic network model formed early 1960s researchers cognitive scientist allan m. collins linguist m. ross quillian psychologist elizabeth f. loftus form represent semantically structured knowledge applied context modern internet extends network hyperlinked human-readable web pages inserting machine-readable metadata pages related enables automated agents access web intelligently perform tasks behalf users term semantic web coined tim berners-lee inventor world wide web director world wide web consortium w3c oversees development proposed semantic web standards defines semantic web web data processed directly indirectly machines many technologies proposed w3c already existed positioned w3c umbrella used various contexts particularly dealing information encompasses limited defined domain sharing data common necessity scientific research data exchange among businesses addition technologies similar goals emerged microformats many files typical computer also loosely divided human-readable documents machine-readable data documents like mail messages reports brochures read humans data calendars addressbooks playlists spreadsheets presented using application program lets viewed searched combined currently world wide web based mainly documents written hypertext markup language html markup convention used coding body text interspersed multimedia objects images interactive forms metadata tags provide method computers categorize content web pages examples field names keywords description author assigned values computing cheap widgets sale john doe metadata tagging categorization computer systems want access share data easily identify relevant values html tool render perhaps web browser software perhaps another user agent one create present page lists items sale html catalog page make simple document-level assertions document title 'widget superstore capability within html assert unambiguously example item number x586172 acme gizmo retail price €199 consumer product rather html say span text x586172 something positioned near acme gizmo €199 etc way say catalog even establish acme gizmo kind title €199 price also way express pieces information bound together describing discrete item distinct items perhaps listed page semantic html refers traditional html practice markup following intention rather specifying layout details directly example use denoting emphasis rather specifies italics layout details left browser combination cascading style sheets practice falls short specifying semantics objects items sale prices microformats extend html syntax create machine-readable semantic markup objects including people organisations events products similar initiatives include rdfa microdata schema.org semantic web takes solution involves publishing languages specifically designed data resource description framework rdf web ontology language owl extensible markup language xml html describes documents links rdf owl xml contrast describe arbitrary things people meetings airplane parts technologies combined order provide descriptions supplement replace content web documents thus content may manifest descriptive data stored web-accessible databases markup within documents particularly extensible html xhtml interspersed xml often purely xml layout rendering cues stored separately machine-readable descriptions enable content managers add meaning content i.e. describe structure knowledge content way machine process knowledge instead text using processes similar human deductive reasoning inference thereby obtaining meaningful results helping computers perform automated information gathering research example tag would used non-semantic web page encoding similar information semantic web page might look like tim berners-lee calls resulting network linked data giant global graph contrast html-based world wide web berners-lee posits past document sharing future data sharing answer question provides three points instruction one url point data two anyone accessing url get data back three relationships data point additional urls data tim berners-lee described semantic web component web 3.0 semantic web sometimes used synonym web 3.0 though definition term varies web 3.0 started emerge movement away centralisation services like search social media chat applications dependent single organisation function guardian journalist john harris reviewed concept favorably early2019 particular work bernerslee project called 'solid based around personal data stores 'pods individuals retain control bernerslee formed startup inrupt advance idea attract volunteer developers challenges semantic web include vastness vagueness uncertainty inconsistency deceit automated reasoning systems deal issues order deliver promise semantic web list challenges illustrative rather exhaustive focuses challenges unifying logic proof layers semantic web world wide web consortium w3c incubator group uncertainty reasoning world wide web urw3-xg final report lumps problems together single heading uncertainty many techniques mentioned require extensions web ontology language owl example annotate conditional probabilities area active research standardization semantic web context web 3.0 care w3c term semantic web often used specifically refer formats technologies enable collection structuring recovery linked data enabled technologies provide formal description concepts terms relationships within given knowledge domain technologies specified w3c standards include semantic web stack illustrates architecture semantic web functions relationships components summarized follows well-established standards yet fully realized intent enhance usability usefulness web interconnected resources creating semantic web services services could useful public search engines could used knowledge management within organization business applications include corporation closed group users management able enforce company guidelines like adoption specific ontologies use semantic annotation compared public semantic web lesser requirements scalability information circulating within company trusted general privacy less issue outside handling customer data critics question basic feasibility complete even partial fulfillment semantic web pointing difficulties setting lack general-purpose usefulness prevents required effort invested 2003 paper marshall shipman point cognitive overhead inherent formalizing knowledge compared authoring traditional web hypertext according marshall shipman tacit changing nature much knowledge adds knowledge engineering problem limits semantic web applicability specific domains issue point domain- organisation-specific ways express knowledge must solved community agreement rather technical means turns specialized communities organizations intra-company projects tended adopt semantic web technologies greater peripheral less-specialized communities practical constraints toward adoption appeared less challenging domain scope limited general public world-wide web finally marshall shipman see pragmatic problems idea knowledge navigator-style intelligent agents working largely manually curated semantic web cory doctorow critique metacrap perspective human behavior personal preferences example people may include spurious metadata web pages attempt mislead semantic web engines naively assume metadata veracity phenomenon well-known metatags fooled altavista ranking algorithm elevating ranking certain web pages google indexing engine specifically looks attempts manipulation peter gärdenfors timo honkela point logic-based semantic web technologies cover fraction relevant phenomena related semantics enthusiasm semantic web could tempered concerns regarding censorship privacy instance text-analyzing techniques easily bypassed using words metaphors instance using images place words advanced implementation semantic web would make much easier governments control viewing creation online information information would much easier automated content-blocking machine understand addition issue also raised use foaf files geolocation meta-data would little anonymity associated authorship articles things personal blog concerns addressed policy aware web project active research development topic another criticism semantic web would much time-consuming create publish content would need two formats one piece data one human viewing one machines however many web applications development addressing issue creating machine-readable format upon publishing data request machine data development microformats one reaction kind criticism another argument defense feasibility semantic web likely falling price human intelligence tasks digital labor markets amazon mechanical turk specifications erdf rdfa allow arbitrary rdf data embedded html pages grddl gleaning resource descriptions dialects language mechanism allows existing material including microformats automatically interpreted rdf publishers need use single format html first research group explicitly focusing corporate semantic web acacia team inria-sophia-antipolis founded 2002 results work include rdf based corese search engine application semantic web technology realm e-learning since 2008 corporate semantic web research group located free university berlin focuses building blocks corporate semantic search corporate semantic collaboration corporate ontology engineering ontology engineering research includes question involve non-expert users creating ontologies semantically annotated content extracting explicit knowledge interaction users within enterprises tim o'reilly coined term web 2.0 proposed long-term vision semantic web web data sophisticated applications manipulate data web data web transforms web distributed file system distributed database system
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