text
stringlengths 6
1.88M
| source
stringclasses 13
values |
|---|---|
apple a5x apple a5x 32-bit system-on-a-chip soc designed apple inc. introduced launch third generation ipad march 7 2012 high performance variant apple a5 apple claims twice graphics performance a5 superseded iphone 5 5c a6 chip fourth generation ipad a6x chip software updates ipad 3rd generation ended 2016 thus ceasing support chip a5x features dual-core arm cortex-a9 cpu 1 ghz quad-core powervr sgx543mp4 gpu clocked 250 mhz apple doubled size a5x memory interface comparison a5 including memory interface subsystem four 32-bit wide lp-ddr2 memory controllers done provide sufficient bandwidth high pixel count third generation ipad retina display unlike a4 a5 a5x covered metal heat spreader package-on-package pop assembly earlier chips ram sat top soc however a5x ram bundled together soc instead a5x sits one side motherboard twin samsung lp ddr2 sdram soldered directly side motherboard a5x manufactured 45 nm process samsung silicon die size increased drastically compared a5 165 mm 3.1 times larger 53.3 mm die area original a4
|
Computer architecture
|
partimage partimage disk cloning utility linux/unix environments partimage save partitions many formats disk image utilities partimage useful number situations commonly encountered network administrators well advanced computer users maintain systems last stable release 2010 since one partimage authors worked fsarchiver broader functionality partimage common uses partimage follows windows users partimage includes experimental support ntfs partimage supports common linux file systems found many linux distributions including debian live distros ping knoppix systemrescuecd notable features include compression disk image files support backup/restore network file server data encryption partimage uses newt gui partimage limited cloning partitions supported filesystem types includes ext2 ext3 reiserfs fat12 fat16 fat16b fat32 hpfs jfs xfs ufs hfs ntfs partimage support ext4 btrfs
|
Computer security
|
numecent numecent irvine california-based software technology company develops software used deliver native software applications premises server farm cloud patented technology called cloudpaging based virtualization allows delivery pre-virtualized software instructions user machine on-demand instructions executed soon received numecent roots started 1999 darpa project u.c irvine arthur hitomi one three scientists formed endeavors technology inc. irvine california-based software development company project connected computers mobile devices internet work groups developed application delivery technology support groups 2000 tadpole technology plc maker mobile computing devices software purchased endeavors 2004 tadpole also acquired stream theory california-based software company developed technology deploying application software internet across enterprise networks focus gaming market two companies constituted genesis technology later became known cloudpaging 2007 patenting application streaming technology tadpole decided focus solely developing business 2008 tadpole changed name endeavors technologies inc 2009 osman kent sold 3dlabs creative labs 2002 acquired endeavors formed numecent holdings company emerged end-user computing market technology two former employees started united kingdom boston ma-based spinoff called software2 help universities deploy microsoft windows applications physical machines cloud 2012 numecent publicly launched osman kent ceo 2013 numecent software2 announced partnership numecent flagship cloudpaging product application jukebox suite deployed 40 universities uk 2015 application jukebox suite dropped product name favor standalone trademarked name cloudpaging march 2015 numecent announced hiring former broadcom executive vice president tom lagatta ceo osman kent promoted role executive chairman january 2017 co-founder cto arthur hitomi became president ceo company ’ main product cloudpaging enables existing windows applications cloudpage pcs run perform act natively installed cloudpaging server conjunction cloudpaging player allows software delivered cloud pre-virtualizing software encrypted divided small fragments company calls pages pages delivered one time executed client computer software also employs statistical modeling dynamically predict pages sent first cloudpaging makes desktop applications fully available faster less disk space required applications also run computer disconnected internet network outage august 2013 company announced service presently branded cloudpaging cdn introduced launch native-as-a-service naas offered conjunction amazon web services multi-tenant cloud via self-hosting option applications virtualized licenses cloudified made available delivery end users without rewrite recompile underlying source code march 2017 company announced android offering named cloudpaging android utilities cloudpaging technology reduce impact application install sizes android devices numecent announced first spin technology approxy 2012 approxy offers white-label delivery service game developers publishers approxy ’ system reduces delay players allowing start playing seconds download additional code necessary play retrieved piece-by-piece october 2014 numecent announced bringing approxy group back numecent parent attempt attract game industry customers required access cloudpaging source code numecent named gartner cool vendor cloud computing 2013 february 2012 company closed series funding round 2m may 2013 numecent closed series b funding 13.6m t-venture deutsche telecom venture funding arm november 2015 company closed series c funding round 15.5m
|
Distributed computing architecture
|
open network install environment open network install environment onie open source install environment acts enhanced boot loader utilizing facilities linux/busybox environment small linux operating system allows end-users channel partners install network operating system part data center provisioning similar way servers provisioned operating system choice onie enables network switch hardware suppliers distributors resellers manage operations based small number hardware stock keeping unit skus turn creates economies scale manufacturing distribution stocking return merchandise authorization rma enabling ecosystem network hardware operating system alternatives
|
Operating systems
|
david andreoff evans david andreoff evans born 1948 st. louis scientist field computational linguistics best known research indexing using natural language processing ontology learning especially medical informatics evans attended stanford university receiving ph.d. computational linguistics 1982 attended inter-university center japanese language studies 1979 faculty carnegie mellon university 1983 1996 founded computational linguistics program laboratory computational linguistics 1986 supported grant digital equipment corporation led research project computational-linguistic approaches indexing retrieval text clarit september 1992 clarit spun-out carnegie-mellon company called claritech technology used index papers politician h. john heinz iii claritech became research development subsidiary justsystems name changed clairvoyance corporation 1996 becoming justsystems evans research 2007 made many contributions field computational linguistics information retrieval authoring books many research papers holder 25 us patents evans elected fellow american college medical informatics 1999
|
Computational linguistics
|
clisp computing clisp implementation programming language common lisp originally developed bruno haible michael stoll atari st. today supports unix microsoft windows operating systems clisp includes interpreter bytecode compiler debugger socket interface high-level foreign language interface strong internationalization support two object systems common lisp object system clos metaobject protocol mop written c common lisp part gnu project free software available terms gnu general public license gpl haible originally intend distribute clisp gpl well-publicised email exchange richard stallman eventually agreed issue stake whether clisp derivative work gnu readline library clisp extremely portable running almost unix-based operating systems well microsoft windows although interpreting bytecode usually slower running compiled native binaries always major issue especially applications like web development i/o bottleneck clisp also easier set popular foss common lisps sbcl paul graham used clisp run software viaweb startup viaweb early web application portions still exist yahoo stores base yahoo shopping conrad barski land lisp uses clisp-specific functions textbook exercises
|
Programming language topics
|
separation protection security computer sciences separation protection security design choice wulf et al identified protection mechanism security policy therefore making protection-security distinction particular case separation mechanism policy principle adoption distinction computer architecture usually means protection provided fault tolerance mechanism hardware/firmware kernel whereas operating system applications implement security policies design security policies rely therefore protection mechanisms additional cryptography techniques major hardware approach security protection use hierarchical protection domains prominent example approach ring architecture supervisor mode user mode approach adopts policy already lower levels hardware/firmware/kernel restricting rest system rely therefore choice distinguish protection security overall architecture design implies rejection hierarchical approach favour another one capability-based addressing examples models protection security separation include access matrix ucla data secure unix take-grant filter separation found models like high-water mark bell–lapadula original revisited information flow strong dependency constraints
|
Computer security
|
unix time unix time also known posix time unix epoch time system describing point time number seconds elapsed since 00:00:00 thursday 1 january 1970 coordinated universal time utc minus leap seconds every day treated contains exactly seconds leap seconds subtracted since epoch used widely unix-like many operating systems file formats however unix time true representation utc leap second utc unix time second came unix time may checked unix systems typing command line systems unix time stored signed 32-bit integer largest value recorded 2 − 1 03:14:07 tuesday 19 january 2038 utc following second clock wrap around negative −2 20:45:52 friday 13 december 1901 utc referred year 2038 problem two layers encoding make unix time first layer encodes point time scalar real number represents number seconds passed since 00:00:00utc thursday 1 january 1970 second layer encodes number sequence bits decimal digits standard utc article labels days using gregorian calendar counts times within day hours minutes seconds examples also show international atomic time tai another time scheme uses seconds displayed format utc every day exactly seconds long gradually losing synchronization earth rotation rate roughly one second per year unix time single signed number increments every second without requiring calculations determine year month day month hour minute required intelligibility humans unix epoch time 00:00:00utc 1 january 1970 problem definition utc exist current form 1972 issue discussed brevity remainder section uses iso 8601 date time format unix epoch 1970-01-01t00:00:00z unix time number zero unix epoch increases exactly per day since epoch thus 2004-09-16t00:00:00z days epoch represented unix time number × extended backwards epoch using negative numbers thus 1957-10-04t00:00:00z days epoch represented unix time number × within day unix time number calculated preceding paragraph midnight utc 00:00:00z increases exactly 1 per second since midnight thus 2004-09-16t17:55:43.54z seconds since midnight first day example represented unix time number dates epoch number still increases thus becoming less negative time moves forward unix time based epoch sometimes referred epoch time scheme means normal utc day duration seconds unix time number changes continuous manner across midnight example end day used examples time representations progress follows leap second occurs utc day exactly seconds long unix time number always increases exactly day experiences discontinuity end day negative leap second yet occurred unix time number would jump 1 start next day positive leap second end day occurs every year half average unix time number increases continuously next day leap second end leap second jumps back 1 returning start next day example happened strictly conforming posix.1 systems end 1998 unix time numbers repeated second immediately following positive leap second unix time number thus ambiguous refer either instant middle leap second instant one second later half second midnight utc theoretical case negative leap second occurs ambiguity caused instead range unix time numbers refer point time unix clock often implemented different type positive leap second handling associated network time protocol ntp yields system conform posix standard see section concerning ntp details dealing periods encompass utc leap second difference two unix time numbers equal duration seconds period corresponding points time common computational technique however leap seconds occur calculations give wrong answer applications level accuracy required necessary consult table leap seconds dealing unix times often preferable use different time encoding suffer problem unix time number easily converted back utc taking quotient modulus unix time number modulo quotient number days since epoch modulus number seconds since midnight utc day given unix time number ambiguous due positive leap second algorithm interprets time midnight never generates time leap second given unix time number invalid due negative leap second generates equally invalid utc time conditions significant necessary consult table leap seconds detect commonly mills-style unix clock implemented leap second handling synchronous change unix time number time number initially decreases leap occurred leaps correct time 1 second leap makes implementation easier described mills paper happens across positive leap second decoded properly paying attention leap second state variable unambiguously indicates whether leap performed yet state variable change synchronous leap similar situation arises negative leap second second skipped slightly late briefly system shows nominally impossible time number detected time_del state corrected type system unix time number violates posix around types leap second collecting leap second state variable along time number allows unambiguous decoding correct posix time number generated desired full utc time stored suitable format decoding logic required cope style unix clock would also correctly decode hypothetical posix-conforming clock using interface would achieved indicating time_ins state entirety inserted leap second indicating time_wait entirety following second repeating seconds count requires synchronous leap second handling probably best way express utc time unix clock form via unix interface underlying clock fundamentally untroubled leap seconds another much rarer non-conforming variant unix time keeping involves encoding tai rather utc linux systems configured way tai leap seconds every tai day exactly 86400 seconds long encoding actually pure linear count seconds elapsed since 1970-01-01t00:00:00tai makes time interval arithmetic much easier time values systems suffer ambiguity strictly conforming posix systems ntp-driven systems systems necessary consult table leap seconds correctly convert utc pseudo-unix-time representation resembles manner time zone tables must consulted convert civil time iana time zone database includes leap second information sample code available source uses information convert tai-based time stamps local time conversion also runs definitional problems prior 1972 commencement current form utc see section utc basis tai-based system despite superficial resemblance unix time encodes times values differ several seconds posix time values simple mathematical relationship utc mandated posix unix time number represented form capable representing numbers applications number simply represented textually string decimal digits raising trivial additional problems however certain binary representations unix times particularly significant unix codice_1 data type represents point time many platforms signed integer traditionally 32bits see directly encoding unix time number described preceding section 32 bits means covers range 136 years total minimum representable date friday 1901-12-13 maximum representable date tuesday 2038-01-19 one second 03:14:07utc 2038-01-19 representation overflow milestone anticipated mixture amusement dread—see year 2038 problem newer operating systems codice_1 widened 64 bits expands times representable approximately 293 billion years directions twenty times present age universe per direction originally controversy whether unix codice_1 signed unsigned unsigned range future would doubled postponing 32-bit overflow 68 years however would incapable representing times prior epoch consensus codice_1 signed usual practice software development platform version 6 qnx operating system unsigned 32-bit codice_1 though older releases used signed type posix open group unix specifications include c standard library includes time types functions defined codice_6 header file iso c standard states codice_1 must arithmetic type mandate specific type encoding posix requires codice_1 integer type mandate signed unsigned unix tradition directly representing non-integer unix time numbers binary fractions instead times sub-second precision represented using composite data types consist two integers first codice_1 integral part unix time second fractional part time number millionths codice_10 billionths codice_11 structures provide decimal-based fixed-point data format useful applications trivial convert others present form utc leap seconds defined 1 january 1972 onwards prior since 1 january 1961 older form utc occasional time steps non-integer numbers seconds also utc second slightly longer si second periodically changed continuously approximate earth rotation prior 1961 utc prior 1958 widespread atomic timekeeping eras approximation gmt based directly earth rotation used instead atomic timescale precise definition unix time encoding utc uncontroversial applied present form utc unix epoch predating start form utc affect use era number days 1 january 1970 unix epoch 1 january 1972 start utc question number days significant unix time meaning unix time values i.e. prior 1 january 1972 precisely defined basis unix times best understood unspecified approximation utc computers era rarely clocks set sufficiently accurately provide meaningful sub-second timestamps case unix time suitable way represent times prior 1972 applications requiring sub-second precision applications must least define form ut gmt use possibility ending use leap seconds civil time considered likely means execute change define new time scale called international time initially matches utc thereafter leap seconds thus remaining constant offset tai happens likely unix time prospectively defined terms new time scale instead utc uncertainty whether occur makes prospective unix time less predictable already utc simply leap seconds result would unix-like operating systems codice_12 command print set current time earliest versions unix time 32-bit integer incrementing rate 60 hz rate system clock hardware early unix systems value 60 hz still appears software interfaces result epoch also differed current value first edition unix programmer manual dated 3 november 1971 defines unix time time since 00:00:00 1 january 1971 measured sixtieths second user manual also commented chronologically-minded user note 2**32 sixtieths second 2.5 years limited range epoch redefined rate changed 1 hz epoch set present value 1 january 1970 00:00:00 utc yielded range 136 years though half range past see discussion signedness indicated definition quoted unix time scale originally intended simple linear representation time elapsed since epoch however consideration details time scales implicitly assumed simple linear time scale already available agreed upon first edition manual definition even specify time zone used several later problems including complexity present definition result unix time defined gradually usage rather fully defined outset posix.1 written question arose precisely define codice_1 face leap seconds posix committee considered whether unix time remain intended linear count seconds since epoch expense complexity conversions civil time representation civil time expense inconsistency around leap seconds computer clocks era sufficiently precisely set form precedent one way posix committee swayed arguments complexity library functions firmly defined unix time simple manner terms elements utc time definition simple even encompass entire leap year rule gregorian calendar would make 2100 leap year 2001 edition posix.1 rectified faulty leap year rule definition unix time retained essential definition unix time encoding utc rather linear time scale since mid-1990s computer clocks routinely set sufficient precision matter commonly set using utc-based definition unix time resulted considerable complexity unix implementations network time protocol execute steps unix time number whenever leap seconds occur unix enthusiasts history holding time_t parties pronounced time tea parties celebrate significant values unix time number directly analogous new year celebrations occur change year many calendars use unix time spread practice celebrating milestones usually time values round numbers decimal celebrated following unix convention viewing codice_1 values decimal among groups round binary numbers also celebrated +2 occurred 13:37:04 utc saturday 10 january 2004 events celebrate typically described n seconds since unix epoch inaccurate discussed due handling leap seconds unix time number seconds elapsed since unix epoch slightly greater unix time number times later epoch vernor vinge novel deepness sky describes spacefaring trading civilization thousands years future still uses unix epoch programmer-archaeologist responsible finding maintaining usable code mature computer systems first believes epoch refers time man first walked moon realizes 0-second one humankind first computer operating systems
|
Operating systems
|
no-force no-force policy used transaction control database theory term no-force refers disk pages related actual database object modified no-force policy transaction commits changes made actual objects required written disk in-place forced record changes must still preserved commit time ensure transaction durable record typically written sequential transaction log actual changes database objects changes written later time frequently changed objects no-force policy allows updates merged reduce number write operations actual database object no-force policy also reduces seek time required commit mostly sequential write operations transaction log rather requiring disk seek many distinct database objects commit
|
Databases
|
programming language programming language formal language comprises set instructions produce various kinds output programming languages used computer programming implement algorithms programming languages consist instructions computers programmable machines use set specific instructions rather general programming languages early ones preceded invention digital computer first probably automatic flute player described 9th century brothers musa baghdad islamic golden age since early 1800s programs used direct behavior machines jacquard looms music boxes player pianos programs machines player piano scrolls produce different behavior response different inputs conditions thousands different programming languages created created every year many programming languages written imperative form i.e. sequence operations perform languages use declarative form i.e desired result specified achieve description programming language usually split two components syntax form semantics meaning languages defined specification document example c programming language specified iso standard languages perl dominant implementation treated reference languages basic language defined standard extensions taken dominant implementation common programming language notation writing programs specifications computation algorithm authors restrict term programming language languages express possible algorithms traits often considered important constitutes programming language include markup languages like xml html troff define structured data usually considered programming languages programming languages may however share syntax markup languages computational semantics defined xslt example turing complete language entirely using xml syntax moreover latex mostly used structuring documents also contains turing complete subset term computer language sometimes used interchangeably programming language however usage terms varies among authors including exact scope one usage describes programming languages subset computer languages similarly languages used computing different goal expressing computer programs generically designated computer languages instance markup languages sometimes referred computer languages emphasize meant used programming another usage regards programming languages theoretical constructs programming abstract machines computer languages subset thereof runs physical computers finite hardware resources john c. reynolds emphasizes formal specification languages much programming languages languages intended execution also argues textual even graphical input formats affect behavior computer programming languages despite fact commonly turing-complete remarks ignorance programming language concepts reason many flaws input formats early computers colossus programmed without help stored program modifying circuitry setting banks physical controls slightly later programs could written machine language programmer writes instruction numeric form hardware execute directly example instruction add value two memory location might consist 3 numbers opcode selects add operation two memory locations programs decimal binary form read punched cards paper tape magnetic tape toggled switches front panel computer machine languages later termed first-generation programming languages 1gl next step development so-called second-generation programming languages 2gl assembly languages still closely tied instruction set architecture specific computer served make program much human-readable relieved programmer tedious error-prone address calculations first high-level programming languages third-generation programming languages 3gl written 1950s early high-level programming language designed computer plankalkül developed german z3 konrad zuse 1943 1945 however implemented 1998 2000 john mauchly short code proposed 1949 one first high-level languages ever developed electronic computer unlike machine code short code statements represented mathematical expressions understandable form however program translated machine code every time ran making process much slower running equivalent machine code university manchester alick glennie developed autocode early 1950s programming language used compiler automatically convert language machine code first code compiler developed 1952 mark 1 computer university manchester considered first compiled high-level programming language second autocode developed mark 1 r. a. brooker 1954 called mark 1 autocode brooker also developed autocode ferranti mercury 1950s conjunction university manchester version edsac 2 devised d. f. hartley university cambridge mathematical laboratory 1961 known edsac 2 autocode straight development mercury autocode adapted local circumstances noted object code optimisation source-language diagnostics advanced time contemporary separate thread development atlas autocode developed university manchester atlas 1 machine 1954 fortran invented ibm john backus first widely used high-level general purpose programming language functional implementation opposed design paper still popular language high-performance computing used programs benchmark rank world fastest supercomputers another early programming language devised grace hopper us called flow-matic developed univac remington rand period 1955 1959 hopper found business data processing customers uncomfortable mathematical notation early 1955 team wrote specification english programming language implemented prototype flow-matic compiler became publicly available early 1958 substantially complete 1959 flow-matic major influence design cobol since direct descendant aimaco actual use time increased use high-level languages introduced requirement low-level programming languages system programming languages languages varying degrees provide facilities assembly languages high-level languages used perform tasks require direct access hardware facilities still provide higher-level control structures error-checking period 1960s late 1970s brought development major language paradigms use languages spawned descendants modern programming languages count least one ancestry 1960s 1970s also saw considerable debate merits structured programming whether programming languages designed support edsger dijkstra famous 1968 letter published communications acm argued goto statements eliminated higher level programming languages 1980s years relative consolidation c++ combined object-oriented systems programming united states government standardized ada systems programming language derived pascal intended use defense contractors japan elsewhere vast sums spent investigating so-called fifth-generation languages incorporated logic programming constructs functional languages community moved standardize ml lisp rather inventing new paradigms movements elaborated upon ideas invented previous decades one important trend language design programming large-scale systems 1980s increased focus use modules large-scale organizational units code modula-2 ada ml developed notable module systems 1980s often wedded generic programming constructs rapid growth internet mid-1990s created opportunities new languages perl originally unix scripting tool first released 1987 became common dynamic websites java came used server-side programming bytecode virtual machines became popular commercial settings promise write run anywhere ucsd pascal popular time early 1980s developments fundamentally novel rather refinements many existing languages paradigms although syntax often based c family programming languages programming language evolution continues industry research current directions include security reliability verification new kinds modularity mixins delegates aspects database integration microsoft linq fourth-generation programming languages 4gl computer programming languages aim provide higher level abstraction internal computer hardware details 3gls fifth-generation programming languages 5gl programming languages based solving problems using constraints given program rather using algorithm written programmer programming languages primitive building blocks description data processes transformations applied like addition two numbers selection item collection primitives defined syntactic semantic rules describe structure meaning respectively programming language surface form known syntax programming languages purely textual use sequences text including words numbers punctuation much like written natural languages hand programming languages graphical nature using visual relationships symbols specify program syntax language describes possible combinations symbols form syntactically correct program meaning given combination symbols handled semantics either formal hard-coded reference implementation since languages textual article discusses textual syntax programming language syntax usually defined using combination regular expressions lexical structure backus–naur form grammatical structure simple grammar based lisp grammar specifies following following examples well-formed token sequences grammar codice_1 codice_2 codice_3 syntactically correct programs semantically correct many syntactically correct programs nonetheless ill-formed per language rules may depending language specification soundness implementation result error translation execution cases programs may exhibit undefined behavior even program well-defined within language may still meaning intended person wrote using natural language example may possible assign meaning grammatically correct sentence sentence may false following c language fragment syntactically correct performs operations semantically defined operation codice_4 meaning value complex type codice_5 defined value codice_6 null pointer type declaration first line omitted program would trigger error undefined variable p compilation however program would still syntactically correct since type declarations provide semantic information grammar needed specify programming language classified position chomsky hierarchy syntax programming languages specified using type-2 grammar i.e. context-free grammars languages including perl lisp contain constructs allow execution parsing phase languages constructs allow programmer alter behavior parser make syntax analysis undecidable problem generally blur distinction parsing execution contrast lisp macro system perl codice_7 blocks may contain general computations c macros merely string replacements require code execution term semantics refers meaning languages opposed form syntax static semantics defines restrictions structure valid texts hard impossible express standard syntactic formalisms compiled languages static semantics essentially include semantic rules checked compile time examples include checking every identifier declared used languages require declarations labels arms case statement distinct many important restrictions type like checking identifiers used appropriate context e.g adding integer function name subroutine calls appropriate number type arguments enforced defining rules logic called type system forms static analyses like data flow analysis may also part static semantics newer programming languages like java c definite assignment analysis form data flow analysis part static semantics data specified machine must instructed perform operations data example semantics may define strategy expressions evaluated values manner control structures conditionally execute statements dynamic semantics also known execution semantics language defines various constructs language produce program behavior many ways defining execution semantics natural language often used specify execution semantics languages commonly used practice significant amount academic research went formal semantics programming languages allow execution semantics specified formal manner results field research seen limited application programming language design implementation outside academia type system defines programming language classifies values expressions types manipulate types interact goal type system verify usually enforce certain level correctness programs written language detecting certain incorrect operations decidable type system involves trade-off rejects many incorrect programs also prohibit correct albeit unusual programs order bypass downside number languages type loopholes usually unchecked casts may used programmer explicitly allow normally disallowed operation different types typed languages type system used type check programs number languages usually functional ones infer types relieving programmer need write type annotations formal design study type systems known type theory language typed specification every operation defines types data operation applicable example data represented codice_8 string many programming languages dividing number string meaning executed invalid operation may detected program compiled static type checking rejected compiler compilation error message may detected program running dynamic type checking resulting run-time exception many languages allow function called exception handler handle exception example always return -1 result special case typed languages single-typed languages often scripting markup languages rexx sgml one data type–—most commonly character strings used symbolic numeric data contrast untyped language assembly languages allows operation performed data generally sequences bits various lengths high-level untyped languages include bcpl tcl varieties forth practice languages considered typed type theory verifying rejecting operations modern languages offer degree typing many production languages provide means bypass subvert type system trading type-safety finer control program execution see casting static typing expressions types determined prior program executed typically compile-time example 1 2+2 integer expressions passed function expects string stored variable defined hold dates statically typed languages either manifestly typed type-inferred first case programmer must explicitly write types certain textual positions example variable declarations second case compiler infers types expressions declarations based context mainstream statically typed languages c++ c java manifestly typed complete type inference traditionally associated less mainstream languages haskell ml however many manifestly typed languages support partial type inference example c++ java c infer types certain limited cases additionally programming languages allow types automatically converted types example int used program expects float dynamic typing also called latent typing determines type-safety operations run time words types associated run-time values rather textual expressions type-inferred languages dynamically typed languages require programmer write explicit type annotations expressions among things may permit single variable refer values different types different points program execution however type errors automatically detected piece code actually executed potentially making debugging difficult lisp smalltalk perl python javascript ruby examples dynamically typed languages weak typing allows value one type treated another example treating string number occasionally useful also allow kinds program faults go undetected compile time even run time strong typing prevents program faults attempt perform operation wrong type value raises error strongly typed languages often termed type-safe safe alternative definition weakly typed refers languages perl javascript permit large number implicit type conversions javascript example expression codice_9 implicitly converts codice_10 number conversion succeeds even codice_10 codice_12 codice_13 codice_14 string letters implicit conversions often useful mask programming errors strong static generally considered orthogonal concepts usage literature differs use term strongly typed mean strongly statically typed even confusingly mean simply statically typed thus c called strongly typed weakly statically typed may seem odd professional programmers c could weakly statically typed however notice use generic pointer void* pointer allow casting pointers pointers without needing explicit cast extremely similar somehow casting array bytes kind datatype c without using explicit cast codice_15 codice_16 programming languages associated core library sometimes known 'standard library especially included part published language standard conventionally made available implementations language core libraries typically include definitions commonly used algorithms data structures mechanisms input output line language core library differs language language cases language designers may treat library separate entity language however language core library often treated part language users language specifications even require library made available implementations indeed languages designed meanings certain syntactic constructs even described without referring core library example java string literal defined instance codice_17 class similarly smalltalk anonymous function expression block constructs instance library codice_18 class conversely scheme contains multiple coherent subsets suffice construct rest language library macros language designers even bother say portions language must implemented language constructs must implemented parts library programming languages share properties natural languages related purpose vehicles communication syntactic form separate semantics showing language families related languages branching one another artificial constructs also differ fundamental ways languages evolved usage significant difference programming language fully described studied entirety since precise finite definition contrast natural languages changing meanings given users different communities constructed languages also artificial languages designed ground specific purpose lack precise complete semantic definition programming language many programming languages designed scratch altered meet new needs combined languages many eventually fallen disuse although attempts design one universal programming language serves purposes failed generally accepted filling role need diverse programming languages arises diversity contexts languages used one common trend development programming languages add ability solve problems using higher level abstraction earliest programming languages tied closely underlying hardware computer new programming languages developed features added let programmers express ideas remote simple translation underlying hardware instructions programmers less tied complexity computer programs computing less effort programmer lets write functionality per time unit natural language programming proposed way eliminate need specialized language programming however goal remains distant benefits open debate edsger w. dijkstra took position use formal language essential prevent introduction meaningless constructs dismissed natural language programming foolish alan perlis similarly dismissive idea hybrid approaches taken structured english sql language designers users must construct number artifacts govern enable practice programming important artifacts language specification implementation specification programming language artifact language users implementors use agree upon whether piece source code valid program language behavior shall programming language specification take several forms including following implementation programming language provides way write programs language execute one configurations hardware software broadly two approaches programming language implementation compilation interpretation generally possible implement language using either technique output compiler may executed hardware program called interpreter implementations make use interpreter approach distinct boundary compiling interpreting instance implementations basic compile execute source line time programs executed directly hardware usually run much faster interpreted software one technique improving performance interpreted programs just-in-time compilation virtual machine execution translates blocks bytecode going used machine code direct execution hardware although commonly used programming languages fully open specifications implementations many programming languages exist proprietary programming languages implementation available single vendor may claim proprietary language intellectual property proprietary programming languages commonly domain specific languages internal scripting languages single product proprietary languages used internally within vendor others available external users programming languages exist border proprietary open example oracle corporation asserts proprietary rights aspects java programming language microsoft c programming language open implementations parts system also common language runtime clr closed environment many proprietary languages widely used spite proprietary nature examples include matlab vbscript wolfram language languages may make transition closed open example erlang originally ericsson internal programming language thousands different programming languages created mainly computing field software commonly built 5 programming languages programming languages differ forms human expression require greater degree precision completeness using natural language communicate people human authors speakers ambiguous make small errors still expect intent understood however figuratively speaking computers exactly told understand code programmer intended write combination language definition program program inputs must fully specify external behavior occurs program executed within domain control program hand ideas algorithm communicated humans without precision required execution using pseudocode interleaves natural language code written programming language programming language provides structured mechanism defining pieces data operations transformations may carried automatically data programmer uses abstractions present language represent concepts involved computation concepts represented collection simplest elements available called primitives programming process programmers combine primitives compose new programs adapt existing ones new uses changing environment programs computer might executed batch process without human interaction user might type commands interactive session interpreter case commands simply programs whose execution chained together language run commands interpreter unix shell command-line interface without compiling called scripting language determining widely used programming language difficult since definition usage varies context one language may occupy greater number programmer hours different one lines code third may consume cpu time languages popular particular kinds applications example cobol still strong corporate data center often large mainframes fortran scientific engineering applications ada aerospace transportation military real-time embedded applications c embedded applications operating systems languages regularly used write many different kinds applications various methods measuring language popularity subject different bias measured proposed combining averaging information various internet sites stackify.com reported ten popular programming languages descending order overall popularity java c c++ python c javascript vb .net r php matlab dialect programming language data exchange language relatively small variation extension language change intrinsic nature languages scheme forth standards may considered insufficient inadequate illegitimate implementors often deviate standard making new dialect cases dialect created use domain-specific language often subset lisp world languages use basic s-expression syntax lisp-like semantics considered lisp dialects although vary wildly say racket clojure common one language several dialects become quite difficult inexperienced programmer find right documentation basic programming language many dialects explosion forth dialects led saying 've seen one forth ... 've seen one forth overarching classification scheme programming languages given programming language usually single ancestor language languages commonly arise combining elements several predecessor languages new ideas circulation time ideas originate one language diffuse throughout family related languages leap suddenly across familial gaps appear entirely different family task complicated fact languages classified along multiple axes example java object-oriented language encourages object-oriented organization concurrent language contains built-in constructs running multiple threads parallel python object-oriented scripting language broad strokes programming languages divide programming paradigms classification intended domain use general-purpose programming languages distinguished domain-specific programming languages traditionally programming languages regarded describing computation terms imperative sentences i.e issuing commands generally called imperative programming languages great deal research programming languages aimed blurring distinction program set instructions program assertion desired answer main feature declarative programming refined paradigms include procedural programming object-oriented programming functional programming logic programming languages hybrids paradigms multi-paradigmatic assembly language much paradigm direct model underlying machine architecture purpose programming languages might considered general purpose system programming languages scripting languages domain-specific languages concurrent/distributed languages combination general purpose languages designed largely educational goals programming language may also classified factors unrelated programming paradigm instance programming languages use english language keywords minority languages may classified deliberately esoteric
|
Programming language topics
|
donna benjamin donna benjamin australian open source community contributor commentator advocate served board positions community organisations including open source industry australia drupal association ada initiative lead organiser 2008 linux.conf.au conference melbourne regularly runs community leadership summit x lca clsxlca workshop focussing community development open source projects 2011 organised crowdfunding campaign called digitise dawn successfully raised funds digitise dawn early feminist journal published australia 1888 1905 2012 received rusty wrench award linux australia recognition contributions runs micro-business called creative contingencies specialises drupal content management platform
|
Operating systems
|
karma attack information security karma attack exploits behaviour wi-fi devices combined lack access point authentication numerous wifi protocols variant evil twin attack details attack first published 2004 dino dai zovi shaun macaulay vulnerable client devices broadcast preferred network list pnl contains ssids access points previously connected willing automatically reconnect without user intervention broadcasts encrypted hence may received wifi access point range karma attack consists access point receiving list giving ssid pnl thus becoming evil twin access point already trusted client done client receives malicious access point signal strongly genuine access point example genuine access point nowhere nearby client attempt authenticate access point attack succeed attack succeeds malicious access point becomes man middle mitm positions deploy attacks victim device distinguishes karma plain evil twin attack use pnl allows attacker know rather simply guess ssids client automatically attempt connect
|
Computer security
|
layer 2 tunneling protocol computer networking layer 2 tunneling protocol l2tp tunneling protocol used support virtual private networks vpns part delivery services isps provide encryption confidentiality rather relies encryption protocol passes within tunnel provide privacy published 2000 proposed standard rfc 2661 l2tp origins primarily two older tunneling protocols point-to-point communication cisco layer 2 forwarding protocol l2f microsoft's point-to-point tunneling protocol pptp new version protocol l2tpv3 appeared proposed standard rfc 3931 2005 l2tpv3 provides additional security features improved encapsulation ability carry data links simply point-to-point protocol ppp ip network example frame relay ethernet atm etc. entire l2tp packet including payload l2tp header sent within user datagram protocol udp datagram virtue transmission udp rather tcp c.f sstp avoids tcp meltdown problem common carry ppp sessions within l2tp tunnel l2tp provide confidentiality strong authentication ipsec often used secure l2tp packets providing confidentiality authentication integrity combination two protocols generally known l2tp/ipsec discussed two endpoints l2tp tunnel called lac l2tp access concentrator lns l2tp network server lns waits new tunnels tunnel established network traffic peers bidirectional useful networking higher-level protocols run l2tp tunnel facilitate l2tp session 'call established within tunnel higher-level protocol ppp either lac lns may initiate sessions traffic session isolated l2tp possible set multiple virtual networks across single tunnel mtu considered implementing l2tp packets exchanged within l2tp tunnel categorized either control packets data packets l2tp provides reliability features control packets reliability data packets reliability desired must provided nested protocols running within session l2tp tunnel l2tp allows creation virtual private dialup network vpdn connect remote client corporate network using shared infrastructure could internet service provider network l2tp tunnel extend across entire ppp session across one segment two-segment session represented four different tunneling models namely l2tp packet consists field meanings time setup l2tp connection many control packets exchanged server client establish tunnel session direction one peer requests peer assign specific tunnel session id control packets using tunnel session id data packets exchanged compressed ppp frames payload list l2tp control messages exchanged lac lns handshaking establishing tunnel session voluntary tunneling method lack confidentiality inherent l2tp protocol often implemented along ipsec referred l2tp/ipsec standardized ietf rfc 3193 process setting l2tp/ipsec vpn follows process complete l2tp packets endpoints encapsulated ipsec since l2tp packet wrapped hidden within ipsec packet original source destination ip address encrypted within packet also necessary open udp port 1701 firewalls endpoints since inner packets acted upon ipsec data decrypted stripped takes place endpoints potential point confusion l2tp/ipsec use terms tunnel secure channel term tunnel-mode refers channel allows untouched packets one network transported another network case l2tp/ppp allows l2tp/ppp packets transported ip secure channel refers connection within confidentiality data guaranteed l2tp/ipsec first ipsec provides secure channel l2tp provides tunnel windows native support configurable control panel l2tp since windows 2000 windows vista added 2 alternative tools mmc snap-in called windows firewall advanced security wfwas netsh advfirewall command-line tool one limitation wfwas netsh commands servers must specified ip address windows 10 added add-vpnconnection set-vpnconnectionipsecconfiguration powershell commands registry key must created client server server behind nat-t device l2tp often used isps internet service example adsl cable resold end user packets travel wholesale network service provider network server called broadband remote access server bras protocol converter router combined legacy networks path end user customer premises equipment bras may atm network ip network l2tp tunnel runs bras acting lac lns edge router boundary ultimate destination isp ip network see example reseller isps using l2tp
|
Internet protocols
|
freebsd version history released november 1993 1.1.5.1 released july 1994 2.0-release announced 22 november 1994 final release freebsd 2 2.2.8-release announced 29 november 1998 freebsd 2.0 first version freebsd claimed legally free unix code approval novell first version widely used beginnings spread internet servers 2.2.9-release released april 1 2006 fully functional april fools day prank seventy-seven months tireless work freebsd developers users children pets freebsd 3.0-release announced 16 october 1998 final release 3.5-release announced 24 june 2000 freebsd 3.0 first branch able support symmetric multiprocessing smp systems using giant lock marked transition a.out elf executables usb support first introduced freebsd 3.1 first gigabit network cards supported 3.2-release 4.0-release appeared march 2000 last 4-stable branch release 4.11 january 2005 supported 31 january 2007 freebsd 4 lauded stability favorite operating system isps web hosting providers first dot-com bubble widely regarded one stable high performance operating systems whole unix lineage among new features freebsd 4 codice_1 introduced part major bsd systems jails way running processes separate environments version 4.8 forked matt dillon create dragonfly bsd almost three years development first 5.0-release january 2003 widely anticipated featuring support advanced multiprocessor application threading ultrasparc ia-64 platforms first 5-stable release 5.3 5.0 5.2.1 cut -current last release 5-stable branch 5.5 may 2006 largest architectural development freebsd 5 major change low-level kernel locking mechanisms enable better symmetric multi-processor smp support released much kernel mp lock sometimes called giant lock one process could execute kernel mode time major changes included n native threading implementation called kernel scheduled entities kse principle similar scheduler activations starting freebsd 5.3 kse default threading implementation replaced 1:1 implementation freebsd 7.0 freebsd 5 also significantly changed block i/o layer implementing geom modular disk i/o request transformation framework contributed poul-henning kamp geom enables simple creation many kinds functionality mirroring gmirror encryption gbde geli work supported sponsorship darpa early versions 5.x much developer previews pronounced instability 5.4 5.5 releases freebsd confirmed technologies introduced freebsd 5.x branch future highly stable high-performing releases freebsd 6.0 released 4 november 2005 final freebsd 6 release 6.4 11 november 2008 versions extended work smp threading optimization along work advanced 802.11 functionality trustedbsd security event auditing significant network stack performance enhancements fully preemptive kernel support hardware performance counters hwpmc main accomplishments releases include removal giant lock vfs implementation better-performing optional libthr library 1:1 threading addition basic security module bsm audit implementation called openbsm created trustedbsd project based bsm implementation found apple open source darwin released bsd-style license freebsd 7.0 released 27 february 2008 final freebsd 7 release 7.4 24 february 2011 new features included sctp ufs journaling experimental port sun zfs file system gcc4 improved support arm architecture jemalloc memory allocator optimized parallel computation ported firefox 3 major updates optimizations relating network audio smp performance benchmarks showed significant performance improvements compared previous freebsd releases well linux new ule scheduler much improved decision made ship 7.0 release older 4bsd scheduler leaving ule kernel compile-time tunable freebsd 7.1 ule default i386 amd64 architectures dtrace support integrated version 7.1 netbsd freebsd 7.2 brought support multi-ipv4/ipv6 jails code supporting dec alpha architecture supported since freebsd 4.0 removed freebsd 7.0 freebsd 8.0 officially released 25 november 2009 freebsd 8 branched trunk august 2009 features superpages xen domu support network stack virtualization stack-smashing protection tty layer rewrite much updated improved zfs support new usb stack usb 3.0 xhci support added freebsd 8.2 multicast updates including igmpv3 rewritten nfs client/server introducing nfsv4 aes acceleration supported intel cpus added freebsd 8.2 inclusion improved device mmap extensions enables implementation 64-bit nvidia display driver x86-64 platform pluggable congestion control framework support ability use dtrace applications running linux emulation added freebsd 8.3 freebsd 8.4 released 7 june 2013 final release freebsd 8 series freebsd 9.0 released 12 january 2012 key features release include new installer bsdinstall ufs journaling zfs version 28 userland dtrace nfsv4-compatible nfs server client usb 3.0 support support running playstation 3 capsicum sandboxing llvm 3.0 base system kernel base system could built clang freebsd 9.0 still used gcc4.2 default playstation 4 video game console uses derived version freebsd 9.0 sony computer entertainment dubbed orbis os freebsd 9.1 released 31 december 2012 freebsd 9.2 released 30 september 2013 freebsd 9.3 released 16 july 2014 20 january 2014 freebsd release engineering team announced availability freebsd 10.0-release key features include deprecation gcc favor clang new iscsi implementation virtio drivers out-of-the-box kvm support fuse implementation freebsd 10.1-release announced 14 november 2014 supported extended term 31 december 2016 subsequent 10.2-release reached eol day october 2017 10.4-release final release branch announced support 10 series terminated october 2018 10 october 2016 freebsd release engineering team announced availability freebsd 11.0-release freebsd 12.0-release announced december 2018 following table presents version release history freebsd operating system timeline shows span single release generation freebsd lasts around 5 years since freebsd project makes effort binary backward limited forward compatibility within release generation allows users 5+ years support trivial-to-easy upgrading within release generation
|
Operating systems
|
algosec algosec provider software network security policy management also known firewall policy management algosec products automate management enforcement security policies across firewalls routers virtual private networks vpns related security devices enterprises use algosec products manage configuration security systems identify vulnerabilities test systems security policies reduce administrative costs ensure compliance regulations pci-dss sarbanes-oxley algosec delivers products standalone modules well via integrated suite algosec security management suite includes integration products suite provides two-way link two processes products available software loaded appliance algosec ’ core technology developed 2001 prof. avishai wool team researchers bell laboratories prof wool teamed yuval baron found algosec 2004 time company headquartered reston virginia 2010 algosec moved headquarters north american sales office roswell georgia atlanta area 2012 algosec moved headquarters ridgefield park new jersey today addition boston office algosec sales offices london singapore research development center petah tikva israel london algosec customers include enterprises managed service providers auditors consultants throughout world
|
Computer security
|
μclinux μclinux variation linux kernel previously maintained fork targets microcontrollers without memory management unit mmu integrated mainline development 2.5.46 project continues develop patches tools microcontrollers homepage lists linux kernel releases 2.0 2.4 2.6 end-of-life mainline letters μc microcontroller name pronounced you-see-linux rather pronouncing letter mu greek μclinux originally created d. jeff dionne kenneth albanowski 1998 initially targeted motorola dragonball family embedded 68k processors specifically 68ez328 series used motorola palmpilot 2.0.33 linux kernel releasing initial work developer community quickly sprang extending work newer kernels microprocessor architectures early 1999 support added motorola freescale coldfire family embedded microprocessors arm processor support added later although originally targeting 2.0 series linux kernels ports based linux 2.4 linux 2.6 linux 2.4 ports forward ported 2.0.36 linux kernel michael leslie evan stawnyczy work rt-control never μclinux extensions applied 2.2 series kernels since version 2.5.46 linux kernel major parts μclinux integrated mainline kernel number processor architectures greg ungerer originally ported μclinux motorola coldfire family processors continues maintain actively push core μclinux support 2.6 series linux kernels regard μclinux essentially longer separate fork linux project continues develop patches supporting tools using linux microcontrollers μclinux support many architectures forms basis many products like network routers security cameras dvd mp3 players voip phone gateways scanners card readers current list includes
|
Computer architecture
|
redis labs redis labs originally garantia data private computer software company based mountain view california provides database management system marketed nosql open source software service using cloud computing company additional offices london tel aviv redis labs founded 2011 ofer bengal previously founder ceo rit technologies yiftach shoolman previously founder president crescendo networks acquired f5 networks july 15 2015 creator redis lead developer salvatore sanfilippo joined redis labs lead open source development redis labs became official sponsor open source project company secured 4 million seed funding angel investors august 2012 additional 9 million series funding led bain capital ventures carmel ventures additional 15m series b funding led existing investors silicon valley bank additional 14 million series c funding led investors august 2017 raised 44 million series funding february 2019 60 million series e funding led francisco partners participation existing investors company announced beta version cloud services gigaom ’ structure launchpad june 2012 according business edge redis enterprise cloud especially suitable “ web companies websites seasonal occasional fluctuations traffic performance needs january 2013 company 1,000 paying customers including electronic arts illumina scopely redis enterprise cloud memcached cloud products became generally available february 2013 late 2013 redis labs announced focus mainly cloud-based redis offering although continue support memcached product september 2013 amazon web services announced redis capabilities elasticache product thereby competing company offering according techcrunch redis labs advantage aws comes redis scalability high availability features elasticache provide october 2013 redis labs acquired myredis competing hosted redis provider december 2013 company least 10,000 users including 1,300 paying customers january 29 2014 company changed name garantia data redis labs september 2014 redis labs reported 3,000 paying customers including bleacher report hoteltonight docker early 2015 redis labs made available redis enterprise pack formerly known redis labs enterprise cluster rlec downloadable software installation enterprise-grade clusters acts container managing running multiple redis databases early 2016 redis labs made available connector package apache spark may 2016 company announced mechanism developers extend redis opened online marketplace offers modules certified work open source redis redis labs ’ enterprise products redis labs provides downloadable software known redis enterprise software redis enterprise vpc cloud computing service known redis enterprise cloud products address two primary challenges faced redis users redis scalable beyond single node limited reliability high availability capabilities redis enterprise software redis enterprise vpc redis enterprise cloud solve problems provide following additional functionalities regular redis installation redis modules expansion redis key-value store multi-model database using custom made data-types introduced salvatore sanfilippo order prevent scope creep core redis redis modules redis source available license current modules include redis enterprise achieve scalability high availability using proprietary dynamic clustering engine services virtualize multiple cloud servers large pool memory consumed users according actual size datasets dataset automatically distributed shards across multiple nodes enables fast transparent recovery node fails improves performance high-throughput use cases datasets also constantly replicated node fails auto-switchover mechanism guarantees data served without interruption provide additional reliability entire dataset constantly replicated nodes persistent storage also backed remote persistent storage disaster recovery redis labs offers pay-per-use pricing model allowing users pay per gb-hour storage used unlike providers price service based size machine instance even users consume machine ’ resources redis enterprise cloud memcached cloud available amazon web services us eu apac windows azure ibm softlayer heroku bluemix appfog appharbor cloud foundry openshift november 2013 company announced redis enterprise cloud memcached cloud plugins new relic ’ plugin central plugin enable developers use new relic monitor redis memcached usage characteristics directly new relic dashboard
|
Distributed computing architecture
|
national identity cards european economic area national identity cards issued citizens governments european union member states except denmark ireland united kingdom also liechtenstein citizens holding national identity card states eea swiss citizenship use identity document within home country also travel document exercise right free movement eea switzerland identity cards state eea swiss citizenship including national identity cards issued residents citizens valid travel document within eea switzerland national identity cards often accepted parts world unofficial identification purposes age verification commercial establishments serve sell alcohol checking hotels sometimes official purposes proof identity/nationality authorities especially machine-readable cards four eea member states issue cards defined eu national identity cards citizens denmark iceland norway united kingdom except residents gibraltar although norway expected start issuing cards 2020 present citizens four countries use passport travel document travelling eea member states switzerland however travelling within schengen area common travel area valid identity documentation driving licence ehic card often sufficient ireland issues passport card valid national identity card eu countries alternative presenting passport eea swiss citizens entitled use valid national identity card travel document exercise right free movement european economic area switzerland strictly speaking necessary eea swiss citizen possess valid national identity card passport enter eea switzerland theory eea swiss citizen outside eea switzerland prove nationality means e.g presenting expired national identity card passport citizenship certificate must permitted enter eea switzerland eea swiss citizen unable demonstrate nationality satisfactorily must nonetheless given 'every reasonable opportunity obtain necessary documents delivered within reasonable period time additionally eea swiss citizens enter number countries territories outside eea switzerland strength national identity cards alone without need present passport border authorities although swedish finnish law allow citizens travel outside eea/switzerland without passport practice meaning direct outbound travel sweden/finland countries id card possible probably including uk brexit deal since change relevant law included swedish law change brexit countries however following accept national id cards eea/swiss citizens short-term visits require passport take residency turkey allows citizens belgium france germany greece italy liechtenstein luxembourg malta netherlands portugal spain switzerland enter short-term visits using national identity card egypt allows citizens belgium france germany italy portugal enter using national identity card short-term visits tunisia allows nationals austria belgium france germany italy luxembourg netherlands portugal spain sweden switzerland enter using national identity card travelling organized tour anguilla dominica saint lucia allow nationals france enter using national id card dominica de facto also allows nationals least germany sweden enter national id card march 2016 gambia allows nationals belgium enter using national id card finally greenland allows nordic citizens enter national id card sweden finland whereas norway introduce 2020 practice eea swiss citizens use id cards passport control takes place arrival greenland airline check-in gate air greenland icelandair accept eea swiss id card although matter european law holders swedish national identity card entitled use travel document european union member state regardless whether belongs schengen area swedish national law recognise card valid travel document outside schengen area july 2015 direct violation european law meant practice leaving schengen directly sweden i.e. without making stopover another schengen country card possible partially changed july 2015 travel non-schengen countries eu others even accept id card permitted similarly finnish citizens leave finland directly non eu/efta country id cards uk border force officials known place extra scrutiny spend longer processing national identity cards issued certain member states deemed limited security features hence susceptible tampering/forgery unlike counterparts schengen area previous legal regime force 7 april 2017 obliged perform 'rapid 'straightforward visual check signs falsification tampering obliged use technical devices – document scanners uv light magnifiers – eea swiss citizens presented passports and/or national identity cards external border checkpoints matter policy ukbf officials required examine physically passports national identity cards presented eea swiss citizens signs forgery tampering addition unlike counterparts schengen area previous legal regime force 7 april 2017 presented passport national identity card eea swiss citizen legally obliged check database lost/stolen/invalidated travel documents – could perform 'rapid 'straightforward database check – could check see traveller database containing persons interest strictly 'non-systematic basis threat 'genuine 'present 'sufficiently serious matter policy ukbf officials required check every eea swiss citizen passport/national identity card warnings index wi database note however effect 7 april 2017 mandatory border officials schengen area check systematic basis travel documents eea swiss citizens crossing external borders relevant databases ref name= reg2017/458 regulation eu 2017/458 european parliament council 15 march 2017 amending regulation eu 2016/399 regards reinforcement checks relevant databases external borders oj l 74 18 march 2017 p.1 /ref reason presented non-machine readable identity card take four times longer ukbf official process card official enter biographical details holder manually computer check wi database large number possible matches returned different configuration entered reduce number possible matches example stansted airport ukbf officials known take longer process italian paper identity cards often need taken plastic wallets particularly susceptible forgery/tampering non-machine readable documents holders biographical details entered manually computer according statistics published frontex 2015 top 6 eu member states whose national identity cards falsified detected external border crossing points schengen area italy spain belgium greece france romania countries remained top 6 2016 varying rules domestic usage identity documents countries demand usage national identity card passport countries allow usage documents like driver licenses countries e.g austria finland sweden national identity cards fully voluntary needed everyone identity documents like driving licences accepted domestically countries minority national identity card since majority passport driving licence n't need identity documents also true ireland passport driving licence less need passport card eea swiss citizens exercising right free movement another eea member state switzerland entitled use national identity card identification document dealing government authorities also private sector service providers example supermarket uk refuses accept german national identity card proof age german citizen attempts purchase age-restricted product insists production uk-issued passport driving licence identity document supermarket would effect discriminating individual basis his/her nationality provision service thereby contravening prohibition art 20 2 directive 2006/123/ec discriminatory treatment relating nationality service recipient conditions access service made available public large service provider 11 june 2014 guardian published leaked internal documents hm passport office uk revealed government officials dealt british passport applications sent overseas treated eu citizen counter-signatories differently depending nationality leaked internal documents showed citizens austria belgium czech republic estonia finland germany hungary latvia lithuania luxembourg malta netherlands poland portugal slovakia slovenia sweden acted counter-signatory support application british passport made someone knew hm passport office would willing accept copy counter-signatory passport national identity card hm passport office considered national identity cards issued citizens member states acceptable taking account 'quality identity card design rigour issuing process relatively low level documented abuse documents uk/schengen borders ability access samples identity cards comparison purposes contrast citizens eu member states bulgaria croatia cyprus france greece italy romania spain acting counter-signatories could submit copy passport national identity card prove identity national identity cards issued member states deemed hm passport office less secure susceptible fraud/forgery day following revelations 12 june 2014 home office hm passport office withdrew leaked internal guidance relating eu citizen counter-signatories submitting copy national identity card instead passport proof identity eu citizen counter-signatories able submit copy passport national identity card 13 july 2005 justice home affairs council called european union member states adopt common designs security features national identity cards december 2005 detailed standards laid soon possible thereafter 4 december 2006 european union member states agreed adopt following common designs minimum security standards national identity cards draft resolution 15 november 2006 card made paper core laminated sides made entirely synthetic substrate data card shall contain least name birth date nationality photo signature card number end date validity cards contain information height eye colour start date validity sex issue place province birth place biographical data card machine readable follow icao specification machine-readable travel documents eu regulation revising schengen borders code entered force 7 april 2017 introduced systematic checks travel documents eu eea swiss citizens relevant databases entering leaving schengen area states member states phase travel documents including national identity cards machine-readable however 2017 greece continues issue solely non-machine readable identity cards italy process phasing issuing non-machine readable paper booklets favour biometric cards eea electronic identity cards comply iso/iec standard 14443 effectively means cards implement electromagnetic coupling card card reader specifications followed capable read proximities less 0.1 metres rfid tags often seen stores attached livestock neither work relatively large distances typically seen us toll booths automated border crossing channels icao specifications adopted nearly european passport booklets basic access control bac means miscreants able read cards unless also physical access card bac authentication keys derive three lines data printed mrz obverse td1 format identity card begins according iso 14443 standard wireless communication card reader start identity card chip transmitted unique identifier theoretically ingenious attacker managed secrete multiple reading devices distributed array eg arrival hall furniture could distinguish bearers mrotds without access relevant chip files concert information attacker might able produce profiles specific particular card consequently bearer defence trivial task electronic cards make new randomised uids every session nh08 preserve level privacy comparable contact cards commercial rfid tags electronic identity cards austria belgium estonia finland germany italy liechtenstein lithuania portugal spain digital signature application upon activation enables bearer authenticate card using confidential pin consequently least theoretically authenticate documents satisfy third party document altered digitally signed application uses registered certificate conjunction public/private key pairs enhanced cards necessarily participate online transactions unknown number national european identity cards issued different functionalities authentication online also additional contact chip containing electronic signature functionality swedish national identity card portugal card emv application removed newer versions 16 january 2016 member states issue variety national identity cards differing technical specifications according differing issuing procedures
|
Computer security
|
theofficialboard official board online contact database database maintains up-to-date corporate organizational data charts world private public companies exceeding 100 million revenue includes 50,000 companies data updated industry experts members site verified company used research organizational structures find contact information corporate executives official board founded amazon apple inc. executive thomas lot 2009 based france june 12 2014 official board released iphone application august 26 2014 official board released 18-month-long survey study presence female executives board members world largest companies concluded women least represented chairman board chief executive officer functions
|
Databases
|
os/vs2 operating system/virtual storage 2 os/vs2 successor operating system os/360 mvt os/360 family
|
Operating systems
|
timing attack cryptography timing attack side-channel attack attacker attempts compromise cryptosystem analyzing time taken execute cryptographic algorithms every logical operation computer takes time execute time differ based input precise measurements time operation attacker work backwards input information leak system measurement time takes respond certain queries much information help attacker depends many variables cryptographic system design cpu running system algorithms used assorted implementation details timing attack countermeasures accuracy timing measurements etc timing attacks often overlooked design phase dependent implementation introduced inadvertently compiler optimizations avoidance timing attacks involves design constant-time functions careful testing final executable code timing attack example attack exploits data-dependent behavioral characteristics implementation algorithm rather mathematical properties algorithm many cryptographic algorithms implemented masked proxy way reduces eliminates data dependent timing information consider implementation every call subroutine always returns exactly x seconds x maximum time ever takes execute routine every possible authorized input implementation timing algorithm leaks information data supplied invocation downside approach time used executions becomes worst-case performance function timing attacks practical many cases execution time square-and-multiply algorithm used modular exponentiation depends linearly number 1 bits key number 1 bits alone nearly enough information make finding key easy repeated executions key different inputs used perform statistical correlation analysis timing information recover key completely even passive attacker observed timing measurements often include noise sources network latency disk drive access differences access access error correction techniques used recover transmission errors nevertheless timing attacks practical number encryption algorithms including rsa elgamal digital signature algorithm 2003 boneh brumley demonstrated practical network-based timing attack ssl-enabled web servers based different vulnerability use rsa chinese remainder theorem optimizations actual network distance small experiments attack successfully recovered server private key matter hours demonstration led widespread deployment use blinding techniques ssl implementations context blinding intended remove correlations key encryption time versions unix use relatively expensive implementation crypt library function hashing 8-character password 11-character string older hardware computation took deliberately measurably long time much two three seconds cases login program early versions unix executed crypt function login name recognized system leaked information timing validity login name even password incorrect attacker could exploit leaks first applying brute-force produce list login names known valid attempt gain access combining names large set passwords known frequently used without information validity login names time needed execute approach would increase orders magnitude effectively rendering useless later versions unix fixed leak always executing crypt function regardless login name validity two otherwise securely isolated processes running single system either cache memory virtual memory communicate deliberately causing page faults and/or cache misses one process monitoring resulting changes access times likewise application trusted paging/caching affected branching logic may possible second application determine values data compared branch condition monitoring access time changes extreme examples allow recovery cryptographic key bits 2017 meltdown spectre attacks forced cpu manufacturers including intel amd arm ibm redesign cpus rely timing attacks early 2018 almost every computer system world affected spectre making powerful example timing attack history following visual basic code demonstrates typical insecure string comparison stops testing soon character n't match example comparing abcde abxde return 3 loop iterations function insecurecompare stra string strb string length integer boolean end function comparison following version runs constant-time testing characters using bitwise operations test without conditional jumps function securecompare stra string strb string length integer boolean end function timing attacks easier mount adversary knows internals hardware implementation even cryptographic system use since cryptographic security never depend obscurity either see security obscurity specifically shannon maxim kerckhoffs principle resistance timing attacks either nothing else exemplar purchased reverse engineered timing attacks side-channel attacks may also useful identifying possibly reverse-engineering cryptographic algorithm used device
|
Computer security
|
joint services publication 440 joint services publication 440 jsp 440 name british 2001 ministry defence 2,400-page restricted security manual detailing requirements units regards areas security physical electronic interpreted media instructions avoiding leaks due hackers journalists foreign spies however small part document publication posted wikileaks 3 october 2009
|
Computer security
|
input/output completion port input/output completion port iocp api performing multiple simultaneous asynchronous input/output operations windows nt versions 3.5 later aix solaris 10 later input/output completion port object created associated number sockets file handles i/o services requested object completion indicated message queued i/o completion port process requesting i/o services notified completion i/o services instead checks i/o completion port message queue determine status i/o requests i/o completion port manages multiple threads concurrency
|
Operating systems
|
marshall carter marshall sylvester carter september 16 1909 – february 18 1993 lieutenant general united states army 1965 1969 served director national security agency carter born september 16 1909 fort monroe virginia son future brigadier general clifton c. carter graduated united states military academy 1931 took m.s degree massachusetts institute technology 1936 carter served aide general george c. marshall marshall time chief staff united states army secretary state secretary defense carter lieutenant general served deputy director central intelligence april 3 1962 april 28 1965 1965 1969 served director national security agency upon retirement military served president george c. marshall research foundation retiring position 1985 carter inducted military intelligence hall fame portrayed ed lauter film thirteen days 2000 based events occurring cuban missile crisis carter buried arlington national cemetery wife preot nichols carter 1912–1997
|
Computer security
|
literatura latino-americana e caribe em ciências da saúde literatura latino-americana e caribe em ciências da saúde literature health sciences latin america caribbean portuguese language acronym lilacs on-line bibliographic database medicine health sciences maintained latin american caribbean center health sciences information also known bireme located são paulo brazil similar medline developed united states national library medicine contains bibliographic references papers published set scientific medical journals region covered medline
|
Databases
|
robologix robologix robotics simulator uses physics engine emulate robotics applications advantages using robotics simulation tools robologix save time design robotics applications also increase level safety associated robotic equipment since various scenarios tried tested system activated robologix provides platform teach test run debug programs written using five-axis industrial robot range applications functions applications include pick-and-place palletizing welding painting robologix developed colin simpson john bud skinner primarily intended educational resource used high schools colleges universities provide laboratory simulation industrial robots institutions george brown college use robologix part online robotics distance education program simulation software allows verification robot reaching ability travel ranges collisions type simulation software provides increased level reliability planning process program development well reducing overall completion/commissioning time ability preview behavior robotic system virtual world allows variety mechanisms devices configurations controllers tried tested applied real world system robologix capacity real-time simulation motion industrial robot using geometric modeling kinematics modeling robologix enables programmers write robot programs use sensors video cameras used obtaining desired position robot end effector addition teach pendant control panel included simulator allows user command robot pick tracked object return home location jogged commands pre-programmed positions robologix control panel consists robot control functions well environment control functions conveyor system controls on-off hard-wired control etc control panel allows user command robot pick tracked object return home location jogged commands pre-programmed positions robotic systems general angular position movements commonly used large course motion linear position movements often used smaller fine increments several command instructions control panel reset home setup zero used automatically set robot specific position calibration realignment robologix provides 12 viewpoints camera angles given robot work envelope viewpoints accessed twelve cam keys allow viewing variety angles perspectives using camera viewpoints user move around 3d animated environment much way would real-world one camera views robot end effector allows real-time visualization positioning end effector gripper approaches workpiece like robot programming languages robologix programs consist data objects program flow data objects reside registers program flow represents list instructions instruction set used program robot robologix program language type scripting language used control software application programming languages generally designed building data structures algorithms scratch scripting languages intended connecting gluing components instructions together consequently robologix instruction set streamlined list program commands used simplify programming process provide rapid application development robologix instruction set contains 16 commands usually written program line-by-line basis commands used instruct robot perform tasks moving specific location picking object executing subroutine waiting etc one popular commands instruction set instruction compares numerical values located two registers register value greater less greater than/equal less than/equal equal equal another register execute next line program condition true command often used jmp lbl instruction control program execution instruction set information stored registers data locations capable holding variable numeric values two main types registers used robologix position registers variable registers position registers contain linear angular data point coordinates include axis joint information a1 a2 a3 etc x z linear cartesian coordinates also 32 variable registers used holding instruction set data position comparisons time-delay information addition position registers variable registers robot software programs also palletizing registers used manage position stack point palletizing applications palletizing one popular applications robots accomplished combining series commands palletizing routine robologix palletizing routine consists five program instructions lines first instruction palletize instruction followed linear motion instruction move stack point stack point top-center workpiece group stack points forms stacking pattern shown adjacent image first stack point stacking pattern located 1,1,1 row column layer incremented time palletizing routine executed
|
Programming language topics
|
toonimo toonimo web-based solution offers on-site user assistance via online walkthroughs toonimo cloud-based digital walkthrough platform helps guide users website funnels toonimo works overlaying human voice audio graphical coachmarks web pages guide orient web users features include analytics dashboard a/b testing functionality personalization suite company serves financial insurance healthcare telecommunication education travel hospitality industries b2b b2b2c situations toonimo founded 2013 dan kotlicki ceo headquarters 1216 broadway new york city ny additional office located tel aviv israel july 14 2014 toonimo announced raised 2.5 million funding continue r ramp marketing sales efforts additional 1 million raised venture investment december 20 2014 toonimo backed lightspeed venture partners real life innovations several private investors
|
Web technology
|
android runtime android runtime art application runtime environment used android operating system replacing dalvik process virtual machine originally used android art performs translation application bytecode native instructions later executed device runtime environment android 2.2 froyo brought trace-based just-in-time jit compilation dalvik optimizing execution applications continually profiling applications time run dynamically compiling frequently executed short segments bytecode native machine code dalvik interprets rest application bytecode native execution short bytecode segments called traces provides significant performance improvements unlike dalvik art introduces use ahead-of-time aot compilation compiling entire applications native machine code upon installation eliminating dalvik interpretation trace-based jit compilation art improves overall execution efficiency reduces power consumption results improved battery autonomy mobile devices time art brings faster execution applications improved memory allocation garbage collection gc mechanisms new applications debugging features accurate high-level profiling applications maintain backward compatibility art uses input bytecode dalvik supplied standard .dex files part apk files .odex files replaced executable linkable format elf executables application compiled using art on-device utility run solely compiled elf executable result art eliminates various application execution overheads associated dalvik interpretation trace-based jit compilation downside art requires additional time compilation application installed applications take slightly larger amounts secondary storage usually flash memory store compiled code android 4.4 kitkat brought technology preview art including alternative runtime environment keeping dalvik default virtual machine subsequent major android release android 5.0 lollipop dalvik entirely replaced art android 7.0 nougat introduced jit compiler code profiling art lets constantly improve performance android apps run jit compiler complements art current ahead time compiler helps improve runtime performance
|
Operating systems
|
internet explorer 6 microsoft internet explorer 6 ie6 sixth major revision internet explorer web browser developed microsoft windows operating systems released august 27 2001 shortly completion windows xp default browser shipped windows xp windows server 2003 also made available windows nt 4.0 windows 98 windows 2000 windows ie6 sp1 last version internet explorer available latter four windows versions ie6 sp2+ ie7 included ie6 sp2+ available ie7 windows xp sp2+ despite dominating market share attaining peak 80 mid-2004 version internet explorer widely criticized security issues lack support modern web standards making frequent appearances worst tech products time lists pc world labeling least secure software planet 2004 mozilla finalised firefox rival ie6 became highly popular acclaimed security add-ons speed modern features tabbed browsing microsoft planned fix issues internet explorer 7 june–august 2005 delayed october 2006 release 5 years ie6 debuted substantial percentage web audience still used outdated browser especially china campaigns established late-2000s encourage users upgrade newer versions internet explorer switch different browsers websites dropped support ie6 entirely notable google dropping support services march 2010 according microsoft modern.ie website 3.1 users china less 1 countries using ie6 internet explorer 6 last version called microsoft internet explorer rebranded windows internet explorer internet explorer 7 onward ie6 released included number enhancements predecessor internet explorer 5 layout engine trident required many programs including microsoft encarta ie6 improved support cascading style sheets adding number properties previously implemented fixing bugs internet explorer box model bug windows xp ie6 introduced redesigned interface based operating system default theme luna addition ie6 added dhtml enhancements content restricted inline frames partial support dom level 1 smil 2.0 msxml engine also updated version 3.0 new features included new version internet explorer administration kit ieak introduced iexpress utility create self-extracting inf-based installation packages media bar windows messenger integration fault collection automatic image resizing p3p meanwhile 2002 gopher protocol disabled ie6 widely used web browser tenure surpassing internet explorer 5.x peak 2002 2003 ie6 attained total market share nearly 90 versions ie combined reaching 95 little change ie market share several years mozilla firefox released gradually began gain popularity microsoft subsequently resumed development internet explorer released internet explorer 7 reducing number ie6 users may 7 2003 microsoft online chat brian countryman internet explorer program manager declared internet explorer would cease distributed separately windows ie6 would last standalone version would however continued part evolution windows updates coming bundled windows upgrades thus internet explorer windows would kept sync however one release fashion ie6 sp2 windows xp sp2 august 2004 microsoft changed plan released internet explorer 7 windows xp sp2 windows server 2003 sp1 late 2006 microsoft internet explorer 6 last version internet explorer microsoft title later versions changed branding windows internet explorer reaction findings anti-competitive tying internet explorer windows raised united states v. microsoft european union microsoft competition case march 4 2011 microsoft urged web users stop using ie6 favor newer versions internet explorer launched website called ie6 countdown would show much percentage world uses ie6 aim get people upgrade security advisory site secunia reported 24 unpatched vulnerabilities internet explorer 6 february 9 2010 vulnerabilities include several moderately critical ratings amount 17 total 144 security risks listed website february 11 2010 june 23 2006 secunia counted 20 unpatched security flaws internet explorer 6 many older browser even individual criticality-level although flaws affect internet explorer running certain versions windows running conjunction certain applications june 23 2004 attacker used two previously undiscovered security holes internet explorer insert spam-sending software unknown number end-user computers malware became known download.ject caused users infect computers back door key logger merely viewing web page infected sites included several financial sites probably biggest generic security failing internet explorer web browsers fact runs level access logged user rather adopting principle least user access consequently malware executing internet explorer process via security vulnerability e.g download.ject example level access user something particular relevance user administrator tools dropmyrights able address issue restricting security token internet explorer process limited user however added level security installed available default offer simple way elevate privileges ad hoc required example access microsoft update art manion representative united states computer emergency readiness team us-cert noted vulnerability report design internet explorer 6 service pack 1 made difficult secure stated manion later clarified concerns addressed 2004 release windows xp service pack 2 browsers begun suffer vulnerabilities identified cert report response belief internet explorer frequency exploitation due part ubiquity since market dominance made obvious target david wheeler argues full story notes apache http server much larger market share microsoft iis yet apache traditionally fewer security vulnerabilities time result issues security experts including bruce schneier 2004 recommended users stop using internet explorer normal browsing switch different browser instead several notable technology columnists suggested idea including wall street journal walt mossberg eweek steven vaughan-nichols july 6 2004 us-cert released exploit report last seven workarounds use different browser especially visiting untrusted sites internet explorer 6 widely used web browser tenure surpassing internet explorer 5.x attaining peak percentage usage share 2002 2003 high 80s together versions 95 slowly declined 2007 lost half market share internet explorer 7 mozilla firefox late 2006 2008 ie6 remained popular successor business use year ie7 came 2008 dailytech article noted survey found 55.2 companies still use ie 6 december 2007 ie 7 23.4 percent adoption rate net applications estimated ie6 market share almost 39 september 2008 according source ie7 users migrate faster ie8 users predecessor ie6 leading ie6 becoming widely used browser summer fall 2009 eight years introduction february 2010 estimates ie6 global market share ranged 10-20 nonetheless ie6 continued maintain plurality even majority presence browser market certain countries notably china south korea google apps youtube dropped support ie6 march 2010 followed facebook chat september january 3 2012 microsoft announced usage ie6 united states dropped 1 august 2012 ie6 still popular ie web browser china also second used browser overall total market share 22.41 behind chinese-made 360 secure browser 26.96 july 2013 net applications reported global market share ie6 amongst internet explorer browsers 10.9 august 2015 ie6 used 1 users countries exception china 3.1 december 2015 ie6 used 1 users countries data available including china south korea common criticism internet explorer speed fixes released discovery security problems microsoft attributes perceived delays rigorous testing posting internet explorer team blog august 17 2004 explained minimum 234 distinct releases internet explorer microsoft supports covering two dozen languages several different revisions operating system browser level language every combination tested patch released may 2006 pc world rated internet explorer 6 eighth worst tech product time certain degree complacency alleged microsoft ie6 near 90 browser market motive innovation strongly present resulting 5 year time ie6 introduction replacement ie7 contributing factor rapid rise free software alternative mozilla firefox unlike modern browsers ie6 fully properly support css version 2 made difficult web developers ensure compatibility browser without degrading experience users advanced browsers developers often resorted strategies css hacks conditional comments forms browser sniffing make websites work ie6 additionally ie6 lacks support alpha transparency png images replacing transparent pixels solid colour background grey unless defined png bkgd chunk workaround way microsoft proprietary alphaimageloader complicated wholly comparable function internet explorer 6 also criticized due instability example following code website would cause program crash ie6 style position relative /style table input /table script x open /script user could crash browser single line code address bar causing pointer overflow ms-its f0 several campaigns later aimed ridding internet explorer 6 browser market increasing lack compatibility modern web standards popular websites began removing support ie6 2010 including youtube parent company google however large company support teams employers forcing staff use ie6 compatibility reasons slowed upgrades microsoft eventually began campaign encourage users stop using ie6 though stating would support ie6 windows xp sp3 including embedded versions support removed however january 12 2016 new microsoft lifecycle support policy internet explorer went effect ie6 support windows versions ended 14 years original release making january 2016 security update multiple versions xp embedded last microsoft publicly issued ie6 internet explorer uses zone-based security framework means sites grouped based upon certain conditions ie allows restriction broad areas functionality also allows specific functions restricted administration internet explorer accomplished internet properties control panel utility also administers internet explorer framework implemented applications patches updates browser released periodically made available windows update web site windows xp service pack 2 adds several important security features internet explorer including popup blocker additional security activex controls activex support remains internet explorer although access local machine zone denied default since service pack 2 however activex control runs authorized user gain privileges user instead granted limited privileges java javascript later solved windows vista version ie 7 supported running browser low-permission mode making malware unable run unless expressly granted permission user internet explorer 6 dropped compatibility mode allowed internet explorer 4 run side side 5.x instead ie6 introduced quirks mode causes emulate many behaviors ie 5.5 rather activated user quirks mode automatically silently activated viewing web pages contain old invalid doctype feature later added major browsers maximize compatibility old poorly-coded web pages internet explorer 6.0 supports windows nt 4.0 service pack 6a windows 98 windows windows 2000 windows xp windows server 2003 service pack 1 update supports versions security version 1 available part windows xp service pack 2 windows server 2003 service pack 1 later service packs versions versions windows xp include internet explorer 7 higher ie6 requires least
|
Operating systems
|
hp neoview hp neoview data warehouse business intelligence computer server line based hewlett packard nonstop line acted database server providing nonstop os nonstop sql lacked transaction processing functionality original nonstop systems line retired longer marketed january 24 2011
|
Computer architecture
|
pretty good privacy pretty good privacy pgp encryption program provides cryptographic privacy authentication data communication pgp used signing encrypting decrypting texts e-mails files directories whole disk partitions increase security e-mail communications phil zimmermann developed pgp 1991 pgp similar software follow openpgp standard nowiki rfc 4880 /nowiki encrypting decrypting data pgp encryption uses serial combination hashing data compression symmetric-key cryptography finally public-key cryptography step uses one several supported algorithms public key bound username e-mail address first version system generally known web trust contrast x.509 system uses hierarchical approach based certificate authority added pgp implementations later current versions pgp encryption include options automated key management server public key fingerprint shorter version public key fingerprint someone get right corresponding public key fingerprint like c3a6 5e46 7b54 77df 3c4c 9790 4d22 b3ca 5b32 ff66 printed business card pgp evolves versions support newer features algorithms able create encrypted messages older pgp systems decrypt even valid private key therefore essential partners pgp communication understand capabilities least agree pgp settings pgp used send messages confidentially pgp uses hybrid cryptosystem combining symmetric-key encryption public-key encryption message encrypted using symmetric encryption algorithm requires symmetric key generated sender symmetric key used also called session key message session key sent receiver session key must sent receiver know decrypt message protect transmission encrypted receiver public key private key belonging receiver decrypt session key use symmetrically decrypt message pgp supports message authentication integrity checking latter used detect whether message altered since completed message integrity property former determine whether actually sent person entity claimed sender digital signature content encrypted changes message result failure decryption appropriate key sender uses pgp create digital signature message either rsa dsa algorithms pgp computes hash also called message digest plaintext creates digital signature hash using sender private key encrypting messages verifying signatures critical public key used send messages someone entity actually 'belong intended recipient simply downloading public key somewhere reliable assurance association deliberate accidental impersonation possible first version pgp always included provisions distributing users public keys 'identity certification also constructed cryptographically tampering accidental garble readily detectable however merely making certificate impossible modify without detected insufficient prevent corruption certificate created users must also ensure means public key certificate actually belong person entity claiming given public key specifically information binding user name key may digitally signed third party user attest association someone actually user name key several levels confidence included signatures although many programs read write information include level certification calculating whether trust key web trust protocol first described phil zimmermann 1992 manual pgp version 2.0 web trust mechanism advantages centrally managed public key infrastructure scheme used s/mime universally used users willing accept certificates check validity manually simply accept satisfactory solution found underlying problem recent openpgp specification trust signatures used support creation certificate authorities trust signature indicates key belongs claimed owner owner key trustworthy sign keys one level level 0 signature comparable web trust signature since validity key certified level 1 signature similar trust one certificate authority key signed level 1 able issue unlimited number level 0 signatures level 2 signature highly analogous trust assumption users must rely whenever use default certificate authority list like included web browsers allows owner key make keys certificate authorities pgp versions always included way cancel 'revoke identity certificates lost compromised private key require communication security retained user less equivalent certificate revocation lists centralised pki schemes recent pgp versions also supported certificate expiration dates problem correctly identifying public key belonging particular user unique pgp public key/private key cryptosystems problem even slightly different guises fully satisfactory solution known pgp original scheme least leaves decision whether use endorsement/vetting system user pki schemes requiring instead every certificate attested central certificate authority accepted correct best publicly available information known method allow person group break pgp encryption cryptographic computational means indeed 1995 cryptographer bruce schneier characterized early version closest 're likely get military-grade encryption early versions pgp found theoretical vulnerabilities current versions recommended addition protecting data transit network pgp encryption also used protect data long-term data storage disk files long-term storage options also known data rest i.e data stored transit cryptographic security pgp encryption depends assumption algorithms used unbreakable direct cryptanalysis current equipment techniques original version rsa algorithm used encrypt session keys rsa security depends upon one-way function nature mathematical integer factoring similarly symmetric key algorithm used pgp version 2 idea might point future found previously undetected cryptanalytic flaws specific instances current pgp idea insecurities exist publicly known current versions pgp added additional encryption algorithms cryptographic vulnerability varies algorithm used however none algorithms current use publicly known cryptanalytic weaknesses new versions pgp released periodically vulnerabilities fixed developers come light agency wanting read pgp messages would probably use easier means standard cryptanalysis e.g rubber-hose cryptanalysis black-bag cryptanalysis e.g installing form trojan horse keystroke logging software/hardware target computer capture encrypted keyrings passwords fbi already used attack pgp investigations however vulnerabilities apply pgp conventional encryption software 2003 incident involving seized psion pdas belonging members red brigade indicated neither italian police fbi able decrypt pgp-encrypted files stored second incident december 2006 see boucher involving us customs agents seized laptop pc allegedly contained child pornography indicates us government agencies find nearly impossible access pgp-encrypted files additionally magistrate judge ruling case november 2007 stated forcing suspect reveal pgp passphrase would violate fifth amendment rights i.e suspect constitutional right incriminate fifth amendment issue opened government appealed case federal district judge ordered defendant provide key evidence suggests 2007 british police investigators unable break pgp instead resorted using ripa legislation demand passwords/keys november 2009 british citizen convicted ripa legislation jailed nine months refusing provide police investigators encryption keys pgp-encrypted files pgp cryptosystem criticized complexity standard implementation low usability user interface including recognized figures cryptography research standard developed 90 uses ineffective serialization format storage keys encrypted data resulted signature-spamming attacks public keys prominent developers gnu privacy guard backwards compatibility openpgp standard results usage relatively weak default choice cryptographic primitives cast5 cipher cfb mode s2k password hashing standard also criticized leaking metadata usage long-term keys lack forward secrecy popular end-user implementations suffered various signature-striping cipher downgrade metadata leakage vulnerabilities attributed complexity standard phil zimmermann created first version pgp encryption 1991 name pretty good privacy inspired name grocery store ralph pretty good grocery featured radio host garrison keillor fictional town lake wobegon first version included symmetric-key algorithm zimmermann designed named bassomatic saturday night live sketch zimmermann long-time anti-nuclear activist created pgp encryption similarly inclined people might securely use bbss securely store messages files license required non-commercial use even nominal charge complete source code included copies posting june 5 2001 entitled pgp marks 10th anniversary zimmermann describes circumstances surrounding release pgp pgp found way onto internet rapidly acquired considerable following around world users supporters included dissidents totalitarian countries affecting letters zimmermann published included testimony us congress civil libertarians parts world see zimmermann published testimony various hearings 'free communications activists called cypherpunks provided publicity distribution decades later cryptoparty activists much via twitter shortly release pgp encryption found way outside united states february 1993 zimmermann became formal target criminal investigation us government munitions export without license cryptosystems using keys larger 40 bits considered munitions within definition us export regulations pgp never used keys smaller 128 bits qualified time penalties violation found guilty substantial several years investigation zimmermann closed without filing criminal charges anyone else zimmermann challenged regulations imaginative way published entire source code pgp hardback book via mit press distributed sold widely anybody wishing build copy pgp could cut covers separate pages scan using ocr program conceivably enter type-in program ocr software available creating set source code text files one could build application using freely available gnu compiler collection pgp would thus available anywhere world claimed principle simple export munitions —guns bombs planes software—was remains restricted export books protected first amendment question never tested court respect pgp cases addressing encryption software however two federal appeals courts established rule cryptographic software source code speech protected first amendment ninth circuit court appeals bernstein case sixth circuit court appeals junger case us export regulations regarding cryptography remain force liberalized substantially throughout late 1990s since 2000 compliance regulations also much easier pgp encryption longer meets definition non-exportable weapon exported internationally except seven specific countries list named groups individuals substantially us trade prohibited various us export controls turmoil zimmermann team worked new version pgp encryption called pgp 3 new version considerable security improvements including new certificate structure fixed small security flaws pgp 2.x certificates well permitting certificate include separate keys signing encryption furthermore experience patent export problems led eschew patents entirely pgp 3 introduced use cast-128 a.k.a cast5 symmetric key algorithm dsa elgamal asymmetric key algorithms unencumbered patents federal criminal investigation ended 1996 zimmermann team started company produce new versions pgp encryption merged viacrypt zimmermann sold commercial rights licensed rsa directly rsadsi changed name pgp incorporated newly combined viacrypt/pgp team started work new versions pgp encryption based pgp 3 system unlike pgp 2 exclusively command line program pgp 3 designed start software library allowing users work command line inside gui environment original agreement viacrypt zimmermann team viacrypt would even-numbered versions zimmermann odd-numbered versions viacrypt thus created new version based pgp 2 called pgp 4 remove confusion could pgp 3 successor pgp 4 pgp 3 renamed released pgp 5 may 1997 december 1997 pgp inc. acquired network associates inc. nai zimmermann pgp team became nai employees nai first company legal export strategy publishing source code nai pgp team added disk encryption desktop firewalls intrusion detection ipsec vpns pgp family export regulation liberalizations 2000 longer required publishing source nai stopped releasing source code early 2001 zimmermann left nai served chief cryptographer hush communications provide openpgp-based e-mail service hushmail also worked veridis companies october 2001 nai announced pgp assets sale suspending development pgp encryption remaining asset kept pgp e-business server original pgp commandline version february 2002 nai canceled support pgp products exception renamed commandline product nai formerly mcafee intel security mcafee continued sell support product name mcafee e-business server 2013 august 2002 several ex-pgp team members formed new company pgp corporation bought pgp assets except command line version nai new company funded rob theis doll capital management dcm terry garnett venrock associates pgp corporation supports existing pgp users honors nai support contracts zimmermann serves special advisor consultant pgp corporation well continuing run consulting company 2003 pgp corporation created new server-based product called pgp universal mid-2004 pgp corporation shipped command line version called pgp command line integrates pgp encryption platform applications 2005 pgp corporation made first acquisition—the german software company glück kanja technology ag pgp deutschland ag 2010 pgp corporation acquired hamburg-based certificate authority tc trustcenter parent company chosensecurity form pgp trustcenter division since 2002 purchase nai pgp assets pgp corporation offered worldwide pgp technical support offices draper utah offenbach germany tokyo japan april 29 2010 symantec corp. announced would acquire pgp 300 million intent integrating enterprise security group acquisition finalized announced public june 7 2010 source code pgp desktop 10 available peer review also 2010 intel corporation acquired mcafee 2013 mcafee e-business server transferred software diversified services sells supports develops name sds e-business server enterprise townsend security currently offers commercial version pgp ibm ibm z mainframe platforms townsend security partnered network associates 2000 create compatible version pgp ibm platform townsend security ported pgp 2008 time ibm z mainframe version pgp relies free z/os encryption facility utilizes hardware acceleration software diversified services also offers commercial version pgp sds e-business server ibm z mainframe may 2018 bug named efail discovered certain implementations pgp could reveal plaintext contents emails encrypted 2003 originally used primarily encrypting contents e-mail messages attachments desktop client pgp products diversified since 2002 set encryption applications managed optional central policy server pgp encryption applications include e-mail attachments digital signatures laptop full disk encryption file folder security protection im sessions batch file transfer encryption protection files folders stored network servers recently encrypted signed http request/responses means client-side enigform server-side mod openpgp module also wordpress plugin available called wp-enigform-authentication takes advantage session management features enigform mod_openpgp pgp desktop 9.x family includes pgp desktop email pgp whole disk encryption pgp netshare additionally number desktop bundles also available depending application products feature desktop e-mail digital signatures im security whole disk encryption file folder security encrypted self-extracting archives secure shredding deleted files capabilities licensed different ways depending features required pgp universal server 2.x management console handles centralized deployment security policy policy enforcement key management reporting used automated e-mail encryption gateway manages pgp desktop 9.x clients addition local keyserver pgp universal server works pgp public keyserver—called pgp global directory—to find recipient keys capability delivering e-mail securely recipient key found via secure https browser session pgp desktop 9.x managed pgp universal server 2.x first released 2005 pgp encryption applications based new proxy-based architecture newer versions pgp software eliminate use e-mail plug-ins insulate user changes desktop applications desktop server operations based security policies operate automated fashion pgp universal server automates creation management expiration keys sharing keys among pgp encryption applications symantec pgp platform undergone rename pgp desktop known symantec encryption desktop pgp universal server known symantec encryption management server current shipping versions symantec encryption desktop 10.3.0 windows mac os platforms symantec encryption server 3.3.2 also available pgp command line enables command line-based encryption signing information storage transfer backup well pgp support package blackberry enables rim blackberry devices enjoy sender-to-recipient messaging encryption new versions pgp applications use openpgp s/mime allowing communications user nist specified standard inside pgp inc. still concern patent issues rsadsi challenging continuation viacrypt rsa license newly merged firm company adopted informal internal standard called unencumbered pgp would use algorithm licensing difficulties pgp encryption importance worldwide many wanted write software would interoperate pgp 5 zimmermann became convinced open standard pgp encryption critical cryptographic community whole july 1997 pgp inc. proposed ietf standard called openpgp gave ietf permission use name openpgp describe new standard well program supported standard ietf accepted proposal started openpgp working group openpgp internet standards track active development many e-mail clients provide openpgp-compliant email security described rfc 3156 current specification rfc 4880 november 2007 successor rfc 2440 rfc 4880 specifies suite required algorithms consisting elgamal encryption dsa triple des sha-1 addition algorithms standard recommends rsa described pkcs 1 v1.5 encryption signing well aes-128 cast-128 idea beyond many algorithms supported standard extended support camellia cipher rfc 5581 2009 signing key exchange based elliptic curve cryptography ecc i.e ecdsa ecdh rfc 6637 2012 support ecc encryption added proposed rfc 4880bis 2014 free software foundation developed openpgp-compliant program called gnu privacy guard abbreviated gnupg gpg gnupg freely available together source code gnu general public license gpl maintained separately several graphical user interfaces guis interact gnupg library encryption decryption signing functions see kgpg seahorse macgpg several vendors also developed openpgp-compliant software development open source openpgp-compliant library openpgp.js written javascript allowed web-based applications use pgp encryption web browser several ios android openpgp-compliant applications ipgmail ios openkeychain android enable key generation encryption/decryption email files apple ios google android operating systems openpgp encryption ensure secure delivery files messages well provide verification created sent message using process called digital signing open source office suite libreoffice implemented document signing openpgp version 5.4.0 linux using openpgp communication requires participation sender recipient openpgp also used secure sensitive files 're stored vulnerable places like mobile devices cloud advancement cryptography parts pgp criticized dated october 2017 roca vulnerability announced affects rsa keys generated buggy infineon firmware used yubikey 4 tokens often used pgp many published pgp keys found susceptible yubico offers free replacement affected tokens
|
Computer security
|
interactive terminology europe interactive terminology europe iate interinstitutional terminology database european union project launched 1999 objective creating web-based interface eu terminology resources make information easily available ensure standardisation throughout eu institutions used eu institutions agencies since summer 2004 public user interface released testing early 2007 officially opened 28 june 2007 new version released 7 november 2018 following full rebuild system state-of-the-art technologies latest software development standards best practices usability accessibility new look feel iate incorporated existing terminology databases eu ’ translation services one interinstitutional database containing approximately 1.4 million multilingual entries following legacy databases imported iate iate intended contain single entry per concept actually contains multiple entries many concepts entries consolidated number entries fallen approximately 1.4 million approximately 1.2 million despite addition many new entries new previously unrecorded concepts project partners european commission european parliament council european union european court justice european court auditors european economic social committee european committee regions european central bank european investment bank translation centre bodies european union iate web site administered eu translation centre luxembourg behalf project partners subject 'domains based eurovoc entire iate glossary database downloaded free zipped format multilanguage glossaries generated using free tool
|
Computational linguistics
|
android gingerbread android gingerbread seventh version android codename android mobile operating system developed google released december 2010 versions longer supported gingerbread release introduced support near field communication nfc —used mobile payment solutions—and session initiation protocol sip —used voip internet telephony gingerbread user interface refined many ways making easier master faster use power-efficient simplified color scheme black background gave vividness contrast notification bar menus user interface components improvements menus settings resulted easier navigation system control nexus smartphone released december 2010 first phone google nexus line ran gingerbread also first one line built-in nfc functionality statistics issued google indicate 0.3 android devices accessing google play run gingerbread new features introduced gingerbread include following
|
Operating systems
|
attack model cryptanalysis attack models attack types classification cryptographic attacks specifying kind access cryptanalyst system attack attempting break encrypted message also known ciphertext generated system greater access cryptanalyst system useful information get utilize breaking cypher cryptography sending party uses cipher encrypt transform secret plaintext ciphertext sent insecure communication channel receiving party receiving party uses inverse cipher decrypt ciphertext obtain plaintext secret knowledge required apply inverse cipher ciphertext secret knowledge usually short number string called key cryptographic attack third party cryptanalyst analyzes ciphertext try break cipher read plaintext obtain key future enciphered messages read usually assumed encryption decryption algorithms public knowledge available cryptographer case modern ciphers published openly assumption called kerckhoffs principle common attack models different attack models used cryptographic primitives generally kind security systems examples attack models
|
Computer security
|
run-length limited run-length limited rll coding line coding technique used send arbitrary data communications channel bandwidth limits rll codes defined four main parameters n k first two n refer rate code remaining two specify minimal maximal k number zeroes consecutive ones used telecommunication storage systems move medium past fixed recording head specifically rll bounds length stretches runs repeated bits signal change runs long clock recovery difficult short high frequencies might attenuated communications channel modulating data rll reduces timing uncertainty decoding stored data would lead possible erroneous insertion removal bits reading data back mechanism ensures boundaries bits always accurately found preventing bit slip efficiently using media reliably store maximal amount data given space early disk drives used simple encoding schemes rll 0,1 fm code followed rll 1,3 mfm code widely used hard disk drives mid-1980s still used digital optical discs cd dvd md hi-md blu-ray higher density rll 2,7 rll 1,7 codes became de facto industry standard hard disks early 1990s hard disk drive information represented changes direction magnetic field disk magnetic media playback output proportional density flux transition computer information represented voltage wire voltage wire relation defined ground level would binary zero positive voltage wire relation ground represents binary one magnetic media hand always carries magnetic flux either north pole south pole order convert magnetic fields binary data encoding method must used translate two one simplest practical codes modified non-return-to-zero-inverted nrzi simply encodes 1 magnetic polarity transition also known flux reversal zero transition disk spinning constant rate bit given equal time period data window magnetic signal represents bit flux reversal occurs start window note older hard disks used one fixed length time data window whole disk modern disks complicated see zoned bit recording method quite simple playback output proportional density ones long run zeros means playback output simple example consider binary pattern 101 data window 1 ns one nanosecond one billionth second stored disk change followed change another change preceding magnetic polarity already positive resulting pattern might look like −−+ value 255 binary ones would written −+−+−+−+ +−+−+−+− zero byte would written ++++++++ −−−−−−−− 512 byte sector zeros would written 4,096 sequential bits polarity since disk drive physical piece hardware rotational speed drive change slightly due change motor speed thermal expansion disk platter physical media floppy disk also become deformed causing larger timing errors timing circuit controller may small variations speed problem long string zeros way disk drive controller know exact position read head thus way know exactly many zeros speed variation even 0.1 precise practical floppy drive could result four bits added removed 4,096 bit data stream without form synchronization error correction data would become completely unusable problem due limits magnetic media possible write many polarity changes certain amount space upper limit many 1 also written sequentially depends linear velocity head gap prevent problem data coded way long repetitions single binary value occur limiting number zeros written consecutively makes possible drive controller stay sync limiting number 1 written row overall frequency polarity changes reduced allowing drive store data amount space resulting either smaller package amount data storage size package codes used record magnetic disks limited length transition-free runs therefore characterized rll codes earliest simplest variants given specific names modified frequency modulation mfm name rll commonly used complex variants given specific names term technically applies first rll code used hard drives rll 2,7 developed ibm engineers first used commercially 1979 ibm 3370 dasd use 4300 series mainframe late 1980s pc hard disks began using rll proper i.e variants complex received proper names mfm rll codes found almost universal application optical disc recording practice since 1980 consumer electronics rlls like efm code rate=8/17 d=2 k=10 employed compact disc cd minidisc md efmplus code rate=8/16 d=2 k=10 used dvd parameters k minimum maximum allowed run-lengths coverage storage technologies references cited article useful generally run-length number bits signal remains unchanged run-length 3 bit 1 represents sequence '111 instance pattern magnetic polarizations disk might '+−−−−++−−−++++++ runs length 1 4 2 3 6 however run length limited coding terminology assumes nrzi encoding 1 bits indicate changes 0 bits indicate absence change sequence would expressed '11000101001000001 runs zero bits counted somewhat confusingly run length number zeros 0 3 1 2 5 preceding adjacent ones one less number bit times signal actually remains unchanged run length limited sequences characterized two parameters k stipulate minimum maximum zero-bit run length occur sequence rll codes generally specified k rll e.g 1,3 rll encoded format 1 bit indicates flux transition 0 indicates magnetic field disk change time interval generally term rll code used refer elaborate encodings original frequency modulation code also called differential manchester encoding seen simple rate-1/2 rll code added 1 bits referred clock bits example extending maximum run length 2 adjacent 0 bits data rate improved 4/5 original ibm group coded recording variant possible eleven 16 codes bit pattern codice_1 encoded prefixing complement codice_1 five cases would violate one rules codice_3 codice_4 code beginning 11 substituted codice_5 e ∨ example note meet definition 0,2 rll sufficient 5-bit code contain two consecutive zeros also necessary pair 5-bit codes combined sequentially contain two consecutive zeros must two zeros last one bit first code first one bit second code two arbitrarily chosen codes required rll code run length limits—0 2 case—apply overall modulated bitstream components represent discrete sequences plain data bits rule must hold arbitrary pair codes without exception input data may arbitrary sequence bits ibm gcr code meets condition since maximum run length zeros beginning 5-bit code one likewise maximum run length end code one making total run length two junction adjacent codes example maximum run length occurring codes seen example given code data 0010 ends zero code next data 1101 begins zero forming run two zeros junction two 5-bit codes modified frequency modulation begins get interesting special properties allow bits written magnetic medium twice density arbitrary bit stream limit close time flux transitions reading equipment detect constrains closely bits recorded medium worst case arbitrary bit stream two consecutive 1 produces two consecutive flux transitions time bits must spaced far enough apart would sufficient time flux transitions reader detect code imposes constraint =1 i.e minimum one 0 two 1 means worst case flux transitions two bit times apart bits twice close together arbitrary bit stream without exceeding reader capabilities doubled recording density compensates 1/2 coding rate code takes two bits represent one bit real information makes equivalent rate-1 code x complement previous encoded bit also previous data bit except clock bits—that x bit 0 01 code—this fm table code gets name inserted clock bits 0 except two 0 data bits example 1,7 rll maps 2 bits data onto three bits disk encoding done two four bit groups encoding rules x becomes x x except x 0 0 becomes x x 0 0 0 encoding according table longest last table match must used exceptions handle situations applying earlier rules would lead violation code constraints example 2,7 rll rate- code mapping n bits data onto 2 n bits disk like mfm minimum run length 50 longer three bit times instead two bits written faster achieving 50 higher effective data density encoding done two three four bit groups western digital wd5010a wd5011a wd50c12 seagate st11r ibm encoded forms begin four end three zero bits giving maximum run length seven example also alternate 1,7 rll encoding sometimes used avoid dc bias helps sending signal long distance types recording media x complement previous encoded bit i.e 1 previous bit 0 0 previous bit 1 example hhh 1,13 code rate-2/3 code developed three ibm researchers hirt hassner heise use 16 mb/s irda vfir physical layer unlike magnetic encoding designed infrared transmitter 0 bit represents 1 bit represents 1 bits consume power transmit designed limit density 1 bits less 50 particular 1,13|5 rll code final 5 indicates additional constraint 5 consecutive 10 bit pairs first eight rows describe standard 1,7 -rll code additional six exceptions increase maximum run zeros 13 legal pattern 100 000 000 000 001 represents 10 11 10 11 followed 01 limit maximum average ones density longest run 1–0 pairs 000 101 010 101 000 code limits ones density average 25.8 example let us encode bit sequence 10110010 different encodings suppose magnetic tape contain 3,200 flux reversals per inch modified frequency modulation 1,3 rll encoding stores data bit two bits tape since guaranteed one 0 non flux reversal bit 1 flux reversal bits possible store 6,400 encoded bits per inch tape 3,200 data bits per inch 1,7 rll encoding also store 6,400 encoded bits per inch tape since takes 3 encoded bits store 2 data bits 4,267 data bits per inch 2,7 rll encoding takes 2 encoded bits store data bit since guaranteed two 0 bits 1 bits possible store 9,600 encoded bits per inch tape 4,800 data bits per inch flux reversal densities hard drives significantly greater improvements storage density seen using different encoding systems
|
Internet protocols
|
democratic national committee cyber attacks democratic national committee cyber attacks took place 2015 2016 computer hackers infiltrated democratic national committee dnc computer network leading data breach cybersecurity experts well u.s. government stated cyberespionage work russian intelligence agencies forensic evidence analyzed several cybersecurity firms crowdstrike fidelis mandiant fireeye strongly indicates two russian intelligence agencies infiltrated dnc computer systems american cybersecurity firm crowdstrike removed hacking programs revealed history encounters groups already named calling one cozy bear fancy bear names used media december 9 2016 cia told u.s. legislators u.s. intelligence community concluded russia conducted cyberattacks operations 2016 u.s. election assist donald trump winning presidency multiple u.s. intelligence agencies concluded specific individuals tied russian government provided wikileaks stolen emails dnc well stolen emails hillary clinton campaign chairman also target cyberattack intelligence organizations additionally concluded russia hacked republican national committee r.n.c well d.n.c. chose leak information obtained r.n.c cyber attacks successfully penetrated dnc computing system began 2015 attacks cozy bear began summer 2015 attacks fancy bear began april 2016 fancy bear group began activities compromised system became apparent groups presumed spying communications stealing opposition research donald trump well reading email chats finally identified crowdstrike may 2016 groups intruders successfully expelled dnc systems within hours detection attacks considered part group recent attacks targeting u.s. government departments several political organizations including 2016 campaign organizations july 22 2016 person entity going moniker guccifer 2.0 claimed wordpress-hosted blog acting alone hacking dnc also claimed send significant amounts stolen electronic dnc documents wikileaks wikileaks revealed source leaked emails however cybersecurity experts firms including crowdstrike fidelis cybersecurity mandiant secureworks threatconnect editor ars technica rejected claims guccifer 2.0 determined basis substantial evidence cyberattacks committed two russian state-sponsored groups cozy bear fancy bear according separate reports new york times washington post u.s. intelligence agencies concluded high confidence russian government behind theft emails documents dnc u.s. intelligence community concluded russia behind cyberattack intelligence officials told washington post reached conclusion passed emails wikileaks know whether russian officials directed leak number experts cybersecurity analysts believe guccifer 2.0 probably russian government disinformation cover story distract attention away dnc breach two russian intelligence agencies president obama russian president vladimir putin discussion computer security issues took place side segment then-ongoing g20 summit china september 2016 obama said russian hacking stopped warning putin joint statement october 7 2016 united states department homeland security office director national intelligence stated us intelligence community confident russian government directed breaches release obtained allegedly obtained material attempt … interfere us election process common among russian intelligence services groups used similar hacking tools strategies believed neither group aware although antithetical american computer intelligence methods fear undermining defeating intelligence operations common practice russian intelligence community since 2004 intrusion part several attacks attempting access information american political organizations including 2016 u.s. presidential campaigns cozy bear fancy bear known adversaries extensively engaged political economic espionage benefits russian federation government believed connected russian intelligence services also access resources demonstrate levels proficiency matching nation-state capabilities cozy bear past year infiltrated unclassified computer systems white house u.s. state department u.s. joint chiefs staff according crowdstrike targeted sectors include defense energy mining financial insurance legal manufacturing media think tanks pharmaceutical research technology industries well universities cozy bear observed attacks occurred western europe brazil china japan mexico new zealand south korea turkey central asia fancy bear operating since mid-2000s crowdstrike reported targeting included aerospace defense energy government media industries fancy bear intrusions occurred united states western europe brazil canada china republic georgia iran japan malaysia south korea targeted defense ministries military organizations parallel russian federation government interests may indicate affiliation main intelligence directorate gru russian military intelligence service specifically fancy bear linked intrusions german bundestag france ’ tv5 monde television station april 2015 secureworks cybersecurity firm headquartered united states concluded march 2015 may 2016 fancy bear target list included merely dnc tens thousands foes putin kremlin united states ukraine russia georgia syria handful republicans targeted however january 25 2018 dutch newspaper de volkskrant tv program nieuwsuur reported 2014 dutch intelligence agency general intelligence security service aivd successfully infiltrated computers cozy bear observed hacking head office dnc subsequently white house first alert national security agency cyber-intrusion cozy bear access dnc systems since summer 2015 fancy bear since april 2016 evidence collaboration knowledge presence within system rather two russian espionage groups compromised systems engaged separately theft identical credentials cozy bear employed sea daddy implant obfuscated powershell script backdoor launching malicious code various times various dnc systems fancy bear employed x agent malware enabled distant command execution transmissions files keylogging well x-tunnel malware dnc leaders became aware compromise april 2016 attacks broadly reflect russian government interest u.s. political system well political leaders policies tendencies proclivities assessing possible beneficial outcomes attacks also broadly reflect russian government interest strategies policies practices u.s. government also globally reflects foreign governments interest ascertaining information donald trump new entry u.s. political leadership roles contrast information likely garnered decades pertaining clintons dnc commissioned cybersecurity company crowdstrike defeat intrusions chief technology officer dmitri alperovitch also cybersecurity expert stated cybersecurity firms fidelis cybersecurity fireeye independently reviewed malware came conclusion crowdstrike—that expert russian hacking groups responsible breach november 2017 us authorities identified 6 russian individuals conducted hack beginning december 2016 russian government arrested sergei mikhailov high ranking government cyber-spy ruslan stoyanov private sector cyber-security expert georgy fomchenkov former government cyber-spy dmitry dokuchaev mikhailov associate charged aiding u.s. intelligence agencies new york times associated dnc hacking although dnc claimed personal financial donor information accessed guccifer 2.0 leaked claimed donor lists detailing dnc campaign contributions gawker smoking gun however information authenticated doubts remain guccifer 2.0 backstory june 2016 person person claimed hacker hacked dnc servers published stolen documents online guccifer 2.0 later also claimed leaked 20.000 emails wikileaks u.s. intelligence community tasked resources debating putin chose summer 2016 escalate active measures influencing u.s. politics director national intelligence james r. clapper said 2011–13 russian protests putin confidence viability politician damaged putin responded propaganda operation former cia officer patrick skinner explained goal spread uncertainty u.s congressman adam schiff ranking member house permanent select committee intelligence commented putin aims said u.s. intelligence agencies concerned russian propaganda speaking disinformation appeared hungary slovakia czech republic poland schiff said increase behavior u.s. schiff concluded russian propaganda operations would continue u.s. election december 9 2016 cia told u.s. legislators u.s. intelligence community concluded russia conducted operations 2016 u.s. election assist donald trump winning presidency multiple u.s intelligence agencies concluded people specific individuals tied russian government gave wikileaks hacked emails democratic national committee d.n.c additional sources john podesta campaign chairman hillary clinton intelligence organizations additionally concluded russia hacked republican national committee r.n.c well d.n.c.—and chose leak information obtained r.n.c cia said foreign intelligence agents russian operatives previously known u.s. cia officials told u.s senators quite clear russia intentions help trump trump released statement december 9 disregarded cia conclusions members u.s. senate intelligence committee traveled ukraine poland 2016 learned russian operations influence affairs u.s senator angus king told portland press herald tactics used russia 2016 u.s. election analogous used countries 30 november 2016 king joined letter seven members u.s. senate intelligence committee asked president obama publicize information intelligence community russia role u.s. election interview cnn senator king warned ignoring problem saying bipartisan issue representatives u.s. congress took action monitor national security united states advancing legislation monitor propaganda 30 november 2016 legislators approved measure within national defense authorization act ask u.s. state department act propaganda inter-agency panel legislation authorized funding 160 million two-year-period initiative developed bipartisan bill countering foreign propaganda disinformation act written u.s senators republican rob portman democrat chris murphy portman urged u.s. government action counter propaganda murphy said election apparent u.s. needed additional tactics fight russian propaganda u.s. senate intelligence committee member ron wyden said frustration covert russian propaganda bipartisan republican u.s senators stated planned hold hearings investigate russian influence 2016 u.s. elections went preference incoming republican president-elect donald trump downplayed potential russian meddling election u.s. senate armed services committee chairman john mccain u.s. senate intelligence committee chairman richard burr discussed plans collaboration investigations russian cyberwarfare election u.s. senate foreign relations committee chairman bob corker planned 2017 investigation senator lindsey graham indicated would conduct sweeping investigation 115th congress december 9 2016 president obama ordered entire united states intelligence community conduct investigation russia attempts influence 2016 u.s. election — provide report left office january 20 2017 lisa monaco u.s homeland security advisor chief counterterrorism advisor president announced study said intrusion foreign nation u.s. national election unprecedented event would necessitate investigation subsequent administrations executive branch intelligence analysis take account data last three presidential elections u.s evidence showed malicious cyberwarfare 2008 2016 u.s. elections
|
Computer security
|
javascript syntax syntax javascript set rules define correctly structured javascript program examples make use log function console object present browsers standard text output javascript standard library lacks official standard text output function given javascript mainly used client-side scripting within modern web browsers almost web browsers provide alert function alert also used commonly used brendan eich summarized ancestry syntax first paragraph javascript 1.1 specification follows javascript case sensitive common start name constructor capitalised letter name function variable lower-case letter example var a=5 console.log // 5 console.log // throws referenceerror defined spaces tabs newlines used outside string constants called whitespace unlike c whitespace javascript source directly impact semantics technique called automatic semicolon insertion asi statements well formed newline parsed considered complete semicolon inserted prior newline authorities advise supplying statement-terminating semicolons explicitly may lessen unintended effects automatic semicolon insertion two issues five tokens either begin statement extension complete statement five restricted productions line breaks allowed certain positions potentially yielding incorrect parsing five problematic tokens open parenthesis open bracket slash plus minus open parenthesis common immediately-invoked function expression pattern open bracket occurs sometimes others quite rare example given spec b c // treated // b c e .foo suggestion preceding statement terminated semicolon suggest instead use leading semicolons lines starting nowiki /nowiki line accidentally joined previous one known defensive semicolon particularly recommended code may otherwise become ambiguous rearranged example b c // treated // b c // e .foo initial semicolons also sometimes used start javascript libraries case appended another library omits trailing semicolon result ambiguity initial statement five restricted productions return throw break continue post-increment/decrement cases inserting semicolons fix problem makes parsed syntax clear making error easier detect return throw take optional value break continue take optional label cases advice keep value label line statement often shows return statement one might return large object literal might accidentally placed starting new line post-increment/decrement potential ambiguity pre-increment/decrement recommended simply keep line return b // returns undefined treated // return // b // written // return b comment syntax c++ many languages // short one-line comment /* long multi-line comment /* comments /* may nested */ syntax error */ variables standard javascript type attached value stored variable starting es6 version language finalised 2015 variables declared codice_1 block level variable codice_2 function level variable codice_3 immutable one however object assigned codice_3 changed properties es6 variables declared codice_2 statement identifier must start letter underscore dollar sign subsequent characters also digits 0-9 javascript case sensitive letters include characters z uppercase characters z lowercase starting javascript 1.5 iso 8859-1 unicode letters \uxxxx unicode escape sequences used identifiers certain javascript implementations sign used identifier contrary specifications supported newer implementations variables lexically scoped function level block level c depend order forward declaration necessary variable declared inside function point block inside function name resolve variable equivalent block scoping variables forward declared top function referred however variable value codice_6 initialized forward reference possible thus statement middle function equivalent declaration statement top function assignment statement point middle function – declaration hoisted assignment function statements whose effect declare variable type codice_7 assign value similar variable statements addition hoisting declaration also hoist assignment – entire statement appeared top containing function – thus forward reference also possible location function statement within enclosing function irrelevant sure understand var func function .. // hoisted function func .. // hoisted block scoping produced wrapping entire block function executing — known immediately-invoked function expression pattern declaring variable using codice_1 keyword variables declared outside function global variable declared higher scope accessed child functions javascript tries resolve identifier looks local function scope identifier found looks outer function declared local one along scope chain reaches global scope global variables reside still found javascript raise codice_9 exception assigning identifier javascript goes exactly process retrieve identifier except found global scope create variable property global object consequence variable never declared global assigned declaring variable keyword codice_2 global code i.e outside function body assigning never declared identifier adding property global object usually window also create new global variable note javascript strict mode forbids assignment undeclared variable avoids global namespace pollution also codice_3 declared without initialization examples variable declarations scope var x 0 // global variable function function f f console.log z // line raise referenceerror exception value z longer available let i=0 10 i++ console.log console.log // throws referenceerror defined const i=0 10 i++ console.log // throws typeerror assignment constant variable const pi // throws syntaxerror missing initializer const declaration javascript language provides six primitive data types primitive data types also provide set named values represent extents type boundaries named values described within appropriate sections value undefined assigned uninitialized variables also returned checking object properties exist boolean context undefined value considered false value note undefined considered genuine primitive type unless explicitly converted undefined value may behave unexpectedly comparison types evaluate false logical context var test // variable declared defined ... var testobj console.log test // test variable exists value ... console.log testobj.myprop // testobj exists property ... console.log undefined == null // unenforced type check displays true console.log undefined === null // enforce type check displays false note built-in language literal undefined thus foolproof way check whether variable undefined versions ecmascript 5 legal someone write robust approach compare using functions like wo n't work expected function isundefined x var u return x === u // like ... function isundefined x return x === void 0 // ... second one function isundefined x return typeof x === undefined // ... third one calling codice_12 raises unknown identifier whereas n't unlike undefined null often set indicate something declared defined empty boolean context value null considered false value javascript note null true primitive-type within javascript language note case single value performing checks enforce type checking null value equal false types surprisingly considered object console.log null == undefined // unenforced type check displays true console.log null === undefined // enforce type check displays false console.log typeof null === 'object // true numbers represented binary ieee-754 doubles provides accuracy nearly 16 significant digits floating point numbers always exactly represent real numbers including fractions becomes issue comparing formatting numbers example console.log 0.2 0.1 == 0.3 // displays true per ecmascript 6 specifications console.log 0.94 0.01 // displays 0.9299999999999999 result routine method used round numbers whenever formatted output numbers may specified notations 345 // integer although one numeric type javascript 34.5 // floating-point number 3.45e2 // another floating-point equivalent 345 0b1011 // binary integer equal 11 0o377 // octal integer equal 255 0xff // hexadecimal integer equal 255 digits represented ... extents +∞ −∞ nan number number type may obtained two program expressions infinity // positive infinity negative obtained -infinity instance nan // not-a-number value also returned failure ... infinity nan numbers typeof infinity // returns number typeof nan // returns number three special values correspond behave ieee-754 describes number constructor unary may used perform explicit numeric conversion var mystring 123.456 var mynumber1 number mystring var mynumber2 +mystring used constructor numeric wrapper object created though little use mynumericwrapper new number 123.456 however impossible use equality operators codice_13 codice_14 determine whether value nan console.log nan == nan // false console.log nan === nan // false console.log isnan nan // true string javascript sequence characters javascript strings created directly literals placing series characters double single quotes strings must written single line may include escaped newline characters \n javascript standard allows backquote character a.k.a grave accent backtick quote multiline literal strings supported certain browsers 2016 firefox chrome internet explorer 11. var greeting hello world var anothergreeting 'greetings people earth individual characters within string accessed using method provided preferred way accessing individual characters within string also works non-modern browsers var h greeting.charat 0 modern browsers individual characters within string accessed strings single character notation arrays var h greeting 0 however javascript strings immutable greeting 0 h // fails applying equality operator == two strings returns true strings contents means length containing sequence characters case significant alphabets thus var x world var compare1 hello +x == hello world // compare1 contains true var compare2 hello +x == hello world // compare2 contains ... quotes type nested unless escaped var x hello world said // fine var x hello world said // good var x hello world said // works escaping possible create string using constructor var greeting new string hello world objects method returning primitive string wrapped within var new string hello typeof // 'object typeof s.valueof // 'string equality two objects behave string primitives var s1 new string hello var s2 new string hello s1 == s2 // false two distinct objects s1.valueof == s2.valueof // true javascript provides boolean data type literals operator returns string primitive types used logical context empty string evaluate due automatic type coercion values complement previous list evaluate including strings object automatic type coercion equality comparison operators codice_13 codice_16 avoided using type checked comparison operators codice_14 codice_18 type conversion required javascript converts operands follows douglas crockford advocates terms truthy falsy describe values various types behave evaluated logical context especially regard edge cases binary logical operators returned boolean value early versions javascript return one operands instead left–operand returned evaluated case conjunction codice_19 case disjunction codice_20 otherwise right–operand returned automatic type coercion comparison operators may differ cases mixed boolean number-compatible operands including strings evaluated number objects evaluated string boolean operand compared numeric value may unexpected expression explicitly cast boolean primitive doubling logical negation operator using function using conditional operator codice_21 // automatic type coercion console.log true == 2 // false ... true → 1 == 2 ← 2 console.log false == 2 // false ... false → 0 == 2 ← 2 console.log true == 1 // true ... true → 1 === 1 ← 1 console.log false == 0 // true ... false → 0 === 0 ← 0 console.log true == 2 // false ... true → 1 == 2 ← 2 console.log false == 2 // false ... false → 0 == 2 ← 2 console.log true == 1 // true ... true → 1 === 1 ← 1 console.log false == 0 // true ... false → 0 === 0 ← 0 console.log false == // true ... false → 0 === 0 ← console.log false == nan // false ... false → 0 == nan console.log nan == nan // false ... nan equivalent anything including nan // type checked comparison conversion types values console.log true === 1 // false ... data types match // explicit type coercion console.log true === 2 // true ... data types values match console.log true === 0 // false ... data types match values differ console.log 1 true false // true ... ±0 nan “ falsy ” numbers console.log 0 true false // true ... empty string “ falsy ” console.log boolean // true ... objects “ truthy ” new operator used create object wrapper boolean primitive however operator return object wrapper returns objects evaluate method must used retrieve wrapped value explicit coercion boolean type mozilla recommends function without used preference boolean object var boolean b // boolean true var f boolean b.valueof // boolean false var n new boolean b // recommended n new boolean b.valueof // preferred 0 || -0 || || null || undefined || b.valueof || new boolean || else b typeof b === object b.tostring === false new ecmascript6 symbol unique immutable identifier example x=symbol 1 y=symbol 1 x==y // false arr= x arr x =1 arr =2 // x unique keys array arr arr x // displays 1 arr // displays 2 x=symbol 3 arr // displays symbol 1 symbol 1 arr x // undefined x=symbol 1 arr x // undefined symbol wrapper also provides access variable free iterator x= 1,2,3,4 // x array iterable ex=x symbol.iterator // provides iterator x exv=ex.next .value =undefined console.log exv // displays 1,2,3,4 javascript language provides handful native objects javascript native objects considered part javascript specification javascript environment notwithstanding set objects always available array javascript object prototyped array constructor specifically designed store data values indexed integer keys arrays unlike basic object type prototyped methods properties aid programmer routine tasks example join slice push arrays use zero-based indexing scheme value inserted empty array means push method occupies 0th index array var myarray // point variable myarray newly ... myarray.push hello world // fill next empty index case 0 console.log myarray 0 // equivalent console.log hello world arrays length property guaranteed always larger largest integer index used array automatically updated one creates property even larger index writing smaller number length property remove larger indices elements arrays may accessed using normal object property access notation myarray 1 // 2nd item myarray myarray 1 two equivalent possible use dot -notation strings alternative representations number myarray.1 // syntax error myarray 01 // myarray 1 declaration array use either array literal array constructor myarray 0 1 4 5 // array length 6 6 elements ... myarray new array 0 1 2 3 4 5 // array length 6 6 elements myarray new array 365 // empty array length 365 arrays implemented defined elements use memory sparse arrays setting uses space two elements like object length array still reported 58 one use object declaration literal create objects behave much like associative arrays languages dog color brown size large dog color // results brown dog.color // also results brown one use object array declaration literals quickly create arrays associative multidimensional technically javascript support multidimensional arrays one mimic arrays-of-arrays cats color brown size large cats 0 size // results large dogs rover color brown size large dogs spot size // results small dogs.rover.color // results brown date object stores signed millisecond count zero representing 1970-01-01 00:00:00 ut range ±10 days several ways providing arguments date constructor note months zero-based new date // create new date instance representing current time/date new date 2010 2 1 // create new date instance representing 2010-mar-01 00:00:00 new date 2010 2 1 14 25 30 // create new date instance representing 2010-mar-01 14:25:30 new date 2010-3-1 14:25:30 // create new date instance string methods extract fields provided well useful tostring var new date 2010 2 1 14 25 30 // 2010-mar-01 14:25:30 // displays '2010-3-1 14:25:30 console.log d.getfullyear '- d.getmonth 1 '- d.getdate // built-in tostring returns something like 'mon mar 01 2010 14:25:30 gmt-0500 est console.log custom error messages created using error class throw new error something went wrong caught try ... catch ... finally blocks described section exception handling math object contains various math-related constants example functions example cosine note math object constructor unlike array date methods static class methods trigonometric functions use angles expressed radians degrees grads /expression/.test string // returns boolean string .search /expression/ // returns position number string .replace /expression/ replacement // examples /tom/.test name tom console.log hello tom console.log name tom .search /tom/ // == 11 letters tom console.log name tom .replace /tom/ john // == name john // \d digit // \d non digit // \s space // \s non space // \w word char // \w non word // one // one // range /\d/.test 0 console.log 'digit 0-9 /.test 6 console.log 'digit 13579 /.test 1 console.log 'odd number /\s\s\s\s\s\s\s/.test 'my name console.log 'format ok /\w\w\w/.test 'tom console.log 'hello tom a-za-z /.test b console.log 'letter // ... z ... z 0 ... 9 alphanumeric // \u0000 ... \uffff unicode hexadecimal // \x00 ... \xff ascii hexadecimal // \t tab // \n new line // \r cr // character // /t.m/.test 'tom console.log 'hi tom tam tim /a|b/.test console.log b // 0 1 match // 0 // 1 // n exactly n // n n // 0 n n less // n range n /ab c/.test ac console.log ok // match ac abc /ab*c/.test ac console.log ok // match ac abc abbc abbbc etc /ab+c/.test abc console.log ok // match abc abbc abbbc etc /ab 3 c/.test abbbc console.log ok // match abbbc /ab 3 c/.test abbbc console.log ok // match abbbc abbbbc abbbbbc etc /ab 1,3 c/.test abc console.log ok // match abc abbc abbbc // string starts // string ends /^my/.test name tom console.log hi /tom /.test name tom console.log hi tom // groups characters /water mark /.test watermark console.log water // match water watermark tom john /.test john console.log hi tom john // /g global // /i ignore upper/lower case // /m allow matches span multiple lines console.log hi tom .replace /tom/i john // == hi john console.log ratatam .replace /ta/ tu // == ratutam console.log ratatam .replace /ta/g tu // == ratutum my_array my_string.split my_delimiter // example my_array dog cat cow .split // my_array== dog cat cow my_array my_string.match my_expression // example my_array start 11:30 12:15 16:45 .match /\d\d \d\d/g // my_array== 11:30 12:15 16:45 var myre \d 4 -\d 2 -\d 2 \d 2 \d 2 \d 2 var results myre.exec date time 2009-09-08 09:37:08 results else console.log find valid date every function javascript instance function constructor // x argument 'return x function body last argument list var add new function x 'return x var add 1 2 console.log // 3 add function may also defined using function expression var add function x var add 1 2 console.log // 3 exists shorthand assigning function expression variable follows function add x var add 1 2 console.log // 3 var add x // var add x x var add 1 2 console.log // 3 function instance properties methods function subtract x console.log subtract.length // 2 expected amount arguments console.log subtract.tostring function subtract x '+ operator overloaded used string concatenation arithmetic addition may cause problems inadvertently mixing strings numbers unary operator convert numeric string number // concatenate 2 strings console.log 'he 'llo // displays hello // add two numbers console.log 2 6 // displays 8 // adding number string results concatenation console.log 2 2 // displays 22 console.log 3 4 // displays 34 7 may expected console.log 3 4 // displays 7 console.log 3 4 7 // displays 77 numbers stay numbers string added // convert string number console.log 2 === 2 // displays true console.log +'hello // displays nan similarly '* operator overloaded convert string number console.log 2 6'*1 // displays 8 console.log 3* 7 // 21 console.log 3'* 7 // 21 console.log 'hello'*'world // displays nan javascript supports following binary arithmetic operators javascript supports following unary arithmetic operators var x 1 console.log ++x // x becomes 2 displays 2 console.log x++ // displays 2 x becomes 3 console.log x // x 3 displays 3 console.log x -- // displays 3 x becomes 2 console.log x // displays 2 x 2 console.log -- x // x becomes 1 displays 1 modulo operator displays remainder division modulus negative numbers involved returned value depends operand var x 17 console.log x 5 // displays 2 console.log x 6 // displays 5 console.log -x 5 // displays -2 console.log -x -5 // displays -2 console.log x -5 // displays 2 always return non-negative number re-add modulus apply modulo operator var x 17 console.log -x 5+5 5 // displays 3 assignment primitive types var x 9 x += 1 console.log x // displays 10 x *= 30 console.log x // displays 300 x /= 6 console.log x // displays 50 x -= 3 console.log x // displays 47 x 7 console.log x // displays 5 assignment object types /** var object_1 1 // assign reference newly created object object_1 var object_2 0 var object_3 object_2 // object_3 references object object_2 object_3.a 2 message // displays 1 2 2 object_2 object_1 // object_2 references object object_1 message // displays 1 1 2 object_2.a 7 // modifies object_1 message // displays 7 7 2 object_3.a 5 // object_3 n't change object_2 message // displays 7 7 5 object_3 object_2 object_3.a=4 // object_3 changes object_1 object_2 message // displays 4 4 4 function message mozilla javascript since version 1.7 destructuring assignment allows assignment parts data structures several variables left hand side assignment pattern resembles arbitrarily nested object/array literal containing l-lvalues leaves receive substructures assigned value var b c e b c 3 4 5 console.log b c // displays 3,4,5 e foo 5 bar 6 baz 'baz 'content var arr baz arr 0 arr 3 foo bar b e console.log b arr // displays 5,6 baz ,content b b // swap contents b console.log b // displays 6,5 b c 3 4 5 // permutations b c b c console.log b c // displays 4,5,3 ecmascript 2015 standard introduces ... operator related concepts spread syntax rest parameters spread syntax provides another way destructure arrays indicates elements specified array used parameters function call items array literal words ... transforms ... foo foo 0 foo 1 foo 2 this.bar ... foo this.bar foo 0 foo 1 foo 2 var 1 2 3 4 // used multiple times expression var b ... ... // b 1 2 3 4 1 2 3 4 // combined non-spread items var c 5 6 ... 7 9 // c 5 6 1 2 3 4 7 9 // comparison without spread operator // creates nested array var // 1 2 3 4 1 2 3 4 // works function calls function foo arg1 arg2 arg3 // use even passes parameters function use foo ... // 1:2:3 → foo 0 1 2 3 // mix non-spread parameters foo 5 ... 6 // 5:1:2 → foo 5 0 1 2 3 6 // comparison without spread operator // assigns array arg1 nothing parameters foo // 1,2,3,4 undefined undefined ... used function declaration indicates rest parameter rest parameter must final named parameter function parameter list assigned array containing arguments passed function excess named parameters words gets rest arguments passed function hence name function foo b ... c foo 1 2 3 4 5 // 3 → c 3 4 5 foo b // 0 → c rest parameters similar javascript arguments object array-like object contains parameters named unnamed current function call unlike arguments however rest parameters true array objects methods .slice .sort used directly ... operator used array objects however proposal extend objects future ecmascript standard variables referencing objects equal identical reference object var obj1 1 var obj2 1 var obj3 obj1 console.log obj1 == obj2 //false console.log obj3 == obj1 //true console.log obj3 === obj1 //true see also string javascript provides four logical operators context logical operation expression evaluates true except following boolean function used explicitly convert primitive type boolean // empty strings return false console.log boolean === false console.log boolean false === true console.log boolean 0 === true // zero nan return false console.log boolean nan === false console.log boolean 0 === false console.log boolean -0 === false // equivalent -1*0 console.log boolean -2 === true // objects return true console.log boolean === true console.log boolean === true console.log boolean === true // types return false console.log boolean null === false console.log boolean undefined === false // equivalent boolean operator evaluates operand boolean returns negation using operator twice row double negative explicitly converts expression primitive type boolean console.log 0 === boolean 0 console.log boolean 0 === 1 console.log 1 === boolean 1 console.log 0 === boolean 0 console.log boolean 0 === 1 console.log 1 === boolean 1 console.log === boolean console.log boolean === console.log === boolean console.log === boolean console.log boolean === console.log === boolean ternary operator also used explicit conversion console.log == false console.log true false // “ truthy ” comparison uses .tostring console.log 0 == false console.log 0 true false // 0 .tostring == 0 console.log 0 == false console.log 0 true false // 0 → 0 ... 0 == 0 ... 0 ← false console.log 1 == true console.log 1 true false // 1 .tostring == 1 console.log 1 == true console.log 1 true false // 1 → 1 ... 1 == 1 ... 1 ← true console.log 2 true console.log 2 true false // 2 .tostring == 2 console.log 2 true console.log 2 true false // 2 → 2 ... 2 1 ... 1 ← true expressions use features post–incrementation i++ anticipated side effect javascript provides short-circuit evaluation expressions right operand executed left operand suffice determine value expression console.log || b // true reason evaluate b. console.log b // false reason evaluate b. console.log c f // c true reason evaluate f. early versions javascript jscript binary logical operators returned boolean value like c-derived programming languages however contemporary implementations return one operands instead console.log || b // true return otherwise return b console.log b // false return otherwise return b programmers familiar behavior c might find feature surprising allows concise expression patterns like null coalescing var || default // assigns default value null empty etc javascript supports following binary bitwise operators examples x=11 6 console.log x // 2 javascript supports following unary bitwise operator javascript supports following binary assignment operators examples x=7 console.log x // 7 x « =3 console.log x // 7- 14- 28- 56 examples str ab cd // abcd str += e // abcde str2 2 2 // 22 4 4 pair curly brackets enclosed sequence statements constitute compound statement used wherever statement used expr else expr2 else conditional operator creates expression evaluates one two expressions depending condition similar statement selects one two statements execute depending condition i.e. conditional operator expressions statements unlike statement conditional operator omit else-branch syntax javascript switch statement follows syntax javascript loop follows syntax javascript codice_22 follows var property_name some_object syntax javascript loop follows condition syntax javascript codice_24 follows condition statement adds given object properties methods following block scope letting referenced local variables document semantics similar statement pascal availability statements hinders program performance believed reduce code clarity since given variable could actually property enclosing statement allowed strict mode javascript supports nested labels implementations loops blocks labelled break statement loops continue although goto reserved word goto implemented javascript loop1 var 0 10 a++ block1 goto block1 // parse error function block possibly empty parameter list normally given name function may use local variables exit function without return statement value returned function gcd segmenta segmentb console.log gcd 60 40 // 20 var mygcd gcd // mygcd reference function gcd note argument s. console.log mygcd 60 40 // 20 functions first class objects may assigned variables number arguments given calling function may necessarily correspond number arguments function definition named argument definition matching argument call value implicitly cast false within function arguments may also accessed object provides access arguments using indices e.g including beyond number named arguments arguments list .length property instance methods etc function add7 x add7 3 // 11 add7 3 4 // 9 primitive values number boolean string passed value objects reference object passed var obj1 1 var obj2 b 2 function foo p foo obj1 3 // affect obj1 3 additional parameter console.log obj1.a obj2.b // writes 1 3 functions declared inside functions access outer function local variables furthermore implement full closures remembering outer function local variables even outer function exited var v top var bar baz function foo foo baz fugly bar // fugly fud even though foo exited console.log v // top convenience types normally subdivided primitives objects objects entities identity equal map property names values slots prototype-based programming terminology objects may thought associative arrays hashes often implemented using data structures however objects additional features prototype chain ordinary associative arrays javascript several kinds built-in objects namely array boolean date function math number object regexp string objects host objects defined language runtime environment example browser typical host objects belong dom window form links etc. objects created using constructor object literal constructor use either built-in object function custom function convention constructor functions given name starts capital letter // constructor var anobject new object // object literal var objecta var objecta2 // a2 create new objects copies var objectb index1 'value 1 index2 'value 2 // custom constructor see object literals array literals allow one easily create flexible data structures var mystructure basis json simple notation uses javascript-like syntax data exchange method simply function assigned property name object unlike many object-oriented languages distinction function definition method definition object-related javascript rather distinction occurs function calling function called method called method standard local variable automatically set object instance left also methods set explicitly—some packages jquery unusual things example foo used constructor nothing special constructor plain function initialises object used keyword norm set newly created blank object note example foo simply assigning values slots functions thus assign different functions different instances prototyping example function foo yz var foo1 new foo 1 var foo2 new foo 0 foo2.prefix b- console.log foo1/2 foo1.pyz foo2.pyz // foo1/2 a-y b-z foo1.m3 px // assigns function evaluated result i.e px var baz prefix c- baz.m4 px // need constructor make object console.log m1/m3/m4 foo1.m1 foo1.m3 baz.m4 // m1/m3/m4 a-x a-x c-x foo1.m2 // throws exception foo1.m2 n't exist constructor functions simply assign values slots newly created object values may data functions example manipulating object function myobject attributea attributeb myobject.staticc blue // myobject function object console.log myobject.staticc // blue object new myobject 'red 1000 console.log object.attributea // red console.log object attributeb // 1000 console.log object.staticc // undefined object.attributec new date // add new property delete object.attributeb // remove property object console.log object.attributeb // undefined delete object // remove whole object rarely used console.log object.attributea // throws exception constructor referenced object prototype constructor slot // use 'new sets prototype slots example // x new foo would set x prototype foo.prototype // foo.prototype constructor slot pointing back foo x new foo // almost equivalent y.constructor foo y.constructor // except x.constructor == y.constructor // true x instanceof foo // true instanceof foo // false // prototype object.prototype // foo.prototype since initialised // instead new foo // even though foo set constructor slot // ignored instanceof prototype's // constructor slot considered functions objects used produce effect similar static properties using c++/java terminology shown function object also special prototype property discussed inheritance section object deletion rarely used scripting engine garbage collect objects longer referenced javascript supports inheritance hierarchies prototyping manner self following example class inherits class created reference base instance copied derive contain value retrieved accessed made clear changing value reflected value implementations allow prototype accessed set explicitly using slot shown function base function derived base new base derived.prototype base // must new derived derived.prototype.constructor derived // required make instanceof work new derived // copies derived.prototype instance hidden prototype slot instanceof derived // true instanceof base // true d.anoverride // derived :anoverride d.abasefunction // base :anewbasefunction console.log d.abasefunction == derived.prototype.abasefunction // true console.log d.__proto__ == base // true mozilla-based implementations false many others following shows clearly references prototypes copied instance creation changes prototype affect instances refer base.prototype.m m2 bar new base console.log bar.m bar.m // bar.m two new top foo new base base.prototype // effect foo *reference* copied console.log foo.m foo.m // foo.m two baz new base console.log baz.m baz.m // baz.m three t.m m1 // affect baz derived classes console.log baz.m1 baz.m // baz.m1 one practice many variations themes used powerful confusing javascript includes codice_25 exception handling statement handle run-time errors codice_25 statement catches exceptions resulting error throw statement syntax follows try catch errorvalue finally initially statements within try block execute exception thrown script control flow immediately transfers statements catch block exception available error argument otherwise catch block skipped catch block want handle specific error case statements finally block always executed used free resources although memory automatically garbage collected either catch finally clause may omitted catch argument required mozilla implementation allows multiple catch statements extension ecmascript standard follow syntax similar used java browser event commonly used trap exceptions onerror function errorvalue url linenr ... return true evaluates expression string parameter include assignment statements variables local functions referenced expression function foo // shows val 9
|
Programming language topics
|
basic sequential access method ibm mainframe operating systems basic sequential access method bsam access method read write datasets sequentially bsam available os/360 os/vs2 mvs z/os related operating systems bsam used devices naturally sequential punched card readers punches line printers magnetic tape also used data devices could also addressed directly magnetic disks bsam offers device independence extent possible api calls used different devices bsam allows programs read write physical blocks data opposed powerful less flexible queued sequential access method qsam allows programs access logical records within physical blocks data bsam user must aware possibility encountering short truncated blocks blocks within dataset shorter blksize dataset particularly end dataset also many cases within dataset qsam none limitations programmer specifies codice_1 data control block dcb indicate use bsam basic access method bsam reads writes member data blocks i/o operation proceeds asynchronously must tested completion using codice_2 macro bsam uses standard system macros codice_3 codice_4 codice_5 codice_6 codice_2 codice_8 macro instruction returns position last block read written codice_9 macro reposition location identified previous codice_8 dataset unblocked logical record length lrecl equal physical block size blksize bsam may utilized simulate directly accessed dataset using codice_8 codice_9 supported direct access device type devd=da primitive applications designed way bsam application program interface compared interface offered open read write close calls using file handles operating systems unix windows codice_9 provides analog seek lseek ftell equivalent codice_8
|
Operating systems
|
entity–attribute–value model entity–attribute–value model eav data model encode space-efficient manner entities number attributes properties parameters used describe potentially vast number actually apply given entity relatively modest entities correspond mathematical notion sparse matrix eav also known object–attribute–value model vertical database model open schema data representation analogous space-efficient methods storing sparse matrix non-empty values stored eav data model attribute-value pair fact describing entity row eav table stores single fact eav tables often described long skinny long refers number rows skinny columns data recorded three columns consider one would try represent general-purpose clinical record relational database clearly creating table set tables thousands columns feasible vast majority columns would null complicate things longitudinal medical record follows patient time may multiple values parameter height weight child example change child grows finally universe clinical findings keeps growing example diseases emerge new lab tests devised would require constant addition columns constant revision user interface situation list attributes changes frequently termed attribute volatility database parlance following shows snapshot eav table clinical findings visit doctor fever morning 1/5/98 entries shown within angle brackets references entries tables shown text rather encoded foreign key values ease understanding example values literal values could also pre-defined value lists latter particularly useful possible values known limited i.e. enumerable example illustrates symptoms findings might seen patient pneumonia eav data described comparable contents supermarket sales receipt would reflected sales line items table database receipt lists details items actually purchased instead listing every product shop customer might purchased n't like clinical findings given patient sales receipt sparse row modeling facts something case sales transaction recorded multiple rows rather multiple columns standard data modeling technique differences row modeling eav may considered generalization row-modeling clinical data repository row modeling also finds numerous uses laboratory test subschema typically modeled way lab test results typically numeric encoded numerically circumstances would need go beyond standard row-modeling eav listed situation arises ontology-modeling environments categories classes must often created fly classes often eliminated subsequent cycles prototyping certain hybrid classes attributes non-sparse present instances attributes highly variable sparse latter suitable eav modeling example descriptions products made conglomerate corporation depend product category e.g. attributes necessary describe brand light bulb quite different required describe medical imaging device common attributes packaging unit per-item cost clinical data entity typically clinical event described general-purpose settings entity foreign key objects table records common information every object thing database – minimum preferred name brief description well category/class entity belongs every record object table assigned machine-generated object id objects table approach pioneered tom slezak colleagues lawrence livermore laboratories chromosome 19 database standard large bioinformatics databases use objects table mandate concurrent use eav design conventional tables used store category-specific details object major benefit central objects table supporting table object synonyms keywords one provide standard google-like search mechanism across entire system user find information object interest without first specify category belongs important bioscience systems keyword like acetylcholine could refer either molecule neurotransmitter biological receptor binds eav table attribute id foreign key attribute definitions table stated however usually multiple metadata tables contain attribute-related information discussed shortly coercing values strings eav data example results simple non-scalable structure constant data type inter-conversions required one wants anything values index value column eav table essentially useless also convenient store large binary data images base64 encoded form table small integers strings therefore larger systems use separate eav tables data type including binary large objects blobs metadata given attribute identifying eav table data stored approach actually quite efficient modest amount attribute metadata given class form user chooses work cached readily memory however requires moving data one table another attribute ’ data type changed happen often mistakes made metadata definition database schema design eav general-purpose means knowledge representation originated concept association lists attribute-value pairs commonly used today first introduced language lisp attribute-value pairs widely used diverse applications configuration files using simple syntax like attribute value example non-database use eav uima uniform information management architecture standard managed apache foundation employed areas natural language processing software analyses text typically marks annotates segment example provided uima tutorial program performs named-entity recognition ner document annotating text segment president bush annotation-attribute-value triple person full_name george w. bush annotations may stored database table eav direct connection av-pairs stead hammond appear first conceived use persistent storage arbitrarily complex data first medical record systems employ eav regenstrief electronic medical record effort led clement macdonald william stead ed hammond tmr medical record system help clinical data repository cdr created homer warner group lds hospital salt lake city utah regenstrief system actually used patient-attribute-timestamp-value design use timestamp supported retrieval values given patient/attribute chronological order systems developed 1970s released commercial systems based e.f. codd relational database model available though help much later ported relational architecture commercialized 3m corporation note codd landmark paper published 1970 heavily mathematical tone unfortunate effect diminishing accessibility among non-computer-science types consequently delaying model acceptance software-vendor circles value subsequent contribution christopher j date codd colleague ibm translating ideas accessible language accompanied simple examples illustrated power overestimated group columbia-presbyterian medical center first use relational database engine foundation eav system open-source trialdb clinical study data management system nadkarni et al first use multiple eav tables one dbms data type eav/cr framework designed primarily luis marenco prakash nadkarni overlaid principles object orientation onto eav built tom slezak object table approach described earlier entity section senselab publicly accessible neuroscience database built eav/cr framework additionally numerous commercial applications use aspects eav internally including oracle designer applied er modeling kalido applied data warehousing master data management lazysoft sentences applied custom software development eav system sit top tabular structure instead directly b tree infinitydb eliminates need one table per value data type term eav database refers database design significant proportion data modeled eav however even database described eav-based tables system traditional relational tables noted eav modeling makes sense categories data clinical findings attributes numerous sparse conditions hold standard relational modeling i.e. one column per attribute preferable using eav mean abandoning common sense principles good relational design clinical record systems subschemas dealing patient demographics billing typically modeled conventionally vendor database schemas proprietary vista system used throughout united states department veterans affairs va medical system known veterans health administration vha open-source schema readily inspectable though uses mumps database engine rather relational database discussed shortly eav database essentially unmaintainable without numerous supporting tables contain supporting metadata metadata tables typically outnumber eav tables factor least three typically standard relational tables example metadata table attribute definitions table mentioned simple eav design values attribute simple primitive data types far database engine concerned however eav systems used representation highly diverse data possible given object class instance may substructure attributes may represent kinds objects turn may substructure arbitrary level complexity car example engine transmission etc. engine components cylinders permissible substructure given class defined within system attribute metadata discussed later thus example attribute random-access-memory could apply class computer class engine represent substructure one incorporates special eav table value column contains references entities system i.e. foreign key values objects table get information given object requires recursive traversal metadata followed recursive traversal data stops every attribute retrieved simple atomic recursive traversal necessary whether details individual class represented conventional eav form traversal performed standard object–relational systems example practice number levels recursion tends relatively modest classes performance penalties due recursion modest especially indexing object ids eav/cr eav classes relationships refers framework supports complex substructure name somewhat misnomer outshoot work eav systems practice many even classes system may represented standard relational form based whether attributes sparse dense eav/cr really characterized detailed metadata rich enough support automatic generation browsing interfaces individual classes without write class-by-class user-interface code basis browser interfaces possible generate batch dynamic sql queries independent class object first consulting metadata using metadata information generate sequence queries data tables queries may arbitrarily recursive approach works well object-at-a-time queries web-based browsing interfaces clicking name object brings details object separate page metadata associated object class also facilitates presentation object details includes captions individual attributes order presented well grouped one approach eav/cr allow columns hold json structures thus provide needed class structure example postgresql version 9.4 offers json binary column jsonb support allowing json attributes queried indexed joined words prof. dr. daniel masys formerly chair vanderbilt university medical informatics department challenges working eav stem fact eav database physical schema way data stored radically different logical schema – way users many software applications statistics packages regard i.e. conventional rows columns individual classes eav table conceptually mixes apples oranges grapefruit chop suey want analysis data using standard off-the-shelf software cases convert subsets columnar form process called pivoting important enough discussed separately metadata helps perform sleight hand lets users interact system terms logical schema rather physical software continually consults metadata various operations data presentation interactive validation bulk data extraction ad hoc query metadata actually used customize behavior system eav systems trade simplicity physical logical structure data complexity metadata among things plays role database constraints referential integrity standard database designs tradeoff generally worthwhile typical mixed schema production systems data conventional relational tables also benefit functionality automatic interface generation structure metadata complex enough comprises subschema within database various foreign keys data tables refer tables within subschema subschema standard-relational features constraints referential integrity used hilt correctness metadata contents terms intended system behavior critical task ensuring correctness means creating eav system considerable design efforts must go building user interfaces metadata editing used people team know problem domain e.g. clinical medicine necessarily programmers historically one main reasons pre-relational tmr system failed adopted sites home institution metadata stored single file non-intuitive structure customizing system behavior altering contents file without causing system break delicate task system authors trusted eav system implemented rdf rdf schema language may conveniently used express metadata schema information may used eav database engine dynamically re-organize internal table structure best efficiency final caveats regarding metadata validation presentation grouping metadata make possible creation code frameworks support automatic user interface generation data browsing well interactive editing production system delivered web task validation eav data essentially moved back-end/database tier powerless respect task middle /web server tier back-end validation always ideal impossible subvert attempting direct data entry table middle tier validation generic framework quite workable though significant amount software design effort must go building framework first availability open-source frameworks studied modified individual needs go long way avoiding wheel reinvention eav modeling alternative terms generic data modeling open schema long standard tool advanced data modelers like advanced technique double-edged used judiciously also employment eav preclude employment traditional relational database modeling approaches within database schema emrs rely rdbms cerner use eav approach clinical-data subschema vast majority tables schema fact traditionally modeled attributes represented individual columns rather rows modeling metadata subschema eav system fact good fit traditional modeling inter-relationships various components metadata trialdb system example number metadata tables schema outnumber data tables ten one correctness consistency metadata critical correct operation eav system system designer wants take full advantages features rdbmss provide referential integrity programmable constraints rather reinvent rdbms-engine wheel consequently numerous metadata tables support eav designs typically third-normal relational form commercial electronic health record systems ehrs use row-modeling classes data diagnoses surgical procedures performed laboratory test results segregated separate tables table entity composite patient id date/time diagnosis made surgery lab test performed attribute foreign key specially designated lookup table contains controlled vocabulary e.g. icd-10 diagnoses current procedural terminology surgical procedures set value attributes e.g. laboratory-test results one may record value measured whether normal low high range id person responsible performing test date/time test performed stated earlier full-fledged eav approach domain attributes given table restricted domain product ids supermarket sales table would restricted domain products products table however capture data parameters always defined standard vocabularies ehrs also provide pure eav mechanism specially designated power-users define new attributes data type maximum minimal permissible values permissible set values/codes allow others capture data based attributes epic tm ehr mechanism termed flowsheets commonly used capture inpatient nursing observation data typical case using eav model highly sparse heterogeneous attributes clinical parameters electronic medical record emrs stated even however accurate state eav modeling principle applied sub-schema database rather contents patient demographics example naturally modeled one-column-per-attribute traditional relational structure consequently arguments eav vs. relational design reflect incomplete understanding problem eav design employed sub-schema database sparse attributes need modeled even need supported third normal form metadata tables relatively database-design problems sparse attributes encountered circumstances eav design applicable relatively rare even encountered set eav tables way address sparse data xml-based solution discussed applicable maximum number attributes per entity relatively modest total volume sparse data also similarly modest example situation problems capturing variable attributes different product types sparse attributes may also occur e-commerce situations organization purchasing selling vast highly diverse set commodities details individual categories commodities highly variable magento e-commerce software employs eav approach address issue another application eav modeling classes attributes sparse dynamic number data rows per class relatively modest – couple hundred rows typically dozen – system developer also required provide web-based end-user interface within short turnaround time dynamic means new classes attributes need continually defined altered represent evolving data model scenario occur rapidly evolving scientific fields well ontology development especially prototyping iterative refinement phases creation new tables columns represent new category data especially labor-intensive programming web-based interfaces support browsing basic editing type- range-based validation case maintainable long-term solution create framework class attribute definitions stored metadata software generates basic user interface metadata dynamically eav/cr framework mentioned earlier created address situation note eav data model essential system designer may consider acceptable alternative creating say sixty tables containing total two thousand rows number rows per class efficiency considerations less important standard indexing class id/attribute id dbms optimizers easily cache data small class memory running query involving class attribute dynamic-attribute scenario worth noting resource description framework rdf employed underpinning semantic-web-related ontology work rdf intended general method representing information form eav rdf triple comprises object property value end jon bentley book writing efficient programs author warns making code efficient generally also makes harder understand maintain one rush tweak code unless one first determined performance problem measures code profiling pinpointed exact location bottleneck done modify specific code needs run faster similar considerations apply eav modeling apply sub-system traditional relational modeling known priori unwieldy clinical data domain discovered system evolution pose significant maintenance challenges database guru currently vice-president core technologies oracle corporation tom kyte example correctly points drawbacks employing eav traditional business scenarios makes point mere flexibility sufficient criterion employing eav however makes sweeping claim eav avoided circumstances even though oracle health sciences division employs eav model clinical-data attributes commercial systems clintrial oracle clinical achilles heel eav difficulty working large volumes eav data often necessary transiently permanently inter-convert columnar row-or eav-modeled representations data error-prone done manually well cpu-intensive generic frameworks utilize attribute attribute-grouping metadata address former latter limitation use less mandated case mixed schemas contain mixture conventional-relational eav data error quotient significant conversion operation called pivoting pivoting required eav data also form row-modeled data example implementations apriori algorithm association analysis widely used process supermarket sales data identify products purchasers given product also likely buy pivot row-modeled data first step many database engines proprietary sql extensions facilitate pivoting packages microsoft excel also support circumstances pivoting necessary considered however structure eav data model perfect candidate relational division see relational algebra good indexing strategy possible get response time less hundred milliseconds billion row eav table microsoft sql server mvp peter larsson proved laptop made solution general available obviously matter approaches take querying eav fast querying standard column-modeled relational data certain types query much way access elements sparse matrices fast non-sparse matrices latter fit entirely main memory sparse matrices represented using structures linked lists require list traversal access element given x-y position access elements matrices represented 2-d arrays performed using fast cpu register operations however chose eav approach correctly problem trying solve price pay respect eav modeling example space schema maintenance versus cpu-time tradeoff originally postulated maier ullman vardi universal data model udm seeks simplify query complex relational schema naive users creating illusion everything stored single giant universal table utilizing inter-table relationships user need concerned table contains attribute c.j date however pointed circumstances table multiply related another genealogy databases individual father mother also individuals business databases addresses stored centrally organization different office addresses shipping addresses insufficient metadata within database schema specify unambiguous joins udm commercialized sap businessobjects limitation worked around creation universes relational views predefined joins sets tables universe developer disambiguates ambiguous joins including multiply-related table view multiple times using different aliases apart way data explicitly modeled udm simply uses relational views intercede user database schema eav differs universal data models also applies transactional systems query oriented read-only systems udm also used basis clinical-data query systems eav implementations necessarily shield user specify class object interest eav-based i2b2 clinical data mart example user searches term option specifying category data user interested example phrase lithium refer either medication used treat bipolar disorder laboratory assay lithium level patient blood blood level lithium must monitored carefully much drug causes severe side effects little ineffective open schema implementation use xml column table capture variable/sparse information similar ideas applied databases support json-valued columns sparse hierarchical data represented json database json support postgresql partially sql server 2016 later attributes queried indexed joined offer performance improvements 1000x naive eav implementations. necessarily make overall database application robust note two ways xml json data stored one way store plain string opaque database server way use database server see structure obviously severe drawbacks storing opaque strings queried directly one form index based contents impossible perform joins based content building application manage data gets extremely complicated using eav models extent infrastructure developed terms metadata tables application-framework code using xml solves problem server-based data validation must done middle-tier browser-based code eav-based frameworks following drawbacks drawbacks remediable creating layer metadata application code creating original advantage create framework vanished fact modeling sparse data attributes robustly hard database-application-design problem matter storage approach used sarka work however proves viability using xml field instead type-specific relational eav tables data-storage layer situations number attributes per entity modest e.g. variable product attributes different product types xml-based solution compact eav-table-based one xml may regarded means attribute-value data representation though based structured text rather relational tables exist several approaches representation tree-structured data xml json formats nested set model relational database hand database vendors begun include json xml support data structures query features like ibm db2 xml data stored xml separate tables using xpath queries part sql statements postgresql json data type indexed queried developments accomplish improve substitute eav model approach noted however uses json xml necessarily use eav model though overlap xml preferable eav arbitrarily hierarchical data relatively modest volume single entity intended scale multi-gigabyte level respect data-manipulation performance xml concerned per-se sparse-attribute problem data model underlying information represented decomposed straightforwardly relational structure xml better suited means data interchange primary storage mechanism eav stated earlier specifically applicable sparse-attribute scenario scenario holds use datatype-specific attribute-value tables indexed entity attribute value manipulated simple sql statements vastly scalable use xml tree structure google app engine mentioned uses strongly-typed-value tables good reason alternative approach managing various problems encountered eav-structured data employ graph database represent entities nodes graph hypergraph attributes links edges graph issue table joins addressed providing graph-specific query languages apache tinkerpop opencog atomspace pattern matcher postgresql version 9.4 includes support json binary columns jsonb queried indexed joined allows performance improvements factors thousand traditional eav table designs db schema based jsonb always less tables one may nest attribute-value pairs jsonb type fields entity table makes db schema easy comprehend sql queries concise programming code manipulate database objects abstraction layer turns much shorter microsoft sql server 2008 offers proprietary alternative eav columns atomic data type e.g. numeric varchar datetime columns designated sparse simply including word sparse column definition create table statement sparse columns optimize storage null values take space useful majority records table null values column indexes sparse columns also optimized rows values indexed addition contents sparse columns particular row table collectively aggregated single xml column column set whose contents form codice_1 fact column set defined table part create table statement sparse columns subsequently defined typically added interesting consequence sql statement codice_2 return individual sparse columns concatenate single xml column whose name column set therefore acts virtual computed column sparse columns convenient business applications product information applicable attributes highly variable depending product type total number variable attributes per product type relatively modest however approach modeling sparse attributes several limitations rival dbmss notably chosen borrow idea engines limitations include many cloud computing vendors offer data stores based eav model arbitrary number attributes associated given entity roger jennings provides in-depth comparison amazon offering simpledb data type limited strings data intrinsically non-string must coerced string e.g. numbers must padded leading zeros wish perform operations sorting microsoft offering windows azure table storage offers limited set data types byte bool datetime double guid int long string google app engine offers greatest variety data types addition dividing numeric data int long float also defines custom data types phone number e-mail address geocode hyperlink google amazon microsoft lets define metadata would prevent invalid attributes associated particular class entity letting create metadata model google lets operate data using subset sql microsoft offer url-based querying syntax abstracted via linq provider amazon offer limited syntax concern built-in support combining different entities joins currently april '10 non-existent three engines operations performed application code may concern application servers co-located data servers vendor data center lot network traffic would generated two geographically separated eav approach justified attributes modeled numerous sparse data captured meet requirement cloud vendors default eav approach often mismatch applications require true back-end database opposed merely means persistent data storage retrofitting vast majority existing database applications use traditional data-modeling approach eav-type cloud architecture would require major surgery microsoft discovered example database-application-developer base largely reluctant invest effort recently therefore microsoft provided premium offering – cloud-accessible full-fledged relational engine sql server azure allows porting existing database applications modest changes one limitation sql azure physical databases limited 500gb size microsoft recommends data sets larger split multiple physical databases accessed parallel queries
|
Databases
|
tlbleed tlbleed cryptographic side-channel attack uses machine learning exploit timing side-channel via translation look-aside buffer tlb modern microprocessors use simultaneous multithreading attack demonstrated experimentally intel processors speculated processors may also potentially vulnerable variant attack proof concept demonstrated recent news amd indicates processors vulnerable attack attack led openbsd project disabling simultaneous multithreading intel microprocessors openbsd project leader theo de raadt stated attack could theoretically addressed preventing tasks different security contexts sharing physical cores fix currently impractical complexity problem
|
Computer security
|
multilisp multilisp functional programming language dialect language lisp dialect scheme extended constructs parallel computing execution shared memory extensions involve side effects rendering multilisp nondeterministic along parallel-programming extensions multilisp also unusual garbage collection task scheduling algorithms like scheme multilisp optimized symbolic computing unlike parallel programming languages multilisp incorporated constructs causing side effects explicitly introducing parallelism designed robert h. halstead jr. early 1980s use 32-processor concert multiprocessor developed massachusetts institute technology mit implemented interlisp influenced development scheme dialects gambit interlisp-vax multilisp achieves parallelism pcall macro codice_1 equivalent codice_2 except arguments codice_3 etc explicitly allowed evaluated parallel circumvents usual order evaluation sequential left right also makes use parallel programming construct called futures resembles forking combined lazy evaluation using construct expression codice_4 written overlap evaluation expressions b computations use result cons call operation performed needs correct information value b
|
Programming language topics
|
apache tajo apache tajo big data relational distributed data warehouse system apache hadoop designed tajo targeting low-latency scalable ad-hoc queries online aggregation etl feature follows sample statement create sql table may look like follows
|
Distributed computing architecture
|
drizzle database server drizzle abandoned free software/open-source relational database management system dbms forked now-defunct 6.0 development branch mysql dbms like mysql drizzle client/server architecture uses sql primary command language old drizzle files distributed version 2 3 gnu general public license gpl portions including protocol drivers replication messaging bsd license early work fork done mid-2008 brian aker ongoing development handled team contributors includes staff members canonical ltd. google six apart sun microsystems rackspace data differential blue gecko intel percona hewlett-packard red hat others drizzle source code along instructions compiling available via project launchpad website october 2010 drizzle 13,478 total contributions 96 total contributors 37 active contributors also announced drizzle entered beta first ga version released march 2011 drizzle actively participated google summer code project since 2010 drizzle targeted web-infrastructure cloud computing markets developers product describe smaller slimmer hopefully faster version mysql drizzle written c++ programming language stores string data utf-8 format developed modern unix-like operating systems including linux freebsd mac os x solaris – general os conforms posix working implementation gnu autotools microsoft windows supported time mainly lack autotools support discussion accomplish sensible manner drizzle re-designed version mysql v6.0 codebase designed around central concept microkernel architecture features query cache authentication system plugins database follow general theme pluggable storage engines introduced mysql 5.1 supports pam ldap http auth authentication via plugins ships via plugin system currently supports logging files syslog remote services rabbitmq gearman drizzle acid-compliant relational database supports transactions via mvcc design plugin points added support replication storage engines query rewrite table functions user-defined functions protocol adapters multiple query caches like mysql drizzle supports concurrent multiple engines via drizzle includes built-in support b+ tree hash indexes drizzle query planner capable using multiple indexes multiple engines satisfy complex queries using temporary in-memory bitmap index operations database triggers drizzle supported dml ddl number additional event-based operations server primebase blob streaming system allows drizzle stream binary large objects blobs via http makes use system triggers drizzle currently must written c++ query matched rewritten dynamically sent server action done parsing occurs wide variety native data types supported including support execute command drizzle operate dynamic multi-statement sql via keyword concurrent operate statements parallel replication drizzle done generating messages using google protocol buffers library messages stored executed remote servers message format non-sql neutral format allowed drizzle replication appliers rabbitmq memcached mysql voldemort apache cassandra drizzle licensed version two three gpl parts libdrizzle client library bsd license
|
Databases
|
features new windows 10 windows 10 introduced number new elements including option use touch-optimized interface known tablet mode traditional desktop interface similar windows 7 along live tiles windows 8 however unlike previous versions windows major features release completed rtm windows 10 continues receive major features changes beyond initial release market microsoft describes windows 10 'operating system service receive ongoing updates features functionality supplemented ability enterprise environments receive non-critical updates slower pace use long-term support milestones receive critical updates security patches ten-year lifespan support terry myerson executive vice president microsoft windows devices group argued goal model reduce fragmentation across windows platform windows 10 codenamed threshold 1 first release windows 10 carries build number 10.0.10240 build n't contain version number microsoft retroactively named version 1507 standing july 2015 matching versioning scheme later updates threshold 1 announced event september 30 2014 first preview following day final release made available windows insiders july 15 2015 followed public release july 29 2015 free upgrade windows 7 windows 8.1 threshold 1 release windows 10 supported users long term servicing branch ltsb new feature indicated release added since windows 8.1 update 1 released april 2014 mail app adds user-configurable swipe gesture controls pop3 email support google calendar support added calendar app settings app expanded similar functionality control panel albeit metro-style user interface map app download maps offline use microsoft edge new browser windows 10 successor internet explorer although internet explorer remain compatibility legacy purposes cortana integrated edge accessible option ask cortana right click menu well reading view ability write notes directly web pages save onenote reading list feature also added users save articles content accessed read later microsoft edge also includes share button toolbar tapping clicking bring system share panel users able share webpage installed applications reading list third-party apps facebook twitter since release microsoft edge scored 402 555 points html5test windows 10 introduced universal windows platform uwp extension windows runtime platform originally introduced windows 8 uwp emphasizes core set apis common variations operating system enabling ability code single application adaptations user interface differences different device families states including desktops laptops tablets smartphones via windows 10 mobile xbox one new device classes surface hub hololens application may also react available displays input device connected monitor suitable docking station uwp app smartphone take appearance app pc information also synchronized versions app different devices notifications licensing windows 10 includes directx 12 alongside wddm 2.0 unveiled march 2014 gdc directx 12 aims provide console-level efficiency closer metal access hardware resources reduced cpu graphics driver overhead performance improvements achieved low-level programming reduce single-threaded cpu bottlenecking caused abstraction higher level apis performance gains achieved allowing developers direct access gpu resources similar low-level rendering initiatives amd mantle apple metal api opengl successor vulkan wddm 2.0 introduces new virtual memory management allocation system reduce workload kernel-mode driver windows 10 brings updates xbox app introduced windows 8 games xbox one streamed windows 10 device excluding smartphones windows 10 introduces game bar provides screenshot video capture functionality windows games users invoke game bar record gameplay take screenshot using appropriate keyboard shortcuts windows 10 also continuously capture gameplays background allows user request last users defined moments gameplay saved hard disk useful user wants save and/or share moment gameplay think explicitly record beforehand windows 10 also allows web apps desktop software using either win32 .net framework packaged distribution windows store desktop software distributed windows store packaged using app-v system allow sandboxing web apps executed remote servers access windows functions notifications camera access windows 8 locally packaged web apps written using html winjs called action center windows 7 windows server 2008 r2 successor called security maintenance title action center windows 10 usurped sidebar provides list received notifications group quick actions buttons different settings areas accessed clicking notifications icon system tray swiping right screen touchscreens windows 10 brings improvements system command-line interface unlike previous versions windows nt win32 console windows resized without restrictions made cover full screen pressing combination keyboard microsoft also enabled use standard keyboard shortcuts cut copy paste within console word wrapping keyboard shortcuts move caret select manipulate text become available features word wrap transparency also included user option disable new features return legacy console wish continuum blanket title group features windows 10 designed enable smoother transitions default interface mode designed use keyboard mouse interface designed touchscreen environments especially hybrid devices laplets enabling tablet mode switches primary interface full screen version start menu opens applications maximized view default taskbar also modified adding back button next start button default hiding buttons opened pinned applications task view used primary means switching programs windows prompt switch two modes automatically certain events occur plugging keyboard mouse tablet switching laplet laptop state vice versa windows 10 brought cortana assistant windows phone 8.1 windows 10 default cortana appears search pane taskbar changed button like tablet mode activated voice using command hey cortana user searches start menu user searches cortana search pane cortana users ask cortana questions weather calendar events types notifications along online information cortana currently requires microsoft account function windows 10 reintroduced start menu seen versions windows prior 8 however unlike versions new start menu includes live tile features windows 8 possible resize start menu view recently added used applications also made full screen tablet users users prefer windows 8-like experience right hand side start menu used pin tiles menu contain limited amount columns depending screen resolution columns divided groups title every group divided 6 8 columns depending user settings allow either 6 8 small sized tiles next task view task switching virtual desktop system accessible via taskbar button keyboard shortcut swiping left touchscreen activating task view shows zoomed display windows currently opened specific monitor clicking window switches task view also displayed window snapped half screen three windows snapped fourths screen prompting window occupy remainder screen task view also allows creation virtual workspaces windows dragged workspaces modern settings app windows 8 continues evolve windows 10 incorporating system setting configuration functionality windows control panel ultimate goal make settings app feature complete obviating need control panel push-button reset function changed utilize files current windows installation rebuild system rather separate recovery image system updates carry new installation re-downloaded separate refresh option removed users given explicit choices within reset process remove personal files applications keep personal files remove applications perform full factory reset mac address randomization wifi introduced try prevent third parties using mac address track devices windows 10 november update windows 10 version 1511 codenamed threshold 2 first major update windows 10 carries build number 10.0.10586 version 1511 referencing date release november 2015 first preview released august 18 2015 final release made available windows insiders november 3 2015 followed public release november 12 2015 existing windows 10 users free upgrade windows 7 windows 8.1 unlike initial release windows branch also made available existing windows phone 8.1-devices xbox one preview release windows server 2016 pre-installed new windows 10 mobile-devices like microsoft lumia 950 threshold 2 release windows 10 supported users current branch businesses cbb changes highlight features new since threshold 1 release windows 10 windows 10 anniversary update windows 10 version 1607 codenamed redstone 1 second major update windows 10 first 2 major updates given redstone codename released july 29 2016 universal windows platform apps support extensions allowing add-ons dlcs apps games respectively furthermore add-ons managed windows settings app anniversary update windows 10 adds windows subsystem linux allows ubuntu user space run natively windows subsystem translate linux system call ubuntu uses windows nt kernel allows bash ubuntu command line apps run within windows console however interoperability restriction bash run windows apps windows run linux software project centennial allows win32 .net apps repackaged appx allow use full set windows runtime apis also allow apps distributed windows store new workspace environment pen users includes virtual sticky notes pen could used take notes sticky notes features optical character recognition ocr highlight relevant text used cortana workspace also includes sketchpad ability take screenshot draw virtual ruler windows 10 creators update windows 10 version 1703 codenamed redstone 2 feature update windows 10 slated released april 11 2017 first preview release seeded windows insiders august 11 2016 redstone 2 release windows 10 currently development branch available windows insiders changes highlights features new since redstone 1 release windows 10 april 2018 update windows 10 version 1803 fifth feature update windows 10 windows 10 october 2018 update windows 10 version 1809 sixth feature update windows 10
|
Operating systems
|
link grammar link grammar lg theory syntax davy temperley daniel sleator builds relations pairs words rather constructing constituents phrase structure hierarchy link grammar similar dependency grammar dependency grammar includes head-dependent relationship whereas link grammar makes head-dependent relationship optional links need indicate direction colored multiplanar link grammar cmlg extension lg allowing crossing relations pairs words relationship words indicated link types thus making link grammar closely related certain categorial grammars example subject–verb–object language like english verb would look left form subject link right form object link nouns would look right complete subject link left complete object link subject–object–verb language like persian verb would look left form object link distant left form subject link nouns would look right subject object links link grammar connects words sentence links similar form catena unlike catena traditional dependency grammar marking head-dependent relationship optional languages becoming mandatory free-word-order languages turkish finnish hungarian lithuanian english subject-verb relationship obvious subject almost always left verb thus specific indication dependency needs made case subject-verb inversion distinct link type employed free word-order languages longer hold link subject verb must contain explicit directional arrow indicate two words link grammar also differs traditional dependency grammars allowing cyclic relations words thus example links indicating head verb sentence head subject sentence well link subject verb three links thus form cycle triangle case cycles useful constraining might otherwise ambiguous parses cycles help tighten set allowable parses sentence example parse left-wall indicates start sentence root node directional wv link arrows points head verb sentence wall-verb link wd link drawn without arrows indicates head noun subject sentence link type wd indicates connects wall w sentence declarative sentence lower-case subtype ss link indicates subject-verb relationship lower-case indicating subject singular note wv wd ss links cycle pa link connects verb complement lower-case indicating predicative adjective case parsing performed analogy assembling jigsaw puzzle representing parsed sentence puzzle pieces representing individual words language represented means dictionary lexis consists words set allowed jigsaw puzzle shapes word shape indicated connector link-type direction indicator indicating right left thus example transitive verb may connectors s- o+ indicating verb may form subject connection left object connection right similarly common noun may connectors d- s+ indicating may connect determiner left d- act subject connecting verb right s+ act parsing identify s+ connector attach s- connector forming link two words parsing completes connectors connected given word may dozens even hundreds allowed puzzle-shapes termed disjuncts example many verbs may optionally transitive thus making o+ connector optional verbs might also take adverbial modifiers e connectors inherently optional complex verbs may additional connectors indirect objects particles prepositions thus part parsing also involves picking one single unique disjunct word final parse must satisfy connect connectors disjunct connectors may also include head-dependent indicators h d. case connector containing head indicator allowed connect connector containing dependent indicator connector without h-d indicators indicators used link decorated arrows indicate link direction recent extension simplifies specification connectors languages little restrictions word-order lithuanian also extensions make easier support languages concatenative morphologies parsing algorithm also requires final graph planar graph i.e links cross constraint based empirical psycho-linguistic evidence indeed languages nearly situations dependency links really cross rare exceptions e.g finnish even english parsed link-grammar introducing complex selective connector types capture situations connectors optional floating-point cost markup cheaper use others thus giving preference certain parses others total cost parse sum individual costs connectors used cheapest parse indicates likely parse used parse-ranking multiple ambiguous parses fact costs local connectors global property algorithm makes essentially markovian nature assignment log-likelihood linkages allows link grammar implement semantic selection predicate-argument relationships certain constructions although syntactically valid extremely unlikely way link grammar embodies ideas present operator grammar costs additive behave like logarithm probability since log-likelihoods additive equivalently somewhat like entropy since entropies additive makes link grammar compatible machine learning techniques hidden markov models viterbi algorithm link costs correspond link weights markov networks bayesian networks link grammar link types understood types sense type theory effect link grammar used model internal language certain non-symmetric compact closed categories pregroup grammars sense link grammar appears isomorphic homomorphic categorial grammars thus example categorial grammar noun phrase bad boy may written whereas corresponding disjuncts link grammar would contraction rules inference rules lambek calculus mapped connecting connectors link grammar directional indicators correspond forward backward-slashes categorical grammar finally single-letter names understood labels easy-to-read mnemonic names rather verbose types np/n etc primary distinction categorical grammars two type constructors forward backward slashes used create new types np/n base types np n link-grammar omits use type constructors opting instead define much larger set base types compact easy-to-remember mnemonics basic rule file svo language might look like thus english sentence boy painted picture would appear similar parses apply chinese conversely rule file null subject sov language might consist following links simple persian sentence man nan xordam من نان خوردم ate bread would look like vso order likewise accommodated arabic many languages concatenative morphology stem plays grammatical role grammar determined suffixes thus russian sentence 'вверху плыли редкие облачка might parse subscripts '.vnndpp used indicate grammatical category primary links wd ei sip api connect together suffixes principle stems could appear without altering structure sentence api link indicates adjective sip denotes subject-verb inversion ei modifier wd link used indicate head noun head verb indicated sentence llxxx links serve attach stems suffixes link-grammar also indicate phonological agreement neighboring words example connector 'ph used constrain determiners appear word 'abstract effectively blocks makes costly use determiner sentence link 'an becomes cheap links roughly previous examples denoting subject denoting object denoting determiner 'wv link indicates head verb w link indicates head noun lower-case letters following upper-case link types serve refine type example ds connect singular noun ss singular subject os singular object lower-case v phv denotes 'vowel lower-case wd denotes declarative sentence vietnamese language sentence bữa tiệc hôm qua là một thành công lớn party yesterday great success may parsed follows link grammar syntax parser library natural language processing written c. available lgpl license parser ongoing project recent versions include improved sentence coverage russian persian arabic language support prototypes german hebrew lithuanian vietnamese turkish programming api python java common lisp autoit ocaml 3rd-party bindings perl ruby javascript node.js current major undertaking project learn grammar morphology new languages using unsupervised learning algorithms link-parser program along rules word lists english may found standard linux distributions e.g. debian package although many years date abiword free word processor uses link grammar on-the-fly grammar checking words linked anywhere underlined green semantic relationship extractor relex layered top link grammar library generates dependency grammar output making explicit semantic relationships words sentence output classified level ssyntr dsyntr meaning-text theory also provides framing/grounding anaphora resolution head-word identification lexical chunking part-of-speech identification tagging including entity date money gender etc tagging includes compatibility mode generate dependency output compatible stanford parser penn treebank-compatible pos tagging link grammar also employed information extraction biomedical texts events described news articles well experimental machine translation systems english german turkish indonesian farsi link grammar link dictionary used generate verify syntactic correctness three different natural language generation systems nlgen nlgen2 microplanner/surreal also used part nlp pipeline opencog ai project
|
Computational linguistics
|
inode inode index node data structure unix-style file system describes file-system object file directory inode stores attributes disk block location object data file-system object attributes may include metadata times last change access modification well owner permission data directories lists names assigned inodes directory contains entry parent children uncertainty linux kernel mailing list reason inode 2002 question brought unix pioneer dennis ritchie replied paper published 1978 ritchie ken thompson strongly suggests etymology also maurice j. bach writes file system relies data structures files beside file content former called metadata —data describes data file associated inode identified integer number often referred i-number inode number inodes store information files directories folders file ownership access mode read write execute permissions file type many types file system implementations maximum number inodes fixed file system creation limiting maximum number files file system hold typical allocation heuristic inodes file system one percent total size inode number indexes table inodes known location device inode number kernel file system driver access inode contents including location file thus allowing access file file inode number found using codice_1 command codice_1 command prints i-node number first column report unix-style file systems reiserfs omit inode table must store equivalent data order provide equivalent capabilities data may called stat data reference codice_3 system call provides data programs file names directory implications operating system kernel in-memory representation data called codice_4 linux systems derived bsd use term codice_5 v vnode referring kernel virtual file system layer posix standard mandates file-system behavior strongly influenced traditional unix file systems inode denoted phrase file serial number defined per-file system unique identifier file file serial number together device id device containing file uniquely identify file within whole system within posix system file following attributes may retrieved codice_3 system call make sense store small files inode save space data block needed look-up time disk access needed file system feature called inlining strict separation inode file data thus longer assumed using modern file systems data file fits space allocated pointers data space conveniently used example ext2 successors stores data symlinks typically file names way data 60 bytes fast symbolic links ext4 file system option called inline_data enabled file system creation allows ext4 perform inlining inode size limited works small files
|
Computer file systems
|
list features removed windows 10 windows 10 version windows nt successor windows 8 features operating system removed comparison windows 8 windows 8.1 changes features offered occurred within subsequent feature updates windows 10
|
Operating systems
|
run game designed yu suzuki traveled europe gain inspiration game stages suzuki small team ten months program game leaving work game critical commercial success becoming one best-selling video games time sega successful arcade cabinet 1980s ported numerous video game consoles home computers spawned number sequels run cited influence upon later video games run 3d driving video game player controls ferrari testarossa spider third-person rear perspective camera placed near ground simulating ferrari driver position limiting player view distance road curves crests dips increases challenge obscuring upcoming obstacles traffic player must avoid object game reach finish line timer game world divided multiple stages end checkpoint reaching end stage provides time near end stage track forks give player choice routes leading five final destinations destinations represent different difficulty levels conclude ending scene among ferrari breaking presented trophy mid-1980s sega experienced success arcades games developed yu suzuki hang-on good seller enduro racer successful enough sega consider second production run motorcycle racing games run suzuki chance develop car racing game original concept base game american film cannonball run fan disliked racing games cars exploded impact wanted gamers enjoy experience driving feel superior suzuki initially conceived game setting across united states requested scout various locations according suzuki boss youji ishii sega president hayao nakayama believed us unsafe suggested europe safer option additionally suzuki concluded us large empty game design scouted europe two weeks bmw 520 ideas tour included frankfurt monaco rome swiss alps french riviera florence milan monaco suzuki inspired use ferrari testarossa playable car game returned japan arranged team find photograph one small team four programmers sound creator five graphic designers developed run suzuki use personnel available assigned projects time result suzuki programming planning spending extra hours studio complete development game within ten months suzuki believed difficult part developing game make fun possible achieved emphasizing design elements wide roads buildings radio soundtrack selection four cabinet designs released equipped steering wheel stick shift acceleration brake pedals two cabinet designs upright one force feedback steering wheel two models sit-down cabinets resemble in-game car use drive motor move main cabinet—turning shaking according onscreen action models feature stereo speakers mounted behind driver head arcade system board made specifically game sega outrun based sega system 16 suzuki stated often unable make games based existing hardware sega would create new board said designs always 3d beginning calculations system 3d even hang-on calculated position scale zoom rate 3d converted backwards 2d always thinking 3d game achieves 3d effects using sprite-scaling technique called super-scaler technology used one year earlier hang-on released september 1986 run fast sprite-scaling 3d motion provide smoother experience contemporary arcade games run original score composed hiroshi kawaguchi previously composed soundtracks games designed suzuki including hang-on soundtrack similar style latin caribbean music three selectable tracks featured passing breeze splash wave magical sound shower additional track last wave plays final score screen run arcade release received positive reviews became one popular arcade games year 1988 golden joystick award game year beating renegade last ninja run received arcade game year award beating renegade bubble bobble 1994 30,000 cabinets sold worldwide making sega best selling arcade cabinet 1980s clare edgeley reviewed arcade game computer video games sinclair user praising graphics element danger gameplay review commodore user described great game driving enthusiasts awarded score 9 10 gary penn writing crash called game highly polished praised attention detail sinclair peter shaw praised realism described frighteningly fast road race game 've ever played run ported numerous home consoles computers 250,000 copies 8-bit computer game ports published u.s. gold sold christmas 1987 run became fastest-selling best-selling computer game uk year sega master system version praised computer video games concluded thrill power arcade version games machine gave master system version score 72 stating master system version came closest original coin-op reviewers dragon described refreshing game provides hours entertainment computer gaming world named year best arcade translation sega reception 8-bit personal computer ports published elsewhere u.s. gold mixed zx spectrum version received positive scores sinclair sinclair user reviewers crash expressed disappointment low quality contrast arcade original games machine gave spectrum version score 61 noting machine technical limitations comparison master system commodore systems commodore versions received positive average reviews though computer video games described commodore 64 port rushed amstrad cpc port received score 8 40 computer video games described travesty 37 score amstrad action reviewer considered one worst arcade conversions ever reactions 16-bit versions generally positive atari st version 1988 described computer video games far perfect came closer arcade original ports 1991 sega genesis version also received positive reviews scoring 90 french gaming magazines joypad joystick well 85 swedish magazine svenska hemdatornytt numerous follow-up titles run including run 3-d 1988 turbo run 1989 run europa 1991 outrunners 1992 run 2 rad mobile 1991 similar run game name adopted subgenre synthwave based game soundtrack selectable in-game conversion run development hertz sharp x68000 according former hertz employee tsunetomo sugawara never released due company management cancelling development likewise 32x version also reportedly development sega never released well run listed among best games time publications next generation retro gamer stuff time organizations g4 nowgamer yahoo writing 1001 video games must play die joao diniz sanches praised run unforgettable design expertly tuned game balance describing game consummate exhibit oversubscribed genre one purest joyous experiences video gaming 2015 run appeared 4th place ign list top 10 influential racing games ever behind pole position gran turismo virtua racing according luke reilly traces run dna found series like test drive need speed project gotham racing burnout well modern racers like forza horizon games driveclub former sega arcade director akira nagai credited run similar games sega arcade success 1980s according nagai run particular really amazing time ... suzuki went make burner number games run still talked special kind wonder taikan games sega arcade business sega lowest performer sales gradually started rise ... personally hang-on run memorable titles helped lift arcade industry slump created entirely new genres
|
Computer architecture
|
timeline dos operating systems article presents timeline events history x86 dos disk operating systems 1973 2016 operating systems named dos generally part scope timeline dos releases forms
|
Computer architecture
|
trusted system security engineering subspecialty computer science trusted system system relied upon specified extent enforce specified security policy equivalent saying trusted system one whose failure would break security policy policy exists trusted system trusted enforce meaning word trust critical carry meaning might expected everyday usage system trusted user one user feels safe use trusts tasks without secretly executing harmful unauthorised programs trusted computing refers whether programs trust platform unmodified expected whether programs innocent malicious execute tasks undesired user trusted system also seen level base security system protection provided handled according different levels.this commonly found military information categorized unclassified u confidential c secret top secret ts beyond.these also enforces policies no-read no-write subset trusted systems division b division implement mandatory access control mac labels often assumed used processing classified information however generally untrue four modes one operate multilevel secure system multilevel mode compartmented mode dedicated mode system-high mode national computer security center yellow book specifies b3 a1 systems used processing strict subset security labels operated according particularly strict configuration central concept u.s. department defense-style trusted systems notion reference monitor entity occupies logical heart system responsible access control decisions ideally reference monitor tamper-proof b always invoked c small enough subject independent testing completeness assured per u.s. national security agency 1983 trusted computer system evaluation criteria tcsec orange book set evaluation classes defined described features assurances user could expect trusted system key provision highest levels assurance b3 a1 dedication significant system engineering toward minimization complexity size often cited trusted computing base tcb defined combination hardware software firmware responsible enforcing system security policy inherent engineering conflict would appear arise higher-assurance systems smaller tcb larger set hardware software firmware lies outside tcb therefore untrusted although may lead technically naive sophists arguments nature trust argument confuses issue correctness trustworthiness contrast tcsec precisely defined hierarchy six evaluation classes—the highest a1 featurally identical b3 differing documentation standards—the recently introduced common criteria cc —which derive blend less technically mature standards various nato countries—provide tenuous spectrum seven evaluation classes intermix features assurances arguably non-hierarchical manner lack philosophic precision mathematical stricture tcsec particular cc tolerate loose identification target evaluation toe support—even encourage—an inter-mixture security requirements culled variety predefined protection profiles strong case made even seemingly arbitrary components tcsec contribute chain evidence fielded system properly enforces advertised security policy even highest e7 level cc truly provide analogous consistency stricture evidentiary reasoning mathematical notions trusted systems protection classified information derive two independent interrelated corpora work 1974 david bell leonard lapadula mitre working close technical guidance economic sponsorship maj. roger schell ph.d. u.s. army electronic systems command ft. hanscom devised known bell-lapadula model less trustworthy computer system modeled terms objects passive repositories destinations data files disks printers subjects active entities—perhaps users system processes threads operating behalf users—that cause information flow among objects entire operation computer system indeed regarded history serializability-theoretic sense pieces information flowing object object response subjects requests flows time dorothy denning purdue university publishing ph.d. dissertation dealt lattice-based information flows computer systems mathematical lattice partially ordered set characterizable directed acyclic graph relationship two vertices either dominates dominated neither defined generalized notion labels —corresponding less full security markings one encounters classified military documents e.g top secret wnintel tk dumbo—that attached entities bell lapadula integrated denning concept landmark mitre technical report—entitled secure computer system unified exposition multics interpretation —whereby labels attached objects represented sensitivity data contained within object though often subtle semantic difference sensitivity data within object sensitivity object labels attached subjects represented trustworthiness user executing subject concepts unified two properties simple security property subject read object dominates greater close enough—albeit mathematically imprecise—interpretation confinement property *-property subject write object dominates properties loosely referred no-read-up no-write-down respectively jointly enforced properties ensure information flow downhill repository whence insufficiently trustworthy recipients may discover extension assuming labels assigned subjects truly representative trustworthiness no-read-up no-write-down rules rigidly enforced reference monitor provably sufficient constrain trojan horses one general classes attack sciz popularly reported worms viruses specializations trojan horse concept bell-lapadula model technically enforces confidentiality secrecy controls i.e address problem sensitivity objects attendant trustworthiness subjects inappropriately disclose dual problem integrity i.e. problem accuracy even provenance objects attendant trustworthiness subjects inappropriately modify destroy addressed mathematically affine models important named creator k. j. biba integrity models include clark-wilson model shockley schell program integrity model seaview model important feature macs entirely beyond control user tcb automatically attaches labels subjects executed behalf users files access modify contrast additional class controls termed discretionary access controls dacs direct control system users familiar protection mechanisms permission bits supported unix since late 1960s and—in flexible powerful form—by multics since earlier still access control lists acls familiar examples dacs behavior trusted system often characterized terms mathematical model—which may less rigorous depending upon applicable operational administrative constraints—that takes form finite state machine fsm state criteria state transition constraints set operations correspond state transitions usually necessarily one descriptive top-level specification dtls entails user-perceptible interface e.g api set system calls unix parlance system exits mainframe parlance element engenders one model operations trusted computing group creates specifications meant address particular requirements trusted systems including attestation configuration safe storage sensitive information trusted systems context national homeland security law enforcement social control policy systems conditional prediction behavior people objects within system determined prior authorizing access system resources example trusted systems include use security envelopes national security counterterrorism applications trusted computing initiatives technical systems security use credit identity scoring systems financial anti-fraud applications general include system probabilistic threat risk analysis used assess trust decision-making authorizing access allocating resources likely threats including use design systems constraints control behavior within system ii deviation analysis systems surveillance used ensure behavior within systems complies expected authorized parameters widespread adoption authorization-based security strategies default state default=deny counterterrorism anti-fraud purposes helping accelerate ongoing transformation modern societies notional beccarian model criminal justice based accountability deviant actions occur – see cesare beccaria crimes punishment 1764 – foucauldian model based authorization preemption general social compliance ubiquitous preventative surveillance control system constraints – see michel foucault discipline punish 1975 alan sheridan tr. 1977 1995 emergent model security geared towards policing risk management surveillance exchange information auditing communication classification developments led general concerns individual privacy civil liberty broader philosophical debate appropriate forms social governance methodologies trusted systems context information theory based definition trust 'trust essential communication channel transferred source destination using channel ed gerck information theory information nothing knowledge meaning context information theory information simply transferred source destination using communication channel transmission information available destination transfer zero information received party party expect—as measured uncertainty party message likewise trust defined gerck nothing friendship acquaintances employee-employer relationships loyalty betrayal overly-variable concepts trust taken purely subjective sense either feeling something purely personal psychological—trust understood something potentially communicable definition trust abstract allowing different instances observers trusted system communicate based common idea trust otherwise communication would isolated domains necessarily different subjective intersubjective realizations trust subsystem man machines may coexist taken together model information theory information expect trust know linking concepts trust seen qualified reliance received information terms trusted systems assertion trust based record information information channels deepening questions leads complex conceptions trust thoroughly studied context business relationships also leads conceptions information quality information integrates trust trustworthiness structure information information system conceived higher quality terms particular definitions accuracy precision means higher trustworthiness introduction calculus trust example 'if connect two trusted systems less trusted taken together given ibm federal software group suggested provides useful definition trust application information technology environment related information theory concepts provides basis measuring trust network centric enterprise services environment notion trust considered requisite achieving desired collaborative service-oriented architecture vision see also trusted systems project part global information society project gisp joint research project world policy institute wpi center advanced studies sci tech policy cas
|
Computer security
|
cocoa api
|
Operating systems
|
gnustep gnustep free software implementation cocoa formerly openstep objective-c frameworks widget toolkit application development tools unix-like operating systems microsoft windows part gnu project gnustep features cross-platform object-oriented ide apart default objective-c interface gnustep also bindings java ruby gnu guile scheme gnustep developers track additions apple cocoa remain compatible roots gnustep application interface roots cocoa nextstep openstep gnustep thus predates cocoa emerged apple acquired next technology incorporated development original mac os x gnustep initially effort gnu developers replicate technically ambitious nextstep programmer-friendly features gnustep began paul kunz others stanford linear accelerator center wanted port hippodraw nextstep another platform instead rewriting hippodraw scratch reusing application design decided rewrite nextstep object layer application depended first version libobjcx enabled port hippodraw unix systems running x window system without changing single line application source openstep specification released public 1994 decided write new objcx would adhere new apis software would become known gnustep gnustep contains set graphical control elements written objective-c programming language graphical user interface gui gnumail composed graphics control elements gnumail interact windowing system e.g x11 wayland graphical user interface rendered gnustep backend provides small set functions used user interface library interface actual windowing system also rendering engine emulates common postscript functions package gnustep-back provides following backends gnustep inherits design principles proposed openstep gnustep predates cocoa cocoa based openstep well objective-c language examples applications written ported gnustep foundation kit provides basic classes wrapper classes data structure classes application kit provides classes oriented around graphical user interface capabilities
|
Operating systems
|
one patch kde2 freebsd one patch kde2 freebsd internet meme russian internet culture question originally posted anime channel rusnet irc network may 8 2004 original post followed translation здравствуйте это канал об аниме -- да -- как мне пропатчить kde2 под freebsd hello anime channel — yes — patch kde2 freebsd first question rhetorical satirized disproportionate amount technical geeky conversations often occurring channel nothing anime later popularized became widely cited russophone chats 2006 phenomenon first received public attention asked many people prior july 6 online conference russian president vladimir putin due provoking campaigns became third popular question proposed asked conference first preved vladimir vladimirovich regard medved however hosts ask question 2007 revived number one frequently asked question similar conference president kazakhstan nursultan nazarbayev nazarbayev answered question seriously describing developments industry kazakhstan possible use open-source software december 2007 question became popular one preceding internet conference ukrainian president viktor yushchenko gave answer saying programmers secretariat able help patch kde2 different operating systems also recommended adoption newer software possible reference existence kde3 time february 2014 openbsd ports developer gave overview linux vacation eastern europe conference belarus patch kde4 openbsd reviving long-lived meme new light
|
Operating systems
|
mkfs computer operating systems mkfs command used format block storage device specific file system command part unix unix-like operating systems unix block storage device must formatted file system mounted accessed operating system filesystem hierarchy command originally implemented first version unix method initialize either dectape using argument rk03 disk pack using r argument initialization process would write formatting data device contained empty file system created super-block i-list free list storage device established root directory entries .. self parent respectively rk03 disk packs 4872 available blocks initialization tapes 578 blocks 512 bytes/block mkfs executable kept /etc directory instead binary directory would inadvertently called destroy information later implementations unix-like operating systems included mkfs command including hp-ux minix sunos linux basic syntax command common modern implementations 'codice_1 type filesystem 'codice_2 target unix device write filesystem data usually device drive partition often command simply wrapper another command performs formatting specific file system example would call command codice_3 passing along appropriate arguments format device codice_4 ext3 filesystem default options command stored file codice_5 usually codice_6 directory depending implementation specific file system requested command may many options specified inode size block size volume label features see file system details filesystem-specific commands mkfs calls may invoked directly user command line linux convention name filesystem-specific commands codice_7 codice_8 abbreviation file system e.g. codice_9 codice_10 codice_11 etc file systems supported command vary implementation include msdos sco bfs cpm ext2 ext3 ext4 minix fat vfat hfs vxfs rf disk rk disk dectape ntfs
|
Computer file systems
|
need budget need budget ynab pronounced why-nab multi-platform personal budgeting program based envelope method 2013 popular personal finance software among lifehacker readers latest version dubbed new ynab launched december 30 2015 web-based application apps iphone ipad android devices previous version ynab 4 released june 2012 ynab 4 maintained 2016 company promises continue support ynab 4 users indefinitely ynab 3 released december 2009 ran multiple platforms using adobe air runtime previous versions included microsoft excel/openoffice.org calc spreadsheet implementation dubbed ynab basic discontinued july 2009 windows-only executable name ynab pro discontinued december 2009 ynab iphone released 2010 runs iphone ipod touch ipad standalone budgeting application instead designed complement ynab desktop application version tailored ipad including budgeting support released 2014 ynab android released september 2011
|
Distributed computing architecture
|
firewall pinhole computer networking firewall pinhole port protected firewall allow particular application gain access service host network protected firewall leaving ports open firewall configurations exposes protected system potentially malicious abuse fully closed firewall prevents applications accessing services side firewall protection mechanism opening pinhole firewall implement user validation authorization firewalls performing network address translation nat function mapping external ip address port socket internal ip address port socket often called pinhole pinholes created manually programmatically temporary created dynamically specific duration dynamic connection permanent signaling functions firewalls sometimes automatically close pinholes period time typically minutes minimize security exposure applications require pinhole kept open often need generate artificial traffic pinhole order cause firewall restart timer
|
Computer security
|
website correlation website correlation website matching process used identify websites similar related websites inherently easy duplicate led proliferation identical websites similar websites purposes ranging translation internet marketing especially affiliate marketing internet crime locating similar websites inherently problematic may different languages different servers different countries different top-level domains website correlation used several known types correlation demonstrating different strengths weaknesses practical website correlation process may require combining two methods save time effort website owners duplicate major portions website code across many domains similarity code structure provide enough information correlation organizations known publicly search-able databases kind correlation include note websites sometimes utilize structure relationship websites coincidentally utilize content management system also known correlated reverse dns lookup websites may served server one ip address one subnet several organizations retain archives ip address data correlate data examples include note correlation via method may misleading websites frequently exist server aka shared hosting relationship websites may authored person organization website owners required provide contact information registrar obtain domain name domain ownership determined via whois protocol provides mechanism searching correlating ownership several organizations retain archives whois information provide searching correlation services examples include note website ownership information falsified outdated hidden public view website correlation via method accurate misleading impossible depending information contained whois records search engines provide search-able databases indexed website content search engine results lists correlated content similarity note method correlation inherently slow one must guess phrases search also related websites may contain literally similar content site translated another language websites frequently categorized tagged similarly via automated manual means examples publicly accessible website categorization databases include note manual categorization tag metadata methods inherently subjective automated categorization tagging methods inherently subject varying weaknesses strengths underlying categorization algorithms tracking ids used analytics affiliate identification frequently embedded website code ids used correlation imply common management websites publicly available websites correlating tracking id include
|
Web technology
|
servage ab servage ab publ swedish cloud service provider headquartered stockholm sweden company parent company levonline servage communication servage hosting corporate name servage resulted words serve age combined almost spells company name name relates company ambition serve customers always keeping systems up-to-date modern technologies 2007 servage hosting became fully owned subsidiary tele5 voice services ab 2008 tele5 voice services ab changed name servage ab chairman tele5 voice services ab board per bergström felt servage better suited brand name international corporation
|
Distributed computing architecture
|
merchant navy united kingdom merchant navy maritime register united kingdom comprises seagoing commercial interests uk-registered ships crews merchant navy vessels fly red ensign regulated maritime coastguard agency mca king george v bestowed title merchant navy british merchant shipping fleets following service first world war number nations since adopted title merchant navy existence significant period english british history owing growth trade imperial expansion dated back 17th century attempt made register seafarers source labour royal navy times conflict registration merchant seafarers failed successfully implemented 1835 merchant fleet grew successive years become world foremost merchant fleet benefiting considerably trade british possessions india far east lucrative trades sugar contraband opium china spices tea carried ships cutty sark helped entrench dominance 19th century first second world wars merchant service suffered heavy losses german u-boat attacks policy unrestricted warfare meant merchant seafarers risk attack enemy ships tonnage lost u-boats first world war around 7,759,090 tons around 14,661 merchant seafarers killed honour sacrifice made merchant seafarers first world war george v granted title merchant navy companies 1928 george v gave edward prince wales title master merchant navy fishing fleets retained accession throne january 1936 relinquished abdication december since edward viii title held sovereigns george vi elizabeth ii united kingdom british empire entered second world war september 1939 george vi issued message anxious days would like express officers men british merchant navy british fishing fleets confidence unfailing determination play vital part defence one would say task less essential people experience allotted navy army air force upon nation depends much foodstuffs raw materials transport troops overseas long glorious history proud bear title master merchant navy fishing fleets know carry duties resolution fortitude high chivalrous traditions calling safe hands god keep prosper great task second world war german u-boats sank nearly 14.7 million tons allied shipping amounted 2,828 ships around two thirds total allied tonnage lost united kingdom alone suffered loss 11.7 million tons 54 total merchant navy fleet outbreak second world war 32,000 merchant seafarers killed aboard convoy vessels war along royal navy convoys successfully imported enough supplies allow allied victory honour sacrifices made two world wars merchant navy lays wreaths remembrance alongside armed forces annual remembrance day service 11 november following many years lobbying bring official recognition sacrifices made merchant seafarers two world wars since merchant navy day became official day remembrance 3 september 2000 ensigns displayed stern vessel displayed gaff yardarm red ensigns defaced flown warrant onboard vessel house flags personal designed company displayed port halyard yardarm despite maintaining dominant position many decades decline british empire rise use flag convenience foreign competition led decline merchant fleet example 1939 merchant navy largest world 33 total tonnage 2012 merchant navy — yet still remaining one largest world — held 3 total tonnage 2010 merchant navy consisted 504 uk registered ships addition uk merchant marine interests possessed 308 ships registered countries 271 foreign-owned ships registered uk 2012 british merchant marine interests consisted 1,504 ships included ships either directly uk-owned parent-owned managed british company amounted alternatively according annual maritime shipping statistics provided british government department transport signatory stcw convention uk ships commanded deck officers engineering officers officers undergo 3 years training known cadetship one approved maritime colleges united kingdom include warsash maritime academy south tyneside college fleetwood plymouth university city glasgow college cadets usually choice two academic routes foundation degree higher national diploma successful completion results qualification marine operations marine engineering generally costs cadetship met sponsorship uk shipping company three years training cadets also go sea period year usually spread across cadetship affords practical education along academic time college prepares candidate separate final oral exam oral exam carried master mariner office maritime coastguard agency successful completion oral exam result award certificate competency international qualification issued uk government allows officer work qualified capacity onboard ship certificates issued different ranks officer usually return complete subsequent series studies reach highest qualification first uk deck officer certificates competency issued 1845 conducted final oral exam master mariner training regime officers set official syllabus merchant navy training board training still encompasses traditional trades celestial navigation ship stability general cargo seamanship includes training business legislation law computerisation deck officers marine engineering principles workshop technology steam propulsion motor diesel propulsion auxiliaries mechanics thermodynamics engineering drawing ship construction marine electrics well practical workshop training engineering officers historically person wishing become captain master prior 1973 five choices attend one three elite naval schools age 12 fixed-base hms conway hms worcester pangbourne nautical college would automatically lead apprenticeship seagoing cadet officer apply one several training programmes elsewhere go sea immediately applying directly merchant shipping company age 17 would three years prior training four years without seagoing experience aboard ship work-clothes mates deck crew direction bo'sun cleaning bilges chipping paint polishing brass cement washing freshwater tanks holystoning teak decks studying navigation seamanship bridge uniform direction officer taking exams become second mate historically composition crew uk ships diverse characteristic extant shipping companies trade extent british empire availability crew different ports one ship might largely british crew another might crew composed many indians chinese african sailors crews outside britain usually drawn areas ship traded far east trading ships either singapore hong kong crews banana boats west indian crews ships trading west africa southern africa african crews ships trading indian ocean including east africa crews indian subcontinent crews made recruits britain commonly used ships trading across north atlantic south america australia new zealand traditionally still ships crew run bosun overseen responsible deck officer usually chief mate ship may also different sub-departments galley radio department hospitality services overseen chief cook radio officer chief steward many roles changed ships crews become smaller commercial shipping ships radio department disappeared along radio officer colloquially known 'sparks replaced changes technology requirement stcw convention deck officers hold individual certification gmdss system electro-technical officers eto also serve aboard ships trained fix maintain complex systems number notable merchant navy personnel include members uk merchant navy awarded victoria cross george cross george medal distinguished service order distinguished service cross actions serving merchant navy canadian philip bent ex-british merchant navy joined british army outbreak world war victoria cross members merchant navy served either world war also received relevant campaign medals second world war many merchant navy members received king commendation brave conduct lloyd london awarded lloyd war medal bravery sea 541 merchant navy personnel bravery 1939–45 many royal humane society medals awards conferred merchant navy seafarers acts humanity war peacetime september 2016 uk government introduced merchant navy medal meritorious service medal awarded serving served merchant navy fishing fleets uk isle man channel islands exemplary service devotion duty rewarding set outstanding example others first state award meritorious service history merchant navy recipients must nominated someone least two written letters support normally required completed 20 years service merchant navy although exceptional circumstances may less british merchant navy consists various private shipping companies decades many companies come gone merged changed name changed owners british shipping represented nationally globally uk chamber shipping headquartered london list british shipping companies past present
|
Databases
|
proiv proiv /proʊ fʊər/ low code development platform developed sold northgatearinso part northgate information solutions group active community around 2500 developers end-users worldwide ranging consultants large multinationals finance institutions tax authorities retailers engineering companies media operators software houses proiv usual application domain database-centric business applications proiv similarities languages abap focus rpg proiv programs consist declarative/non-procedural specifications control overall structure program database access implicit sequence execution proiv programmers refer timing cycle procedural subroutines added programmer written 3gl-like language proiv calls logic note proiv programs referred functions confusing differs usual use term programming languages proiv developed sushil k. garg working hawaii 1976 general automation system early 1980s licensed mcdonnell information systems mdis mdis converted proiv run pick-based systems spin known application language liberator proiv ported several different platforms separate teams garg brought ports together one company named pro computer sciences pcs headquartered laguna hills california pcs subsequently acquired mdis 1988 second half 1980s proiv team entered 4gl grand prix contests 1987 1988 1990 product finished second occasion 2000 mcdonnell information systems changed name northgate information solutions proiv supports wide variety operating systems virtue write run anywhere virtual machine model similar java proiv version 8.0 server supported platforms proiv version 8.0 supported client/browser platforms key blank supported server-side proiv applications highly portable small degree care part programmer server platform technology supported current releases includes linux microsoft windows solaris aix hp-ux openvms plus oracle db2 sql server postgresql pervasive sql rms vsam c-isam proiv also runs ibm iseries ibm mainframes programmers familiar proiv consistent nature proiv 4gl productivity proiv intended application domains typically high programmers effective even without extensive technical skills/knowledge applications implemented proiv typically runtime-efficient perform well scalability also typically good little care part programmer key feature proiv independence technologies platforms long-term users passed two three decades technological change using core functionality developed proiv fresh release proiv users immediate access latest technologies without losing development work invested existing proiv applications applications designed one platform easily switched another minimal modification proiv little object-orientation makes limited amount procedural abstraction available programmer proiv little support analytical/statistical/mathematical functions example include basic trigonometric functions proiv-supplied gui client renders rich-client ui applications written proiv based around activex technology works windows client platforms consequently programmers development environments supplied more-recent proiv releases also work windows client platform proiv inbuilt support interprocess communication ipc mechanisms although added via ability extend proiv kernel c. proiv bus task technology allowing service calls proiv application systems proprietary rather based existing standard rpc similar mechanism formal/rigorous definition syntax semantics proiv available programmers make problem resolution difficult inexperienced
|
Programming language topics
|
zimperium zimperium inc. privately owned mobile security company based united states offices dallas texas san francisco california company known developing several mobile threat defense software solutions zimperium ltd. founded 2010 chairman cto itzhak avraham 2011 elia yehuda joined co-founder 2013 assets zimperium ltd. acquired zimperium inc. new company incorporated delaware 2014 zimperium inc. released zips android app intrusion prevention system smartphone software uses machine learning monitor user habits detect prevent possible phone hacking 2015 zimperium inc. researched developed security systems group software bugs affect series android operating systems called stagefright bug 2016 company partnered blackberry partnership consisted integration zips zimperium enhancing mobile security ios android platforms zimperium inc. raised 60m private investors including samsung telstra sierra ventures softbank warburg pincus company partnered several technology companies including softbank group deutsche telekom telstra smartone oracle microsoft mobileiron january 2018 zimperium inc assigned intellectual property including granted patents trademarks ally bank security collateral zimperium inc global company hundreds customers customers include enterprises sizes large federal local government agencies leading mobile operators major oem partners
|
Computer security
|
sinch company sinch telecommunications cloud communications platform service paas company headquartered stockholm sweden sinch also offices 30 cities worldwide including atlanta london madrid san francisco singapore sydney sinch initially founded may 2014 andreas bernström stockholm san francisco originally technology behind rebtel sinch spun-out 12 million funding focusing mobile first app developer market sinch launched voice instant messaging products may 2014 quickly launched sms api product end 2014 2016 clx communications acquired sinch total consideration sek 138.9 million debt-free basis founded 2008 clx acquired numerous companies industry 2009 2018 february 2019 announced clx launched new corporate brand visual identity unify business units name acquiring sinch 2016 leveraged brand name encompass entire company accurately immediately depict current offerings mission sinch effectively inherited history clx communications considered different brand one launched 2014 clx completed initial public offering ipo listed nasdaq stockholm october 2015 since february 2019 company found mid cap list technology sector ticker 'sinch sinch platform based voice ip webrtc pstn sms verification instant messaging technologies power products provides sdk developers add app get access sinch product range available ios android javascript since sinch brand name leveraged clx communications product portfolio grown encompass services rich communications services rcs thanks strategic partnership clx google 2017 well operator portfolio inherited symsoft company acquired clx 2009 sinch listed lead411 2014 hottest san francisco companies ceo founder andreas announced one 9 innovative people voip 2014
|
Distributed computing architecture
|
windows xp editions windows xp released several editions since original release 2001 windows xp available many languages addition add-ons translating user interface also available certain languages first two editions released microsoft windows xp home edition designed home users windows xp professional designed business power users windows xp professional offers number features unavailable home edition including march 2004 european commission fined microsoft €497 million £395 million 784 million ordered company provide version windows without windows media player commission concluded microsoft broke european union competition law leveraging near monopoly market pc operating systems onto markets work group server operating systems media players unsuccessful appeals 2004 2005 microsoft reached agreement commission would release court-compliant version windows xp edition n. version include company windows media player instead encourages users pick download media player microsoft wanted call version reduced media edition eu regulators objected suggested edition n name n signifying media player home professional editions windows xp sold price version windows media player included dell hewlett-packard lenovo fujitsu siemens chosen stock product however dell offer operating system short time consumer interest low roughly 1,500 units shipped oems reported sales consumers n editions windows xp also include windows movie maker microsoft made available separate download december 2005 korean fair trade commission ordered microsoft make available editions windows xp windows server 2003 contain windows media player windows messenger like european commission decision decision based grounds microsoft abused dominant position market push products onto consumers unlike decision however microsoft also forced withdraw non-compliant versions windows south korean market k kn editions windows xp home edition professional edition released august 2006 available english korean editions contain links third-party instant messenger media player software edition windows xp home intended sale certain low-cost netbooks appear labeled windows xp home edition ulcpc ulcpc standing ultra-low-cost personal computer version comes preinstalled oem solutions providing desktops blade pc hardware addition copy windows xp professional includes remote desktop license windows xp starter edition lower-cost version windows xp available thailand vietnam turkey indonesia india philippines russia colombia brazil argentina peru bolivia chile mexico ecuador uruguay malaysia venezuela similar windows xp home limited low-end hardware run 3 programs time features either removed disabled default according microsoft press release windows xp starter edition low-cost introduction microsoft windows xp operating system designed first-time desktop pc users developing countries starter edition includes special features certain markets consumers may computer literate found home edition include localised help features may speak english country-specific computer wallpaper screensavers default settings designed easier use typical windows xp installations malaysian version example contains desktop background kuala lumpur skyline addition starter edition also unique limitations prevent displacing expensive versions windows xp three applications run starter edition application may open maximum three windows maximum screen resolution 1024×768 support workgroup networking domains addition starter edition licensed low-end processors like intel celeron amd duron sempron also 512 mb limit main memory 120 gb disk size limit microsoft made clear however total disk space per partition per disk also fewer options customizing themes desktop taskbar october 9 2006 microsoft announced reached milestone 1 million units windows xp starter edition sold mass market however starter edition much success many markets available pirated versions higher end versions windows popular legal counterparts markets non-genuine copies xp professional obtained mall stores typically charge amount cds/dvds taken files original retail value unlicensed copies windows xp professional typically cost 0.70 since uses 1 cd compared around 30 properly licensed copy xp starter edition code-named freestyle development first released september 2002 initial release available solely conjunction computers included media center capabilities could purchased separately first major update released 2004 distributed tier 1 oems previously sold windows xp media center edition pc updated 2005 first edition available system builders many features windows xp media center edition 2005 including screen dancers auto playlist dj high end visual screen savers taken windows xp plus packages originally shipped add-ons windows xp enhance users experience windows xp machine preview version windows xp media center edition microsoft ehome division shown ces 2002 final version released july 2002 2005 release microsoft focused efforts building new media center features home premium ultimate editions windows vista windows 7 windows media center built-in unlike releases windows xp media center edition available retail purchase without necessary hardware notable feature unique edition windows media center provides large-font remotely accessible interface 10-foot user interface television viewing computer well recording playback tv guide dvd playback video playback photo viewing music playback unlike competing commercial digital video recorder products microsoft charge monthly subscription fee media center tv guide service due strict hardware requirements microsoft sell media center edition retail markets alongside home professional editions microsoft distributes msdn subscribers oem system builders certain countries consumers generally purchase media center pre-installed new computer reseller sells oem versions microsoft software media center edition consumer-oriented edition windows xp updated new features annual basis five-year development windows vista mce 2005 release example includes update windows movie maker supports burning dvds new visual style called royale support media center extenders soundspectrum g-force sound visualizations microsoft also released remote control receiver infrared blaster mce 2005 new specially designed wireless computer keyboard mce 2005 released september 2005 using media center extenders xbox 360 media center edition also able connect stream recorded tv music pictures network connection media center edition retains features included windows xp professional simply add-on professional installed provided valid mce product key setup professional features left including remote desktop encrypting file system however ability join active directory domain removed marketed home product need domain support one value registry needed circumvent restriction installation mce 2005 in-place upgrade previous version already joined domain ability retained unless user uses windows media center extender case ability lost restored presumably microsoft introduced limit media center extender devices introduced version rely fast user switching component component must disabled order join domain media center higher hardware requirements editions windows xp mce 2005 requires least 1.6 ghz processor directx 9.0 hardware-accelerated gpu ati radeon 9 series nvidia geforce fx series higher 256 mb system ram functionality media center extender support use multiple tuners hdtv playback/recording carries higher system requirements media center much restricted range hardware supports software dvr solutions media center tuners must standardized driver interface originally required hardware mpeg-2 encoder closed caption support number features media center remote controls standardized terms button labels functionality degree general layout edition intended specially designed notebook/laptop computers called tablet pcs windows xp tablet pc edition compatible pen-sensitive screen supporting handwritten notes portrait-oriented screens except msdn volume license subscribers windows xp tablet edition could purchased separately tablet pc edition superset windows xp professional difference tablet functionality including alternate text input tablet pc input panel basic drivers support tablet pc specific hardware requirements install tablet pc edition include tablet digitizer touchscreen device hardware control buttons including ctrl-alt-delete shortcut button scrolling buttons least one user-configurable application button two releases service pack 2 windows xp includes tablet pc edition 2005 free upgrade version brought improved handwriting recognition improved input panel allowing used almost every application input panel also revised extend speech recognition services input correction applications windows xp tablet pc edition based windows xp professional includes software features provided addition includes following components following downloadable packs released microsoft add functionality windows xp tablet pc edition utilizes ink object means data input storage data type created part windows xp tablet pc edition api allows users manipulate process handwritten data including recognition results cases pressure information part stroke properties ink changed much way properties objects data saved allow future reference many applications referencing ink object also allow handwritten notes filtered searched based recognition results stored ink saved integrated operating system tablet pc input panel tip allows handwriting converted text use non-full-screen applications integrated handwriting recognition windows xp tablet pc edition 2005 recognize print cursive mixed writing accuracy increased configuring recognizer expect left-handed writing right-handed writing recognition variety languages available install recognizer pack handwriting engine trained recognize particular handwriting style user must modify handwriting better recognized system order use feature effectively speech recognition functionality also incorporated tablet input panel compared previous versions substantially improved speech recognition engine version 6 also ships office 2003 tutorial microphone wizard training modules included possible dictate text using speech certain supported applications control windows gui applications using speech although accuracy improvements made windows vista surpass features update windows xp tablet pc edition containing ink analysis stylusinput api support introduced windows vista also available 2006 microsoft made available two additional editions windows xp home edition hardware manufacturers wanted provide subscription-based pay go-based models selling computers editions named windows xp home edition subscription computers windows xp home edition prepaid computers respectively part microsoft flexgo initiative described company-issued press release making pcs accessible dramatically reducing entry cost enabling customers pay computer use purchase prepaid cards market trials starting first emerging markets inadequate access consumer credit unpredictable income high entry costs prevent many consumers purchasing computer editions targeted towards emerging markets india brazil hungary vietnam editions contain additional components enforce subscription models via metering metering typically enforced hardware component prevent tampering installation windows operates normal mode limited access mode hardware locked mode depending state subscription computer positive time balance operates normal mode functions regular windows xp home edition machine time balance expires machine operate limited access mode amount time set hardware manufacturer five hours default entering hardware locked mode limited access mode screen uses high-contrast low-resolution display settings hardware locked mode operating system disabled entirely message displayed boot-up instructions re-enable machine two distinct editions windows xp released support 64-bit hardware windows xp 64-bit edition designed run intel itanium family microprocessors native ia-64 mode two versions windows xp 64-bit edition released edition discontinued january 2005 hewlett-packard last distributor itanium-based workstations stopped selling itanium systems marketed 'workstations july 2005 windows xp 64-bit edition longer supported security updates made available windows xp 64-bit edition marketed itanium version microsoft windows xp editions instead separate edition made solely itanium processor 64-bit instructions mostly analogous windows xp professional numerous older technologies dao jet database ntvdm windows windows longer present support ms-dos win16 applications absent original version also lacks media applications windows media player netmeeting windows movie maker integrated cd burning although wmp netmeeting added 2003 version similar ability previous alternate architecture ports windows windows nt 4.0 powerpc mips r4x00 alpha run 16-bit x86 code via windows windows windows xp 64-bit edition run standard x86 32-bit applications wow64 windows-on-windows 64-bit emulation layer original itanium processor contains on-chip ia-32 decoder deemed far slow serious use running 400 mhz microsoft intel wrote software 32 64-bit translator dubbed ia-32 execution layer allows real time translation x86 32-bit instructions ia-64 instructions allowing 32-bit applications run albeit significantly slowly native code edition supports x86-64 extension intel ia-32 architecture x86-64 implemented amd amd64 found amd opteron athlon 64 chips selected sempron processors implemented intel intel 64 formerly known ia-32e em64t found intel pentium 4 intel later chips released april 25 2005 windows xp professional x64 edition uses version 5.2.3790.1830 core operating system binaries version used windows server 2003 sp1 latest versions operating system development even service packs updates windows xp x64 windows server 2003 x64 distributed unified packages much manner windows 2000 professional server editions x86 initial development phases 2003–2004 windows xp professional x64 edition named windows xp 64-bit edition x86 extended systems later windows xp 64-bit edition extended systems opposed 64-bit edition itanium systems rtm version windows xp professional x64 edition based windows server 2003 service pack 1 codebase reason service pack 2 windows xp x64 edition released march 13 2007 service pack 2 32-bit versions windows xp fact due earlier release date 32-bit version many key features introduced service pack 2 32-bit x86 editions windows xp already present rtm version 64-bit x86-64 counterpart service pack 2 first last released service pack windows xp professional x64 edition windows xp professional x64 edition uses technology named windows-on-windows 64-bit wow64 permits execution 32-bit x86 applications first employed windows xp 64-bit edition itanium reused x64 editions windows xp windows server 2003 since x86-64 architecture includes hardware-level support 32-bit instructions wow64 switches processor 32- 64-bit modes according microsoft 32-bit software running wow64 similar performance executing 32-bit windows fewer threads possible overheads 32-bit processes shown *32 task manager 64-bit processes extra text present although 32-bit applications run transparently mixing two types code within process allowed 64-bit application link 32-bit library dll similarly 32-bit application link 64-bit library may lead need library developers provide 32- 64-bit binary versions libraries windows xp x64 edition includes 32- 64-bit versions internet explorer 6 order allow possibility third-party browser plugins activex controls may yet available 64-bit versions older 32-bit drivers services supported 64-bit windows video audio codecs xvid oggds 32-bit dlls supported long media player uses 32-bit well 64-bit windows include ntvdm windows windows native support execution ms-dos 16-bit windows applications written windows 3.1 primary benefit moving 64-bit increase maximum allocatable virtual memory single standard process 32-bit windows operating system limited total 2,093,056 kilobytes 2gb minus one 4kb page large address aware 32-bit processes allocate 4gb windows xp x64 support much memory although theoretical memory limit 64-bit computer address 16exabytes windows xp x64 limited 128gb physical memory 8 terabytes virtual memory per process practical limit usually size pagefile windows xp professional x64 edition windows xp 64-bit edition version 2003 releases windows xp include internet information services 6.0 matches version shipped windows server 2003 versions xp include 5.1 64-bit versions windows xp also immune certain types viruses malware target 32-bit systems since system files 64-bit extra registers x86-64 architecture result performance improvements certain kinds applications often result slight decrease performance compared application implemented 32 bit x86 code running windows xp 32 bit editions microsoft released number editions windows xp targeted towards developers embedded devices use specific consumer electronics set-top boxes kiosks/atms medical devices arcade video games point-of-sale terminals voice internet protocol voip components editions belong windows embedded subfamilies windows xp embedded systems binary identical windows xp professional licensed embedded devices windows xp embedded commonly abbreviated xpe componentized version professional edition windows xp original equipment manufacturer free choose components needed thereby reducing operating system footprint also reducing attack area compared xp professional unlike windows ce microsoft operating system portable devices consumer electronics xp embedded provides full windows api support full range applications device drivers written microsoft windows system requirements state xpe run devices least 32 mb compact flash 32 mb ram p-200 microprocessor xpe released november 28 2001 october 2008 newest release windows xp embedded service pack 3 devices targeted xpe included automatic teller machines arcade games slot machines cash registers industrial robotics thin clients set-top boxes network attached storage nas time clocks navigation devices railroad locomotives etc custom versions os deployed onto anything full-fledged pc even though xpe supports hardware xp professional supports x86 architecture licensing restrictions prevent deployed standard pcs however microsoft made exceptions rule allowing xpe alongside standard oem install windows dell notebooks contain embedded xp installation part mediadirect 2.0 feature also found acer ones well samsung q1 windows embedded standard 2009 succeeded xpe 2h 2008 windows embedded standard 2009 derived windows xp embedded since microsoft time development componentized version windows vista windows embedded standard 2009 includes silverlight .net framework 3.5 internet explorer 7 windows media player 11 rdp 6.1 network access protection microsoft baseline security analyzer support managed windows server update services system center configuration manager windows embedded standard 7 succeeded windows embedded standard 2009 april 2010 componentized version windows 7 windows embedded point service wepos specialization windows xp embedded released may 25 2005 focuses point sale device market fuel pumps self checkout stations automated teller machines cash registers available purchase directly microsoft instead licensed original equipment manufacturers windows embedded posready 2009 succeeded wepos january 2009 windows embedded posready 2009 derived wepos since microsoft time development componentized version windows vista windows embedded posready 7 succeeded windows embedded posready 2009 july 2011 based windows 7 sp1 july 2006 microsoft introduced thin-client variant windows xp embedded called windows fundamentals legacy pcs targets older machines early original pentium available software assurance customers intended would like upgrade windows xp take advantage security management capabilities afford purchase new hardware windows thin pc succeeded windows fundamentals legacy pcs june 2011 based windows embedded standard 7 sp1
|
Operating systems
|
playstation portable system software playstation portable system software official firmware playstation portable uses xrossmediabar xmb user interface similar playstation 3 console updates add new functionality well security patches prevent homebrew applications plugins executed system updates obtained four ways system software updates used consoles region sony recommends downloading system software updates released region corresponding system place purchase system software updates added various features including web browser adobe flash player 6 support additional codecs images audio video playstation 3 connectivity well patches several security exploits vulnerabilities execution homebrew programs battery must least 50 charged else system prevent update installing power supply lost writing system software console longer able operate unless system booted service mode sent sony repair still warranty current version software 6.61 made available january 15 2015 minor update released three years release previous version 6.60 2011 playstation portable uses xrossmediabar xmb graphical user interface also used playstation 3 ps3 console variety sony bravia hdtvs blu-ray disc players many sony products xmb displays icons horizontally across screen seen categories users navigate using left right buttons d-pad move icons forward back across screen highlighting one time opposed using kind pointer select option one category selected usually specific options available select spread vertically selected icon users may navigate among options using buttons d-pad basic features offered xmb implementations varies based device software version psp console xmb top level icons photos music videos games networking allows use web browser settings extras also xmb offers degree multitasking psp using home button playing music would allow users browse photos without stopping music xmb proved successful user interface sony products psp ps3 next generation sony video game consoles playstation 4 playstation vita longer use user interface example xmb replaced livearea interface ps vita playstation portable comes web browser browsing internet web browser version netfront browser made access co. ltd. released free 2.00 system software update browser supports common web technologies http cookies forms css well basic javascript capabilities version 2.50 upgrade added unicode utf-8 character encoding auto-select options browser encoding menu also introduced saving input history online forms version 2.70 psp system software introduced basic flash capabilities browser however player runs flash version 6 five iterations behind current desktop version 11 making websites difficult view three different rendering modes normal just-fit smart-fit normal display page changes just-fit attempt shrink elements make whole page fit screen preserve layout smart-fit display content order appears html size adjustments instead drop element preceding element starts go screen browser also limited tabbed browsing maximum three tabs website tries open link new window browser opens new tab parents limit content enabling browser start control blocks access web browser creating 4-digit pin settings security additionally browser configured run proxy server protected security pin enable use web filtering monitoring software network recently trendmicro psp added feature enabled via subscription filter monitor content psp psp browser slower compared modern browsers often runs memory due limitations put place sony alternatively homebrew allowed custom version browser released utilizes 32/64 mb psp ram allows browser load pages faster memory larger pages opera mini also used psp pspkvm homebrew application sun java virtual machine claimed provide much faster loading times default browser provides better web page compatibility like many video game consoles playstation portable capable photo audio video playback variety formats however unlike sony home consoles playstation 3 playstation 4 possible play blu-ray dvd movies playstation portable directly since lacks standard blu-ray dvd drive umd drive exist umd movies umd format never saw implementation device playstation portable result market limited compared optical media formats movies released umd since 2011 final harry potter movie one final releases format playstation portable also supports feature known remote play allows psp access many features playstation 3 console remote location using ps3 wlan capabilities home network internet however unlike later remote play feature playstation vita playstation 4 remote play capabilities psp ps3 much limited although ps3 capabilities related main user interface accessible remote play playback dvds blu-ray discs playstation 2 games playstation 3 games copy-protected files stored ps3 hard drive supported actual remote play psp ps3 games supported select ps3 titles furthermore psp-2000 psp-3000 psp-n1000 use skype voip service starting system software version 3.90 service allows skype calls made wi-fi psp go bluetooth modem feature possible use voip service original psp-1000 console due hardware limitations also existed services psp room playstation portable similar playstation 3 online community-based service known playstation home homebrew development popular time playstation portable besides official firmware ofw made sony custom firmware also written custom firmware simply cfw also commonly seen playstation portable handheld consoles custom firmware allows running unsigned code homebrew applications umd backups emulators consoles well psone games disc images converted psp format unlike official system software usually allow signed retailed copies software run famous custom firmware include m33 custom firmware dark_alex well made others custom firmware 5.50gen series minimum edition me/lme cfw pro cfw since early days hackers working psp discovered exploits system software 1.00 1.50 allowed run unsigned code psp many psp-1000 users downgraded consoles versions order install custom firmware corresponding higher version system software later exploits discovered recent versions system software allowing installation homebrew content sony put significant effort blocking custom firmware third party devices content psp consoles effort quite successful psp july 2007 dark_alex officially stopped work psp citing perceived problems sony one reasons departure custom firmware continue developed updated however would different successor playstation vita unlike psp currently native cfw ps vita besides popular henakau exploit allowed users run unsigned code n't technically custom firmware exists ecfw ps vita meaning custom firmware psp running psp emulator ps vita features ecfw expected much limited real cfw ps vita unless usage adrenaline homebrew upgrade existing emulator adds usb support fixed ps1 emulation blue colour filter gaming platforms sony gaming platforms next generation gaming platforms generation
|
Operating systems
|
secure-adaptive architecture pertaining web services secure-adaptive architecture saa refers particular approach towards security management issues inherent data transfer computer networks relating certain services micropayments saa personal information end-user name banking information personal identity numbers social security numbers retained two main benefits end-user chance identity theft fraud considerably reduced service provider means direct communication end-user financial institution unnecessary saa uses best class proven security techniques ensure safe transfer data network resources include protocols ssl communications client-side authentication aes encryption saa requires consistent pervasive real-time monitoring network resources ensure security
|
Web technology
|
banburismus banburismus cryptanalytic process developed alan turing bletchley park britain second world war used bletchley park hut 8 help break german kriegsmarine naval messages enciphered enigma machines process used sequential conditional probability infer information likely settings enigma machine gave rise turing invention ban measure weight evidence favour hypothesis concept later applied turingery methods used breaking lorenz cipher aim banburismus reduce time required electromechanical bombe machines identifying likely right-hand middle wheels enigma hut 8 performed procedure continuously two years stopping 1943 sufficient bombe time became readily available banburismus development clock method invented polish cryptanalyst jerzy różycki hugh alexander regarded best banburists i. j good considered process intellectual game job easy enough trivial difficult enough cause nervous breakdown first months arriving bletchley park september 1939 alan turing correctly deduced message-settings kriegsmarine enigma signals enciphered common grundstellung starting position rotors super-enciphered bigram trigram lookup table trigram tables book called kenngruppenbuch k book however without bigram tables hut 8 unable start attacking traffic breakthrough achieved narvik pinch disguised armed trawler polares way narvik norway seized north sea 26 april 1940 germans time destroy cryptographic documents captured material revealed precise form indicating system supplied plugboard connections grundstellung 23 24 april operators log gave long stretch paired plaintext enciphered message 25th 26th bigram tables part capture hut 8 able use settings-lists read retrospectively kriegsmarine traffic intercepted 22 27 april allowed partial reconstruction bigram tables start first attempt use banburismus attack kriegsmarine traffic 30 april onwards eligible days least 200 messages received partial bigram-tables deciphered indicators first day broken 8 may 1940 thereafter celebrated foss day honour hugh foss cryptanalyst achieved feat task took november year time intelligence date show banburismus could work also allowed much bigram tables reconstructed turn allowed 14 april 26 june broken however kriegsmarine changed bigram tables 1 july end 1940 much theory banburismus scoring system worked first lofoten pinch trawler krebs 3 march 1941 provided complete keys february – bigram tables k book consequent decrypts allowed statistical scoring system refined banburismus could become standard procedure kriegsmarine enigma mid-1943 banburismus utilised weakness indicator procedure encrypted message settings kriegsmarine enigma traffic unlike german army airforce enigma procedures kriegsmarine used grundstellung provided key lists messages particular day pair days meant three-letter indicators enciphered rotor settings depth normally indicators two messages never could happen part-way message rotor positions became starting position rotors another message parts two messages overlapped way depth principle behind banburismus relatively simple seems rather similar index coincidence two sentences english german written one count made often letter one message corresponding letter message matches would occur sentences random strings letters random sequence repeat rate single letters expected 1 26 around 3.8 german navy messages shown 1 17 5.9 two messages depth matches occur plaintexts however messages depth two ciphertexts compare random giving repeat rate 1 26 allows attacker take two messages whose indicators differ third character slide looking giveaway repeat pattern shows align depth comparison two messages look repeats made easier punching messages onto thin cards 250 mm high 10 several metres wide different cards different lengths message hole top column card represented position hole bottom represented z two message-cards laid top light-box light shone repeat made much simpler detect count repeats cards printed banbury oxfordshire became known 'banburies bletchley park hence procedure using banburismus application scritchmus procedure see gives clue possible right-hand rotor message indicator vfg xcybgdslvwbdjlkwipehvygqzwdthrqxikeesqsspzxarixeabqiruckhgwuebpf message indicator vfx ynscfccpvipemsgizwflhesciyspvrxmcfqaxvxdvuqilbjuabnlkmkdjmenunq hut 8 would punch onto banburies count repeats valid offsets −25 letters +25 letters two promising positions offset eight letters shows nine repeats including two bigrams overlap 56 letters 16 promising position looks like offset seven shows single trigram overlap 57 letters turing method accumulating score number decibans allows calculation situations likely represent messages depth might expected former winner odds 5:1 latter 2:1 turing calculated scores number single repeats overlaps many letters number bigrams trigrams tetragrams often represented german word plaintext scores calculated according type message traffic analysis even position within message tabulated relevant values summed banburists assessing pairs messages see likely depth bletchley park used convention indicator plaintext vfx eight characters ahead vfg terms third differing letter x g+8 scritchmus part banburismus procedure could lead identification right-hand fast wheel banburist might evidence various message-pairs third indicator letter differing showing x q−2 h x−4 b g+3 would search deciban sheets distances odds better 1:1 i.e scores ≥ +34 attempt made construct 'end wheel alphabet forming 'chains end-wheel letters repeats could construct chain follows compared progressive offsets known letter-sequence enigma rotor quite possibilities discounted due violating either reciprocal property no-self-ciphering property enigma machine so-called end-wheel alphabet already limited nine possibilities merely establishing letter-chain five letters derived mere four message-pairs hut 8 would try fitting letter-chains — ones letters common first chain — nine candidate end-wheel alphabets eventually hope left one candidate maybe looking like end-wheel alphabet forces conclusion end wheel fact rotor rotor ii would caused mid-wheel turnover stepped e f yet middle span letter-chain f -- -- -- -- -o likewise possible mid-wheel turnovers precluded rotor turnover q r part alphabet spanned chain different enigma wheels different turnover points presumably measure designers machine improve security however complication allowed bletchley park deduce identity end wheel end wheel identified principles extended handle middle rotor though added complexity search overlaps message-pairs sharing first indicator letter overlaps could therefore occur 650 characters apart workload beyond manual labour bp punched messages onto 80-column cards used hollerith machines scan tetragram repeats better told banburies set light boxes overlap evaluate whole repeat pattern armed set probable mid-wheel overlaps hut 8 could compose letter-chains middle wheel much way illustrated end wheel turn scritchmus would give least partial middle wheel alphabet hopefully least possible choices rotor middle wheel could eliminated turnover knowledge done identifying end wheel taken together probable right hand middle wheels would give set bombe runs day would significantly reduced 336 possible
|
Computer security
|
optware optware free software package manager embedded systems originally developed distribution mechanism unslung linux distribution linksys nslu2 optware adopted variety hobbyist communities device developers optware used number platforms including webos community working palm pre pixi wl-500g wl-hdd wl-500gx wl-500gp asus routers plug computers pogoplug v1 v2 pro biz dockstars etc asustor synology nas devices late 2010 first optware android released novaports team nook color optware packages currently run following devices
|
Operating systems
|
hbgary hbgary subsidiary company mantech international focused technology security past two distinct affiliated firms carried hbgary name hbgary federal sold products us federal government hbgary inc. clients included information assurance companies computer emergency response teams computer forensic investigators february 29 2012 hbgary inc. announced acquired services firm mantech international time hbgary federal reported closed company founded greg hoglund 2003 2008 joined mcafee security innovation alliance ceo made presentations black hat briefings rsa conference computer security conferences hbgary also analyzed ghostnet operation aurora events 2010 offices sacramento california washington d.c. bethesda maryland hbgary federal set aaron barr ceo instead hoglund provide services tools us government might require security clearance hbgary federal could meet revenue projections early 2011 negotiations sale hbgary federal progress two interested companies hbgary acquired mantech international february 2012 2010 aaron barr ceo hbgary federal alleged could exploit social media gather information hackers early 2011 barr claimed used techniques infiltrate anonymous partly using irc facebook twitter social engineering e-mails depict intention release information identities anonymous members b-sides conference sell possible clients including fbi e-mails barr explained identified list suspected anonymous members tracing connections social media main programmer criticized methodology communiqué anonymous denied association individuals barr named february 5–6 2011 anonymous compromised hbgary website copied tens thousands documents hbgary federal hbgary inc. posted tens thousands companies emails online usurped barr twitter account apparent revenge anonymous also claimed wiped barr ipad remotely though act remains unconfirmed anonymous group responsible attacks would go become lulzsec documents taken anonymous show hbgary federal working behalf bank america respond wikileaks planned release bank internal documents potential proactive tactics wikileaks include feeding fuel feuding groups disinformation creating messages around actions sabotage discredit opposing organization submitting fake documents wikileaks calling error additional emails published november 2016 wikileaks two employees hbgary referenced blog post endorsed manipulating translation software order 'mitigate damaging content within information leaks emails indicate palantir technologies berico technologies law firm hunton williams recommended bank america us justice department cooperated project e-mails appear show u.s. chamber commerce contracted firms spy discredit unions liberal groups conflict anonymous caused substantial public relations damage result involved organizations took steps distance hbgary hbgary federal reported hbgary federal contracted us government develop astroturfing software could create army multiple fake social media profiles later reported data security firm hbgary federal among persona management software contract bidders listed government website job ultimately awarded firm appear fedbizopps.gov page interested vendors contract awarded firm called ntrepid speaks wrote raw story hbgary made numerous threats cyber-attacks wikileaks dossier recently exposed emails revealed hbgary inc. working development new type windows rootkit code named magenta would undetectable almost impossible remove october 2010 greg hoglund proposed barr creating large set unlicensed windows 7 themes video games movies appropriate middle east asia would contain back doors part ongoing campaign attack support wikileaks products integrated products i.e recon digital dna responder 29 february 2012 mantech international announced purchase hbgary inc. financial terms acquisition disclosed say asset purchase excludes legal financial liabilities
|
Computer security
|
eric corley eric gordon corley born december 16 1959 also frequently referred pen name emmanuel goldstein figure hacker community directs non-profit organization 2600 enterprises inc. publishes magazine called associated monthly meet-ups around world hosts hacker convention hackers planet earth hope pseudonym derived fictional opposition leader george orwell dystopian novel nineteen eighty-four 1993 corley testified united states house representatives subcommittee telecommunications corley questioned relation content 2600 part discussions concerning digital telephony bill also known communications assistance law enforcement act corley editor best 2600 hacker odyssey released july 2008 book consists articles magazine set chronological order show evolution internet technology follow-up book dear hacker letters editor 2600 published 2010 corley host weekly radio programs hook wbai-fm wall wusb-fm hook often includes panel guests frequently centered technological topics wall usually narrated eric corley covered wide range topics hook air since 1988 corley directed 2001 film freedom downtime documentary incarcerations kevin mitnick bernie also examines alleged distortions mainstream media coverage mitnick case
|
Computer security
|
amd k8 amd k8 hammer also code-named sledgehammer computer processor microarchitecture designed amd successor amd k7 athlon microarchitecture k8 first implementation amd64 64-bit extension x86 instruction set architecture processors based k8 core include k8 core similar k7 radical change integration amd64 instructions on-chip memory controller memory controller drastically reduces memory latency largely responsible performance gains k7 k8 perceived pc community use codename k8 athlon 64 processor family amd longer uses k-nomenclatures originally stood kryptonite since k-nomenclature naming convention beyond k8 appeared official amd documents press releases beginning 2005 amd refers codename k8 processors family 0fh processors 10h 0fh refer main result cpuid x86 processor instruction hexadecimal numbering 0f h h represents hexadecimal numbering equals decimal number 15 10 h equals decimal number 16 k10h form sometimes pops improper hybrid k code family identifier number
|
Computer architecture
|
natural language toolkit natural language toolkit commonly nltk suite libraries programs symbolic statistical natural language processing nlp english written python programming language developed steven bird edward loper department computer information science university pennsylvania nltk includes graphical demonstrations sample data accompanied book explains underlying concepts behind language processing tasks supported toolkit plus cookbook nltk intended support research teaching nlp closely related areas including empirical linguistics cognitive science artificial intelligence information retrieval machine learning nltk used successfully teaching tool individual study tool platform prototyping building research systems 32 universities us 25 countries using nltk courses nltk supports classification tokenization stemming tagging parsing semantic reasoning functionalities
|
Computational linguistics
|
abstraction principle computer programming software engineering programming language theory abstraction principle principle abstraction basic dictum aims reduce duplication information program usually emphasis code duplication whenever practical making use abstractions provided programming language software libraries principle sometimes stated recommendation programmer sometimes stated requirement programming language assuming self-understood abstractions desirable use origins principle uncertain reinvented number times sometimes different name slight variations read recommendation programmer abstraction principle generalized n't repeat principle recommends avoiding duplication information general also avoiding duplication human effort involved software development process recommendation programmer formulation benjamin c. pierce types programming languages 2002 abstraction principle reads emphasis original requirement programming language formulation david a. schmidt structure typed programming languages 1994 abstraction principle reads name abstraction principle appears long list books give necessarily incomplete list together formulation succinct principle plays central role design patterns object-oriented programming although writings topic give name principle influential book gang four states focus encapsulating concept varies theme many design patterns statement rephrased authors find varies encapsulate century principle reinvented extreme programming slogan definition principle rather succinct first appearance duplicate code later elaborated applicable issues software development automate every process worth automating find performing task many times script abstraction principle often stated context mechanism intended facilitate abstraction basic mechanism control abstraction function subroutine data abstractions include various forms type polymorphism elaborate mechanisms may combine data control abstractions include abstract data types including classes polytypism etc quest richer abstractions allow less duplication complex scenarios one driving forces programming language research design inexperienced programmers may tempted introduce much abstraction program—abstraction wo n't used complementary principle emphasize issue ai n't gon na need generally kiss principle since code usually subject revisions following abstraction principle may entail refactoring code effort rewriting piece code generically needs amortized estimated future benefits abstraction rule thumb governing devised martin fowler popularized rule three states piece code copied twice i.e would end three copies needs abstracted n't repeat dry principle generalization developed context multi-tier architectures related code necessity duplicated extent across tiers usually different languages practical terms recommendation rely automated tools like code generators data transformations avoid repetition addition optimizing code hierarchical/recursive meaning abstraction level programming also refers interfaces hardware communication layers also called abstraction levels abstraction layers case level abstraction often synonymous interface example examining shellcode interface higher lower level languages level abstraction changes operating system commands example c register circuit level calls commands example assembly binary case example boundary interface abstraction levels stack
|
Programming language topics
|
mcdram multi-channel dram mcdram pronounced em cee dee ram 3d-stacked dram used intel xeon phi processor codenamed knights landing version hybrid memory cube developed partnership micron competitor high bandwidth memory many cores xeon phi processors along associated vector processing units enable consume many gigabytes per second traditional dram dimms supply multi-channel part mcdram full name reflects cores many channels available access mcdram processors access attached dimms high channel count leads mcdram high bandwidth 400+ gb/s although latencies similar dimm access physical placement processor imposes limits capacity 16 gb launch much smaller capacity off-package dram 384gb memory partitioned boot time used cache distant ddr remainder mapped physical address space application request pages virtual memory assigned either distant ddr directly portion ddr cached mcdram portion mcdram used cache one way via thecodice_1 api used cache latency miss accessing mcdram ddr slightly higher going directly ddr applications may need tuned avoid excessive cache misses
|
Computer architecture
|
linux mobile devices learned article linux range use linux kernel-based operating systems ubiquitously found diverse hardware platforms article linux mobile devices use linux kernel-based operating systems sorts mobile devices whose primary human interface device hid touchscreen mainly comprises smartphones tablet computers also mobile phones personal digital assistants pdas portable media players come touchscreen separately list many linux kernel-based operating systems used mobile devices differ one another parts middleware entire middleware employ individual uis
|
Operating systems
|
alchemy microarchitecture alchemy microarchitecture low power microprocessor design developed alchemy semiconductor implementing mips32 instruction set mips technologies first processor implementing au1 central processing unit products include amd alchemy au1000 au1550 sun ray 2 family thin clients. several cowon pmp devices dell drac5 remote administration cards airport extreme base station embedded products networking sun microsystems 4g systems mtx-1 accesscube meshcube alchemy semiconductor fabless semiconductor company based austin texas founded may 2000 purchased license mips architecture mips32 instruction set mips technologies developed au1 microprocessor au1000 au1550 socs alchemy semiconductor acquired amd 2002 summer 2006 sold alchemy processor line raza microelectronics december 2007 raza microelectronics changed name rmi corporation june 2009 netlogic microsystems acquired rmi 183.4 million stock september 2011 broadcom acquired netlogic shares transaction valued around 3.7bn
|
Computer architecture
|
readyboost readyboost codenamed emd disk caching software component developed microsoft windows vista included later versions windows operating system readyboost enables nand memory mass storage devices including compactflash sd cards usb flash drives used write cache hard drive random access memory effort increase computing performance readyboost relies superfetch technology like superfetch adjusts cache based user activity features including readydrive implemented manner similar readyboost using readyboost-capable flash memory nand memory devices caching allows windows vista later service random disk reads better performance without cache caching applies disk content page file system dlls flash devices typically slower mechanical hard disk sequential i/o maximize performance readyboost includes logic recognizes large sequential read requests hard disk service requests compatible device plugged windows autoplay dialog offers additional option use flash drive speed system additional readyboost tab added drive properties dialog amount space used configured minimum cache size 250 mb vista fat32 formatting drive maximum 4 gb windows 7 ntfs exfat formatting maximum cache size 32 gb per device windows vista allows one device used windows 7 allows multiple caches one per device total 256 gb readyboost compresses encrypts data placed flash device aes-128 microsoft stated 2:1 compression ratio typical 4 gb cache would usually contain 8 gb data device compatible useful must conform requirements considerations readyboost available windows server 2008 according jim allchin future releases windows readyboost able use spare ram networked windows pcs system 512 mb ram minimum requirement windows vista see significant gains readyboost one test case adding 1 gb readyboost memory sped operation 11.7 seconds 2 seconds however increasing physical memory ram 512 mb 1 gb without readyboost reduced 0.8 seconds system performance readyboost monitored windows performance monitor price ram decreased ram installed computers mitigations provided readyboost systems insufficient memory decreased core idea readyboost flash memory e.g usb flash drive ssd much faster seek time typical magnetic hard disk less 1 ms allowing satisfy requests faster reading files hard disk also leverages inherent advantage two parallel sources read data whereas windows 7 enables use eight flash drives allowing nine parallel sources usb 2.0 flash drives slower sequential reads writes modern desktop hard drives desktop hard drives sustain anywhere 2 10 times transfer speed usb 2.0 flash drives equal slower usb 3.0 firewire ieee 1394 sequential data usb 2.0 faster flash drives faster random access times typically around 1 ms compared 12 ms mainstream desktop hard drives laptop computers performance shifts favor flash memory laptop memory expensive desktop memory many laptops also relatively slow 4200 rpm 5400 rpm hard drives versions vista prior sp1 readyboost failed recognize cache data upon resume sleep restarted caching process making readyboost ineffective machines undergoing frequent sleep/wake cycles problem fixed vista sp1 since flash drives wear finite though large number writes readyboost eventually wear drive uses according microsoft windows client performance group drive able operate least ten years
|
Operating systems
|
privacy software privacy software software built protect privacy users software typically works conjunction internet usage control limit amount information made available third parties software apply encryption filtering various kinds privacy software refer two different types protection one type protecting user internet privacy world wide web software products mask hide user ip address outside world order protect user identity theft second type protection hiding deleting users internet traces left pc surfing internet software erase users internet traces software hide encrypt user traces others using pc know surfing one solution enhance privacy software whitelisting whitelisting process company identifies software allow try recognize malware whitelisting permits acceptable software run either prevents anything else running lets new software run quarantined environment verify validity whereas whitelisting allows nothing run unless whitelist blacklisting allows everything run unless black blacklist includes certain types software allowed run company environment example company might blacklist peer-to-peer file sharing systems addition software people devices web sites also whitelisted blacklisted intrusion detection systems designed detect types malicious network traffic computer usage detected firewall systems capture network traffic flows examine contents packet malicious traffic encryption another form privacy security organizations secure channel sending information use encryption stop unauthorized eavesdroppers encryption process converting original message form read anyone except intended receiver steganography sometimes used hide messages eavesdropping e-surveillance privacy different anonymity applicability usage anonymity subordinate privacy might desired exchange retrieval publication specific information uses privacy software free legal issues instance regulations export cryptography united states similarly key disclosure law also requires individuals surrender cryptographic keys law enforcement agencies encryption laws india also carry many legal restrictions diverse situations. ref name= http //perry4law.co.in/blog/ p=67 /ref talks also pipeline include cyber security technologies like encryption related software wassenaar arrangement thereby making export cumbersome. ref name= http //perry4law.co.in/cyber_security/ p=61 /ref
|
Computer security
|
esafe esafe protect previously known eliashim antivirus line software security products developed eliashim ltd. based haifa israel. distributed esafe technologies inc. seattle usa eliashim acquired aladdin knowledge systems december 1998. esafe protect consumer desktop version distributed aladdin discontinued 2002 following years esafe brand evolved gateway-based fully featured content security product sold aladdin knowledge systems integrated security appliance march 2009 aladdin knowledge systems merged safenet inc. esafe evolved become safenet esafe content security product line
|
Computer security
|
bitmessage bitmessage decentralized encrypted peer-to-peer trustless communications protocol used one person send encrypted messages another person multiple subscribers june 2013 software experienced surge new adoptions news reports email surveillance us national security agency bitmessage conceived software developer jonathan warren based design decentralized digital currency bitcoin software released november 2012 mit license bitmessage gained reputation reach warrantless wiretapping conducted national security agency nsa due decentralized nature protocol encryption difficult crack result downloads bitmessage program increased fivefold june 2013 news broke classified email surveillance activities conducted nsa bitmessage also mentioned experimental alternative email popular science cnet ransomware programs instruct affected users use bitmessage communicate attackers
|
Computer security
|
domainkeys domainkeys informally dk deprecated e-mail authentication system designed yahoo verify domain name e-mail sender message integrity aspects domainkeys along parts identified internet mail combined create domainkeys identified mail dkim widely used domainkeys dkim published may 2007 domainkeys historical protocol dkim standards-track replacement
|
Computer security
|
dma attack dma attack type side channel attack computer security attacker penetrate computer device exploiting presence high-speed expansion ports permit direct memory access dma dma included number connections lets connected device camcorder network card storage device useful accessory internal pc card transfer data computer maximum speed possible using direct hardware access read write directly main memory without operating system supervision interaction legitimate uses devices led wide adoption dma accessories connections attacker equally use facility create accessory connect using port potentially gain direct access part physical memory address space computer bypassing os security mechanisms lock screen read computer steal data cryptographic keys install run spyware exploits modify system allow backdoors malware preventing physical connections ports prevent dma attacks many computers connections implementing dma also disabled within bios uefi unused depending device nullify reduce potential type exploit examples connections may allow dma exploitable form include firewire cardbus expresscard thunderbolt pci pci express modern operating systems non-system i.e user-mode applications prevented accessing memory locations explicitly authorized virtual memory controller called memory management unit mmu addition containing damage may caused software flaws allowing efficient use physical memory architecture forms integral part security operating system however kernel-mode drivers many hardware devices user-mode vulnerabilities allow direct unimpeded access physical memory address space physical address space includes main system memory well memory-mapped buses hardware devices controlled operating system reads writes ordinary ram ohci 1394 specification allow devices performance reasons bypass operating system access physical memory directly without security restrictions sbp2 devices easily spoofed allowing operating system tricked allowing attacker read write physical memory thereby gain unauthorised access sensitive cryptographic material memory systems may still vulnerable dma attack external device firewire expresscard thunderbolt expansion port like pci pci express general connects attached devices directly physical rather virtual memory address space therefore systems firewire port may still vulnerable pcmcia/cardbus/pc card expresscard port would allow expansion card firewire installed attacker could example use social engineering attack send lucky winner rogue thunderbolt device upon connecting computer device direct unimpeded access physical address space would able bypass almost security measures os ability read encryption keys install malware control system devices attack also easily executed attacker physical access target computer addition abovementioned nefarious uses beneficial uses dma features used kernel debugging purposes tool called inception attack requiring machine expansion port susceptible attack another application known exploit vulnerability gain unauthorized access running windows mac os linux computers spyware finfirewire dma attacks prevented physical security potentially malicious devices kernel-mode drivers many powers compromise security system care must taken load trusted bug-free drivers example recent 64-bit versions microsoft windows require drivers tested digitally signed microsoft prevent non-signed drivers installed iommu technology applies concept virtual memory system busses may used close security vulnerability well increase system stability intel brands iommu vt-d. amd brands iommu amd-vi linux supports iommus use block i/o transactions allowed however iommus mostly used instead give guest virtual machines passthrough access host hardware newer operating systems may take steps prevent dma attacks recent linux kernels include option disable dma firewire devices allowing functions windows 8.1 prevent access dma ports unattended machine console locked never allowing sensitive data stored ram unencrypted another mitigation venue dma attacks however protection reading ram content enough writing ram via dma may compromise seemingly secure storage outside ram code injection example latter kind attack tresor-hunt exposes cryptographic keys never stored ram certain cpu registers tresor-hunt achieves overwriting parts operating system microsoft recommends changes default windows configuration prevent concern
|
Computer security
|
trusted email open standard trusted email open standard teos anti-spam technique proposed eprivacy group 2003 federal trade commission anti-spam summit edited stephen cobb cissp 35-page white paper describing standard downloaded 30,000 times publication april 2003 end year many elements teos later appeared letter microsoft ceo bill gates submitted u.s. senate commerce committee hearings anti-spam legislation letter outlined microsoft position spam crisis handled basic level teos proposes framework trusted identity email senders based secure fast lightweight signatures email headers optimized dns-based systems flexibility ease implementation teos also provides common-language framework making trusted assertions content individual message isps email recipients rely assertions manage email
|
Computer security
|
ximss xml interface messaging scheduling signaling ximss xml-based api ip communications ximss api introduced communigate systems communigate pro often referred cgp server starting version 5.1 summer 2006 announcement described ximss based open proposed standard ximss based previous xml rfcs clear whether formal proposal defining ximss standards body communigate explicitly specify rfc referring basis ximss server implementation ximss communigate pro applications publicly available using ximss communigate flash-based pronto integrated messaging client explicitly clear documentation whether ximss freely implemented servers clients without permission communigate description open implies level freedom expressed purpose ximss offer single client interface based widely-familiar open technologies i.e http xml complex communications services email calendaring im voip etc provided one server specified ximss intrinsically bound cgp server however specified functional scope clearly inspired cgp feature set
|
Internet protocols
|
mobilecho mobilecho created grouplogic inc. mobile file management system iphone ipad first introduced may 23 2011 techcrunch disrupt new york city mobilecho information technology software securely integrating iphones ipads android phones tablets corporate file servers networks mobilecho installed corporate file servers departments installed iphones ipads android phones tablet computers users allows storage secure transfer files back forth directly servers iphones ipads android phones tablets mobilecho ios client grouplogic enterprise file sharing synching solution activecho january 2011 apple inc. stated 80 fortune 100 companies deployed tested ipad due consumerization enterprise – trend new technology emerging within consumer market first spreading enterprise organizations statistic increased 15 since october 2010 consumerization enterprise allowed employees bring personal tablet computers ipads work environment employees use connect corporate file server network trend raised security issues within enterprise employees unable bring corporate security infrastructure home ipads ios devices currently native file system accessible users inherently capable accessing corporate files without using third-party cloud providers like dropbox mobileme users emailing files workarounds believe compromise enterprise security
|
Computer file systems
|
bounce address bounce address email address bounce messages delivered many variants name none used universally including return path reverse path envelope envelope sender mail 5321-from return address from_ errors-to etc uncommon single document use several names names refer email address provided mail command smtp session ordinarily bounce address seen email users without standardization name may cause confusion email message thought resembling traditional paper letter envelope header fields subject along body message analogous letterhead body letter normally presented visible user however envelope analogy contents mail rcpt fields smtp session neither normally visible user common information letter envelope values always case example electronic mailing lists information seen header come person sent email list bounce address set mailing list software problems delivering mailing list messages handled correctly envelope information looked resolve email go body email examined mail transfer agents mta using smtp protocol use rcpt command determine email go mail command indicate came original usage provide information return bounce messages since late 1990s uses come typically take advantage properties bounce address extended uses include mailing list handling variable envelope return path verp email authentication spam filtering backscatter reduction bounce address tag validation various terms different origins sometimes different meanings although differences often become moot modern internet
|
Computer security
|
migration virtualization context virtualization guest simulation entire computer actually merely software virtual machine vm running host computer hypervisor migration also known teleportation process running virtual machine moved one physical host another little disruption service ideally process completely transparent resulting disruption service downtime practice always minor pause availability though may low enough hard real-time systems affected virtualization far frequently used network services user applications generally tolerate brief delays may involved perceived impact similar longer-than-usual kernel delay actual process heavily dependent particular virtualization package use general process follows note practice regular maintenance operations required merge snapshot stack manageable number files improve performance optimize storage redundant overwrites merged migration similar failover capability virtualization suites provide true failover host may suddenly completely failed precludes latest state vm copied backup host however backup host everything except latest changes may indeed able resume operation last known coherent state operations similar systems provide one capability may provide
|
Computer architecture
|
grid resource allocation manager globus resource allocation manager gram software component globus toolkit locate submit monitor cancel jobs grid computing resources provides reliable operation stateful monitoring credential management file staging gram provide job scheduler functionality fact front-end interoperability bridge functionality provided external scheduler natively support globus web service protocols jobs submitted gram targeted single computation resource consist optional input file staging phase job execution optional output file staging cleanup stage gram4 jobs described internally using job description language earlier gram system known gram2 predecessor resource specification language rsl used instead planning efforts underway enable future versions gram use job submission description language instead
|
Distributed computing architecture
|
rocket u2 rocket u2 suite database management dbms supporting software owned rocket software includes two multivalue database platforms unidata universe products operating environments run current unix linux windows operating systems derivatives pick operating system family also includes developer web-enabling technologies including systembuilder/sb+ sb/xa u2 web development environment webde uniobjects wintegrate universe originally developed vmark software unidata originally developed unidata corporation universe unidata used vertical application development embedded vertical software applications 1997 unidata corporation merged vmark systems form ardent software march 2000 ardent software acquired informix ibm subsequently acquired database division informix april 2001 making universe unidata part ibm db2 product family ibm subsequently created information management group data management one sub-areas ibm u2 family comprised unidata universe along tools systembuilder extensible architecture sb/xa u2 web development environment u2 web de wintegrate 1 october 2009 announced rocket software purchased entire u2 portfolio ibm u2 portfolio grouped name rocketu2 systems made one accounts accounts directories stored host operating system initially contain set files needed system function properly includes system voc vocabulary file contains every command filename keyword alias script pointers classes voc entries also created user files similar tables relational database file unique name distinguish files zero multiple unique records logically related files made two parts data file file dictionary dict data file contains records store actual data file dictionary may contain metadata describe contents output contents file hashed files u2 system uses hashing algorithm allocate file records groups based record ids searching data hashed file system searches group record id stored making search process efficient quicker searching whole file nonhashed files used store data little logical structure program source code xml plain text type file stored subdirectory within account directory host operating system may read edited using appropriate tools files made records similar rows within tables relational database record unique key called record id distinguish records file record ids typically hashed data retrieved quickly efficiently records including record ids store actual data pure ascii strings binary data stored u2 example hardware representation floating-point number would converted ascii equivalent stored usually records divided fields sometimes called attributes u2 field separated field mark hexadecimal character fe thus string codice_1 might represent record employee file 123-45-6789 record id john jones first field jjones company.com second field 4321.00 monthly salary stored third field up-arrow standard pick notation field mark xfe thus first three fields record including record id trailing field mark would use 49 bytes storage given value uses many bytes needed example another record file john jones 10 bytes may replaced marjorie q. humperdink 21 bytes yet name uses much storage needs plus one field mark fields may broken values even subvalues values separated value marks character xfd subvalues separated subvalue marks character xfc thus john jones happened get second email address record may updated codice_2 close bracket represents value mark since email address id record separate file sql terms outer join u2 terms translate provides reason u2 may classified multivalued database raw information called data record set logical grouped data e.g employee record data stored form fields/attributes like name address etc universe unidata structured basic language universe basic unibasic respectively similar pick/basic naturally operates structures multivalue database also structured database query language retrieve uniquery used select records processing ad hoc queries reports rocketu2 provides set client tools allow software developers access u2 databases software languages client tool interfaces include universe unidata support tls transport level data encryption record file level encryption data rest using openssl additional api encryption functionality also available allow custom solutions meet specific regulatory requirements rocketu2 offers three professional certification designations related u2 product family rocket software universe unidata limited ability create web-based front-ends universe/unidata content since rocket software provides sql access database products sql-based product used build web-based ui databases regardless using files tables u2 third-party application framework used build web interfaces
|
Databases
|
abusive hosts blocking list abusive hosts blocking list ahbl internet abuse tracking filtering system developed summit open source development group based original summit blocking list 2000–2002 dnsbls shut jan 1 2015 appear blacklisting entire internet ahbl operated several dnsbl lists one rhsbl list use various types services data mostly added removed automatically ahbl preferred manage certain categories hand accuracy dnsbl list developed use smtp services real-time blocking system means data collected various sources 24 hours day 7 days week real time merged database data included spam sources open proxies open relays ddos drones usenet spam sources controversial shoot sight listing policy ircbl list reduced version dnsbl include spam sources data unnecessary use irc networks chat systems rhsbl list domain-based rather ip4r included domains owned and/or operated spammers known abusive domains domains used send e-mail request domain owner commonly used block domains address e-mail well surbl type systems scan links e-mail torbl list ip4r based list tor nodes included tor nodes including entrance transit exit nodes tor network list contained entrance transit nodes exit nodes ahbl recommends using torbl e-mail blocking purposes march 26 2014 blacklist administrator brielle bruns announced abusive hosts blocking list dnsbls shut ahbl site also published announcement several ahbl actions since creation led harsh criticism members spam fighting community overly aggressive unreasonable one example complete blocking spain largest internet service provider telefónica.es 6 months ever increasing amount spam illegal 419 coming rima-tde.net ip space ahbl also publicly spoken spamhaus .mail icann proposal later rejected icann ahbl also listed godaddy hosting services due continued hosting free speech store richard scoville attempted sue ahbl past listing escalated repeated attempts resolve issue godaddy abuse department told enforce tos aup unless forced law enforcement second major source controversy comes ahbl shoot sight listing policy commonly used administrators force isps take action entities ahbl considers abusers entities make legal cart00ney threats ahbl similar organizations threatening ahbl lawsuit years december 17 2005 richard scoville operator website free speech store sued ahbl sosdg associated individuals bexar county texas 3.525 million us claiming various damages business suit dismissed prejudice january 6 2006 lack jurisdiction
|
Computer security
|
business process network business process networks bpn also referred business service networks business process hubs enable efficient execution multi-enterprise operational processes including supply chain planning execution bpn extends implements organization service-orientation enterprise applications execute processes bpns combine integration services application services often support particular industry process order management logistics management automated shipping receiving others organizations derive primary value e.g. revenue attain goals outside 'four walls enterprise-—by selling consumers b2c businesses b2b thus businesses seek efficiently manage processes span multiple organizations one process supply chain management bpns gaining popularity partly changing nature supply chains supply chains become truly global trends global sourcing offshoring asia india low-cost production regions world continue add complexity effective trading partner management supply chain visibility transition global sourcing challenging companies companies requisite strategies infrastructure extended process control effectively make transition global sourcing majority supply managers continue use mix e-mail phone fax collaborate offshore suppliers—-none standardized easily integrated enable informed business decisions actions distant trading partners introduce new standards new systems multiple time zones new processes different levels technological maturity supply chain bpns help reduce complexity providing common framework information exchange visibility collaboration bpns also increasingly used enable manage operational business process outsourcing bpo functions human resources finance information technology ‘ non-core ’ relative business business functions whereby bpn facilitates collaboration document movement organization outsourcing firm bpns implemented using host technology platforms including limited traditional edi value-added networks vans industry exchanges b2b gateways point point integration brokers vpns mechanisms enable trading partners connect electronically collaborate conduct business amongst bpns accelerated growth web services service-oriented architectures soa technologies simplify integration people processes systems business process networks often managed using multi-tenant architectures rapidly enable seamless many-to-many one-to-many hub-spoke model connectivity trading partners across extended supply chain multi-tenant frameworks also ensure trading partners work single shared set applications collaboration tools hosted network provider mitigating integration barriers hurdles heterogeneous back-end infrastructures systems across trading community vans industry exchanges bring added benefit pre-connected trading partners often ranging tens thousands enable faster trading community implementation lower overall cost manage maintain connections
|
Web technology
|
unified threat management unified threat management utm approach information security single hardware software installation provides multiple security functions contrasts traditional method point solutions security function utm simplifies information-security management providing single management reporting point security administrator rather managing multiple products different vendors utm appliances gaining popularity since 2009 partly all-in-one approach simplifies installation configuration maintenance setup saves time money people compared management multiple security systems instead several single-function appliances needing individual familiarity attention support network administrators centrally administer security defenses one computer prominent utm brands sophos sonicwall check point utms minimum converged security features like features commonly found utms although utm offers ease management single device also introduces single point failure within infrastructure additionally approach utm may go one basic information assurance security approaches defense depth utm would replace multiple security products compromise utm layer break entire defense-in-depth approach
|
Computer security
|
privilege separation computer programming computer security privilege separation technique program divided parts limited specific privileges require order perform specific task used mitigate potential damage computer security vulnerability common method implement privilege separation computer program fork two processes main program drops privileges smaller program keeps privileges order perform certain task two halves communicate via socket pair thus successful attack larger program gain minimal access even though pair programs capable performing privileged operations privilege separation traditionally accomplished distinguishing real user id/group id effective user id/group id using setuid 2 /setgid 2 related system calls specified posix incorrectly positioned gaps allow widespread network penetration many network service daemons specific privileged operation open raw socket internet socket well known ports range administrative utilities require particular privileges run-time well software tends separate privileges revoking completely critical section done change user runs unprivileged account action known dropping root unix-like operating systems unprivileged part usually run nobody user equivalent separate user account privilege separation also done splitting functionality single program multiple smaller programs assigning extended privileges particular parts using file system permissions way different programs communicate operating system scope potential vulnerabilities limited since crash less privileged part exploited gain privileges merely cause denial-of-service attack separation privileges one major openbsd security features implementation postfix focused implementing comprehensive privilege separation solaris implements separate set functions privilege bracketing
|
Computer security
|
real-time clock alarm real time clock alarm feature used allow computer 'wake shut execute tasks every day certain day sometimes found 'power management section motherboard bios setup however newer bios setups include rtc alarm option although still set within user applications wake lan wake ring ipmi functions could also used start computer turned linux real time clock alarm set retrieved using /proc/acpi/alarm /sys/class/rtc/rtc0/wakealarm alternatively rtcwake utility may used prevents problems using local time instead utc automatically processing /etc/adjtime file systemd used wake system run task specific time microsoft windows different programs could used 'wake computer standby hibernation task scheduler settings power management used 'wake computer run task
|
Operating systems
|
sciencelogic sciencelogic software service vendor produces information technology management monitoring solutions operations cloud computing company product monitoring management system performs discovery dependency mapping monitoring alerting ticketing runbook automation dashboarding reporting networks compute storage applications sciencelogic platform monitors on-premises cloud-based assets enabling customers use public cloud services amazon web services aws microsoft azure google cloud manage hybrid multi-cloud workloads sciencelogic founded reston virginia 2003 dave link christopher cordray richard chart 2005 company tripled revenue growth year-over year triple digit growth 2005-2007 2008 sciencelogic posted 5.9m revenue also 2008 inc. magazine placed sciencelogic annual list america 500 fastest growing private companies 350 also including 42 top 100 services companies year 2009 position list 490 sciencelogic also ranked 59 deloitte 2009 technology fast 500 ranking 2003 2009 sciencelogic overall sales growth 70 2010 sciencelogic received 15 million series funding new enterprise associates 2012 sciencelogic raised additional 15 million funding intel capital 2013 sciencelogic monitoring software chosen deployed whoa networks inc 2014 sciencelogic introduced cloudmapper automatically discovers maps relationships assets public cloud services aws well customers premises hybrid environment dependency mapping enables customers identify non-performing assets environments
|
Computer security
|
godi godi package management system ocaml programming language provides dependency management ocaml similar way cpan provides package management perl godi derived netbsd pkgsrc system acronym godi simultaneously stands gerd ocaml distribution general ocaml distribution gerd first name project initiator gerd stolpmann last update project discontinued came 2014
|
Operating systems
|
amsrefs amsrefs package extension package latex facilitates creation bibliographies citations latex documents use amsrefs allows retention rich markup makes references easier reuse publishing environments web book journal formats citation services package available free american mathematical society website purpose amsrefs provide simpler flexible way use many bibliography citation features users latex bibtex come expect amsrefs designed encourage preservation structured markup bibliography throughout entire lifetime document rough draft final archival version replacing unstructured .bbl file format latex fully structured format package compatible “ showkeys ” “ hyperref ” “ backrefs ” packages implements functionality “ cite ” package amsrefs provides bibliography style controlled completely latex instead determined partly bibtex style file partly latex data format used database file latex document thus amsrefs-format database valid latex document printed directly also author send article embedded references publisher without loss internal structural information entries possible use amsrefs package without abandoning one ’ existing bibtex database files amsrefs may distributed and/or modified latex project public license either version 1.3c license option later version
|
Programming language topics
|
polish grid infrastructure pl-grid polish grid infrastructure pl-grid nationwide computing infrastructure built 2009-2011 scientific project pl-grid polish infrastructure supporting computational science european research space purpose enable scientific research based advanced computer simulations large-scale computations using computer clusters provide convenient access computer resources research teams also outside communities high performance computing centers operate first decade twenty-first century european countries advanced grid programs created besides european worldwide consolidation took place form various projects concerned grid technology hpc egee e-irg prace deisa omii-europe poland also undertaken efforts build national grid without infrastructure would possible polish scientific communities participate many research programs particularly eu 7th framework programme another reason initiate steps towards polish grid creation fact poland number intensively cooperating geographically dispersed research teams increasing case cooperation tools gathering sharing accumulated knowledge global scale essential 2007 support almost european countries egi design study project created goal prepare rules integration national grids national grid initiatives europe stable production infrastructure european grid initiative would begin operation 2010 helped start work establishing national grid initiative poland already 2007 setting pl-grid consortium pl-grid consortium established five polish supercomputing networking centers 2009-2011 activity consortium supported pl-grid project co-funded european regional development fund within innovative economy operational programme result operation consortium establishment polish grid infrastructure pl-grid formed merger new powerful computational resources purchased installed data centers belonging pl-grid consortium computational resources available polish grid infrastructure pl-grid include end pl-grid project 5.8 pbytes storage capacity 588 tflops computing power one clusters within polish grid infrastructure zeus supercomputer installed academic computer centre cyfronet agh university science technology kraków 2010 2011 2012 efficient supercomputer poland pl-grid infrastructure resources available scientific software packages allow researchers field biology quantum chemistry physics numerical computations simulation conduct large-scale computations adf amber autodock blast blender cfour clustal cpmd dalton fluent gamess gaussian gromacs mathematica matlab meep molpro mopac namd nwchem openfoam pov-ray r turbomole within pl-grid infrastructure available several tools support design running scientific applications distributed computational resources organization computational experiments visualization applications results resources management g-eclipse gridspace2 qosqosgrid migrating desktop aside user-end tools several software packages administrators also developed namely acarm-ng keyfs security-related projects also useful standalone solutions pl-grid contribution open source community creation national grid infrastructure enterprise large potential innovation mentioned government documents setting directions development polish science technology economy fulfill aim „ growth competitiveness polish science ” innovative economy operational program science sector must strengthened provision suitable research base grid infrastructure constituted base specialized systems specific various fields science created involving services tools oriented used types applications polish grid infrastructure continuously maintained extended within plgrid plus project 2012-2014 domain-oriented services resources polish infrastructure supporting computational science european research space – plgrid plus “ important task preparation specific computing environments – called domain grids – i.e. solutions services extended infrastructure including software tailored needs different groups scientists
|
Distributed computing architecture
|
zeus web server zeus web server proprietary web server unix unix-like platforms including solaris freebsd hp-ux linux developed zeus technology software company located cambridge england original authors company founders university cambridge graduates damian reeves adam twiss support aix tru64 mac os x dropped 10 june 2008 new zws releases made since january 2010 company longer offers similar server solution july 2011 company acquired riverbed technology ended support zws november 30 2014 zeus designed high-performance web server commonly used hardware vendors submitting specweb99 benchmarks hardware specweb99 benchmark retired 2005 replaced specweb2005 specweb2005 submissions made using zeus 2008 longer among top performers addition static content serving zeus supported dynamic content via cgi fastcgi apache jserv isapi nsapi mod_perl ssi zeus distributed authentication content zdac proprietary fastcgi-like protocol zeus mainly competed commercial web servers oracle iplanet web server also claimed high degree compatibility apache http server including .htaccess support url rewriting system comparable apache mod_rewrite expectation apache users would migrate zeus server load increased nsapi isapi supported ease migrations microsoft iis sun java system web server
|
Web technology
|
naver whale naver whale hangul 네이버 웨일 south korean freeware web browser developed naver corporation also available english became available android april 13 2018 since browser based chromium since inception 2011 google chrome apps compatible browser pages translated naver papago service translate korean japanese many languages naver whale browser extensions accessed whale store
|
Internet protocols
|
index register index register computer cpu processor register used modifying operand addresses run program typically vector/array operations contents index register added cases subtracted immediate address one part instruction form effective address actual data operand special instructions typically provided test index register test fails increments index register immediate constant branches typically start loop instruction sets allow one index register used case additional instruction fields specify index registers use normally processors allow instruction specify multiple index registers add contents together ibm line computers contents 'd together early computers without form indirect addressing array operations performed modifying instruction address required several additional program steps used computer memory scarce resource computer installations early era well early microcomputers two decades later index registers commonly known b-line early british computers first used british manchester mark 1 computer 1949 general index registers became standard part computers technology second generation roughly 1954–1966 machines ibm 700/7000 mainframe series starting ibm 704 1954 though optional smaller machines ibm 650 ibm 1401 early small machines index registers include an/usq-17 around 1960 9 series real-time computers scientific data systems early 1960s intel 8080 allowed indirect addressing via register first microprocessor true index register appears motorola 6800 similar mos technology 6502 made good use two registers modern computer designs generally include dedicated index registers instead allow general purpose register contain address allow constant value machines contents another register added offset form effective address early computers designed way include pdp-6 ibm system/360 simple example index register use assembly language pseudo-code sums 100 entry array 4-byte words
|
Computer architecture
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.