text
stringlengths 6
1.88M
| source
stringclasses 13
values |
|---|---|
malumpos malware malumpos point sale malware designed steal scrape customer ’ credit debit card detail point sale system designed way records point sale ’ data running oracle micros payment system restaurant collected data used 333,000 customer sites around world malumpos malware targets hotels us businesses put retail customers risk pos ram scraper written delphi programming language malumpos monitors processes scrapes stolen data infected pos system ram first stores stolen credit debit card details customer infected point sale system swiped sends data cybercriminal empty customer bank balance details sold black market much like point sale malware malumpos get computer unknowingly conceals identity nvidia display driver nvidia display driv3r malware appears legitimate software victims peripherals function correctly malware infects oracle micros oracle forms shift4 systems systems accessed via internet explorer
|
Computer security
|
netware core protocol netware core protocol ncp network protocol used products novell inc usually associated client-server operating system novell netware originally supported primarily ms-dos client stations later support platforms microsoft windows classic mac os linux windows nt mac os x various flavors unix added ncp used access file print directory clock synchronization messaging remote command execution network service functions originally took advantage easy network configuration little memory footprint ipx/spx protocol stack since mid-1990s tcp/ip implementation available novell edirectory uses ncp synchronizing data changes servers directory service tree original ipx/spx implementation provided novell netware platform obsolete tcp/ip implementation uses tcp/udp port 524 relies slp name resolution ncp operation ipx/spx networks bare ipx protocol used packet type field set 17 workstation client station side ipx socket number 0x4003 used server side socket number 0x0451 ncp pdu following structure ncp type field determines type operation individual requests identified sequence number modulo 256 connection number identifies individual client station connection server novell netware servers version 2.x supported 255 connections connection number occupied 1 octet later extended 2 octets task number value 3 requests 1 replies data field starts ncp function number octet distinguishes individual services contents length rest data field depends ncp function
|
Computer file systems
|
diskless remote boot linux drbl diskless remote boot linux nfs-/nis server providing diskless systemless environment client machines could used providing drbl-server installation possible machine debian ubuntu mandriva red hat linux fedora centos suse already installed unlike ltsp uses distributed hardware resources makes possible clients fully access local hardware thus making feasible use server machines less power also includes clonezilla partitioning disk cloning utility similar symantec ghost drbl comes terms gnu gpl license providing user ability customize drbl excels two main categories disk cloning clonezilla packaged drbl uses partimage avoid copying free space gzip compress hard disk images stored image restored multiple machines simultaneously using multicast packets thus greatly reducing time takes image large numbers computers drbl live cd allows without actually installing anything machines simply booting one machine server cd pxe booting rest machines hybrid client hybrid client excellent way make use old hardware using old hardware thin clients good solution disadvantages hybrid client make drbl allows one set multiple hybrid clients relative ease client computer set boot network card using pxe etherboot client requests ip address tftp image boot provided drbl server client boots initial ram disk provided drbl server via tftp proceeds mount nfs share also provided drbl server root partition client boots either linux distribution drbl server installed clonezilla installer various linux distributions depending particular client configured drbl server system resources reside local machine except storage resides drbl server main bottleneck drbl installation storage drbl server client workstation fast storage server raid fast network gigabit ethernet ideal type environment
|
Operating systems
|
brute-force attack cryptography brute-force attack consists attacker submitting many passwords passphrases hope eventually guessing correctly attacker systematically checks possible passwords passphrases correct one found alternatively attacker attempt guess key typically created password using key derivation function known exhaustive key search brute-force attack cryptanalytic attack theory used attempt decrypt encrypted data except data encrypted information-theoretically secure manner attack might used possible take advantage weaknesses encryption system exist would make task easier password-guessing method fast used check short passwords longer passwords methods dictionary attack used brute-force search takes long longer passwords passphrases keys possible values making exponentially difficult crack shorter ones brute-force attacks made less effective obfuscating data encoded making difficult attacker recognize code cracked making attacker work test guess one measures strength encryption system long would theoretically take attacker mount successful brute-force attack brute-force attacks application brute-force search general problem-solving technique enumerating candidates checking one brute-force attacks work calculating every possible combination could make password testing see correct password password length increases amount time average find correct password increases exponentially resources required brute-force attack grow exponentially increasing key size linearly although u.s. export regulations historically restricted key lengths 56-bit symmetric keys e.g data encryption standard restrictions longer place modern symmetric algorithms typically use computationally stronger 128- 256-bit keys physical argument 128-bit symmetric key computationally secure brute-force attack so-called landauer limit implied laws physics sets lower limit energy required perform computation per bit erased computation temperature computing device kelvins k boltzmann constant natural logarithm 2 0.693 irreversible computing device use less energy even principle thus order simply flip possible values 128-bit symmetric key ignoring actual computing check would theoretically require 2 − 1 bit flips conventional processor assumed calculation occurs near room temperature ~300 k von neumann-landauer limit applied estimate energy required ~10 joules equivalent consuming 30 gigawatts power one year equal 30×10 w×365×24×3600 9.46×10 j 262.7 twh 1 world energy production full actual computation – checking key see solution found – would consume many times amount furthermore simply energy requirement cycling key space actual time takes flip bit considered certainly greater 0 however argument assumes register values changed using conventional set clear operations inevitably generate entropy shown computational hardware designed encounter theoretical obstruction see reversible computing though computers known constructed commercial successors governmental asic solutions become available also known custom hardware attacks two emerging technologies proven capability brute-force attack certain ciphers one modern graphics processing unit gpu technology field-programmable gate array fpga technology gpus benefit wide availability price-performance benefit fpgas energy efficiency per cryptographic operation technologies try transport benefits parallel processing brute-force attacks case gpus hundreds case fpga thousand processing units making much better suited cracking passwords conventional processors various publications fields cryptographic analysis proved energy efficiency today fpga technology example copacobana fpga cluster computer consumes energy single pc 600 w performs like 2,500 pcs certain algorithms number firms provide hardware-based fpga cryptographic analysis solutions single fpga pci express card dedicated fpga computers wpa wpa2 encryption successfully brute-force attacked reducing workload factor 50 comparison conventional cpus hundred case fpgas aes permits use 256-bit keys breaking symmetric 256-bit key brute force requires 2 times computational power 128-bit key fifty supercomputers could check billion billion 10 aes keys per second device could ever made would theory require 3×10 years exhaust 256-bit key space underlying assumption brute-force attack complete keyspace used generate keys something relies effective random number generator defects algorithm implementation example number systems originally thought impossible crack brute force nevertheless cracked key space search found much smaller originally thought lack entropy pseudorandom number generators include netscape implementation ssl famously cracked ian goldberg david wagner 1995 debian/ubuntu edition openssl discovered 2008 flawed similar lack implemented entropy led breaking enigma code credential recycling refers hacking practice re-using username password combinations gathered previous brute-force attacks special form credential recycling pass hash unsalted hashed credentials stolen re-used without first brute forced certain types encryption mathematical properties defeated brute force example one-time pad cryptography every cleartext bit corresponding key truly random sequence key bits 140 character one-time-pad-encoded string subjected brute-force attack would eventually reveal every 140 character string possible including correct answer – answers given would way knowing correct one defeating system done venona project generally relies pure cryptography upon mistakes implementation key pads truly random intercepted keypads operators making mistakes – errors case offline attack attacker access encrypted material one try key combinations without risk discovery interference however database directory administrators take countermeasures online attacks example limiting number attempts password tried introducing time delays successive attempts increasing answer complexity e.g requiring captcha answer verification code sent via cellphone and/or locking accounts unsuccessful logon attempts website administrators may prevent particular ip address trying predetermined number password attempts account site reverse brute-force attack single usually common password tested multiple usernames encrypted files process may repeated select passwords strategy attacker generally targeting specific user
|
Computer security
|
dictionary attack cryptanalysis computer security dictionary attack form brute force attack technique defeating cipher authentication mechanism trying determine decryption key passphrase trying hundreds sometimes millions likely possibilities words dictionary dictionary attack based trying strings pre-arranged listing typically derived list words dictionary hence phrase dictionary attack contrast brute force attack large proportion key space searched systematically dictionary attack tries possibilities deemed likely succeed dictionary attacks often succeed many people tendency choose short passwords ordinary words common passwords simple variants obtained example appending digit punctuation character dictionary attacks relatively easy defeat e.g using passphrase otherwise choosing password simple variant word found dictionary listing commonly used passwords possible achieve time–space tradeoff pre-computing list hashes dictionary words storing database using hash key requires considerable amount preparation time allows actual attack executed faster storage requirements pre-computed tables major cost less issue today low cost disk storage pre-computed dictionary attacks particularly effective large number passwords cracked pre-computed dictionary need generated completed password hashes looked almost instantly time find corresponding password refined approach involves use rainbow tables reduce storage requirements cost slightly longer lookup-times see lm hash example authentication system compromised attack pre-computed dictionary attacks rainbow table attacks thwarted use salt technique forces hash dictionary recomputed password sought making precomputation infeasible provided number possible salt values large enough
|
Computer security
|
charity programming language charity experimental purely functional programming language developed university calgary supervision robin cockett based ideas hagino tatsuya completely grounded category theory disregarding interactions outside world charity programs guaranteed terminate stay productive “ charity interesting exercise non-turing-complete programming languages capable expressing ackermann function alas seems active last 10 years though would interest anyone interested seeing far one take non-tc language ” links added shown examples include also solving tower hanoi problem source charity also related total functional programming languages language allows ordinary recursive data types might found ml required finite corecursive data types allowed potentially infinite control structure operating recursive data types primitive recursion paramorphism control structure corecursive data types primitive co-recursion apomorphism neither control structure operate kind data paramorphisms terminate apomorphisms productive
|
Programming language topics
|
hylemetry term hylemetry modern day parlance refers type banknote authentication invented g. schirripa spagnolo 2008 used first time international context 2010 hylemetric approach based biometry identification unique random characteristic used create template uniquely identifying object hylemetric identification requires properties unique permanent measurable non-invasive i.e. characteristics measured without modifying anything typical example security metallic fibers distributed inside banknotes composition two greek words hyle metros aristotle used term ὕλη hyle mean non-living matter since biometric identification given excellent results comes naturally apply similar criteria uniquely identify “ non-living matter ” banknotes hylemetric approach based biometry identification unique random characteristic used create template uniquely identifying object theory every random irreproducible characteristic could used hylemetric identification however valid feature also needs following properties typical example security metallic fibers distributed inside banknotes seen image right put inside paper pulp making banknote paper distribution number absolutely random possible create hylemetric template uniquely identifies particular banknote starting analysis fibers distribution approach also valid non-living matter identified one correct characteristics
|
Computer security
|
malware analysis malware analysis study process determining functionality origin potential impact given malware sample virus worm trojan horse rootkit backdoor malware malicious software computer software intended harm host operating system steal sensitive data users organizations companies malware may include software gathers user information without permission three typical use cases drive need malware analysis method malware analysis performed typically falls one two types examining malicious software involves several stages including limited following note hosted sandboxes malwr use one products hood malwr uses cuckoo
|
Computer security
|
mach kernel mach kernel developed carnegie mellon university support operating system research primarily distributed parallel computing mach often mentioned one earliest examples microkernel however versions mach microkernels mach derivatives basis modern operating system kernels gnu hurd apple operating systems macos ios ipados tvos watchos project carnegie mellon ran 1985 1994 ending mach 3.0 true microkernel mach developed replacement kernel bsd version unix new operating system would designed around mach derivatives exist within number commercial operating systems include using xnu operating system kernel incorporates earlier non-microkernel mach major component mach virtual memory management system also adopted 4.4bsd bsd developers csrg appears modern bsd-derived unix systems freebsd mach logical successor carnegie mellon accent kernel lead developer mach project richard rashid working microsoft since 1991 various top-level positions revolving around microsoft research division another original mach developers avie tevanian formerly head software next chief software technology officer apple inc. march 2006 mach name mach evolved euphemization spiral developers naming phase bike lunch rainy pittsburgh mud puddles tevanian joked word muck could serve backronym multi-user multiprocessor universal communication kernel italian cmu engineer dario giuse later asked project leader rick rashid project current title received muck answer though spelled pronounced according italian alphabet wrote mach rashid liked giuse spelling mach much prevailed key concept original unix operating system idea pipe pipe abstraction allowed data moved unstructured stream bytes program program using pipes users programmers could link together multiple programs complete tasks feeding data several small programs turn contrasted typical operating systems era required single large program could handle entire task alternately used files pass data resource expensive time consuming pipes built underlying input/output system system turn based model drivers expected periodically block waited tasks complete instance printer driver might send line text line printer nothing printer completed printing line case driver would indicate blocked operating system would allow program run printer indicated ready data pipes system limited resource memory one program filled memory assigned pipe would naturally block normally would cause consuming program run emptying pipe contrast file entire file read written next program use pipes made movement data across multiple programs occur piecemeal fashion without programmer intervention however implementation pipes memory buffers meant data copied program program time consuming resource intensive operation made pipe concept unsuitable tasks quick turnaround low latency needed case device drivers operating system kernel core functionality instead written single large program operating system added new functionality computer networking instance size complexity kernel grew unix pipes offered conceptual system could used build arbitrarily complex solutions small interacting programs smaller programs easy program maintain well defined interfaces simplified programming debugging qualities even valuable device drivers small size bug-free performance extremely important strong desire model kernel basis small interacting programs one first systems use pipe-like system basis operating system aleph kernel developed university rochester introduced concept ports essentially shared memory implementation aleph kernel reduced providing access hardware including memory ports conventional programs using ports system implemented behavior device drivers user programs concept greatly reduced size kernel allowed users experiment different drivers simply loading connecting together runtime greatly eased problems developing new operating system code otherwise generally required machine restarted general concept small kernel external drivers became known microkernel aleph implemented data general eclipse minicomputers tightly bound machine far ideal required memory copied programs involved considerable performance overhead also quite expensive nevertheless aleph proved basis system sound went demonstrate computer clustering copying memory early ethernet interface around time new generation central processors cpus coming market offering 32-bit address spaces initially optional support memory management unit mmu mmu handled instructions needed implement virtual memory vm system keeping track pages memory use various programs offered new solution port concept using copy write mechanism used vm instead copying data programs sent data needed instruct mmu provide access memory system would implement interprocess communications system dramatically higher performance concept picked carnegie-mellon adapted aleph perq workstation implemented using copy-on-write port successful resulting accent kernel limited practical use run existing software moreover accent tightly tied perq aleph eclipse major change experimental kernels mach decision make version existing 4.2bsd kernel re-implemented accent message-passing concepts kernel would binary compatible existing bsd software making system immediately useful everyday use still useful experimental platform additionally new kernel would designed start support multiple processor architectures even allowing heterogeneous clusters constructed order bring system quickly possible system would implemented starting existing bsd code re-implementing bit bit inter-process communication-based ipc-based programs thus mach would begin monolithic system similar existing unix systems evolve toward microkernel concept time mach started largely effort produce cleanly defined unix-based highly portable accent result short list generic concepts mach developed accent ipc concepts made system much unix-like nature even able run unix programs little modification mach introduced concept port representing endpoint two-way ipc ports security rights like files unix allowing unix-like model protection applied additionally mach allowed program handle privileges would normally given operating system order allow user space programs handle things like interacting hardware mach like unix operating system becomes primarily collection utilities unix mach keeps concept driver handling hardware therefore drivers present hardware included microkernel architectures based hardware abstraction layer exokernels could move drivers microkernel main difference unix instead utilities handling files handle task operating system code moved kernel user space resulting much smaller kernel rise term microkernel unlike traditional systems mach process task consist number threads common modern systems mach first system define tasks threads way kernel job reduced essentially operating system maintaining utilities scheduling access hardware existence ports use ipc perhaps fundamental difference mach traditional kernels unix calling kernel consists operation known system call trap program uses library place data well known location memory causes fault type error system first started kernel set handler faults program causes fault kernel takes examines information passed carries instructions mach ipc system used role instead order call system functionality program would ask kernel access port use ipc system send messages port although messages triggered system calls would kernels mach pretty much kernel did—handling actual request would program thread concurrency support benefited message passing ipc mechanisms since tasks consisted multiple code threads mach could freeze unfreeze message handling allowed system distributed multiple processors either using shared memory directly mach messages adding code copy message another processor needed traditional kernel difficult implement system sure different programs n't try write memory different processors however mach ports process memory access make well defined easy implement made first-class citizen system ipc system initially performance problems strategies developed minimize impact like predecessor accent mach used single shared-memory mechanism physically passing message one program another physically copying message would slow mach relies machine memory management unit mmu quickly map data one program another data written would physically copied process called copy-on-write messages also checked validity kernel avoid bad data crashing one many programs making system ports deliberately modeled unix file system concepts allowed user find ports using existing file system navigation concepts well assigning rights permissions would file system development system would easier would code worked exist traditional program could built using existing tools could also started debugged killed using tools monokernel bug new code would take entire machine require reboot whereas mach would require program restarted additionally user could tailor system include exclude whatever features required since operating system simply collection programs could add remove parts simply running killing would program finally mach features deliberately designed extremely platform neutral quote one text mach number disadvantages however relatively mundane one clear find ports unix problem solved time programmers agreed number well known locations file system serve various duties approach worked mach ports well mach operating system assumed much fluid ports appearing disappearing time without mechanism find ports services represented much flexibility would lost mach initially hosted additional code written directly existing 4.2bsd kernel allowing team work system long complete work started already functional accent ipc/port system moved key portions os tasks threads virtual memory portions completed various parts bsd system re-written call mach change 4.3bsd also made process 1986 system complete point able run dec vax although little practical value goal making microkernel realized soon followed versions ibm rt pc sun microsystems 68030-based workstations proving system portability 1987 list included encore multimax sequent balance machines testing mach ability run multiprocessor systems public release 1 made year release 2 followed next year throughout time promise true microkernel yet delivered early mach versions included majority 4.3bsd kernel system known poe server resulting kernel actually larger unix based idea however move unix layer kernel user-space could easily worked even replaced outright unfortunately performance proved major problem number architectural changes made order solve problem unwieldy unix licensing issues also plaguing researchers early effort provide non-licensed unix-like system environment continued find use well development mach resulting mach 3 released 1990 generated intense interest small team built mach ported number platforms including complex multiprocessor systems causing serious problems older-style kernels generated considerable interest commercial market number companies midst considering changing hardware platforms existing system could ported run mach would seem would easy change platform underneath mach received major boost visibility open software foundation osf announced would hosting future versions osf/1 mach 2.5 investigating mach 3 well mach 2.5 also selected nextstep system number commercial multiprocessor vendors mach 3 led number efforts port operating systems parts microkernel including ibm workplace os several efforts apple build cross-platform version classic mac os mach originally intended replacement classical monolithic unix reason contained many unix-like ideas instance mach used permissioning security system patterned unix file system since kernel privileged running kernel-space os servers software possible malfunctioning malicious programs send commands would cause damage system reason kernel checked every message validity additionally operating system functionality located user-space programs meant needed way kernel grant programs additional privileges operate hardware instance mach esoteric features also based ipc mechanism instance mach able support multi-processor machines ease traditional kernel extensive work needs carried make reentrant interruptible programs running different processors could call kernel time mach bits operating system isolated servers able run like program processor although theory mach kernel would also reentrant practice n't issue response times fast simply wait serve requests turn mach also included server could forward messages programs even network area intense development late 1980s early 1990s unfortunately use ipc almost tasks turned serious performance impact benchmarks 1997 hardware showed mach 3.0-based unix single-server implementations 50 slower native unix study exact nature performance problems turned number interesting facts one ipc problem overhead associated memory mapping needed support added small amount time making call rest 80 time spent due additional tasks kernel running messages primary among port rights checking message validity benchmarks 486dx-50 standard unix system call took average 21μs complete equivalent operation mach ipc averaged 114μs 18μs hardware related rest mach kernel running various routines message given syscall nothing full round-trip bsd would require 40μs whereas user-space mach system would take 500μs mach first seriously used 2.x versions performance slower traditional monolithic operating systems perhaps much 25 cost considered particularly worrying however system also offering multi-processor support easy portability many felt expected acceptable cost pay mach 3 attempted move operating system user-space overhead became higher still benchmarks mach ultrix mips r3000 showed performance hit great 67 workloads example getting system time involves ipc call user-space server maintaining system clock caller first traps kernel causing context switch memory mapping kernel checks caller required access rights message valid another context switch memory mapping complete call user-space server process must repeated return results adding total four context switches memory mappings plus two message verifications overhead rapidly compounds complex services often code paths passing many servers source performance problems another centered problems trying handle memory properly physical memory ran low paging occur traditional monolithic operating systems authors direct experience parts kernel called others allowing fine-tune pager avoid paging code used mach n't possible kernel real idea operating system consisted instead use single one-size-fits-all solution added performance problems mach 3 attempted address problem providing simple pager relying user-space pagers better specialization turned little effect practice benefits wiped expensive ipc needed call performance problems related mach support multiprocessor systems mid-1980s early 1990s commodity cpus grew performance rate 60 year speed memory access grew 7 year meant cost accessing memory grew tremendously period since mach based mapping memory around programs cache miss made ipc calls slow ipc overhead major issue mach 3 systems however concept multi-server operating system still promising though still requires research developers careful isolate code modules call server server instance majority networking code would placed single server thereby minimizing ipc normal networking tasks developers instead stuck original poe concept single large server providing operating system functionality order ease development allowed operating system server run either user-space kernel-space allowed develop user-space advantages original mach idea move debugged server kernel-space order get better performance several operating systems since constructed using method known co-location among lites mklinux osf/1 nextstep/openstep/macos chorus microkernel made feature basic system allowing servers raised kernel space using built-in mechanisms mach 4 attempted address problems time radical set upgrades particular found program code typically writable potential hits due copy-on-write rare thus made sense map memory programs ipc instead migrate program code used local space program led concept shuttles seemed performance improved developers moved system semi-usable state mach 4 also introduced built-in co-location primitives making part kernel mid-1990s work microkernel systems largely stagnant although market generally believed modern operating systems would microkernel based 1990s primary remaining widespread uses mach kernel apple macos sibling ios run atop heavily modified hybrid open software foundation mach kernel osfmk 7.3 called xnu also used osf/1 xnu file systems networking stacks process memory management functions implemented kernel file system networking process memory management functions invoked user mode via ordinary system calls rather message passing xnu mach messages used communication user-mode processes requests user-mode code kernel kernel user-mode servers analysis demonstrated ipc performance problem obvious seemed recall single-side syscall took 20μs bsd 114μs mach running system 114 11 due context switch identical bsd additional 18 used mmu map message user-space kernel space adds 29μs longer traditional syscall much rest majority actual problem due kernel performing tasks checking message port access rights would seem important security concern fact makes sense unix-like system instance single-user operating system running cell phone robot might need features exactly sort system mach pick-and-choose operating system would valuable likewise mach caused problems memory moved operating system another task really makes sense system one address space dos early mac os single large address space shared programs systems mapping provide benefits realizations led series second generation microkernels reduced complexity system placed almost functionality user space instance l4 kernel version 2 includes seven system calls uses 12k memory whereas mach 3 includes 140 functions uses 330k memory ipc calls l4 486dx-50 take 5μs faster unix syscall system 20 times fast mach course ignores fact l4 handling permissioning security leaving user-space programs select much little overhead require potential performance gains l4 tempered fact user-space applications often provide many functions formerly supported kernel order test end-to-end performance mklinux co-located mode compared l4 port running user-space l4 added 5 –10 overhead compared mach 29 newer microkernels revitalized industry whole projects gnu hurd received new attention result following list operating system kernels derived mach operating systems kernels derived mach
|
Computer architecture
|
scheme 48 scheme 48 programming language dialect language scheme implementation using interpreter emits bytecode foreign function interface calling functions language c comes library regular expressions regex interface portable operating system interface posix supported portable scheme library slib basis scheme shell scsh used academic research free open-source software released bsd license called scheme 48 first version written 48 hours august 1986 authors say intended understood 48 hours scheme 48 uses virtual machine interpret bytecode written restricted dialect scheme called prescheme translated c compiled native binary prescheme pre-scheme statically-typed dialect scheme efficiency low-level machine access c retaining many desirable features scheme
|
Programming language topics
|
hytrust hytrust american company specialising security compliance control software virtualization information technology infrastructure company founded 2007 based mountain view california hytrust founded 2009 partnered vmware symantec cisco systems citrix systems backed 5.5 million funding trident capital epic ventures 10.5 million funding raised granite ventures cisco systems 2010 summer 2013 company raised 18.5 million oversubscribed c round investments intel capital in-q-tel carahsoft fortinet previous investors web site also mentions mcafee trend micro ca technologies rsa vce hytrust founded company president eric chiu vice president renata budko vice president boris strongin engineer boris belov hytrust chiu budko worked cemaphore systems – company specialising disaster recovery microsoft exchange hytrust ceo chairman john de santis – formerly vice president cloud services vmware chairman ceo tricipher software security infrastructure company november 2013 hytrust acquired highcloud security cloud encryption management software provider acquisition added encryption key management hytrust products spring 2015 company raised 33 million series funding hytrust products based company patented intelligent security control system virtualized ecosystems hytrust cloudcontrol vmware vsphere-compatible virtual appliance sits virtual infrastructure administrators whenever administrative request submitted infrastructure appliance determines whether request complies organization security policies permitting denying accordingly logging requests records produced used regulatory compliance auditing troubleshooting forensic analysis company also provides private cloud logging active directory root access two-factor authentication vi segmentation host hardening multi-tenant policy enforcement secondary approval services encryption key management advises organizations manage virtualized cloud computing environments hytrust partnered intel 2014 create hytrust boundarycontrol technology lets companies set policies control access cloud virtualized data stored boundarycountrol designed work intel txt technology company released hytrust datacontrol 3.0 2015 technology encrypts data virtual machines rest keeps data secure used
|
Distributed computing architecture
|
united states v. ancheta united states america v. ancheta u.s. vs. ancheta 06-051 c.d cal name lawsuit jeanson james ancheta downey california u.s. government handled united states district court central district california first botnet related prosecution u.s history ancheta violated prohibited acts accessing transmitting malware intent consequence disrupting interstate foreign commerce case first prosecution united states america individual sentenced prison profiting use botnets used maliciously launch destructive denial service attacks sending large quantities spam across internet 57-month prison sentence ancheta longest history defendant spread malware ancheta pleaded guilty conspiring violate computer fraud abuse act causing damage computers used federal government united states national defence accessing protected computer without authorization purpose commit various types fraud dates june 25 2004 september 15 2004 los angeles county ancheta others knowingly conspired violate us code refers knowingly causing transmission program information code command result conduct cause damage without authorization computer used interstate foreign commerce communication cause loss one-year period aggregating least 5000 value secondly acheta others conspired violate us code refers access without authorization computer used interstate foreign commerce communication intentionally intimate transmission computer multiple commercial electronic email messages affect interstate foreign commerce finally ancheta charged laundering monetary instruments faced criminal forfeiture jeanson james ancheta time crime 20-year-old high school drop-out found rxbot software online decided going use create botnet army established set website would rent computer zombies hackers could employ fulfill whatever malicious job planned ancheta used least one computer system place residence accessed internet dial telephone line configure command botnet conduct business communication co-conspirator residing boca raton florida referred sobe also involved previous experience launching computer attacks internet bot program infects computer enables remote control computer security vulnerability computer system exploited hacker order install run malware case worm program installs set run background process daemon remains undetectable computer user infected computer often referred zombie computer ancheta depended building block botnet army ancheta engaged computers function unison network formation referred botnet controller called bot herder ancheta primary purpose engaging large numbers computers amplify attack reduce time taken execute greatest value provide relatively high level anonymity 2005 federal trade commission conjunction 35 government agencies organized initiative encourage internet service providers actively monitor identify quarantine customers whose computers appeared compromised transformed zombies appear remote control hackers one largest botnet implementations around time 2005 found dutch police botnet 1.5 million computers crime ring control zombie computers often employed response anti-spam laws spam filtering spammers started hiring virus writers hackers help architect armies zombie computers send spam email unsuspecting users computers around world february 2012 federal communications commission unveiled yet another plan calls internet service providers take specific steps combat online threats botnets july 2004 ancheta obtained access server internet hosting company set irc server utilizing ircd program created channel irc controlled remotely ancheta developed computer worm installed executed would report back irc channel controlled scan computers similar vulnerabilities leave open future unauthorized control ancheta initially developed worm modifying existing trojan called rxbot ddos attacks one use case botnets another major purpose use proxy server email spam propagation 2004 reported unsolicited email doubled late 2003 rising 310 billion message 700 billion messages worms like conficker originally found 2008 still remain threat significantly sophisticated disallowing updates communicated encrypted channels ancheta advertised sale bots purpose launching distributed denial-of-service ddos attacks send spam sold access bots clusters usually 10,000 time ancheta acted consultant advised buyer exact number bots would need successfully accomplish designated attack would offer separate channels additional cost assist control direction bots providing temporary control channel buyer around time crime estimated average botnet 20,000 computers size also profited sale developed worm would configure best propagation buyers also option using malware launch attack use worm offering ancheta accepted payments paypal would misleadingly describe nature transaction hosting web hosting dedicated box services total 17 different counts case count 1 violation refers conspiracy ancheta others commit offense defraud us agency violated us code counts 2 11 violation counts 2 3 4 involved intentionally causing damage accessing unauthorized computer belonging king pao electronic co sanyo electric software completed would caused damage exceeding 5000 launching distributed denial service ddos attack company whose name remains confidential completed would caused damage exceeding 5000 furtherance conspiracy ancheta committed various overt acts including payments accomplices directing numerous computers adware servers controlled ancheta servers unsuspecting users would redirected download malware counts 5 6 included knowingly causing transmission malicious code protected computers belonging naval air weapons station china lake us defense information systems agency used justice national defence national security naws china lake major navy research testing evaluation facility disa provides communication support president top executive staff us government count 7 11 violation ancheta knowingly accessed without authorization computers involved interstate foreign commerce installing adware without notice consent sole intent defraud 8,744 53,321 computers different count accessed without authorization monetary amounts 1306.52 7966.10 different count accepted payment services counts 12 16 violation knowing property involved financial transaction represents proceeds unlawful activity ancheta conducted financial transactions involved proceeds specified unlawful activity proceeds used intent promote unlawful activity proceeds selling worms rental botnet passed legitimate online transactions payments web hosting dedicated box services anchta also transferring payments internet hosting companies additional access servers used commit fraud november 2004 may 2005 varying amounts funds transferred wells fargo bank fdcservers sago networks count 17 violation ancheta required forfeit property involved offence included 2998.81 generated sale internet bots proxies deposited wells fargo account approximately 58,357.86 proceeds generated surreptitious install adware protected computers linked paypal account owned ancheta 1993 bmw 325 property used commit facilitate commission violations including desktop computers laptops hard drives
|
Computer security
|
davfs2 computer networking davfs2 linux tool connecting webdav shares though local disks open-source gpl-licensed file system mounting webdav servers communicating kernel davfs2 either use fuse file system api coda network file system protocol sockets davfs2 uses neon webdav library communicating web server davfs2 e.g used apache web server subversion installations
|
Computer file systems
|
iguana computing independent group unix-alikes networking activists iguana developers wombat system iguana also operating system os personality provides set services memory management process protection iguana designed base provision operating system services embedded systems among others provides underlying os wombat version paravirtualised linux designed provide legacy support embedded systems wombat works combination kenge iguana also used along create qualcomm rex os designed cell phones
|
Operating systems
|
apache traffic server apache traffic server ats modular high-performance reverse proxy forward proxy server generally comparable nginx squid created inktomi distributed commercial product called inktomi traffic server inktomi acquired yahoo shortly yahoo released ts source apache apache incubator project july 2009 guest editor yahoo online publication ostatic stated yahoo uses ts production serve 30 billion objects per day sites like yahoo homepage yahoo sports mail finance april 21 2010 apache board accepted traffic server tlp graduating project incubation latest stable version 8.0.2 released january 29 2019 latest long-term support version 6.2.3 released august 4 2018. ats released two stable versions version 6 long-term support version ats version 8 latest stable release quarterly minor versions scheduled beginning version 4.0 releases considered stable production follow regular semantic versioning developer preview releases made instead git master branch considered preview quality times long-term support provided last minor version within major release one added year ats good support next generation http protocol v6.0.0 http/2 a.k.a h2 tls fast yet site scores 100 ats actively developed supported several large companies well many individual contributors ostatic post describes ts shipping ... http web proxy caching solution also ... server framework build fast servers protocols traffic server benchmarked handle 200,000 requests per second small objects cache talk 2009 cloud computing expo members yahoo ts team stated ts used production yahoo handle 400tb traffic per day using 150 commodity machines ostatic post describes ts product literally hundreds developer-years context cloud computing ts would sit conceptually edge cloud routing requests come yahoo used edge services shown graphic distributed 2009 cloud computing expo depicting yahoo private cloud architecture practical terms typical server configuration might use ts serve static content images javascript cascading style sheets css hypertext markup language html files route requests dynamic content web server apache http server
|
Web technology
|
outbound content compliance outbound content compliance outbound content security relatively new segment computer security field aims detect prevent outbound content violates policy organization and/or government regulations deals internal threats opposite traditional security solutions firewall anti-virus anti-spam etc dealing external threats therefore sometimes called inside-out security business environment purpose prevent confidential and/or private data leaks protected information may belong company customers us canada european countries enacted laws mandating protection types computer-based information us laws including related provisions sarbanes-oxley hipaa gramm-leach-bliley act interest segment heated string high-profile data breaches personal information millions people stolen endangered
|
Computer security
|
gena gena stands general event notification architecture gena base defines http notification architecture transmits notifications http resources http resource could object might need send receive notification example distribution list buddy list print job etc defined internet-draft draft-cohen-gena-p-base-01.txt expired gena base client arbiter provides ability send receive notifications using http tcp/ip administratively scoped unreliable multicast udp provisions made use intermediary arbiters called subscription arbiters handle routing notifications intended destination july 13–14 1998 university california irvine convened wisen workshop internet-scale event notification event brought together number experts various fields included presentation gena josh cohen microsoft delegates showcased event notification architectures haggled requirements josh final slide includes bullet points gena implemented microsoft products wish collaborate agree standard gena comply interest event notification appears waned 1998 participants unable come common definitions required definition notification services protocols gena briefly considered use internet printing protocol found niche part universal plug play upnp architecture gena base client arbiter
|
Internet protocols
|
udp-lite udp-lite lightweight user datagram protocol sometimes udp lite connectionless protocol allows potentially damaged data payload delivered application rather discarded receiving station useful allows decisions integrity data made application layer application codec significance bits understood udp-lite described rfc 3828 udp-lite based user datagram protocol udp unlike udp either none packet protected checksum udp-lite allows partial checksums covers part datagram arbitrary count octets beginning packet therefore deliver packets partially corrupted designed multimedia protocols voice ip voip streamed video receiving packet damaged payload better receiving packet conventional udp transmission control protocol tcp single bit error cause bad checksum meaning whole packet must discarded way bit errors promoted entire packet errors even damage data trivial computing checksum udp-lite uses checksum algorithm used udp tcp modern multimedia codecs like g.718 adaptive multi-rate amr audio h.264 mpeg-4 video resilience features already built syntax structure stream allows codec detect errors stream b potentially correct least conceal error playback codecs ideal partners udp-lite since designed work damaged data stream better codecs receive perhaps 200 bytes bits damaged rather conceal loss entire packet discarded due bad checksum application layer understands significance data transport sees udp packets means error protection added necessary higher layer example forward error correction scheme application best place decide parts stream sensitive error protect accordingly rather single brute force checksum covers everything equally example seen research hammer et al udp-lite coupled amr codec give improved speech quality lossy network conditions since modern link layers protect carried data strong cyclic redundancy check crc discard damaged frames making effective use udp lite requires link layer aware network layer data carried since current ip stacks implement cross-layer interactions making effective use udp-lite currently requires specially modified device drivers ip protocol identifier 136 udp-lite uses set port numbers assigned internet assigned numbers authority iana use udp support udp-lite added linux kernel version 2.6.20 support udp-lite added freebsd kernel r264212 changeset also mfc'ed back stable/10 became available freebsd 10.1-release bsd socket api extended support udp-lite third parameter socket system call set ipproto_udplite request udp-lite socket one also easily set part packet covered checksum starting beginning including header packet smaller 12 octets sent setup checksum cover whole packet receiving side socket default drop packets covered completely udp emulation permit smaller coverage one use allow packets minimum 12 octets user data checksummed packet smaller coverage silently dropped bad packet coverage length least 20 octets including header checksum correct delivered application whole part payload still corrupted could covered checksum checksum correct incidentally latter unlikely checksum incorrect packet dropped actually impossible know error inside payload data udp-lite header packet could actually destined different program smallest possible coverage 8 octets headers need included checksum packets smaller length coverage always dropped independent settings ignoring sniffers interested traffic conforming standard udp-lite supported following operating systems
|
Internet protocols
|
max software max also known max/msp/jitter visual programming language music multimedia developed maintained san francisco-based software company cycling '74 thirty-year history used composers performers software designers researchers artists create recordings performances installations max program modular routines existing shared libraries application programming interface api allows third-party development new routines named external objects thus max large user base programmers unaffiliated cycling '74 enhance software commercial non-commercial extensions program extensible design simultaneously represents program structure graphical user interface gui max described lingua franca developing interactive music performance software 1980s miller puckette began work max 1985 institut de recherche et coordination acoustique/musique ircam paris originally called patcher first version provided composers graphical interface creating interactive computer music scores macintosh point development max could n't perform real-time sound synthesis software instead sent control messages external hardware synthesizers samplers using midi similar protocol earliest widely recognized use composition pluton 1988 piano computer piece philippe manoury software synchronized computer piano controlled sogitec 4x audio processing 1989 ircam developed max/fts faster sound version max ported ircam signal processing workstation ispw next also known audio max would prove forerunner max msp audio extensions adding ability real-time synthesis using internal hardware digital signal processor dsp board year ircam licensed software opcode systems 1990s opcode launched commercial version named max 1990 developed extended david zicarelli however 1997 opcode considering cancelling instead zicarelli acquired publishing rights founded new company cycling '74 continue commercial development timing fortunate opcode acquired gibson guitar 1998 ended operations 1999 ircam in-house max development also winding last version produced jmax direct descendant max/fts developed 1998 silicon graphics sgi later linux systems used java graphical interface c real-time backend eventually released open-source software meanwhile puckette independently released fully redesigned open-source composition tool named pure data pd 1996 despite underlying engineering differences ircam versions continued tradition cycling '74 first max release 1997 derived partly puckette work pure data called max/msp max signal processing initials miller smith puckette remains notable max many extensions incarnations made max capable manipulating real-time digital audio signals without dedicated dsp hardware meant composers could create complex synthesizers effects processors using general-purpose computer like macintosh powerbook g3 1999 netochka nezvanova collective released nato.0+55 suite externals added extensive real-time video control max 2000s though nato became increasingly popular among multimedia artists development stopped 2001 softvns another set extensions visual processing max released 2002 canadian media artist david rokeby cycling '74 released set video extensions jitter alongside max 4 2003 adding real-time video opengl graphics matrix processing capabilities max 4 also first version run windows max 5 released 2008 redesigned patching gui first time max commercial history 2010s 2011 max 6 added new audio engine compatible 64-bit operating systems integration ableton live sequencer software extension called gen compile optimized max patches higher performance max 7 released 2014 focused 3d rendering improvements september 25 2018 max 8 recent major version software released new features include mc new way work multiple channels javascript support node max vizzie 2 june 6 2017 ableton announced purchase cycling '74 max continuing published cycling '74 david zicarelli remaining company programs sharing max visual programming concepts commonly used real-time audio video synthesis processing max named composer max mathews considered descendant music language though graphical nature disguises fact like music-n languages max distinguishes two levels time event scheduler dsp corresponds distinction k-rate a-rate processes csound control rate vs. audio rate supercollider basic language max sibling programs data-flow system max programs named patches made arranging connecting building-blocks objects within patcher visual canvas objects act self-contained programs reality dynamically linked libraries may receive input one visual inlets generate output visual outlets objects pass messages outlets inlets connected objects max supports six basic atomic data types transmitted messages object object int float list symbol bang signal msp audio connections several complex data structures exist within program handling numeric arrays table data hash tables coll data xml information pattr data json-based dictionaries dict data msp data structure buffer~ hold digital audio information within program memory addition jitter package adds scalable multi-dimensional data structure handling large sets numbers storing video datasets matrix data max typically learned acquiring vocabulary objects function within patcher example metro object functions simple metronome random object generates random integers objects non-graphical consisting object name several arguments-attributes essence class properties typed object box objects graphical including sliders number boxes dials table editors pull-down menus buttons objects running program interactively max/msp/jitter comes 600 objects standard package extensions program written third-party developers max patchers e.g encapsulating functionality patcher sub-program max patch objects written c c++ java javascript order execution messages traversing graph objects defined visual organization objects patcher result organizing principle max unusual program logic interface presented user typically related though newer versions max provide several technologies standard gui design max documents named patchers bundled stand-alone applications distributed free sold commercially addition max used author audio midi plugin software ableton live max live extension increased integration laptop computers live music performance electronic music elsewhere max/msp max/jitter received attention development environment available serious laptop music/video performance
|
Programming language topics
|
http/3 http/3 h3 upcoming third major version hypertext transfer protocol used exchange binary information world wide web http/3 draft based previous rfc draft named hypertext transfer protocol http quic quic transport layer network protocol initially developed google user space congestion control used user datagram protocol udp 28 october 2018 mailing list discussion mark nottingham chair ietf http quic working groups made official request rename http-over-quic http/3 clearly identify another binding http semantics wire protocol ... people understand separation quic pass development quic working group http working group finalizing publishing draft subsequent discussions followed stretched several days nottingham proposal accepted fellow ietf members november 2018 gave official seal approval http-over-quic become http/3
|
Internet protocols
|
larry mcvoy larry mcvoy born 1962 concord massachusetts united states ceo bitmover company makes bitkeeper version control system used february 2002 early 2005 manage source code linux kernel earned bs ms degrees computer science 1985 1987 respectively university wisconsin–madison work generally included performance enhancements various unix operating systems developed employers mcvoy worked sun worked peer-to-peer scm system named teamware would form basis later bitkeeper product mcvoy started working linux kernel around 0.9.7 version developed lmbench kernel benchmark lmbench maintained 2009 carl staelin bitkeeper source control system also developed integrated linux development process 2002 mcvoy decided charge use bitkeeper linux development community prompted development git tool began serving source control system linux kernel 2005 working sun early 1990s mcvoy number high-profile unix community members urged company open-source flagship unix product sunos compete microsoft new windows nt operating system proposal would created copyleft version sunos time linux reached 1.0 version
|
Operating systems
|
fred teeven fredrik fred teeven born 5 august 1958 retired dutch politician people party freedom democracy vvd jurist teeven served member house representatives parliamentary leader livable netherlands party house representatives 23 may 2002 30 january 2003 2003 rejoined people party freedom democracy general election 2006 served member house representatives 30 november 2006 14 october 2010 became state secretary security justice cabinet rutte ii general election 2012 served member house representatives 20 september 2012 5 november 2012 26 march 2015 23 march 2017 teeven born province north holland studied law vu university amsterdam public management university twente working first tax collector became prosecutor becoming known crimefighter since led many investigations organised crime teeven involved prosecutions dési bouterse mink kok johan verhoek willem holleeder 2002 teeven succeeded pim fortuyn front runner lijsttrekker livable netherlands leefbaar nederland 23 may 2002 30 january 2003 parliamentary group leader livable netherlands house representatives also member house representatives 23 may 2002 – 30 january 2003 found would front runner 2003 elections quit party returned former post public prosecutor 2006 teeven announced return politics time people party freedom democracy vvd dutch general election 2006 6th candidate list vvd elected house representatives 30 november 2006 main spokesperson justice policy dutch general election 2010 3rd candidate list vvd cabinet formation 2010 first rutte cabinet teeven became undersecretary security justice taking office 14 october 2010 resigned day mp 5 november 2012 continued undersecretary security justice second rutte cabinet meanwhile mp 20 september 2012 5 november 2012 undersecretary security justice tasked dealing prevention family law youth justice copyright law 10 march 2015 justice minister ivo opstelten resigned together teeven former informed house representatives wrongly early 2000s deal made teeven state prosecutor 1994 deal concerned money paid drug trafficker whose money seized received compensation origin money could proved illegal opstelten mentioned house representatives lower amount one actually paid receipt transaction gone missing later surfaced wake scandal house chairman van miltenburg resigned 12 december 2015 became clear suppressed two letters whistle blower justice department already mentioned right details 'deal putting letters shredder resigning state secretary teeven served member house representatives 26 march 2015 23 march 2017 teeven currently works bus driver public transportation company connexxion consultant public relations cybercrime
|
Computer security
|
open archives initiative protocol metadata harvesting open archives initiative protocol metadata harvesting oai-pmh protocol developed harvesting metadata descriptions records archive services built using metadata many archives implementation oai-pmh must support representing metadata dublin core may also support additional representations protocol usually referred oai protocol oai-pmh uses xml http version 2.0 protocol released 2002 document last updated 2015 creative commons license by-sa late 1990s herbert van de sompel ghent university working researchers librarians los alamos national laboratory us called meeting address difficulties related interoperability issues e-print servers digital repositories meeting held santa fe new mexico october 1999 key development meeting definition interface permitted e-print servers expose metadata papers held structured fashion repositories could identify copy papers interest interface/protocol named santa fe convention several workshops held 2000 acm digital libraries conference elsewhere share ideas santa fe convention discovered workshops problems faced e-print community also shared libraries museums journal publishers others needed share distributed resources address needs coalition networked information digital library federation provided funding establish open archives initiative oai secretariat managed herbert van de sompel carl lagoze oai held meeting cornell university ithaca new york september 2000 improve interface developed santa fe convention specifications refined e-mail oai-pmh version 1.0 introduced public january 2001 workshop washington d.c. another february berlin germany subsequent modifications xml standard w3c required making minor modifications oai-pmh resulting version 1.1 current version 2.0 released june 2002 contained several technical changes enhancements backward compatible oai protocol adopted many digital libraries institutional repositories digital archives although registration mandatory encouraged several large registries oai-compliant repositories commercial search engines use oai-pmh acquire resources google initially included support oai-pmh launching sitemaps however decided support standard xml sitemaps format may 2008 2004 yahoo acquired content oaister university michigan obtained metadata harvesting oai-pmh wikimedia uses oai-pmh repository provide feeds wikipedia related site updates search engines bulk analysis/republishing endeavors especially dealing thousands files harvested every day oai-pmh help reducing network traffic resource usage incremental harvesting nasa mercury metadata search system uses oai-pmh index thousands metadata records global change master directory gcmd every day mod_oai project using oai-pmh expose content web crawlers accessible apache web servers oai-pmh based client–server architecture harvesters request information updated records repositories requests data based datestamp range restricted named sets defined provider data providers required provide xml metadata dublin core format may also provide xml formats number software systems support oai-pmh including fedora ethos british library gnu eprints university southampton open journal systems public knowledge project desire2learn dspace mit hyperjournal university pisa digibib digibis mycore primo digitool rosetta metalib ex libris archivalware ptfs door elab lugano switzerland panfmp pangaea data library simpledl roaring development joai number large archives support protocol including arxiv cern document server dedicated workshop cern workshop innovations scholarly communication held cern geneva regular basis since 2001 co-organised university geneva cern every two years june oai8 held june 19th-21st 2013 oai9 held june 17–19 2015 oai10 held june 21 23 2017
|
Internet protocols
|
powerhouse programming language powerhouse trademarked name byte-compiled fourth-generation programming language 4gl originally produced quasar corporation later renamed cognos incorporated hewlett-packard hp3000 mini-computer initially composed five components powerhouse introduced 1982 bundled together single product quiz quick/qdesign previously available separately new batch processor qtp 1983 quasar changed name cognos corporation began porting application development tools platforms notably digital equipment corporation vax data general eclipse mv ibm as/400 along unix platforms vendors cognos also began extending product line add-ons powerhouse example architect end-user applications written powerhouse example multiview subsequent development product added support platform-specific relational databases hp allbase/sql dec rdb microsoft sql server well cross-platform relational databases oracle sybase ibm db2 powerhouse language represented considerable achievement compared languages like cobol pascal pl/1 powerhouse substantially cut amount labour required produce useful applications chosen platforms achieved use central data-dictionary compiled file extended attributes data fields natively available dbms frequently used programming idioms order support data dictionary powerhouse tightly coupled underlying database management system and/or file system target platforms case hp3000 image shallow-network dbms ksam indexed file system entire powerhouse language reflected origins described data dictionary need describe attributes applications unless need change fly example change size item make fit within constraints defined item simple quick screens could generated four lines source code screenname name screen programmer assigned program filename file name accessed data dictionary whether items file would fit screen would determined many items size n't fit program would modified eliminate unneeded items change size items size etc file couple items quick easy generate screen data entry deletion simply look data index simple quiz reports almost easy one-file report simple items file would sent screen maybe desired fashion simple since qtp programs usually involved adding deleting modifying data much need simple code programs care exercised potential danger whole file files data could wiped rather easily quick quiz qtp programs could run compiled converted machine language uncompiled source code compiled programs generally ran faster good method modifications source code corrupt object code quick screens used primarily data entry could call quick screens quiz reports qtp applications update data also things done source code order generate compiled code example go command run source code equivalent build command generate compiled code commands could abbreviated first three characters writing source code access could abbreviated acc well define report screen etc quiz reports could routed printer screen ascii text files set report device printer screen disk command given right access commands novice could write simple report programs dangerous though novice could easily destroy data security whether one call interpreters access quiz also access qtp quick like virtual machine languages powerhouse cpu intensive sometimes produced visibly negative impact overall transaction performance necessitating hardware upgrades cognos practice tying license fees hardware performance metrics resulted high licensing costs powerhouse users cognos initially attempted move intel platform 1988 dos-based powerhouse pc product used numerous partners build bespoke applications small medium-sized customers entirely unsuccessful time however cognos eventually produced axiant c.1995 ported powerhouse-like syntax intel-based microsoft windows visual development environment linked sql aware dbms running machines radical changes wrought pc revolution began time powerhouse introduced eventually brought cost host computers extent high-priced software development tools powerhouse became unattractive customers around 1999 powerhouse web released order support development web-aware applications products like business intelligence financial performance management run commodity architectures high-end unix servers form core cognos product line cognos acquired ibm january 30 2008 powerhouse application development tools including powerhouse server axiant 4gl powerhouse web acquired ibm unicom systems division unicom global december 31 2013 unicom continues support worldwide customer base products
|
Programming language topics
|
sentence embedding sentence embedding collective name set techniques natural language processing nlp sentences mapped vectors real numbers sentence embedding used machine learning software libraries pytorch tensorflow way testing sentence encodings apply sentences involving compositional knowledge sick corpus entailment sick-e relatedness sick-r best results obtained using bilstm network trained stanford natural language inference snli corpus pearson correlation coefficient sick-r 0.885 result sick-e 86.3 slight improvement previous scores presented sick-r 0.888 sick-e 87.8 using concatenation bidirectional gated recurrent unit infersent sentence embeddings training code learning general purpose distributed sentence representations via large scale multi-task learning
|
Computational linguistics
|
content threat removal content threat removal ctr cyber security technology intended defeat threat posed handling digital content cyberspace unlike defences including antivirus software sandboxed execution rely able detect threats similarly content disarm reconstruction ctr designed remove threat without knowing whether done acts without knowing data contains threat detection strategies work detecting unsafe content blocking removing content content deemed safe delivered destination contrast content threat removal assumes data hostile delivers none destination regardless whether actually hostile although data delivered business information carried data delivered using new data created purpose advanced attacks continuously defeat defences based detection often referred zero day attacks soon discovered attack detection mechanisms must updated identify neutralise attack systems unprotected attacks succeed attackers skilled finding new ways evading detection polymorphic code used evade detection known unsafe data sandbox detection allows attacks evade dynamic analysis content threat removal defence works intercepting data way destination business information carried data extracted data discarded entirely new clean safe data built carry information destination effect building new data carry business information unsafe elements original data left behind discarded includes executable data macros scripts malformed data triggers vulnerabilities applications ctr form content transformation transformations provide complete defence content threat ctr applicable user-to-user traffic email chat machine-to-machine traffic web services data transfers intercepted in-line application layer proxies transform way information content delivered remove threat ctr works extracting business information data possible extract information executable code means ctr directly applicable web browsing since web pages code however applied content downloaded uploaded web sites although web pages transformed render safe web browsing isolated remote access protocols used reach isolated environment subjected ctr ctr provides solution problem stegware naturally removes detectable steganography eliminates symbiotic permutation steganography normalisation deep secure pioneered development ctr number products services incorporate ctr including application layer proxies email web services icap internet content adaptation protocol sidecar servers uploaded downloaded content garrison provide remote desktop isolation solution display content converted video signal recoded video stream using separate hardware chips process removes threat content display content
|
Computer security
|
electronic waste electronic waste e-waste describes discarded electrical electronic devices used electronics destined refurbishment reuse resale salvage recycling material recovery disposal also considered e-waste informal processing e-waste developing countries lead adverse human health effects environmental pollution electronic scrap components cpus contain potentially harmful materials lead cadmium beryllium brominated flame retardants recycling disposal e-waste may involve significant risk health workers communities developed countries great care must taken avoid unsafe exposure recycling operations leaking materials heavy metals landfills incinerator ashes electronic-waste electronic waste created electronic product discarded end useful life rapid expansion technology consumption driven society results creation large amount e-waste every minute european weee directive classifies waste ten categories large household appliances including cooling freezing appliances small household appliances equipment including monitors consumer electronics including tvs lamps luminaires toys tools medical devices monitoring control instruments automatic dispensers include used electronics destined reuse resale salvage recycling disposal well re-usables working repairable electronics secondary raw materials copper steel plastic etc. term waste reserved residue material dumped buyer rather recycled including residue reuse recycling operations loads surplus electronics frequently commingled good recyclable non-recyclable several public policy advocates apply term e-waste e-scrap broadly surplus electronics cathode ray tubes crts considered one hardest types recycle crts relatively high concentration lead phosphors confused phosphorus necessary display united states environmental protection agency epa includes discarded crt monitors category hazardous household waste considers crts set aside testing commodities discarded speculatively accumulated left unprotected weather damage crt devices often confused dlp rear projection tv different recycling process due materials composed eu member states operate system via european waste catalogue ewc european council directive interpreted member state law uk form list wastes directive however list ewc gives broad definition ewc code 16 02 13* hazardous electronic waste requiring waste operators employ hazardous waste regulations annex 1a annex 1b refined definition constituent materials waste also require assessment via combination annex ii annex iii allowing operators determine whether waste hazardous debate continues distinction commodity waste electronics definitions exporters accused deliberately leaving difficult-to-recycle obsolete non-repairable equipment mixed loads working equipment though may also come ignorance avoid costly treatment processes protectionists may broaden definition waste electronics order protect domestic markets working secondary equipment high value computer recycling subset electronic waste working reusable laptops desktops components like ram help pay cost transportation larger number worthless pieces achieved display devices less negative scrap value 2011 report ghana e-waste country assessment found 215,000 tons electronics imported ghana 30 brand new 70 used used product study concluded 15 reused scrapped discarded contrasts published uncredited claims 80 imports ghana burned primitive conditions rapid changes technology changes media tapes software mp3 falling prices planned obsolescence resulted fast-growing surplus electronic waste around globe technical solutions available cases legal framework collection logistics services need implemented technical solution applied display units crt lcd led monitors processors cpu gpu apu chips memory dram sram audio components different useful lives processors frequently out-dated software longer optimized likely become e-waste display units often replaced working without repair attempts due changes wealthy nation appetites new display technology problem could potentially solved modular smartphones phonebloks types phones durable technology change certain parts phone making environmentally friendly able simply replace part phone broken reduce e-waste estimated 50 million tons e-waste produced year usa discards 30 million computers year 100 million phones disposed europe year environmental protection agency estimates 15–20 e-waste recycled rest electronics go directly landfills incinerators 2006 united nations estimated amount worldwide electronic waste discarded year 50 million metric tons according report unep titled recycling – e-waste resources amount e-waste produced – including mobile phones computers – could rise much 500 percent next decade countries india united states world leader producing electronic waste tossing away 3 million tons year china already produces 2.3 million tons 2010 estimate domestically second united states despite banned e-waste imports china remains major e-waste dumping ground developed countries society today revolves around technology constant need newest high-tech products contributing mass amount e-waste since invention iphone cell phones become top source e-waste products made last two years electrical waste contains hazardous also valuable scarce materials 60 elements found complex electronics 2013 apple sold 796 million idevices ipod iphone ipad cell phone companies make cell phones made last consumer purchase new phones companies give products short lifespans know consumer want new product buy make united states estimated 70 heavy metals landfills comes discarded electronics agreement number discarded electronic devices increasing considerable disagreement relative risk compared automobile scrap example strong disagreement whether curtailing trade used electronics improve conditions make worse according article motherboard attempts restrict trade driven reputable companies supply chain unintended consequences one theory increased regulation electronic wastes concern environmental harm nature economies creates economic disincentive remove residues prior export critics trade used electronics maintain still easy brokers calling recyclers export unscreened electronic waste developing countries china india parts africa thus avoiding expense removing items like bad cathode ray tubes processing expensive difficult developing countries become toxic dump yards e-waste developing countries receiving foreign e-waste often go repair recycle forsaken equipment yet still 90 e-waste ended landfills developing countries 2003 proponents international trade point success fair trade programs industries cooperation led creation sustainable jobs bring affordable technology countries repair reuse rates higher defenders trade used electronics say extraction metals virgin mining shifted developing countries recycling copper silver gold materials discarded electronic devices considered better environment mining also state repair reuse computers televisions become lost art wealthier nations refurbishing traditionally path development south korea taiwan southern china excelled finding retained value used goods cases set billion-dollar industries refurbishing used ink cartridges single-use cameras working crts refurbishing traditionally threat established manufacturing simple protectionism explains criticism trade works like waste makers vance packard explain criticism exports working product example ban import tested working pentium 4 laptops china bans export used surplus working electronics japan opponents surplus electronics exports argue lower environmental labour standards cheap labour relatively high value recovered raw materials lead transfer pollution-generating activities smelting copper wire china malaysia india kenya various african countries electronic waste sent countries processing sometimes illegally many surplus laptops routed developing nations dumping grounds e-waste united states ratified basel convention ban amendment domestic federal laws forbidding export toxic waste basel action network estimates 80 electronic waste directed recycling u.s. get recycled put container ships sent countries china figure disputed exaggeration epa institute scrap recycling industries world reuse repair recycling association independent research arizona state university showed 87–88 imported used computers higher value best value constituent materials contained official trade end-of-life computers thus driven reuse opposed recycling proponents trade say growth internet access stronger correlation trade poverty haiti poor closer port new york southeast asia far electronic waste exported new york asia haiti thousands men women children employed reuse refurbishing repair re-manufacturing unsustainable industries decline developed countries denying developing nations access used electronics may deny sustainable employment affordable products internet access force deal even less scrupulous suppliers series seven articles atlantic shanghai-based reporter adam minter describes many computer repair scrap separation activities objectively sustainable opponents trade argue developing countries utilize methods harmful wasteful expedient prevalent method simply toss equipment onto open fire order melt plastics burn away non-valuable metals releases carcinogens neurotoxins air contributing acrid lingering smog noxious fumes include dioxins furans bonfire refuse disposed quickly drainage ditches waterways feeding ocean local water supplies june 2008 container electronic waste destined port oakland u.s. sanshui district mainland china intercepted hong kong greenpeace concern exports electronic waste raised press reports india ghana côte d'ivoire nigeria research undertaken countering weee illegal trade cwit project funded european commission found europe 35 3.3 million tons e-waste discarded 2012 ended officially reported amounts collection recycling systems 65 6.15 million tons either guiyu shantou region china massive electronic waste processing community often referred e-waste capital world traditionally guiyu agricultural community however mid-1990s transformed e-waste recycling center involving 75 local households additional 100,000 migrant workers thousands individual workshops employ laborers snip cables pry chips circuit boards grind plastic computer cases particles dip circuit boards acid baths dissolve precious metals others work strip insulation wiring attempt salvage tiny amounts copper wire uncontrolled burning disassembly disposal led number environmental problems groundwater contamination atmospheric pollution water pollution either immediate discharge surface runoff especially near coastal areas well health problems including occupational safety health effects among directly indirectly involved due methods processing waste six many villages guiyu specialize circuit-board disassembly seven plastics metals reprocessing two wire cable disassembly greenpeace environmental group sampled dust soil river sediment groundwater guiyu found high levels toxic heavy metals organic contaminants places lai yun campaigner group found 10 poisonous metals lead mercury cadmium guiyu one example digital dumps similar places found across world nigeria ghana india guiyu likely one oldest largest informal e-waste recycling sites world however many sites worldwide including india ghana agbogbloshie nigeria philippines research involving informal e-waste recycling done guiyu handful studies describe exposure levels e-waste workers community environment example locals migrant workers delhi northern union territory india scavenge discarded computer equipment extract base metals using toxic unsafe methods bangalore located southern india often referred silicon valley india growing informal e-waste recycling sector studies found e-waste workers slum community higher levels v cr mn mo sn tl pb workers e-waste recycling facility processes dismantling disposing electronic waste developing countries led number environmental impacts illustrated graphic liquid atmospheric releases end bodies water groundwater soil air therefore land sea animals – domesticated wild crops eaten animals human drinking water one study environmental effects guiyu china found following separate study agbogbloshie e-waste dump ghana found presence lead levels high 18,125 ppm soil us epa standard lead soil play areas 400 ppm 1200 ppm non-play areas scrap workers agbogbloshie e-waste dump regularly burn electronic components auto harness wires copper recovery releasing toxic chemicals like lead dioxins furans environment environmental impact processing different electronic waste components e-waste presents potential security threat individuals exporting countries hard drives properly erased computer disposed reopened exposing sensitive information credit card numbers private financial data account information records online transactions accessed willing individuals organized criminals ghana commonly search drives information use local scams electronic files government contracts discovered hard drives found agbogbloshie multimillion-dollar agreements united states security institutions defense intelligence agency dia transportation security administration homeland security resurfaced agbogbloshie recycling essential element e-waste management properly carried greatly reduce leakage toxic materials environment mitigate exhaustion natural resources however need encouraged local authorities community education one major challenges recycling printed circuit boards electronic wastes circuit boards contain precious metals gold silver platinum etc base metals copper iron aluminum etc one way e-waste processed melting circuit boards burning cable sheathing recover copper wire open- pit acid leaching separating metals value conventional method employed mechanical shredding separation recycling efficiency low alternative methods cryogenic decomposition studied printed circuit board recycling methods still investigation properly disposing reusing electronics help prevent health problems reduce greenhouse-gas emissions create jobs reuse refurbishing offer environmentally friendly socially conscious alternative downcycling processes u.s. environmental protection agency encourages electronic recyclers become certified demonstrating accredited independent third party auditor meet specific standards safely recycle manage electronics work ensure highest environmental standards maintained two certifications electronic recyclers currently exist endorsed epa customers encouraged choose certified electronics recyclers responsible electronics recycling reduces environmental human health impacts increases use reusable refurbished equipment reduces energy use conserving limited resources two epa-endorsed certification programs responsible recyclers practices r2 e-stewards certified companies ensure meeting strict environmental standards maximize reuse recycling minimize exposure human health environment ensure safe management materials require destruction data used electronics certified electronics recyclers demonstrated audits means continually meet specific high environmental standards safely manage used electronics certified recycler held particular standard continual oversight independent accredited certifying body certification board accredits oversees certifying bodies ensure meet specific responsibilities competent audit provide certification u.s. retailers offer opportunities consumer recycling discarded electronic devices us consumer electronics association cea urges consumers dispose properly end-of-life electronics recycling locator www.greenergadgets.org list includes manufacturer retailer programs use strictest standards third-party certified recycling locations provide consumers assurance products recycled safely responsibly cea research found 58 percent consumers know take end-of-life electronics electronics industry would much like see level awareness increase consumer electronics manufacturers retailers sponsor operate 5,000 recycling locations nationwide vowed recycle one billion pounds annually 2016 sharp increase 300 million pounds industry recycled 2010 sustainable materials management smm electronic challenge created united states environmental protection agency epa 2012 participants challenge manufacturers electronics electronic retailers companies collect end-of-life eol electronics various locations send certified third-party recycler program participants able publicly promote report 100 responsible recycling companies electronics takeback coalition etbc campaign aimed protecting human health limiting environmental effects electronics produced used discarded etbc aims place responsibility disposal technology products electronic manufacturers brand owners primarily community promotions legal enforcement initiatives provides recommendations consumer recycling list recyclers judged environmentally responsible major benefits rise recycling waste collection created producers consumers valuable materials recovered kept away landfill incineration still many problems present epr system including “ ensure proper enforcement recycling standards waste positive net value role competition ” kunz et al. many stakeholders agreed needs higher standard accountability efficiency improve systems recycling everywhere well growing amount waste opportunity downfall since gives us chances create efficient system make recycling competition cost-effective producers agreed needs higher drive competition allows wider range producer responsibility organizations choose e-waste recycling certified electronics recycler program electronic recyclers comprehensive integrated management system standard incorporates key operational continual improvement elements quality environmental health safety performance grassroots silicon valley toxics coalition promotes human health addresses environmental justice problems resulting toxins technologies world reuse repair recycling association wr3a.org organization dedicated improving quality exported electronics encouraging better recycling standards importing countries improving practices fair trade principles take back tv project electronics takeback coalition grades television manufacturers find responsible coalition view also efforts raise awareness potentially hazardous conditions dismantling e-waste american prisons silicon valley toxics coalition prisoner-rights activists environmental groups released toxic sweatshops report details prison labor used handle e-waste resulting health consequences among workers groups allege since prisons adequate safety standards inmates dismantling products unhealthy unsafe conditions many developed countries electronic waste processing usually first involves dismantling equipment various parts metal frames power supplies circuit boards plastics often hand increasingly automated shredding equipment typical example nadin electronic waste processing plant novi iskar bulgaria—the largest facility kind eastern europe advantages process human ability recognize save working repairable parts including chips transistors ram etc disadvantage labor cheapest countries lowest health safety standards alternative bulk system hopper conveys material shredding unsophisticated mechanical separator screening granulating machines separate constituent metal plastic fractions sold smelters plastics recyclers recycling machinery enclosed employs dust collection system emissions caught scrubbers screens magnets eddy currents trommel screens employed separate glass plastic ferrous nonferrous metals separated smelter leaded glass crts reused car batteries ammunition lead wheel weights sold foundries fluxing agent processing raw lead ore. copper gold palladium silver tin valuable metals sold smelters recycling hazardous smoke gases captured contained treated mitigate environmental threat methods allow safe reclamation valuable computer construction materials hewlett-packard product recycling solutions manager renee st. denis describes process move giant shredders 30 feet tall shreds everything pieces size quarter disk drive shredded pieces big hard get data ideal electronic waste recycling plant combines dismantling component recovery increased cost-effective processing bulk electronic waste reuse alternative option recycling extends lifespan device devices still need eventual recycling allowing others purchase used electronics recycling postponed value gained device use recycling raw materials end-of-life electronics effective solution growing e-waste problem electronic devices contain variety materials including metals recovered future uses dismantling providing reuse possibilities intact natural resources conserved air water pollution caused hazardous disposal avoided additionally recycling reduces amount greenhouse gas emissions caused manufacturing new products another benefit recycling e-waste many materials recycled re-used materials recycled include ferrous iron-based non-ferrous metals glass various types plastic “ non-ferrous metals mainly aluminum copper re-smelted re-manufactured ferrous metals steel iron also re-used due recent surge popularity 3d printing certain 3d printers designed fdm variety produce waste easily recycled decreases amount harmful pollutants atmosphere excess plastic printers comes byproduct also reused create new 3d printed creations benefits recycling extended responsible recycling methods used u.s. responsible recycling aims minimize dangers human health environment disposed dismantled electronics create responsible recycling ensures best management practices electronics recycled worker health safety consideration environment locally abroad europe metals recycled returned companies origin reduced cost committed recycling system manufacturers japan pushed make products sustainable since many companies responsible recycling products imposed responsibility manufacturers requiring many redesign infrastructure result manufacturers japan added option sell recycled metals one factors exacerbate e-waste problem diminishing lifetime many electrical electronic goods two drivers particular trend one hand consumer demand low cost products mitigates product quality results short product lifetimes manufacturers sectors encourage regular upgrade cycle may even enforce though restricted availability spare parts service manuals software updates planned obsolescence consumer dissatisfaction state affairs led growing repair movement often community level repair cafės restart parties promoted restart project right repair spearheaded us farmers dissatisfied non-availability service information specialised tools spare parts high-tech farm machinery movement extends far beyond farm machinery example restricted repair options offered apple coming criticism manufacturers often counter safety concerns resulting unauthorised repairs modifications computer components reused assembling new computer products others reduced metals reused applications varied construction flatware jewellery substances found large quantities include epoxy resins fiberglass pcbs pvc polyvinyl chlorides thermosetting plastics lead tin copper silicon beryllium carbon iron aluminium elements found small amounts include cadmium mercury thallium elements found trace amounts include americium antimony arsenic barium bismuth boron cobalt europium gallium germanium gold indium lithium manganese nickel niobium palladium platinum rhodium ruthenium selenium silver tantalum terbium thorium titanium vanadium yttrium almost electronics contain lead tin solder copper wire printed circuit board tracks though use lead-free solder spreading rapidly following ordinary applications residents living around e-waste recycling sites even involve e-waste recycling activities also face environmental exposure due food water environmental contamination caused e-waste easily contact e-waste contaminated air water soil dust food sources general three main exposure pathways inhalation ingestion dermal contact studies show people living around e-waste recycling sites higher daily intake heavy metals serious body burden potential health risks include mental health impaired cognitive function general physical health damage see also electronic waste hazardous dna damage also found prevalent e-waste exposed populations i.e adults children neonates populations control area dna breaks increase likelihood wrong replication thus mutation well lead cancer damage tumor suppressor gene prenatal exposure e-waste found adverse effects human body burden pollutants neonates guiyu one famous e-waste recycling sites china found increased cord blood lead concentration neonates associated parents participation e-waste recycling processes well long mothers spent living guiyu e-waste recycling factories workshops pregnancy besides higher placental metallothionein small protein marking exposure toxic metals found among neonates guiyu result cd exposure higher cd level guiyu neonates related involvement e-waste recycling parents high pfoa exposure mothers guiyu related adverse effect growth new-born prepotency area prenatal exposure informal e-waste recycling also lead several adverse birth outcomes still birth low birth weight low apgar scores etc longterm effects behavioral learning problems neonates future life children especially sensitive e-waste exposure several reasons smaller size higher metabolism rate larger surface area relation weight multiple exposure pathways example dermal hand-to-mouth take-home exposure measured 8-time potential health risk compared adult e-waste recycling workers studies found significant higher blood lead levels bll blood cadmium levels bcl children living e-waste recycling area compared living control area example one study found average bll guiyu nearly 1.5 times compared control site 15.3 ug/dl compared 9.9 ug/dl cdc united states set reference level blood lead 5 ug/dl highest concentrations lead found children parents whose workshop dealt circuit boards lowest among recycled plastic exposure e-waste cause serious health problems children children exposure developmental neurotoxins containing e-waste lead mercury cadmium chromium pbdes lead higher risk lower iq impaired cognitive function adverse effects certain age groups decreased lung function children e-waste recycling sites found studies also found associations children e-waste exposure impaired coagulation hearing loss decreased vaccine antibody tilters e-waste recycling area occupational safety health administration osha summarized several potential safety hazards recycling workers general crushing hazards hazardous energy released toxic metals osha also specified chemical components electronics potentially harm e-recycling workers health lead mercury pcbs asbestos refractory ceramic fibers rcfs radioactive substances.besides united states chemical hazards specific occupational exposure limits oels set osha national institute occupational safety health niosh american conference governmental industrial hygienists acgih details health consequences chemical hazards see also electronic waste electronic waste substances informal e-recycling industry refers small e-waste recycling workshops automatic procedures personal protective equipment ppe hand formal e-recycling industry refers regular e-recycling facilities sorting materials e-waste automatic machinery manual labor pollution control ppe common sometimes formal e-recycling facilities dismantle e-waste sort materials distribute downstream recycling department recover materials plastic metals health impact e-waste recycling workers working informal industry formal industry expect different extent studies three recycling sites china suggest health risks workers formal e-recycling facilities jiangsu shanghai lower compared worked informal e-recycling sites guiyu another study e-waste recycling india hair samples collected workers e-waste recycling facility e-waste recycling slum community informal industry bangalore levels v cr mn mo sn tl pb significantly higher workers e-waste recycling facility compared e-waste workers slum community however co ag cd hg levels significantly higher slum community workers compared facility workers even formal e-recycling industry workers exposed excessive pollutants studies formal e-recycling facilities france sweden found workers overexposure compared recommended occupational guidelines lead cadmium mercury metals well bfrs pcbs dioxin furans workers formal industry also exposed brominated flame-retardants reference groups occupational health safety e-waste recycling workers employers workers take actions suggestions e-waste facility employers workers given california department public health illustrated graphic policy conventions security general
|
Computer security
|
idl programming language idl short interactive data language programming language used data analysis popular particular areas science astronomy atmospheric physics medical imaging idl shares common syntax pv-wave originated codebase though languages subsequently diverged detail also two free implementations gnu data language gdl fawlty language fl idl vectorized numerical interactive commonly used interactive processing large amounts data including image processing syntax includes many constructs fortran c. idl originated early vax/vms/fortran syntax still shows heritage findgen function example returns one-dimensional array floating point numbers values equal series integers starting 0 note operation second line applies vectorized manner whole 100-element array created first line analogous way general-purpose array programming languages apl j k would example contains divide zero idl report arithmetic overflow store nan value corresponding element array first one array elements finite nan excluded visualization generated plot command array programming languages idl fast vector operations sometimes fast well-coded custom loop fortran c quite slow elements need processing individually hence part art using idl array programming language matter numerically heavy computations make use built-in vector operations predecessor versions idl developed 1970s laboratory atmospheric space physics lasp university colorado boulder lasp david stern involved efforts allow scientists test hypotheses without employing programmers write modify individual applications first program evolutionary chain idl stern developed named rufus simple vector-oriented calculator ran pdp-12 accepted two-letter codes specified arithmetic operation input registers serve operands destination register version rufus developed pdp-8 mars mariner spectrum editor mmed mmed used lasp scientists interpret data mariner 7 mariner 9 later stern wrote program named sol also ran pdp-8 unlike predecessors true programming language fortran-like syntax sol array-oriented language primitive graphics capabilities stern left lasp found research systems inc. rsi 1977 first rsi product idl pdp-11 release graphics supported idl primarily tektronix terminals raster graphics displays rsi sold first idl licenses nasa goddard space flight center ball aerospace technologies corp. 1979 two years later rsi released initial vax/vms version idl written vax-11 macro fortran took advantage vax virtual memory 32-bit address space national center atmospheric research ncar university michigan university colorado naval research laboratory started use idl version 1987 rsi shifted development work idl unix environment required complete re-write code c rather port existing version vax idl stern ali bahrami rewrote idl unix sun 3 taking advantage re-write extend improve language subsequently idl expanded ported several variants unix vms linux microsoft windows 1992 mac os 1994 widgets added idl 1992 providing event-driven programming graphical user interfaces 1997 ion idl net web server-based system commercially released first version envi application remote sensing multispectral hyperspectral image analysis written idl released 1994 envi created developed owned better solutions consulting llc purchased bsc october 2000 eastman kodak coincident purchase rsi rsi sold marketed supported envi terms license agreement bsc llc 1994 october 2000 new object pointer types limited object-oriented programming capabilities added idl 1997 idl applied widely space science example solar physics european space agency used idl process almost pictures halley comet taken giotto spacecraft team repairing hubble space telescope used idl help diagnose anomalies main mirror 1995 astronauts board space shuttle used idl loaded laptop study ultraviolet radiation currently amongst applications idl used analysis secchi part stereo mission nrl usa rutherford appleton laboratory uk rsi became wholly owned subsidiary itt industries march 2004 15 may 2006 rsi began business itt visual information solutions effective 31 october 2011 result restructuring company became exelis visual information solutions idl owned maintained harris geospatial solutions computer language idl features make idl simple use interactively also cause difficulties building large programs single namespace particularly problematic example language updates include new built-in functions occasion invalidated large scientific libraries arrays passed reference mechanism advertised feature language pass data back subroutine – contrast array slices copied passed data modifications flow back array ranges subroutine exits violating principle least surprise many historical irregularities survive early heritage language requiring individual workarounds programmer example preceding issue alleviated using compiler option also provision idl eula effect australia result sections 47d 47h country copyright act following graphics created idl source code included
|
Programming language topics
|
commitment ordering commitment ordering co class interoperable serializability techniques concurrency control databases transaction processing related applications allows optimistic non-blocking implementations proliferation multi-core processors co also increasingly utilized concurrent programming transactional memory especially software transactional memory stm achieving serializability optimistically co also name resulting transaction schedule history property originally defined 1988 name dynamic atomicity co compliant schedule chronological order commitment events transactions compatible precedence order respective transactions co broad special case conflict serializability effective means reliable high-performance distributed scalable achieve global serializability modular serializability across collection database systems possibly use different concurrency control mechanisms co also makes system serializability compliant already not-co-compliant database system augmented co component commitment order coordinator—coco orders commitment events co compliance neither data-access transaction operation interference co provides low overhead general solution global serializability distributed serializability instrumental global concurrency control distributed concurrency control multi database systems transactional objects possibly highly distributed e.g. within cloud computing grid computing networks smartphones atomic commitment protocol acp type fundamental part solution utilized break global cycles conflict precedence serializability graph co general property necessary condition guarantees global serializability database systems involved share concurrency control information beyond atomic commitment protocol unmodified messages knowledge whether transactions global local database systems autonomous thus co variants general technique require typically costly distribution local concurrency control information e.g. local precedence relations locks timestamps tickets generalizes popular strong strict two-phase locking ss2pl property conjunction two-phase commit protocol 2pc de facto standard achieve global serializability across ss2pl based database systems result co compliant database systems different concurrency control types transparently join ss2pl based solutions global serializability addition locking based global deadlocks resolved automatically co based multi-database environment important side-benefit including special case completely ss2pl based environment previously unnoticed fact ss2pl furthermore strict commitment ordering sco raz 1991c intersection strictness co provides better performance shorter average transaction completion time resulting better transaction throughput ss2pl whenever read-write conflicts present identical blocking behavior write-read write-write conflicts comparable locking overhead advantage sco especially significant lock contention strictness allows ss2pl sco use effective database recovery mechanisms two major generalizing variants co exist extended co eco raz 1993a multi-version co mvco raz 1993b well provide global serializability without local concurrency control information distribution combined relevant concurrency control allow optimistic non-blocking implementations use additional information relaxing co constraints achieving better concurrency performance vote ordering vo generalized co gco raz 2009 container schedule set property technique co variants local vo necessary condition guaranteeing global serializability atomic commitment protocol acp participants share concurrency control information generalized autonomy property co variants inter-operate transparently guaranteeing global serializability automatic global deadlock resolution also together mixed heterogeneous environment different variants commitment ordering co raz 1990 1992 1994 2009 schedule property referred also dynamic atomicity since 1988 commit ordering commit order serializability strong recoverability since 1991 latter misleading name since co incomparable recoverability term strong implies special case means schedule strong recoverability property necessarily co property vice versa 2009 co characterized major concurrency control method together previously known since 1980s three major methods locking time-stamp ordering serialization graph testing enabler interoperability systems using different concurrency control mechanisms federated database system loosely defined multidatabase system typically distributed communication network transactions span multiple possibly distributed databases enforcing global serializability system problematic even every local schedule single database serializable still global schedule whole system necessarily serializable massive communication exchanges conflict information needed databases reach conflict serializability would lead unacceptable performance primarily due computer communication latency problem achieving global serializability effectively characterized open public disclosure co 1991 inventor yoav raz raz 1991a see also global serializability enforcing co effective way enforce conflict serializability globally distributed system since enforcing co locally database transactional object also enforces globally database may use possibly different type concurrency control mechanism local mechanism already provides conflict serializability enforcing co locally cause additional aborts since enforcing co locally affect data access scheduling strategy mechanism scheduling determines serializability related aborts mechanism typically consider commitment events order co solution requires communication overhead since uses unmodified atomic commitment protocol messages already needed distributed transaction reach atomicity atomic commitment protocol plays central role distributed co algorithm enforces co globally breaking global cycles cycles span two databases global conflict graph co special cases generalizations interoperable achieve global serializability transparently utilized together single heterogeneous distributed environment comprising objects possibly different concurrency control mechanisms commitment ordering including special cases together generalizations see co variants provides general high performance fully distributed solution central processing component central data structure needed guaranteeing global serializability heterogeneous environments multidatabase systems multiple transactional objects objects states accessed modified transactions e.g. framework transactional processes within cloud computing grid computing co solution scales network size number databases without negative impact performance assuming statistics single distributed transaction e.g. average number databases involved single transaction unchanged proliferation multi-core processors optimistic co oco also increasingly utilized achieve serializability software transactional memory numerous stm articles patents utilizing commit order already published e.g. zhang et al 2006 commitment ordering co special case conflict serializability co enforced non-blocking mechanisms transaction complete task without data-access blocked allows optimistic concurrency control however commitment could blocked co schedule commitment events partial precedence order transactions corresponds precedence partial order respective transactions directed conflict graph precedence graph serializability graph induced conflicting access operations usually read write insert/modify/delete operations co also applies higher level operations conflicting noncommutative well conflicts operations upon multi-version data commitment decision events generated either local commitment mechanism atomic commitment protocol different processes need reach consensus whether commit abort protocol may distributed centralized transactions may committed concurrently commit partial order allows conflicting operations different conflicting operations induce different partial orders transactions conflict graph cycles schedule violate serializability transactions cycle committed case partial order commitment events found thus cycles conflict graph need broken aborting transactions however conflict serializable schedule made co without aborting transaction properly delaying commit events comply transactions precedence partial order co enforcement sufficient concurrency control mechanism since co lacks recoverability property supported well fully distributed global commitment ordering enforcement algorithm exists uses local co participating database needs unmodified atomic commitment protocol messages communication distributed algorithm combination local database co algorithm processes atomic commitment protocol fully distributed atomic commitment protocol essential enforce atomicity distributed transaction decide whether commit abort procedure always carried distributed transactions independently concurrency control co common example atomic commitment protocol two-phase commit protocol resilient many types system failure reliable environment processes usually fail together e.g. integrated circuit simpler protocol atomic commitment may used e.g. simple handshake distributed transaction participating processes arbitrary known special participant transaction coordinator i.e. type one-phase commit protocol atomic commitment protocol reaches consensus among participants whether commit abort distributed global transaction spans participants essential stage protocol yes vote either explicit implicit participant means obligation voting participant obey decision protocol either commit abort otherwise participant unilaterally abort transaction explicit vote protocol commits transaction yes votes received participants thus missing vote typically considered otherwise protocol aborts transaction various atomic commit protocols differ abilities handle different computing environment failure situations amounts work computing resources needed different situations entire co solution global serializability based fact case missing vote distributed transaction atomic commitment protocol eventually aborts transaction database system local co algorithm determines needed commitment order database characterization co order depends local precedence order transactions results local data access scheduling mechanisms accordingly yes votes atomic commitment protocol scheduled unaborted distributed transaction follows vote means yes vote precedence relation conflict exists two transactions second voted first completed either committed aborted prevent possible commit order violation atomic commitment protocol happen since commit order protocol necessarily voting order precedence relation exists voted concurrently vote ordering strategy ensures also atomic commitment protocol maintains commitment order necessary condition guaranteeing global co local co database without global co local co property meaning database co compliant may violated however since database systems schedule transactions independently possible transactions precedence orders two databases compatible global partial order exists embed respective local partial orders together co precedence orders also commitment orders participating databases distributed transaction compatible local precedence orders transaction without knowing typically coordination database systems exists conflicts since needed communication massive unacceptably degrades performance means transaction resides global cycle involving two databases global conflict graph case atomic commitment protocol fail collect votes needed commit transaction vote ordering strategy least one database delay vote transaction indefinitely comply commitment precedence order since waiting completion another preceding transaction global cycle delayed indefinitely another database different order means voting-deadlock situation involving databases cycle result protocol eventually abort deadlocked transaction global cycle since transaction missing least one participant vote selection specific transaction cycle aborted depends atomic commitment protocol abort policies timeout mechanism common may result one needed abort per cycle preventing unnecessary aborts abort time shortening achieved dedicated abort mechanism co abort break global cycle involving distributed transaction deadlocked transactions possibly conflict deadlocked thus blocked free voted worthwhile noting database involved voting-deadlock continues vote regularly transactions conflict deadlocked transaction typically almost outstanding transactions thus case incompatible local partial commitment orders action needed since atomic commitment protocol resolves automatically aborting transaction cause incompatibility means vote ordering strategy also sufficient condition guaranteeing global co following concluded global co implies global serializability global co algorithm comprises enforcing local co participating database system ordering commits local transactions see enforcing co locally enforcing vote ordering strategy theorem global transactions global cycle elimination process voting deadlock explained detail following observation first assumed simplicity every transaction reaches ready-to-commit state voted least one database implies blocking locks occurs define wait vote commit graph directed graph transactions nodes directed edge first transaction second transaction first transaction blocks vote commit second transaction opposite conventional edge direction wait-for graph blocking happens second transaction conflict first transaction see thus wait vote commit graph identical global conflict graph cycle wait vote commit graph means deadlock voting hence deadlock voting cycle conflict graph local cycles confined single database eliminated local serializability mechanisms consequently global cycles left eliminated atomic commitment protocol aborts deadlocked transactions missing blocked respective votes secondly also local commits dealt note enforcing co also waiting regular local commit local transaction block local commits votes transactions upon conflicts situation global transactions change also without simplifying assumption final result also local commitment local transactions without voting atomic commitment finally blocking lock excluded far needs considered lock blocks conflicting operation prevents conflict materialized lock released transaction end may block indirectly either vote local commit another transaction get ready state effect direct blocking vote local commit case cycle generated conflict graph blocking lock also represented edge added edges representing events blocking-by-a-lock conflict graph becoming augmented conflict graph presence co augmented conflict graph fact reversed edge local-commit voting wait-for graph edge exists first transaction either local global second second waiting first end order either voted global locally committed local global cycles across two databases graph generate voting-deadlocks graph global cycles provide complete characterization voting deadlocks may include combination materialized non-materialized conflicts cycles materialized conflicts also cycles regular conflict graph affect serializability one lock related non-materialized conflicts cycle prevent cycle regular conflict graph make locking related deadlock global cycles voting-deadlocks need broken resolved maintain global serializability resolve global deadlocks involving data access locking indeed broken atomic commitment protocol due missing votes upon voting deadlock comment observation also explains correctness extended co eco global transactions voting order must follow conflict graph order vote blocking order relation graph path exists two global transactions local transactions voted local commits blocked upon conflicts results voting-deadlock situations resulting global cycle elimination process eco voting-deadlock situation summarized follows also following locking based special case concluded voting-deadlocks key operation distributed co global cycle elimination voting-deadlock resolution atomic commitment resulting aborted transactions re-executions time consuming regardless concurrency control used databases schedule transactions independently global cycles unavoidable complete analogy cycles/deadlocks generated local ss2pl distribution transaction operation scheduling coordination results autonomy violation typically also substantial performance penalty however many cases likelihood made low implementing database transaction design guidelines reduce number conflicts involving global transaction primarily properly handling hot spots database objects frequent access avoiding conflicts using commutativity possible e.g. extensively using counters finances especially multi-transaction accumulation counters typically hot spots atomic commitment protocols intended designed achieve atomicity without considering database concurrency control abort upon detecting heuristically finding e.g. timeout sometimes mistakenly unnecessarily missing votes typically unaware global cycles protocols specially enhanced co including co variants prevent unnecessary aborts accelerate aborts used breaking global cycles global augmented conflict graph better performance earlier release upon transaction-end computing resources typically locked data example existing locking based global deadlock detection methods timeout generalized consider also local commit vote direct blocking besides data access blocking possible compromise mechanisms effectively detecting breaking frequent relatively simple handle length-2 global cycles using timeout undetected much less frequent longer cycles commitment ordering enforced locally single database dedicated co algorithm algorithm/protocol provides special case co. important protocol utilized extensively database systems generates co schedule strong strict two phase locking protocol ss2pl release transaction locks transaction either committed aborted see ss2pl proper subset intersection 2pl strictness generic local co algorithm raz 1992 algorithm 4.1 algorithm independent implementation details enforces exactly co property block data access nonblocking consists aborting certain set transactions needed upon committing transaction aborts uniquely determined given time minimal set undecided neither committed aborted transactions run locally cause serializability violation future later generate cycles committed transactions conflict graph abort set committed transaction committing transaction abort commit time committed doomed aborted set consists undecided transactions directed edges conflict graph committed transaction size set increase transaction waiting committed ready state processing ended typically decreases time transactions decided thus unless real-time constraints exist complete transaction preferred wait committing transaction let set decrease size another serializability mechanism exists locally eliminates cycles local conflict graph cycle involving transaction exists set empty eventually abort set member needed otherwise set stabilize transactions local cycles aborting set members occur break cycles since case co conflicts generate blocking commit local cycles augments conflict graph see indicate local commit-deadlocks deadlock resolution techniques ss2pl used e.g. like timeout wait-for graph local cycle augmented conflict graph least one non-materialized conflict reflects locking-based deadlock local algorithm applied local augmented conflict graph rather regular local conflict graph comprises generic enhanced local co algorithm single local cycle elimination mechanism guaranteeing local serializability handling locking based local deadlocks practically additional concurrency control mechanism always utilized even solely enforce recoverability generic co algorithm affect local data access scheduling strategy runs alongside local concurrency control mechanism affects commit order reason need abort transactions needed aborted serializability violation prevention combined local concurrency control mechanism net effect co may delay commit events voting distributed environment comply needed commit order delay special cases example ss2pl average significantly less following theorem concluded proliferation multi-core processors variants generic local co algorithm also increasingly utilized concurrent programming transactional memory especially software transactional memory achieving serializability optimistically commit order e.g. ramadan et al 2009 zhang et al 2006 von parun et al 2007 numerous related articles patents utilizing co already published database system multidatabase environment assumed software architecture point view co component implements generic co algorithm locally commitment order coordinator coco designed straightforward way mediator single database system atomic commitment protocol component raz 1991b however coco typically integral part database system coco functions vote commit ready global transactions processing ended according local commitment order vote abort transactions database system initiated abort database system initiate abort transaction many reasons pass atomic commitment decision database system local transactions identified voting needed determining commitment order coco maintains updated representation local conflict graph local augmented conflict graph capturing also locking deadlocks undecided neither committed aborted transactions data structure e.g. utilizing mechanisms similar locking capturing conflicts data-access blocking coco component interface database system receive conflict ready processing ended readiness vote global transaction commit local one abort notifications database system also interfaces atomic commitment protocol vote receive atomic commitment protocol decision global transaction decisions delivered coco database system interface well local transactions commit notifications proper commit order coco including interfaces enhanced implements another variant co see plays role database concurrency control mechanism beyond voting atomic commitment coco also guarantees co locally single isolated database system interface atomic commitment protocol databases participate distributed transactions i.e. transactions span single database use shared concurrency control information use unmodified atomic commitment protocol messages reaching atomicity maintaining local commitment ordering one generalizing variants see necessary condition guaranteeing global serializability proof technique found raz 1992 different proof method raz 1993a also sufficient condition mathematical fact derived definitions serializability transaction means complying co global serializability guaranteed condition condition local concurrency control information sharing databases beyond atomic commit protocol messages atomic commitment minimal requirement distributed transaction since always needed implied definition transaction raz 1992 defines database autonomy independence complying requirement without using additional local knowledge using definition following concluded however definition autonomy implies example transactions scheduled way local transactions confined single database identified autonomous database system realistic transactional objects restrictive less realistic general purpose database systems autonomy augmented ability identify local transactions compliance general property extended commitment ordering eco see makes eco necessary condition raz 2009 notion generalized autonomy captures intended notion autonomy definition probably broadest definition possible context database concurrency control makes co together useful concurrency control information distribution generalizing variants vote ordering vo see co variants necessary condition global serializability i.e. union co generalizing variants necessary set vo may include also new unknown useful generalizing variants commitment ordering co solution technique global serializability summarized follows database transactional object multidatabase environment complies co i.e. arranges local transactions commitments votes global distributed transactions atomic commitment protocol according local database partial order induced local conflict graph serializability graph respective transactions global co global serializability guaranteed database co compliance achieved effectively local conflict serializability based concurrency control mechanism neither affecting transaction execution process scheduling aborting also database autonomy violated low overhead incurred detecting conflicts e.g. locking data-access blocking already detected purposes ordering votes local transactions commits according conflicts case incompatible partial orders two databases global partial order embed respective local partial orders together global cycle spans two databases global conflict graph generated together co results cycle blocked votes voting-deadlock occurs databases cycle however allowed concurrent voting database typically almost outstanding votes continue execute case atomic commitment protocol fails collect votes needed blocked transactions global cycle consequently protocol aborts transaction missing vote breaks global cycle voting-deadlock resolved related blocked votes free executed breaking global cycle global conflict graph ensures global co global serializability maintained thus case incompatible local partial commitment orders action needed since atomic commitment protocol resolves automatically aborting transaction cause incompatibility furthermore also global deadlocks due locking global cycles augmented conflict graph least one data access blocking result voting deadlocks resolved automatically mechanism local co necessary condition guaranteeing global serializability databases involved share concurrency control information beyond unmodified atomic commitment protocol messages i.e. databases autonomous context concurrency control means every global serializability solution autonomous databases must comply co otherwise global serializability may violated thus likely violated quickly high-performance environment co solution scales network size number databases without performance penalty utilizes common distributed atomic commitment architecture distinguishing characteristic co solution distributed serializability techniques fact requires conflict information distributed e.g. local precedence relations locks timestamps tickets makes uniquely effective utilizes unmodified atomic commitment protocol messages already used instead common way achieve distributed serializability distributed system distributed lock manager dlm dlms communicate lock non-materialized conflict information distributed environment typically suffer computer communication latency reduces performance system co allows achieve distributed serializability general conditions without distributed lock manager exhibiting benefits already explored multidatabase environments particular reliability high performance scalability possibility using optimistic concurrency control desired conflict information related communications network incurred overhead delays automatic distributed deadlock resolution distributed transactional systems rely atomic commitment protocol coordinate atomicity whether commit abort among processes distributed transaction also typically recoverable data i.e. data transactions control e.g. database data confused recoverability property schedule directly accessed single transactional data manager component also referred resource manager handles local sub-transactions distributed transaction portion single location e.g. network node even data accessed indirectly entities distributed system transaction i.e. indirect access requires direct access local sub-transaction thus recoverable data distributed transactional system typically partitioned among transactional data managers system transactional data managers typically comprise participants system atomic commitment protocol participant complies co e.g. using ss2pl cocos combination see entire distributed system provides co theorems participant considered separate transactional object thus distributed serializability furthermore co utilized together atomic commitment protocol also distributed deadlocks i.e. deadlocks span two data managers caused data-access locking resolved automatically thus following corollary concluded theorem also means ss2pl co variant used locally transactional data manager data manager exclusive control data distributed lock manager often utilized enforce distributed ss2pl needed distributed ss2pl serializability relevant wide range distributed transactional applications easily designed meet theorem conditions implementing distributed optimistic co doco generic local co algorithm utilized atomic commitment protocol participants system data access blocking thus local deadlocks previous theorem following corollary distributed database system utilizes ss2pl resides two remote nodes b database system two transactional data managers resource managers one node database data partitioned two data managers way exclusive control local node portion data handles data locks without knowledge manager distributed transaction data managers need execute available atomic commitment protocol two distributed transactions formula_3 formula_2 running concurrently access data x y. x exclusive control data manager b manager access x b respective local sub-transactions b portions formula_3 formula_2 nodes following database system schedule certain point time following formula_3 holds read-lock x formula_2 holds read-locks thus formula_27 formula_30 blocked lock compatibility rules ss2pl executed distributed deadlock situation also voting-deadlock see distributed global cycle length 2 number edges conflicts 2 frequent length local sub-transactions following states since atomic commitment protocol receive votes blocked sub-transactions voting-deadlock eventually abort transaction missing vote timeout either formula_3 formula_2 timeouts fall close resolve global deadlock remaining transaction complete running voted committed aborted transaction immediately restarted re-executed scenario conflicts non-materialized global voting-deadlock reflected cycle global wait-for graph global conflict graph see exact characterization voting-deadlocks global cycles however database system utilize co variant exactly conflicts voting-deadlock situation resolution conflicts either materialized non-materialized depending co variant used example sco used distributed database system instead ss2pl two conflicts example materialized local sub-transactions ready states vote blocking occurs two transactions one node co voting rule applied independently b due conflicts formula_52 voted formula_53 ends formula_54 voted formula_55 ends voting-deadlock conflict graph global cycle conflicts materialized resolved atomic commitment protocol distributed serializability maintained unlikely distributed database system possible principle occurs multi-database employ ss2pl b employs sco case global cycle neither wait-for graph serializability graph still augmented conflict graph union two various combinations summarized following table comment examples describe real recommended utilization co example hypothetical demonstration certain experimental distributed memory-resident databases advocate multi single-threaded core music transactional environments single-threaded refers transaction threads serial execution transactions purpose possible orders magnitude gain performance e.g. h-store voltdb relatively conventional transaction execution multiple threads core described music independent way cores distributed may reside one integrated circuit chip many chips possibly distributed geographically many computers environment recoverable transactional data partitioned among threads cores implemented conventional way distributed co described previous sections doco strictness exist automatically however downsides exist straightforward implementation environment practicality general-purpose solution questionable hand tremendous performance gain achieved applications bypass downsides situations comment music straightforward implementation described uses example usual distributed co voting transaction thread blocking atomic commitment protocol needed demonstration connection implementation h-store project music environment local schedules serial thus local optimistic co oco see global co enforcement vote ordering strategy condition atomic commitment protocol met automatically results distributed co compliance thus distributed serializability automatic global voting deadlock resolution furthermore also local strictness follows automatically serial schedule theorem 5.2 raz 1992 page 307 co vote ordering strategy applied also global strictness guaranteed note serial locally mode allows strictness optimistic data access blocking together following concluded special case schedule property classes e.g. ss2pl sco strictly contained co class generalizing classes eco mvco strictly contain co class i.e. include also schedules co compliant generalizing variants also guarantee global serializability without distributing local concurrency control information database generalized autonomy property uses local information relaxing co constraints utilizing additional local information better concurrency performance eco uses knowledge transactions local i.e. confined single database mvco uses availability data versions values like co generalizing variants non-blocking interfere transaction operation scheduling seamlessly combined relevant concurrency control mechanism term co variant refers general co eco mvco combination relevant concurrency control mechanism property including multi-version based eco mveco generalizing variants guarantee global serializability local concurrency control information distribution known may discovered strong strict two phase locking ss2pl also referred rigorousness rigorous scheduling means read write locks transaction released transaction ended either committed aborted set ss2pl schedules proper subset set co schedules property widely utilized database systems since implies co databases use participate global transactions generate together serializable global schedule using atomic commitment protocol needed atomicity multi-database environment database modification addition needed case participate co distributed solution set undecided transactions aborted committing local generic co algorithm empty locks hence algorithm unnecessary case transaction voted database system immediately entering ready state i.e. completing running task locally locks released database system decided atomic commitment protocol thus condition global co enforcing theorem kept automatically local timeout mechanism used database system resolve local ss2pl deadlocks aborting blocked transactions breaks potential local cycles global conflict graph real cycles augmented conflict graph also database system potential global cycles side effect atomic commitment protocol abort mechanism relatively slow independent aborts several entities typically may result unnecessary aborts one transaction per global cycle situation different local wait-for graph based mechanisms identify global cycles atomic commitment protocol break global cycle resulting voting deadlock resolved earlier another database local ss2pl together atomic commitment implying global serializability also deduced directly transactions including distributed obey 2pl ss2pl rules atomic commitment protocol mechanism needed consensus commit rather end phase-two synchronization point probably reason without considering atomic commitment voting mechanism automatic global deadlock resolution noticed co strict commitment ordering sco raz 1991c intersection strictness special case recoverability co provides upper bound schedule concurrency properties exist implemented using blocking mechanisms locking similar used popular ss2pl similar overheads unlike ss2pl sco block read-write conflict possibly blocks commit instead sco ss2pl identical blocking behavior two conflict types write-read write-write result sco shorter average blocking periods concurrency e.g. performance simulations single database significant variant locks ordered sharing identical sco clearly show approximately 100 gain transaction loads also identical transaction loads sco reach higher transaction rates ss2pl lock thrashing occurs concurrency means given computing resources transactions completed time unit higher transaction rate throughput average duration transaction shorter faster completion see chart advantage sco especially significant lock contention sco practical ss2pl since ss2pl provides besides serializability also strictness widely utilized basis efficient recovery databases failure ss2pl mechanism converted sco one better performance straightforward way without changing recovery methods description sco implementation found perrizo tatarinov 1998 see also semi-optimistic database scheduler ss2pl proper subset sco another explanation sco less constraining provides concurrency ss2pl implementing optimistic commitment ordering oco generic local co algorithm utilized without data access blocking thus without local deadlocks oco without transaction operation scheduling constraints covers entire co class special case co class rather useful co variant mechanism characterization extended commitment ordering eco raz 1993a generalizes co local transactions transactions confined single database distinguished global distributed transactions transactions span two databases commitment order applied global transactions thus local database schedule eco property chronological partial order commit events global transactions unimportant local transactions consistent order respective local conflict graph distributed algorithm guarantee global eco exists co algorithm needs unmodified atomic commitment protocol messages order guarantee global serializability database needs guarantee also conflict serializability transactions local concurrency control mechanism condition eco local serializability weaker co allows concurrency cost little complicated local algorithm however practical overhead difference co exists transactions assumed global e.g. information available transactions local eco reduces co. global transaction committed generic local database eco algorithm aborts minimal set undecided transactions neither committed aborted either local transactions global run locally cause later cycle conflict graph set aborted transactions unique contrary co optimized transaction assigned weight determined transaction importance computing resources already invested running transaction optimization carried example reduction max flow networks problem raz 1993a like co set time dependent becomes empty eventually practically almost needed implementations transaction committed set empty set optimization applicable local database concurrency control mechanism separate eco algorithm ensures local cycles eliminated unlike co implies serializability however practically also co local concurrency mechanism utilized least ensure recoverability local transactions always committed concurrently even precedence relation exists unlike co overall transactions local partial order determined local conflict graph possible temporary local cycles since cycles eliminated local serializability mechanism allows also global transactions voted committed concurrently transitively indirect preceding via conflict global transactions committed transitively preceding local transactions state analogy distributed co algorithm stronger concurrent voting condition transitively preceding transactions need committed condition guaranteeing global eco summarized similarly co global eco global cycles global conflict graph eliminated atomic commitment together local serializability i.e. database system maintains serializability locally local cycles eliminated imply global serializability cycles eliminated means database system multidatabase environment provides local serializability mechanism enforces vote ordering strategy theorem generalization co vote ordering strategy global serializability guaranteed local co needed anymore similarly co well eco voting-deadlock situation summarized follows co means also global deadlocks due data-access locking least one lock blocking voting deadlocks automatically resolved atomic commitment multi-version commitment ordering mvco raz 1993b generalization co databases multi-version resources resources read-only transactions block blocked better performance utilizing resources common way nowadays increase concurrency performance generating new version database object time object written allowing transactions read operations several last relevant versions object mvco implies one-copy-serializability 1ser 1sr generalization serializability multi-version resources like co mvco non-blocking combined relevant multi-version concurrency control mechanism without interfering introduced underlying theory mvco conflicts generalized different versions resource differently earlier multi-version theories different versions conflict chronological order replaced version order possibly reversed keeping usual definitions conflicting operations results regular augmented conflict graphs remain unchanged similarly co distributed mvco enforcing algorithm exists mixed environment single-version multi-version resources single-version special case multi-version co mvco algorithm needs unmodified atomic commitment protocol messages additional communication overhead locking-based global deadlocks translate voting deadlocks resolved automatically analogy co following holds mvco generalized employ generalization eco mveco co based snapshot isolation cosi intersection snapshot isolation si mvco si multiversion concurrency control method widely utilized due good performance similarity serializability 1ser several aspects theory raz 1993b mvco described utilized later fekete et al 2005 articles si e.g. cahill et al 2008 see also making snapshot isolation serializable references analyzing conflicts si order make serializable method presented cahill et al 2008 serializable snapshot isolation serializablesi low overhead modification si provides good performance results versus si small penalty enforcing serializability different method combining si mvco cosi makes si serializable well relatively low overhead similarly combining generic co algorithm single-version mechanisms furthermore resulting combination cosi mvco compliant allows cosi compliant database systems inter-operate transparently participate co solution distributed/global serializability see besides overheads also protocols behaviors need compared quantitatively one hand serializable si schedules made mvco cosi possible commit delays needed without aborting transactions hand serializablesi known unnecessarily abort restart certain percentages transactions also serializable si schedules co variants e.g. ss2pl sco oco eco mvco global serializability achieved via atomic commitment protocol based distributed algorithms co variants atomic commitment protocol instrument eliminate global cycles cycles span two databases global augmented thus also regular conflict graph implicitly global data structure implementation needed cases either incompatible local commitment orders two databases global partial order embed respective local partial orders together data-access locking related voting deadlock implying global cycle global augmented conflict graph missing votes atomic commitment protocol breaks cycle aborting undecided transaction see distributed co algorithm differences various variants exist local level within participating database systems local co instance variant role determine position every global transaction transaction spans two databases within local commitment order i.e. determine transaction turn voted locally atomic commitment protocol thus co variants exhibit behavior regard atomic commitment means interoperable via atomic commitment using software interfaces typically provided services already standardized atomic commitment primarily two phase commit protocol e.g. x/open xa transparently utilized together distributed environment co variant instance possibly associated relevant local concurrency control mechanism type summary single global transaction participate simultaneously databases may employ possibly different co variant concurrently running processes database running concurrently local global transactions database atomic commitment protocol indifferent co distinguish various co variants global cycle generated augmented global conflict graph may span databases different co variants generate broken local abort voting deadlock resolved atomic commitment exactly way single co variant environment local cycles possibly mixed materialized non-materialized conflicts serializability data-access-locking deadlock related e.g. sco resolved locally respective variant instance local mechanisms vote ordering vo generalized co gco raz 2009 union co variants useful concept global serializability technique comply vo local serializability general form commutativity based including multi-versioning vote order strategy voting local precedence order needed combining results co variants following concluded
|
Databases
|
domain relational calculus computer science domain relational calculus drc calculus introduced michel lacroix alain pirotte declarative database query language relational data model drc queries form x either domain variable constant formula_2 denotes drc formula result query set tuples x x make drc formula true language uses operators tuple calculus logical connectives ∧ ∨ ¬ existential quantifier ∃ universal quantifier ∀ used bind variables computational expressiveness equivalent relational algebra let b c mean rank name id enterprise relation let e f mean name deptname id department relation find captains starship uss enterprise formula_3 example b c denotes result set set table enterprise find names enterprise crew members stellar cartography formula_4 example 're looking name b condition f c requirement need find enterprise crew members stellar cartography department alternate representation previous example would formula_5 example value requested f domain directly placed formula c domain variable re-used query existence department since already holds crew member id
|
Databases
|
reboot restore rx reboot restore rx horizon data sys freeware application microsoft windows acts alternative windows steadystate allows users restore computer back established baseline helps prevent long term damage computer operating system os upon installation administrator reboot restore rx establish baseline baseline point computer return upon reboot administrator allowed update baseline done tray icon program program operates outside windows master boot record mbr protects mbr also allows user boot windows even windows otherwise unbootable whether software change blue screen death alternative windows steadystate reboot restore rx works maintain computer constant state alternatives including faronic deep freeze toolwiz time machine reboot restore rx pro formerly drive vaccine rollback rx latter two developed developer reboot restore rx horizon data sys reboot restore rx received generally favourable reviews received many awards review techrepublic said looking make -accessible pc junk proof consistently reliable reboot restore rx definitely nice product consider preserving peace freeware release might nearly customizable microsoft steadystate time least system thank allowing condition deteriorate rapidly abuse review product lifehacker wrote nothing worse rebooting computer thinking everything fine find something busted need troubleshoot especially bad start problems driver update series windows updates 're stuck trying figure thing caused problem first place reboot restore rx takes hassle app even restore windows wo n't boot reboot restore rx award best new product 31st annual tech learning awards
|
Computer security
|
greg kroah-hartman greg kroah-hartman gkh major linux kernel developer linux kernel maintainer codice_1 branch staging subsystem usb driver core debugfs kref kobject sysfs kernel subsystems userspace i/o hans j. koch tty layer also created linux-hotplug udev project linux driver project worked novell suse labs division works linux foundation co-author linux device drivers 3rd edition author linux kernel nutshell used contributing editor linux journal also contributes articles lwn.net computing news site kroah-hartman frequently helps documentation kernel driver development talks tutorials 2006 released cd image material introduce programmer working linux device driver development kroah-hartman strong advocate stable kernel–user space api i.e advocate stable kernel interface/binary kernel interface general user space programs also initiated development opensuse tumbleweed bleeding-edge rolling release model edition opensuse
|
Operating systems
|
pheme project pheme 36-month research project establishing veracity claims made internet unverified content dominant prolific social media messages big data typically presents challenges information volume variety velocity social media presents fourth establishing veracity pheme project aims analyse content real time determine accurate claims made claims propagate social network individual chooses whether pass information based accurate think analysing language used spread information network well spatial temporal context information used build real-time lie detector social media help example emergency services already integrate social media part alerting response systems flag potential hoax emergencies evaluating authority sources automatically also project goal based treatment news information comes example tweet bbc news article would hold weight one unknown source project named greek goddess pheme pheme addresses social media lies two scenarios information healthcare particularly damaging wrong information used journalists pheme addresses speculation controversy misinformation disinformation project partnership university sheffield part gate university warwick king college london saarland university germany modul university vienna four companies also taking part atos ihub nairobi ontotext swissinfo pheme funded eu
|
Computational linguistics
|
labyrinth computer game labyrinth computer game 1986 graphic adventure game developed lucasfilm games published activision based fantasy film labyrinth tasks player navigating maze solving puzzles evading dangers player goal find defeat main antagonist jareth within 13 real-time hours unlike adventure games period labyrinth feature command-line interface instead player uses two scrolling word wheel menus screen construct basic sentences labyrinth first adventure game created lucasfilm project led designer david fox invented word wheels avoid text parsers syntax guessing typical text-based adventure games early development team collaborated author douglas adams week-long series brainstorming sessions inspired much final product labyrinth received positive reviews united states bigger commercial success film upon based design influenced lucasfilm subsequent adventure title critically acclaimed maniac mansion labyrinth computer game graphic adventure game player maneuvers character maze solving puzzles evading dangers adaptation 1986 film labyrinth many whose events characters reproduced game however follow plot film beginning player enters name sex favorite color last two fields determine appearance player character afterward short text-based adventure sequence unfolds wherein player enters movie theater watch film labyrinth game changes graphic adventure format jareth main antagonist appears projection screen transports protagonist labyrinthine prison player goal locate destroy jareth within 13 real-time hours otherwise protagonist trapped maze forever traveling maze player passes series scrolling hallways contain doors enemies things radar bar screen allows player see hallway miniature form locations doorways items characters given hallway displayed unlike adventure games period labyrinth feature command-line interface instead typing commands player selects two scrolling word wheels one verbs one nouns example verb congratulate may selected one wheel noun jareth inputs command congratulate jareth based player items location available verbs nouns change context-sensitively lucasfilm games began design labyrinth computer game 1985 company head george lucas requested tie-in video game movie name production lucasfilm common lucasfilm games projects lucas provided little direction team labyrinth first licensed game developed company earlier products rescue fractalus eidolon original intellectual properties according project leader david fox working license frees ways restricts adaptation team pressured reuse events characters labyrinth film felt obligated follow source material saw film adventure story chose set adaptation adventure game genre however fox disliked genre then-reliance text parsers syntax guessing created word wheel menus replacement meant supply limited set words still let lot things order streamline game without hampering player freedom game visual design shared lucasfilm habitat massively multiplayer online game production time early development game team screened rough cut film afterward sent london lucasfilm management one-week brainstorming session douglas adams author hitchhiker guide galaxy adams worked previously infocom development book 1984 video game adaptation also present meetings writer christopher cerf friend film director jim henson brenda laurel activision game publisher team worked extensively adams period laurel later wrote every day fresh blast wild intelligent humor stoked creativity team view pinnacle meetings adams idea opening sequence suggested reference wizard oz famous transition black-and-white color transition text-based format graphical one fox given job taking notes trip although hoped complete design emerge meetings returned london sheets sheets ideas sifted find usable concepts however material influenced game many adams suggestions used retrospectively fox felt opening sequence mistake called tedious believed alienated potential fans labyrinth released 1986 commodore 64 apple ii msx united states labyrinth commercially successful film upon based commodore magazine mark cotone lauded game puzzle design detailed graphics newcomer-friendly interface believed experienced players would enjoy depth challenging puzzles keith campbell commodore user praised animation dubbed superb game —which found unusual given status tie-in product however campbell hesitated call adventure game wrote word wheels rather tedious genre veterans roy wagner computer gaming world summarized labyrinth well done game excellent user interface writing computer video games matthew woodley praised game variety interface disliked long loading times believed small price pay brilliant game however labyrinth criticized three reviewers zzap 64 although praised visuals co-reviewer paul sumner called game slow-paced action title simplistic adventure co-reviewer julian rignall considered boring real disappointment given lucasfilm strong track record labyrinth first adventure game produced lucasfilm became critically acclaimed commercially successful developer genre game technology mechanics influenced company subsequent title maniac mansion whose scumm engine reused many lucasfilm adventure games word wheels predecessor game point-and-click interface gary winnick artist labyrinth went lead production maniac mansion ron gilbert fox contributed maniac mansion well later directed lucasfilm zak mckracken alien mindbenders retrospectively writers australian broadcasting corporation regarded labyrinth solid first attempt inferior real classics made afterward lucasfilm
|
Computer architecture
|
international protein index international protein index ipi defunct protein database launched 2001 european bioinformatics institute ebi closed 2011 purpose provide proteomics community resource enables last version ipi contained complete reference sets six animal species homo sapiens human mus musculus mouse rattus norvegicus rat bos taurus cattle gallus gallus chicken danio rerio zebrafish one plant species arabidopsis thaliana thale cress human mouse rat datasets first developed combining information taken swiss-prot trembl ensembl refseq databases 2001 ipi launched databases cataloguing human genes varied greatly links since much data produced giving complete picture databases collaborated synchronize data currently many model organisms reference set genes/proteins catalogued ensembl/uniprot respectively well species specific databases redundancy ipi retired 2011 ebi advised users services employ uniprotkb accession numbers protein identifiers
|
Databases
|
arcsde arcsde spatial database engine server-software sub-system produced marketed esri aims enable usage relational database management systems spatial data spatial data may used part geodatabase geographic technologies incorporated gti australia originally designed database software named spatial database engine sdbe development shifted salamanca software pvt ltd. developed first production version sdbe originally used interbase dbms president esri jack dangermond announced sde gis'95 conference vancouver british columbia esri purchased salamanca software 1996 esri rebranded software arcsde follow naming convention products arcsde grew meet need users geographic data robust multi-user editing storage access extremely large geospatial databases arcsde supports esri geodatabase implementation product began stand-alone software esri integrated arcgis version 9.2 2013 esri announced plans deprecate arcsde command line tools arcsde application server following forthcoming release arcgis 10.2. release 10.1 esri sells arcsde component arcgis server part arcgis family software products integrates geographic-information query mapping spatial analysis editing within multi-user enterprise dbms environment 2010 alternative tools connecting arcmap dbms postgres sql server.. st-links pgmap blue spatial server arcsde enables organizations move traditional approach — managing separate collections geographic data files — integrated environment one manage spatial data continuous database accessible entire organization simultaneously easily publishable web arcsde application server facilitates storing managing spatial data raster vector survey dbms makes data available many applications arcsde allows one manage spatial data four commercial databases ibm db2 informix microsoft sql server oracle starting 9.3 release esri added support open-source postgresql database arcsde serves data advanced arcgis desktop products arcview arceditor arcinfo arcgis development products arcgis engine arcgis server arcview 3.x well arcims key component managing multi-user esri-based gis traditional rdbms software keeps track tables records contained database arcsde pushes relational model higher client software manage geographic data comprise several tables seamlessly user need awareness dealings particulars rdbms gis environment routes connections database arcsde middleware manages storing retrieval data
|
Databases
|
mos technology 6508 mos technology 6508 8-bit microprocessor designed mos technology based popular 6502 6508 augmented two additional features internal 8-bit digital i/o port 256 bytes internal static ram internal ram mapped cpu address space 0000- 00ff 0100- 01ff serve zero page stack space i/o port available location 0001 data-direction register 0000 layout used 6510 may different strapping/bonding variants chip datasheet lists pin 40 clock phase two cbm900 computer 6508 controlling floppydisk pin 40 set overflow pin also offered 40-pin 6502 omitted 28-pin 650x variants 6503–6507 pin 6500 family cpus sets overflow flag p register tested using bvc/bvs instructions using tight polling loop 3 machine cycles constructed tighter minimum two instructions test branch loop using pin functionality
|
Computer architecture
|
reception criticism whatsapp security privacy features article provides detailed historic account reception criticism security privacy features whatsapp messaging service may 20 2011 unconfirmed security researcher netherlands pseudonym whatsapphack published dutch websites tweakers.net geenstijl method whatsapp accounts could hijacked researcher noticed flaw authentication process allowed researcher hijack account trying login another phone number intercepting verification sms text message specific conditions remained outbox symbian phone whatsapp client would attempt send android verification message could obtained reading radio tool named logcat researcher would copy send intercepted verification message real number phone using sms gateway spoof sender phone number number researcher tried maliciously login method worked whatsapp issued patch within one day publication articles android symbian clients whatsapp security mechanism design would disable account phone original owner phone number whatsapp account may 2011 another security hole reported left communication whatsapp susceptible packet analysis whatsapp communications encrypted data sent received plaintext meaning messages could easily read packet traces available may 2012 security researchers noticed new updates whatsapp longer sent messages plaintext cryptographic method implemented subsequently described broken august 2012 whatsapp support staff said messages encrypted latest version whatsapp software ios android blackberry windows phone symbian without specifying cryptographic method january 6 2012 unknown hacker published website made possible change status arbitrary whatsapp user long phone number known make work required restart app according hacker one many security problems whatsapp january 9 whatsapp reported resolved problem although measure actually taken block website ip address reaction windows tool made available download providing functionality problem since resolved form ip address check currently logged-in sessions german tech site h demonstrated use whatsapi hijack whatsapp account september 14 2012 shortly legal threat whatsapi developers alleged characterized h apparent reaction security reports whatsapi source code taken days whatsapi team since returned active development march 31 2013 saudi arabian communications information technology commission citc issued statement regarding possible measures whatsapp among applications unless service providers took serious steps comply monitoring privacy regulations february 2014 public authority data privacy german state schleswig-holstein advised using whatsapp service lacked privacy protection end-to-end client side encryption technology whatsapp started implementing end-to-end encryption late 2014 finished april 2016 major privacy security problem subject joint canadian-dutch government investigation primary concern whatsapp required users upload mobile phone entire address book whatsapp servers whatsapp could discover among users contacts available via whatsapp fast convenient way quickly find connect user contacts also using whatsapp meant address book mirrored whatsapp servers including contact information contacts using whatsapp information consisted solely phone numbers without additional information name contact stored hashed though salted form late 2015 dutch government released press-statement claiming whatsapp changed hashing method making much harder reverse thus fully complies rules regulations user need send friend request send messages another user due contact discovery mentioned november 2014 whatsapp introduced feature named read receipts alerts senders messages read recipients within week whatsapp introduced update allowing users disable feature message recipients send acknowledgements december 1 2014 indrajeet bhuyan saurav kar 17 years old demonstrated whatsapp message handler vulnerability allows anyone remotely crash whatsapp sending specially crafted message 2kb size escape problem user receives specially crafted message delete his/her whole conversation start fresh chat opening message keeps crashing whatsapp unless chat deleted completely early 2015 whatsapp launched web client used browser bhuyan also found two security issues compromised user privacy whatsapp photo privacy bug whatsapp web photo sync bug february 2015 dutch university student named maikel zweerink published app set prove anyone could track whatsapp user status also keep eye changing profile pictures privacy settings status messages regardless privacy settings march 2 2016 whatsapp introduced document-sharing feature initially allowing users share pdf files contacts however whatsapp default state automatically downloading attachments raised concerns press risk security support document sharing expanded beyond pdf files august 2016 whatsapp announced start sharing account information facebook consisting phone number account owner aggregated analytical data address books metadata users shared according whatsapp account information shared track basic metrics often people use services better fight spam whatsapp connecting phone number facebook systems facebook offer better friend suggestions show relevant ads account means facebook target advertisements facebook platform better making links users based phone numbers make friend suggestions users based whatsapp data user data shared advertisers used internally facebook services whatsapp emphasizes content user messages still kept private thanks end-to-end encryption means whatsapp read content chats however users given choice opt sharing data facebook advertisement purposes october 2016 article 29 working party stated serious concerns regarding manner information relating updated terms service privacy policy provided users consequently validity users ’ consent april 5 2016 end-to-end encryption users communications including file transfers voice calls supported users latest client encryption enabled default uses curve25519 key exchange hkdf generation session keys aes-256 cbc mode encryption hmac-sha256 integrity verification sha512 generating two 30 digit fingerprints users identity keys verify needed even company would unable decrypt users communications amnesty international security professionals praised move us federal bureau investigation criticised threatening work law enforcement telegram another messaging service reported bbc used islamic state extremists whatsapp messaging service provides end-to-end encryption among others threema wickr signal silent phone line also provide encryption default imessage viber provide special circumstances telegram provides end-to-end encryption opt-in feature support end-to-end encrypted group messaging whatsapp score 6 7 points electronic frontier foundation secure messaging scorecard received points communications encrypted transit communications encrypted keys provider n't access allowing users verify contacts identities past messages secure encryption keys stolen completed recent independent security audit security designs properly documented missing point code open independent review january 13 2017 guardian reported security researcher tobias boelter found whatsapp policy forcing re-encryption initially undelivered messages without informing recipient constituted serious loophole whereby whatsapp could disclose compelled disclose content messages whatsapp open whisper systems officials disagreed assessment follow-up article boelter explained greater detail considered specific vulnerability article since removed guardian due inaccuracies boelter representation facts complaints 73 renowned security researchers guardian forced substantially revise correct articles well therefore june 2017 guardian readers ’ editor paul chadwick wrote guardian wrong report january popular messaging service whatsapp security flaw serious huge threat freedom speech chadwick also noted since guardian article whatsapp better secured introduction optional two-factor verification february however important note feature already introduced public beta versions whatsapp early november 2016 months guardian wrote alleged issue january 15 2017 research team ruhr university bochum published security analysis group messaging protocols whatsapp signal threema among deficiencies found whatsapp servers effectively control membership groups consequently server add arbitrary phone numbers groups including future communication becomes insecure even though manipulations could detected weakens end-to-end security guarantees october 2017 german software company open-xchange criticised whatapps slack using proprietary software stated plans create open source alternative may 2019 revealed security vulnerability whatsapp allowing remote person install spyware making call even need answered later june 2019 another vulnerability revealed allowing user transform audio call video call without victim consent without victim noticing bug bounty 5000 usd offered bug june 2019 whatsapp announced would take legal action users send disproportionately high number messages using communication platform company reiterated platform meant private messaging businesses interact customers business app notification website company stated beginning december 7 2019 whatsapp take legal action determine engaged assisting others abuse violates terms service automated bulk messaging
|
Computer security
|
hotbit hotbit hb-8000 msx home computer developed sold brazilian subsidiary sharp corporation epcom home computer division mid-1980s msx machines popular brazil time virtually killed competing 8 bit microcomputers brazilian market hotbit three versions 1.0 1.1 gray white case 1.2 black case rom slightly modified solve ascii table compatibility issue popular brazilian msx gradiente expert
|
Computer architecture
|
web application description language web application description language wadl machine-readable xml description http-based web services wadl models resources provided service relationships wadl intended simplify reuse web services based existing http architecture web platform language independent aims promote reuse applications beyond basic use web browser wadl submitted world wide web consortium sun microsystems 31 august 2009 consortium current plans standardize wadl rest equivalent soap web services description language wsdl also used describe rest web services service described using set resource elements resource contains param elements describe inputs method elements describe request response resource request element specifies represent input types required specific http headers required response describes representation service response well fault information deal errors following listing shows example wadl description yahoo news search application multiple tools generate java code existing wadl app xmlns= http //research.sun.com/wadl/2006/10 xmlns xs= http //www.w3.org/2001/xmlschema /app
|
Web technology
|
emso simulator emso simulator equation-oriented process simulator graphical interface modeling complex dynamic steady-state processes cape-open compliant emso stands environment modeling simulation optimization alsoc project portuguese acronym free environment simulation optimization control processes based ufrgs develops maintains distributes object-oriented software pre-built models available emso modeling library eml new models written emso modeling language user embed models coded c c++ fortran simulation environment
|
Programming language topics
|
db13w3 db13w3 13w3 style d-subminiature connector commonly used analog video interfaces used primarily sun microsystems silicon graphics sgi ibm risc workstations well displays apple computer next computer intergraph corporation 13w3 connector longer used modern displays superseded use analog displays vga connector display market moved digital flat panel displays turn replaced almost entirely digital connections dvi hdmi displayport connector contains 10 standard signal pins 3 larger positions fitted either special pins two concentric contacts coaxial cable special high-current pins used video signals computer side pins female coaxial connectors large positions male coaxial connectors carry video signal split red green/gray blue standard signal pins carry four grounds three sense pins used communicate monitor vertical sync horizontal sync composite sync signal 13w3 connector converted standard vga connector using commonly available cables adapters allows multisync monitors became prevalent personal computing late 1980s used workstations long sync-on-green compatible likewise later-generation sun monitors began supporting multisync 1998 connected via similar cables personal computers even though 13w3 standard connector sync signals maintained different pins based display system sun intergraph ibm sgi use different pin configurations monitor sense id sync signals sun sgi even two different pin configurations without display data channel support sun ddc connector used least upa graphics adapters creator 3d expert 3d corresponding monitors gd5410 gd5510 make matching correct cable monitor virtually impossible many monitors 13w3 connectors support separate sync supplied pc systems converters exist allow connecting newer monitors vga connectors older systems workstations popular cable series dip switches built used set sync signals variant db13w3 connector high-current pins instead high-frequency pins used video applications also used 3com superstack ethernet switches carry dc power
|
Computer architecture
|
android lollipop android lollipop codenamed android l development fifth major version android mobile operating system developed google spanning versions 5.0 5.1.1 unveiled june 25 2014 google i/o 2014 conference became available official over-the-air ota updates november 12 2014 select devices run distributions android serviced google nexus google play edition devices source code made available november 3 2014 fifth major update twelfth version android one prominent changes lollipop release redesigned user interface built around design language known material design made retain paper-like feel interface changes include improvements notifications accessed lockscreen displayed within applications top-of-the-screen banners google also made internal changes platform android runtime art officially replacing dalvik improved application performance changes intended improve optimize battery usage statistics issued google indicate lollipop versions 14.5 share combined android devices accessing google play android lollipop succeeded android marshmallow released october 2015 release internally codenamed lemon meringue pie android 5.0 first unveiled codename android l june 25 2014 keynote presentation google i/o developers conference alongside lollipop presentation focused number new android-oriented platforms technologies including android tv in-car platform android auto wearable computing platform android wear health tracking platform google fit part presentation dedicated new cross-platform design language referred material design expanding upon card motifs first seen google design increased use grid-based layouts responsive animations transitions padding depth effects lighting shadows designer matías duarte explained unlike real paper digital material expand reform intelligently material physical surfaces edges seams shadows provide meaning touch material design language used android across google suite web software well providing consistent experience across platforms android 5.0 introduces refreshed notification system individual notifications displayed cards adhere material design language batches notifications grouped app produced notifications displayed lock screen cards heads notifications also displayed large banners across top screen along respective action buttons do-not-disturb feature also added notifications recent apps menu redesigned use three-dimensional stack cards represent open apps individual apps also display multiple cards recents menu web browser open tabs lollipop also contains major new platform features developers 5,000 new apis added use applications example possibility save photos raw image format additionally dalvik virtual machine officially replaced android runtime art new runtime environment introduced technology preview kitkat art cross-platform runtime supports x86 arm mips architectures 32-bit 64-bit environments unlike dalvik uses just-in-time compilation jit art compiles apps upon installation run exclusively compiled version technique removes processing overhead associated jit process improving system performance lollipop also aims improve battery consumption series optimizations known project volta among changes new battery saver mode job scheduling apis restrict certain tasks occur wi-fi batching tasks reduce overall amount time internal radios active new developer tool called battery historian used tracking battery consumption apps use android extension pack apis also provide graphics functions new shaders aiming provide pc-level graphics 3d games android devices number system-level enterprise-oriented features also introduced banner android work samsung knox security framework initially planned used foundation android work instead google opted use technology segregating personal work-oriented data device along accompanying apis managing environment smart lock feature devices also configured users perform device unlocking pin pattern trusted location proximity designated bluetooth device nfc tag lollipop additionally device encryption enabled default capable devices however due performance issues change held successor android marshmallow developer preview android l build lpv79 released nexus 5 2013 nexus 7 june 26 2014 form flashable images source code gpl-licensed components developer preview released via android open source project aosp july 2014 second developer preview build lpv81c released august 7 2014 alongside beta version google fit platform sdk previous build second developer preview build available nexus 5 2013 nexus 7 october 15 2014 google officially announced android l would known android 5.0 lollipop company also unveiled launch devices android5.0including motorola nexus 6 htc nexus 9for release november 3 2014 google stated nexus including nexus 4 5 7 10 google play edition devices would receive updates lollipop coming weeks one developer preview build nexus devices new sdk revision application developers would released october 17 2014 update schedules third-party android devices may vary manufacturer full source code android5.0 pushed aosp november 3 2014 allowing developers oems begin producing builds operating system december 2 2014 factory images nexus smartphones tablets updated 5.0.1 version introduces bug fixes serious bug affects nexus 4 devices prevents audio working phone calls device-specific lollipop 5.0.2 lrx22g version released first-generation nexus 7 december 19 2014 android5.1 updated version lollipop unveiled february 2015 part indonesian launch android one preloaded android one devices sold indonesia philippines google officially announced 5.1 releasing updates existing devices march 9 2015 2015 amazon.com forked lollipop produce fire os 5 bellini amazon fire hd-series devices
|
Operating systems
|
synchronous serial interface synchronous serial interface ssi widely used serial interface standard industrial applications master e.g controller slave e.g sensor ssi based rs-422 standards high protocol efficiency addition implementation various hardware platforms making popular among sensor manufacturers ssi originally developed max stegmann gmbh 1984 transmitting position data absolute encoders – reason servo/drive equipment manufacturers refer ssi port stegmann interface formerly covered german patent de 34 45 617 expired 1990 suitable applications demanding reliability robustness measurements varying industrial environments different serial peripheral interface bus spi ssi differential simplex non-multiplexed relies time-out frame data spi single-ended duplex multiplex uses select-line frame data however spi peripherals microcontrollers implement ssi external differential driver-ics program-controlled timing ssi synchronous point point serial communication channel digital data transmission synchronous data transmission one data transmitted synchronizing transmission receiving sending ends using common clock signal since start stop bits present allows better use data transmission bandwidth message bits makes whole transmission process simpler easier clock needs bandwidth included determining total bandwidth required communication two devices general mentioned earlier point point connection master e.g plc microcontroller slave e.g rotary encoders master controls clock sequence slave transmits current data/value shift register invoked master data clocked shift register master slave synchronized common clock controller clock data signals transmitted according rs-422 standards rs-422 also known ansi/tia/eia-422-b technical standard specifies electrical characteristics balanced voltage digital interface circuit data transmitted using balanced differential signalling i.e clock data lines basically twisted pair cables inputs use opto-coupler galvanic isolation details see driven rs-422/485 levels data output sensor driven rs-422/485 line driver differential signalling improves resistance electromagnetic interference emi hence making reliable communication channel long transmission lengths harsh external environments interface simple design illustrated figure consists 2 pairs wires one transmitting clock signals master transmitting data slave clock sequences triggered master need arises different clock frequencies used ranging 100 khz 2 mhz number clock pulses depends number data bits transmitted simplest ssi slave interface uses retriggerable monostable multivibrator monoflop freeze current value sensor current frozen values slave stored shift registers values clocked sequentially initiated controller design revolutionized integration microcontrollers fpgas asics interface data format designed way ensure proper communication data protocol data transmission based three different subsequent parts leading- ” 1 data-bits trailing- 0 main significance type format ensure proper working interface hence secure data transmission free hardware software errors idle state clock high level also sensor output high level used detecting broken wire contacts helps observing proper working condition interface n-clock pulses rising edges data completely transmitted next clock pulse rising edge n+1 sensor output goes low level used detect short circuit cable high even n+1 rising edges means interface short circuit readings multiple slaves three enabled time connecting common clock however avoid ground loops electrically isolate slave complete galvanic isolation opto-couplers needed following keywords useful understanding ssi data transmission procedure diagram illustrates single data transmission using ssi protocol ssi initially idle mode data clock lines stay high slave keeps updating current data transmission mode evoked master initiates train clock pulses slave receives beginning clock signal 1 automatically freezes current data first rising edge 2 clock sequence msb sensor ’ value transmitted consequent rising edges bits sequentially transmitted output transmission complete data word 3 i.e lsb transmitted additional rising edge clock sets clock line high data line set low remains period time tm recognize transfer timeout clock signal data-output request received within time data transmitted multiple transmission slave starts updating value data line set high idle mode clock pulses within time tm marks end single transmission data word slave receives clock signal time tp =tm updated position value frozen transmission value begins described earlier multiple transmissions data happens continuous clocking even transmission least significant bit i.e clock pulses allow monoflop go steady state illustrated initial sequences single transmission idle state clock data lines high arrival first falling edge transmission mode evoked similarly data bits transmitted sequentially starting msb every rising edge transmission lsb means transmission data completed additional rising edge pushes data line low signifying end transmission particular data continuous clock pulses even i.e next clock pulses comes time tw tm value slave updated monoflop still unsteady value shift register still contains value next rising edge i.e n+1 rising edge transmission data continues msb data transmitted earlier re-transmitted end tw follows procedure earlier transmissions leading multiple transmissions data value slave updated timing two clock pulses transfer timeout tm multiple transmission used check data integrity two consecutive received values compared transmission failures indicated differences two values transmission data controlled master transmission interrupted time stopping clock sequence period longer tm slave automatically recognize transfer timeout go idle mode since ssi based rs-422 standards necessary select appropriate cables stay within limits cabling length clock frequencies relation cable length clock frequency shown following figure used conservative guide curve based upon empirical data using 24 awg standard copper conductor unshielded twisted-pair telephone cable shunt capacitance 52.5 pf/meter 16 pf/foot terminated 100 ohm resistive load cable length restriction shown curve based upon assumed load signal quality requirements high data rates used application limited shorter cables possible use longer cables low data rates used dc resistance cable limits length cable low data rate applications increasing noise margin voltage drop cable increases ac effects cable limit quality signal limit cable length short distances high data rates used examples data rate cable length combinations vary 90 kbit/s 1.2 km 10 mbit/s 5m rs-422 cables characteristics different twisted pair 24 awg 52.5 pf/meter 16 pf/foot also employed within bounds mentioned first determine absolute loop resistance capacitance values typical 24 awg cable provided cable length associated data signalling rate desired figure convert values equivalent lengths cable actually used example longer distances would possible using 19 awg shorter distances would necessary 28 awg maximum permissible length cable separating master slave function data signalling rate influenced tolerable signal distortion amount longitudinally coupled noise ground potential differences introduced master slave circuit accordingly users advised restrict cable length minimum type length cable used must capable maintaining necessary signal quality needed particular application furthermore cable balance must maintain acceptable crosstalk levels generated received manufacturers organizations added additional information basic ssi protocol done mainly ensure proper data transmission secure transmission indicate end data transmission crc bits parity bits added simple words used identifying byte correctly interpreted received original specification multiple transmissions used ensure data integrity case two consecutive transmissions data initiated compared error transmission however reduces protocol efficiency 50 compared parallel data transmission limitations interface negligible applications industrial automation ssi handle short distance communication 1.2 km supports one master device 1.2 km rather good distance communication automation industry standards compared advanced communication systems based field buses ethernet ssi limited master slave architecture simple point point communication master slave another disadvantage hardware slave acknowledgment i.e detection slave communication
|
Internet protocols
|
eurowordnet eurowordnet system semantic networks european languages based wordnet language develops wordnet interconnected interlingual links stored interlingual index ili unlike original princeton wordnet wordnets freely available original eurowordnet project dealt dutch italian spanish german french czech estonian wordnets frozen wordnets languages developed varying degrees examples eurowordnet available free access full database however charged cases openthesaurus babelnet may serve free alternative
|
Computational linguistics
|
scoreboarding scoreboarding centralized method first used cdc 6600 computer dynamically scheduling pipeline instructions execute order conflicts hardware available scoreboard data dependencies every instruction logged instructions released scoreboard determines conflicts previously issued incomplete instructions instruction stalled unsafe continue scoreboard monitors flow executing instructions dependencies resolved stalled instruction issued instructions decoded order go following four stages control execution instructions scoreboard maintains three status tables detailed algorithm scoreboard control described scoreboarding method must stall issue stage functional unit available case future instructions could potentially executed wait structural hazard resolved techniques like tomasulo algorithm avoid structural hazard also resolve war waw dependencies register renaming
|
Computer architecture
|
text corpus linguistics corpus plural corpora text corpus large structured set texts nowadays usually electronically stored processed corpus linguistics used statistical analysis hypothesis testing checking occurrences validating linguistic rules within specific language territory corpus may contain texts single language monolingual corpus text data multiple languages multilingual corpus multilingual corpora specially formatted side-by-side comparison called aligned parallel corpora two main types parallel corpora contain texts two languages translation corpus texts one language translations texts language comparable corpus texts kind cover content translations exploit parallel text kind text alignment identifying equivalent text segments phrases sentences prerequisite analysis machine translation algorithms translating two languages often trained using parallel fragments comprising first language corpus second language corpus element-for-element translation first language corpus order make corpora useful linguistic research often subjected process known annotation example annotating corpus part-of-speech tagging pos-tagging information word part speech verb noun adjective etc added corpus form tags another example indicating lemma base form word language corpus working language researchers use interlinear glossing used make annotation bilingual corpora structured levels analysis applied particular number smaller corpora may fully parsed corpora usually called treebanks parsed corpora difficulty ensuring entire corpus completely consistently annotated means corpora usually smaller containing around one three million words levels linguistic structured analysis possible including annotations morphology semantics pragmatics corpora main knowledge base corpus linguistics analysis processing various types corpora also subject much work computational linguistics speech recognition machine translation often used create hidden markov models part speech tagging purposes corpora frequency lists derived useful language teaching corpora considered type foreign language writing aid contextualised grammatical knowledge acquired non-native language users exposure authentic texts corpora allows learners grasp manner sentence formation target language enabling effective writing text corpora also used study historical documents example attempts decipher ancient scripts biblical scholarship archaeological corpora short duration provide snapshot time one shortest corpora time may 15–30 year amarna letters texts 1350 bc corpus ancient city example kültepe texts turkey may go series corpora determined find site dates
|
Computational linguistics
|
vincent moscaritolo vincent moscaritolo american computer security expert known work encryption applications mobile devices 2012 2015 distinguished member technical staff silent circle designed original messaging technologies silent circle uses 2015 left silent circle co-found 4th-a technologies llc robbie hanson 4th-a technologies develops technologies restore restore people inalienable right “ secure documents ” designed zerodark.cloud framework simplifies development apps interact cloud performs tasks syncing messaging collaboration uses zero-knowledge encryption ensuring data cloud compromised also produced storm4 secure cloud storage service vincent involved design invention production system software network applications 30 years addition producing cryptographic products concern use encryption technology criminal terrorist actors compelled offer assistance training law enforcement intelligence community cryptographic issues participated specialized venues fbi information technology study group drug enforcement administration office investigative technology infragard cloud security alliance vincent moscaritolo experience includes roles distinguished member technical staff silent circle principal cryptographic engineer pgp corporation senior operating system engineer apple computer principal software specialist digital equipment corporation vincent one co founders silent circle developer secure messaging technology used silent circle blackphone designed silent circle instant messaging protocol scimp inventor progressive encryption used silent text app pgp focused engineering cryptographic products os x platform including cross platform core crypto library secure file deletion virtual disk client network kernel engine redirection module also responsible obtaining maintaining nist fips-140 validation pgp cryptographic core apple notable founding mac-crypto conference key mac developers industry leaders legends met discuss topics ranging cryptosystems digital cash security issues feedback sessions developers able directly discuss requirements apple engineers also involved original cypherpunk group mid 1980s founded startup called datavox produced banktalk one first voice response systems financial marketplace included user-tailorable audio menu system provided general information balance account transactions able communicate bank mainframes existing atm network vincent latest project zerodark.cloud framework moscaritolo published article s4 open-source crypto library verifying authenticity public keys moscaritolo designed silent circle instant messaging protocol scimp uses new progressive encryption technology cryptographic projects include development public key authentication extension file servers authoring ietf draft secure authorization protocol distributed systems development code technotes pgp cryptographic toolkit number presentations tutorials modern cryptosystems security also contributor vanish self destructing data project university washington holds patents related cryptographic techniques designs pass laws could criminals avid outdoorsman vincent usually spends weekends hiking snowshoeing deep woods southern oregon daughter son background variety fields including motorcycle racing number martial arts trauma medicine
|
Computer security
|
row hammer row hammer also written rowhammer unintended undesirable side effect dynamic random-access memory dram memory cells leak charges interact electrically possibly leaking changing contents nearby memory rows addressed original memory access bypass isolation dram memory cells results high cell density modern dram triggered specially crafted memory access patterns rapidly activate memory rows numerous times row hammer effect used privilege escalation computer security exploits network-based attacks also theoretically possible fast network connection attacker victim different hardware-based techniques exist prevent row hammer effect occurring including required support processors types dram memory modules row hammer rarely never affects ddr ddr2 sdram modules affects many ddr3 ddr4 sdram modules dynamic ram dram bit stored data occupies separate memory cell electrically implemented one capacitor one transistor charge state capacitor charged discharged determines whether dram cell stores 1 0 binary value huge numbers dram memory cells packed integrated circuits together additional logic organises cells purposes reading writing refreshing data memory cells blue squares illustration organised matrices addressed rows columns memory address applied matrix broken row address column address processed row column address decoders illustration vertical horizontal green rectangles respectively row address selects row read operation selection also known row activation bits cells row transferred sense amplifiers form row buffer red squares illustration exact bit selected using column address consequently read operations destructive nature design dram requires memory cells rewritten values read transferring cell charges row buffer write operations decode addresses similar way result design entire rows must rewritten value single bit changed result storing data bits using capacitors natural discharge rate dram memory cells lose state time require periodic rewriting memory cells process known refreshing another result design dram memory susceptible random changes stored data known soft memory errors attributed cosmic rays causes different techniques counteract soft memory errors improve reliability dram error-correcting code ecc memory advanced variants lockstep memory commonly used increased densities dram integrated circuits ics led physically smaller memory cells capable storing smaller charges resulting lower operational noise margins increased rates electromagnetic interactions memory cells greater possibility data loss result disturbance errors observed caused cells interfering operation manifesting random changes values bits stored affected memory cells awareness disturbance errors dates back early 1970s intel 1103 first commercially available dram ic since dram manufacturers employed various mitigation techniques counteract disturbance errors improving isolation cells performing production testing however researchers proved 2014 analysis commercially available ddr3 sdram chips manufactured 2012 2013 susceptible disturbance errors using term row hammer name associated side effect led observed bit flips opportunity row hammer effect occur ddr3 memory primarily attributed ddr3 high density memory cells results associated interactions cells rapid dram row activations determined primary cause frequent row activations cause voltage fluctuations associated row selection lines observed induce higher-than-natural discharge rates capacitors belonging nearby adjacent cases memory rows called victim rows affected memory cells refreshed lose much charge disturbance errors occur tests show disturbance error may observed performing around 139,000 subsequent memory row accesses cache flushes one memory cell every 1,700 cells may susceptible tests also show rate disturbance errors substantially affected increased environment temperature depends actual contents dram certain bit patterns result significantly higher disturbance error rates variant called double-sided hammering involves targeted activations two dram rows surrounding victim row illustration provided section variant would activating yellow rows aim inducing bit flips purple row case would victim row tests show approach may result significantly higher rate disturbance errors compared variant activates one victim row neighbouring dram rows different methods exist less successful detection prevention correction mitigation row hammer effect tests show simple ecc solutions providing single-error correction double-error detection sec ded capabilities able correct detect observed disturbance errors include two flipped bits per memory word flipping three bits prevents ecc noticing modification effective solution introduce frequent memory refreshing refresh intervals shorter usual 64 ms technique results higher power consumption increased processing overhead vendors provide firmware updates implement type mitigation one complex prevention measures performs counter-based identification frequently accessed memory rows proactively refreshes neighbouring rows another method issues additional infrequent random refreshes memory rows neighbouring accessed rows regardless access frequency research shows two prevention measures cause negligible performance impacts since release ivy bridge microarchitecture intel xeon processors support so-called pseudo target row refresh ptrr used combination ptrr-compliant ddr3 dual in-line memory modules dimms mitigate row hammer effect automatically refreshing possible victim rows negative impact performance power consumption used dimms ptrr-compliant xeon processors default fall back performing dram refreshes twice usual frequency results slightly higher memory access latency may reduce memory bandwidth 2–4 lpddr4 mobile memory standard published jedec includes optional hardware support so-called target row refresh trr prevents row hammer effect without negatively impacting performance power consumption additionally manufacturers implement trr ddr4 products although part ddr4 memory standard published jedec internally trr identifies possible victim rows counting number row activations comparing predefined chip-specific maximum activate count mac maximum activate window values refreshes rows prevent bit flips mac value maximum total number row activations may encountered particular dram row within time interval equal shorter amount time neighbouring rows identified victim rows trr may also flag row victim row sum row activations two neighbouring rows reaches mac limit within time window due necessity huge numbers rapidly performed dram row activations row hammer exploits issue large numbers uncached memory accesses cause cache misses detected monitoring rate cache misses unusual peaks using hardware performance counters version 5.0 memtest86 memory diagnostic software released december 3 2013 added row hammer test checks whether computer ram susceptible disturbance errors works computer boots uefi without uefi boots older version hammer test memory protection way preventing processes accessing memory assigned one concepts behind modern operating systems using memory protection combination security-related mechanisms protection rings possible achieve privilege separation processes programs computer systems general divided parts limited specific privileges require perform particular task using privilege separation also reduce extent potential damage caused computer security attacks restricting effects specific parts system disturbance errors explained section effectively defeat various layers memory protection short circuiting low hardware level practically creating unique attack vector type allows processes alter contents arbitrary parts main memory directly manipulating underlying memory hardware comparison conventional attack vectors buffer overflows aim circumventing protection mechanisms software level exploiting various programming mistakes achieve alterations otherwise inaccessible main memory contents initial research row hammer effect published june 2014 described nature disturbance errors indicated potential constructing attack provide examples working security exploit subsequent october 2014 research paper imply existence security-related issues arising row hammer effect march 9 2015 google project zero revealed two working privilege escalation exploits based row hammer effect establishing exploitable nature x86-64 architecture one revealed exploits targets google native client nacl mechanism running limited subset x86-64 machine instructions within sandbox exploiting row hammer effect escape sandbox gain ability issue system calls directly nacl vulnerability tracked mitigated modifying nacl allow execution codice_1 cache line flush machine instruction previously believed required constructing effective row hammer attack second exploit revealed project zero runs unprivileged linux process x86-64 architecture exploiting row hammer effect gain unrestricted access physical memory installed computer combining disturbance errors memory spraying exploit capable altering page table entries ptes used virtual memory system mapping virtual addresses physical addresses results exploit gaining unrestricted memory access due nature inability x86-64 architecture make codice_1 privileged machine instruction exploit hardly mitigated computers use hardware built-in row hammer prevention mechanisms testing viability exploits project zero found half 29 tested laptops experienced disturbance errors occurring vulnerable laptops less five minutes running row-hammer-inducing code tested laptops manufactured 2010 2014 used non-ecc ddr3 memory july 2015 group security researchers published paper describes architecture- instruction-set-independent way exploiting row hammer effect instead relying codice_1 instruction perform cache flushes approach achieves uncached memory accesses causing high rate cache eviction using carefully selected memory access patterns although cache replacement policies differ processors approach overcomes architectural differences employing adaptive cache eviction strategy algorithm proof concept approach provided native code implementation pure javascript implementation runs firefox 39 javascript implementation called rowhammer.js uses large typed arrays relies internal allocation using large pages result demonstrates high-level exploit low-level vulnerability october 2016 researchers vusec systems network security group vu amsterdam published drammer android app uses rowhammer methods reliably gain root access several popular models smartphones vulnerability acknowledged cve-2016-6728 patch released google within month mitigate effect however due general nature possible implementations attack effective software patch difficult reliably implement fact june 2018 proposals made academia industry either impractical deploy insufficient stopping attacks mitigate attacks researchers vusec systems proposed lightweight defense prevents dma-based attacks isolating dma buffers guard rows software states vulnerable rowhammer attacks attacker thus needs find right target states order utilise rowhammer errors practice one main challenges identifying target states typically done domain experts mainstream fault tolerance community responded rowhammer attacks systematic methodology used identify validate evaluate rowhammer attack target states exploitability work based well-established fault injection-based experimental methodology generalised attack target states found practical target states previously unknown
|
Computer security
|
tvheadend tvheadend sometimes tvh short server application reads video streams linuxtv sources publishes internet streams supports multiple inputs dvb-t usb tuner stick sat ip tuner instance combining together single channel listing tvh servers ip signal providers allowing networks tvh servers combined tvh typically used send video receiver devices like smart televisions set top boxes throughout household network also used forward signals long distance links even countries also includes electronic program guide information available ability record programs like dvr including ability transcode mpeg2 h264 h265
|
Operating systems
|
file system api file system api application programming interface utility user program requests services file system operating system may provide abstractions accessing different file systems transparently file system apis may also include interfaces maintenance operations creating initializing file system verifying file system integrity defragmentation operating system includes apis needed file systems supports microsoft windows file system apis ntfs several fat file systems linux systems include apis ext2 ext3 reiserfs btrfs name early operating systems capable handling tape disk file systems provided basic interfaces coordination device allocation deallocation required addition file systems provided services interfaces defined additional file system types hierarchy structure supported media increased additional features needed specialized functions multi-user systems required apis writing user data file system provided use directly user program run-time library run-time library programming languages may provide type conversion formatting blocking file systems provide identification records key may include re-writing existing record operation sometimes called codice_1 record exists reading user data sometimes called get may include direction forward reverse case keyed file system specific key writing run-time libraries may intercede user program positioning includes adjusting location next record may include skipping forward reverse well positioning beginning end file open api may explicitly requested implicitly invoked upon issuance first operation process object may cause mounting removable media establishing connection another host validating location accessibility object updates system structures indicate object use usual requirements requesting access file system object include additional information may necessary example requested via programming language library may provide coordination among modules process addition forwarding request file system must expected something may go wrong processing open depending programming language additional specifications open may establish modules handle conditions libraries specify library module file system permitting analysis opening program unable perform meaningful action result failure example failure attempt open necessary input file action may report failure abort program languages simply return code indicating type failure always must checked program decides report continue close may cause dismounting ejecting removable media updating library file system structures indicate object longer use minimal specification close references object additionally file systems provide specifying disposition object may indicate object discarded longer part file system similar open must expected something may go wrong considerations handling failure similar open information data file called metadata metadata maintained file system example last-modification date various dates depending file system location beginning file size file file system backup utility saved current version files items usually altered user program additional meta data supported file systems may include owner file group file belongs well permissions and/or access control i.e access updates various users groups may perform whether file normally visible directory listed items usually modifiable file system utilities may executed owner applications store metadata images metadata may include camera model settings used take photo audio files meta data may include album artist recorded recording comments recording may specific particular copy file i.e different copies recording may different comments update owner file documents may include items like checked-by approved-by etc renaming file moving file subdirectory one directory another deleting file examples operations provide file system management directories metadata operations permitting restricting access directory various users groups users usually included filesystem used directories files records may added deleted modified usually causes inefficiencies underlying data structures things like logically sequential blocks distributed across media way causes excessive repositioning partially used even empty blocks included linked structures incomplete structures inconsistencies may caused device media errors inadequate time detection impending loss power actual power loss improper system shutdown media removal rare occasions file system coding errors specialized routines file system included optimize repair structures usually invoked user directly triggered within file system internal counters number levels structures number inserted objects may compared thresholds may cause user access suspended specific structure usually displeasure user users effected may started low priority asynchronous tasks may deferred time low user activity sometimes routines invoked scheduled system manager case defragmentation api kernel-level kernel provides interfaces filesystems developers also space filesystem code resides differs old schema kernel uses facilities talk filesystem driver vice versa contrary kernel one handles filesystem layout filesystem one directly access hardware cleanest scheme resolves difficulties major rewrite old scheme modular kernels allows adding filesystems kernel module even third party ones non-modular kernels however requires kernel recompiled new filesystem code closed-source kernels makes third party filesystem impossible unixes unix-like systems linux used modular scheme variation scheme used ms-dos dos 4.0 onward compatibles support cd-rom network file systems instead adding code kernel old scheme using kernel facilities kernel-based scheme traps calls file identifies redirected kernel equivalent function handled specific filesystem driver filesystem driver directly access disk contents using low-level bios functions api driver-based kernel provides facilities file system code resides totally external kernel even module modular kernel cleaner scheme filesystem code totally independent allows filesystems created closed-source kernels online filesystem additions removals system examples scheme windows nt os/2 respective ifss api filesystems kernel like kernel-based apis automatically trapped another api driver-based os scheme used windows 3.1 providing fat filesystem driver 32-bit protected mode cached vfat bypassed dos fat driver kernel msdos.sys completely later windows 9x series 95 98 vfat iso9660 filesystem driver along joliet network shares third party filesystem drivers well adding original dos apis lfn api ifs drivers intercept already existent dos file apis also add new ones within 32-bit protected mode executable however api completely documented third parties found make-it-by-yourself scenario even worse kernel-based apis api user space filesystem directly use kernel facilities accesses disks using high-level operating system functions provides functions library series utilities use access filesystem useful handling disk images advantage filesystem made portable operating systems high-level operating system functions uses common ansi c disadvantage api unique application implements one examples scheme hfsutils adflib filesystems least disk ones need equivalent functions provided kernel possible easily port filesystem code one api another even different types example ext2 driver os/2 simply wrapper linux vfs os/2 ifs linux ext2 kernel-based hfs driver os/2 port hfsutils os/2 ifs also exists project uses windows nt ifs driver making ntfs work linux
|
Computer file systems
|
autonomous peripheral operation computing autonomous peripheral operation hardware feature found modern microcontroller architectures off-load certain tasks embedded autonomous peripherals order minimize latencies improve throughput hard real-time applications well save energy ultra-low-power designs forms autonomous peripherals microcontrollers first introduced around 2005 allowing embedded peripherals work independently cpu even interact certain pre-configurable ways off-loads event-driven communication peripherals help improve real-time performance due lower latency allows potentially higher data throughput due added parallelism since 2009 scheme improved newer implementations continue functioning sleep modes well thereby allowing cpu remain dormant longer periods time order save energy partially driven iot market conceptually autonomous peripheral operation seen generalization mixture direct memory access dma hardware interrupts peripherals issue event signals called event generators producers whereas target peripherals called event users consumers implementations peripherals configured pre-process incoming data perform various peripheral-specific functions like comparing windowing filtering averaging hardware without pass data cpu processing known implementations include
|
Computer architecture
|
memory forensics memory forensics forensic analysis computer memory dump primary application investigation advanced computer attacks stealthy enough avoid leaving data computer hard drive consequently memory ram must analyzed forensic information prior 2004 memory forensics done ad hoc basis using generic data analysis tools like strings grep tools specifically created memory forensics therefore difficult use also provide limited information general primary usage extract text memory dump many operating systems provide features kernel developers end-users actually create snapshot physical memory either debugging core dump blue screen death purposes experience enhancement hibernation computing case microsoft windows crash dumps hibernation present since microsoft windows nt microsoft crash dumps always analyzable microsoft windbg windows hibernation files hiberfil.sys nowadays convertible microsoft crash dumps using utilities like moonsols windows memory toolkit designed matthieu suiche february 2004 michael ford introduced memory forensics security investigations article sysadmin magazine article demonstrated analysis memory based rootkit process utilized existing linux crash utility well two tools developed specifically recover analyze memory forensically memget mempeek 2005 dfrws issued memory analysis forensics challenge response challenge tools generation specifically designed analyze memory dumps created tools knowledge operating system internal data structures thus capable reconstructing operating system process list process information although intended research tools proved operating system level memory forensics possible practical subsequently several memory forensics tools developed intended practical use include commercial tools like memoryze moonsols windows memory toolkit winen belkasoft live ram capturer etc open source tools like volatility new features added analysis linux mac os x memory dumps substantial academic research carried unlike microsoft windows mac os x interest relatively new initiated matthieu suiche 2010 black hat briefings security conference currently memory forensics standard component incident response since 2010 started see utilities focusing visualization aspect memory analysis moonsols livecloudkd presented matthieu suiche microsoft bluehat security briefings inspired new feature microsoft livekd written mark russinovich allow virtual machines introspection accessing memory guest virtual machine host virtual machine order either analyze directly assistance microsoft windbg acquire memory dump microsoft crash dump file format
|
Computer security
|
information diving information diving practice recovering technical data sometimes confidential secret discarded material recent times chiefly data storage elements discarded computers notably recoverable data remaining hard drives charge discarding computers usually neglect erase hard drive often circumstances information diver copy installed software e.g. word processors operating systems computer games etc. data may also available credit card information stored machine companies claim especially careful customer data number data breaches type entity e.g. education health care insurance government ... suggest problems well uk information diving referred binology earlier times available discarded data included printed manuals design records famous case student jerry schneider discovered discarded manuals telephone system ordering shipping system able build business selling 'surplus gear ordered telephone company though internal company department today files letters memos photographs ids passwords credit cards found dumpsters many people consider sensitive information items discarded may recovered information recovered sometimes usable fraudulent purposes see also identity theft physical information security two mit students purchased large number obsolete computers yard sales like found everything credit card information tax return data published paper remembrance things past documenting discoveries supposedly information diving common 1980s due lax security businesses became aware need increased security early 1990s sensitive documents shredded placed dumpsters still considerable internet activity subject dumpster diving unlikely stopped widespread introduction document shredding security mythology curious hackers malicious crackers commonly use technique dumpster diving commonly practiced watchdog organizations seeking information groups investigating trinity foundation successfully used technique report activities televangelist robert tilton also obtained information benny hinn using practice also sometimes used attorneys agents seeking enforce court-ordered money judgments judgment debtor trash may contain information assets more-readily located levying
|
Computer security
|
z/architecture z/architecture initially briefly called esa modal extensions esame ibm 64-bit instruction set architecture implemented mainframe computers ibm introduced first z/architecture-based system z900 late 2000 later z/architecture systems include ibm z800 z990 z890 system z9 system z10 zenterprise 196 zenterprise 114 zec12 zbc12 z13 z14 z/architecture retains backward compatibility previous 32-bit-data/31-bit-addressing architecture esa/390 predecessors way back 32-bit-data/24-bit-addressing system/360 ibm z13 last z systems server support running operating system esa/390 architecture mode however 24-bit 31-bit problem-state application programs originally written run esa/390 architecture unaffected change z/os address space called 64-bit address space 16 exabytes size z/os address space 8 billion times size former 2-gigabyte address space operating systems including z/os generally restrict code execution first 2 gb 31 address bits 2 addressable bytes virtual address space reasons efficiency compatibility rather architectural limits z/os implementation java programming language exception z/os virtual memory implementation supports multiple 2 gb address spaces permitting 2 gb concurrently resident program code 64-bit version linux system z allows code execute within 64-bit address ranges programmers need store large amounts data 64-bit address space usually suffices applications need 16 exabyte data address space employ extended addressability techniques using additional address spaces data-only spaces data-only spaces available user programs called spaces similar areas virtual storage program create 2 gigabytes unlike address space dataspace hiperspace contains user data contain system control blocks common areas program code run dataspace hiperspace dataspace differs hiperspace dataspaces byte-addressable whereas hiperspaces page-addressable traditionally ibm mainframe memory byte-addressable kind memory termed central storage ibm mainframe processors much 1980s 1990s supported another kind memory expanded storage expanded storage 4kb-page addressable application wants access data expanded storage must first moved central storage similarly data movement central storage expanded storage done multiples 4kb pages initially page movement performed using relatively expensive instructions paging subsystem code overhead moving single groups pages central expanded storage reduced introduction mvpg move page instruction admf asynchronous data mover facility capability mvpg instruction admf explicitly invoked—generally middleware z/os z/vm acp —to access data expanded storage uses namely mid-1990s central expanded storage physically different areas memory processor since mid-1990s central expanded storage merely assignment choices underlying processor memory choices made based specific expected uses example expanded storage required hiperbatch function uses mvpg instruction access hiperspaces addition hiperspace paging cases mentioned uses expanded storage including z/os removed support expanded storage memory z/os central storage z/vm continues support expanded storage ibm described mvpg moves single page central processor execute instructions page move completed mvpg mainframe instruction move page opcode x'b254 compared mvcl move character long instruction move 256 bytes within main memory using single instruction instructions comply definitions atomicity although used single instruction within documented timing non-overlap restrictions need move 256 bytes within main memory historically addressed software mvc loops mvcl introduced 1970 announcement system/370 mvpg patented announced ibm 1989 advantages admf asynchronous data mover facility introduced 1992 goes beyond capabilities mvpg move page instruction limited single page move groups pages central expanded storage macro instruction named iosadmf described api avoids direct low-level use admf used read write data hiperspace hiperspaces created using dspserv create provide reentrancy iosadmf used together list form execute form z/vse version 4 z/tpf version 1 z/vm version 5 operating systems presumably successors require z/architecture z/architecture supports running multiple concurrent operating systems applications even use different address sizes allows software developers choose address size advantageous applications data structures platform solutions inc. psi previously marketed itanium-based servers compatible z/architecture ibm bought psi july 2008 psi systems longer available flex-es zpdt hercules emulator also implement z/architecture hitachi mainframes running newer releases vos3 operating system implement esa/390 plus hitachi-unique cpu instructions including 64-bit instructions hitachi likely inspired z/architecture formally collaborated ibm z900-g2/z800 cpus introduced 2002 hitachi machines z/architecture-compatible july 7 2009 ibm occasion announcing new version one operating systems implicitly stated architecture level set 4 als 4 exists implemented system z10 subsequent machines als 4 also specified loadxx archlvl 3 whereas earlier z900 z800 z990 z890 system z9 specified archlvl 2 earlier announcements system z10 simply specified implements z/architecture additions 50+ new machine instructions 1 mb page frames hardware decimal floating point unit hdfu
|
Computer architecture
|
tntnet tntnet web server software coded c++ enables c++ programs bundle requests modules enables developing web applications c++ get post requests interpreted tntnet server sent web application program send reply back network tntnet free software released gnu lesser general public license lgpl tntnet provides many features script-based cgi different tradeoffs c++ based tntnet allows use methods object-oriented programming polymorphism also supported modern scripting languages tntnet web application compiled ahead time script-based cgis often interpreted compiled modules native generally faster scripts programs cgid fastcgi used improve performance script-based cgis tntnet directly integrates web application webserver webservers often apis apache http server uses module system internet information services iis uses internet server application programming interface isapi tntnet originally used apache module system changed due difficulty interfacing apache c api maintaining benefits using c++ situation tommi mäkitalo developed tntnet framework tntnet also webserver present source code way tntnet acts layer front actual web application use webserver part receives http requests interpretes sends binary web application part web application webserver communicate constantly extra libraries provide tools programmer tntnet uses library tools named cxxtools build applications written using tntnet cxxtools needed library tntdb database abstraction layer programs developed using tntdb depend specific type underlying database system tntdb handle following database systems
|
Web technology
|
unspecified behavior unspecified behavior behavior may vary different implementations programming language program said contain unspecified behavior source code may produce executable exhibits different behavior compiled different compiler compiler different settings indeed different parts executable respective language standards specifications may impose range possible behaviors exact behavior depends implementation may completely determined upon examination program source code unspecified behavior often manifest resulting program external behavior may sometimes lead differing outputs results potentially causing portability problems enable compilers produce optimal code respective target platforms programming language standards always impose certain specific behavior given source code construct failing explicitly define exact behavior every possible program considered error weakness language specification would infeasible c c++ languages non-portable constructs generally grouped three categories implementation-defined unspecified undefined behavior exact definition unspecified behavior varies c++ defined behavior well-formed program construct correct data depends implementation c++ standard also notes range possible behaviors usually provided unlike implementation-defined behavior requirement implementation document behavior similarly c standard defines behavior standard provides two possibilities imposes requirements chosen instance unspecified behavior different undefined behavior latter typically result erroneous program construct data requirements placed translation execution constructs c c++ distinguish implementation-defined behavior unspecified behavior implementation-defined behavior implementation must choose particular behavior document example c/c++ size integer data types choice behavior must consistent documented behavior within given execution program many programming languages specify order evaluation sub-expressions complete expression non-determinism allow optimal implementations specific platforms e.g utilise parallelism one sub-expressions side effects result evaluating full-expression may different depending order evaluation sub-expressions example given codice_1 codice_2 modify codice_3 result stored codice_4 may different depending whether codice_5 codice_6 evaluated first c c++ languages also applies function arguments example resulting program write two lines output unspecified order languages java order evaluation operands function arguments explicitly defined
|
Programming language topics
|
feud video game feud 1987 computer game msx zx spectrum home computers among others player takes role sorcerer learic cursed aging must fight evil twin leanoric time runs first game mastertronic distributed bulldog software label countries distributed halloween learic leanoric twins powerful sorcerers hated one day leanoric cast aging curse learic learic player one day defeat leanoric dying real enemy leanoric achieve objective player must collect many herbs scattered across map mix cauldron make offensive defensive spells spells vary fireballs lightning invisibility even turning peaceful villagers zombies compass indicates leanoric location several herbs found garden tended gardener gardener though slow-moving also able inflict damage learic leanoric non-player character thing collecting herbs mix cauldron hunting order attack version game translated brazilian portuguese contains bug causes lock using sprites spell translated version devas
|
Computer architecture
|
minc minc minc c data specification language written mid-1980s princeton university graduate student named lars graf kind naming known recursive acronym contains many though syntactical capabilities c programming language used implement simple procedural programs executed runtime parser say minc need compiled way minc continues used handful programs written 1980s e.g real-time cmix intents purposes superseded modern scripting languages perl python tcl controversial aspect language whether pronounced mink min-see
|
Programming language topics
|
statement computer science computer programming statement syntactic unit imperative programming language expresses action carried program written language formed sequence one statements statement may internal components e.g. expressions many imperative languages e.g c make distinction statements definitions statement containing executable code definition instantiating identifier expression evaluates value distinction also made simple compound statements latter may contain statements components following major generic kinds statements pseudocoded pseudocoded statements immediate corresponding syntax typical imperative language like pascal c fortran etc appearance statements shapes look programs programming languages characterized type statements use e.g curly brace language family many statements introduced identifiers like repeat often statement keywords reserved used names variables functions imperative languages typically use special syntax statement looks quite different function calls common methods describe syntax statements backus–naur form syntax diagrams semantically many statements differ subroutine calls handling parameters usually actual subroutine parameter evaluated subroutine called contrasts many statement parameters evaluated several times e.g condition loop e.g loop body loop technically statement parameters call-by-name parameters call-by-name parameters evaluated needed see also lazy evaluation call-by-name parameters available statement like behaviour implemented subroutines see lisp languages without call-by-name parameters semantic description loop conditional usually beyond capabilities language therefore standard documents often refer semantic descriptions natural language languages statements contrast expressions statements return results executed solely side effects expressions always return result often side effects among imperative programming languages algol 68 one statement return result languages mix imperative functional styles lisp family distinction expressions statements made even expressions executed sequential contexts solely side effects whose return values used considered 'expressions purely functional programming statements everything expression distinction frequently observed wording statement executed expression evaluated found codice_17 codice_18 functions found languages python found codice_17 applied statements codice_18 applied expressions languages fixed set statements defined language experiments extensible languages allow programmer define new statements
|
Programming language topics
|
geonames geonames geographical database available accessible various web services creative commons attribution license geonames database contains 25,000,000 geographical names corresponding 11,800,000 unique features features categorized one nine feature classes subcategorized one 645 feature codes beyond names places various languages data stored include latitude longitude elevation population administrative subdivision postal codes coordinates use world geodetic system 1984 wgs84 data accessible free charge number web services daily database export core geonames database provided official public sources quality may vary wiki interface users invited manually edit improve database adding correcting names move existing features add new features etc geonames feature represented web resource identified stable uri uri provides access content negotiation either html wiki page rdf description feature using elements geonames ontology ontology describes geonames features properties using web ontology language feature classes codes described skos language wikipedia articles url linked rdf descriptions geonames data linked dbpedia data rdf linked data crowdsourcing schemes geonames edit interface allows everyone sign edit database hence false information entered information remain undetected especially places accessed frequently studies inaccuracies classifies loss granularity coordinates e.g. due truncation low-resolution geocoding cases wrong feature codes near-identical places placement places outside designated countries manually correcting inaccuracies tedious error prone due database size may require experts literature provides works automatically resolving computing boundary information help detect inconsistencies near-identical places placement locations cities wrong parents provinces countries singh rafiei show boundary information derived work move 20 locations geonames better positions spatial hierarchy accuracy moves 90
|
Web technology
|
iphone 5c iphone 5c marketed stylized lowercase c iphone 5c smartphone designed marketed apple inc sixth generation iphone device part iphone series unveiled september 10 2013 released september 20 2013 along higher-end counterpart iphone 5s iphone 5c variant iphone 5 similar hardware specifications hard-coated polycarbonate shell instead aluminium original iphone 5 iphone 5c available several color options shipped ios 7 iphone 5c sold discounted price point comparison 5s unlike apple usual practice lowering price previous model upon release new version iphone 5 explicitly discontinued replaced 5c september 9 2014 16 32 gb iphone 5c models replaced 8 gb model announcement iphone 6 iphone 6 plus september 9 2015 8 gb version discontinued iphone 6s announced iphone 5c redesigned using polycarbonate housing strengthened steel band however due material design changes phone weighs 132 grams 20 grams heavier 5 5s still lighter older iphone models design iphone 5c also considerably thicker closely similar design ipod touch 5th generation models also available variety colors different coating finish minor changes include different camera assembly design mute/ringer switch iphone received positive reviews design claiming durable iphone ever unlike subsequent models excluding iphone xr iphone 5c offered several colours blue green yellow coral pink white features ios apple mobile operating system user interface ios based concept direct manipulation using multi-touch gestures interlock control elements consist sliders switches buttons interaction os includes gestures swipe tap pinch reverse pinch specific definitions within context ios operating system multi-touch interface internal accelerometers used applications respond shaking device one common result undo command rotating vertically one common result switching portrait landscape mode iphone 5c supplied ios 7 released september 20 2013 jony ive designer ios 7 new elements described update bringing order complexity highlighting features refined typography new icons translucency layering physics gyroscope-driven parallaxing major changes design design ios 7 os x mavericks version 10.9 noticeably depart skeuomorphic elements green felt game center wood newsstand leather calendar favor flatter graphic design phone act hotspot sharing internet connection wi-fi bluetooth usb also accesses app store online application distribution platform ios developed maintained apple service allows users browse download applications itunes store developed xcode ios sdk published apple ios 7 adds airdrop ad-hoc wi-fi sharing platform users share files iphone 5 onwards ipod touch 5th generation ipad 4th generation ipad mini operating system also adds control center gives ios users access commonly used controls apps swiping screen–including lock screen–users things switch airplane mode turn wi-fi adjust display brightness similar basic functions device also includes new integrated flashlight function operate reverse camera flash led flashlight functions media player includes apple maps passbook mapping application includes turn-by-turn navigation spoken directions 3d views major cities real-time traffic users rotate device horizontally landscape mode access collage album covers 5c includes siri intelligent personal assistant knowledge navigator application uses natural language user interface answer questions make recommendations perform actions delegating requests set web services apple claims software adapts user individual preferences time personalizes results ios 7 adds new male female voices new system setting functionalities redesign match rest operating system integration twitter wikipedia bing photos highest operating system supports currently ios 10 2016. ios 11 support iphone phone ceased production september 2015 also 32-bit iphone facebook comes integrated apple native apps facebook features directly accessed within native apps calendar sync facebook events use facebook like button within apple app store itunes radio internet radio service also included iphone 5c free ad-supported service available itunes users featuring siri integration ios users able skip tracks customize stations purchase station songs itunes store users also search history previous songs iphone 5c uses hardware iphone 5 minor changes iphone 5c uses system chip soc called apple a6 chip powered iphone 5 soc comprises 1.3 ghz dual-core processor 1 gb ram tri-core powervr sgx543mp3 running 266 mhz. ref name= geekbench test 28/9 /ref iphone 5c new lte antennas cover lte bands smartphone according apple device made unibody hard-coated polycarbonate body steel-reinforced frame also acts antenna iphone 5c available multiple bright colors back — blue green pink yellow white black glass front features 4-inch retina multi-touch display 640×1136 pixel resolution storage capacities available fixed 8 16 32 gb plug-in memory card supported iphone 5c retains 8 mp back camera similar iphone 5 different camera assembly front camera accessible facetime camera app lower resolution 1.2 megapixels rechargeable lithium-ion battery charge capacity 1510mah slightly improved upon iphone 5 1440mah battery integrated replaced user rated ≤225 hours standby time ≤8 hours talk time iphone 5c lacks major new features introduced iphone 5s iphone 5s touch id fingerprint scanner also 64-bit a7 soc m7 motion co-processor however iphone 5c support snapping still photos video recording 3x digital zooming iphone 5c uses nano sim card iphone 5s iphone 5 iphone media event apple announced case iphone 5c available six colors black white pink yellow blue green holes cut case show color iphone back case making almost two-tone looking device although resulted “ iphone ” inscription back appear “ hon. ” cases phone colors make thirty different color combinations inside case lined soft microfiber outside made silicone first time apple released case iphone since iphone 4 iphone 4 bumpers apple also released previously announced dock iphone 5c first time apple made dock since iphone 4 dock received overwhelmingly negative reviews apple online store due incompatibility phone cases iphone 5c received generally mixed reviews phone regarded solid polycarbonate shell considered downgrade lacked 'premium look feel compared aluminum bodies iphone 5 iphone 5s reviewers generally noted iphone 5s offered features thanks 64-bit a7 soc m7 motion co-processor storage space relatively small additional upfront cost 650 usd versus 550 usd march 2014 iphone 5c period phones sold side side 8 gb version iphone 5c released 2014 described unusable 4.9gb available user installing ios 8 contrast iphone 5s offers minimum 16 gb storage iphone 5c regarded expensive compete affordable flagship smartphones nexus 5 oneplus one smartphones designed developing markets moto g. iphone 5s 5c sold nine million units first three days set record first weekend smartphone sales 5s selling three times units iphone 5c first day release 1 iphone us iphone 5s 0.3 iphone 5c. ref name= cnet ip5s/c sales 1 /ref commentators viewed iphone 5c flop supply chain cuts signifying decline demand october 2013 apple ceo tim cook admitted company overstocked iphone 5c shortages iphone 5s result failing anticipate sales ratio phones six months release iphone 5c march 25 2014 apple announced sales iphone line crossed 500 million units break many units iphone 5c iphone 5c among top three best selling phones us three months launch
|
Operating systems
|
windows hpc server 2008 windows hpc server 2008 released microsoft 22 september 2008 successor product windows compute cluster server 2003 like wccs windows hpc server 2008 designed high-end applications require high performance computing clusters hpc stands high performance computing version server software claimed efficiently scale thousands cores includes features unique hpc workloads new high-speed networkdirect rdma highly efficient scalable cluster management tools service-oriented architecture soa job scheduler mpi library based open-source mpich2 cluster interoperability standards high performance computing basic profile hpcbp specification produced open grid forum ogf june 2008 system built collaboratively national center supercomputing applications ncsa microsoft ranked 23 top500 list ranking world fastest supercomputers linpack score 68.5 teraflops ncsa supercomputer uses windows server hpc red hat enterprise linux 4 november 2011 ranking dropped 253 since windows computers dropped top500 list linux also replaced operating systems list november 2008 rankings published top500 windows hpc system built shanghai supercomputer center achieved peak performance 180.6 teraflops ranked 11 list june 2015 last windows machine left list dropped later ranked 436 barely made top500 windows azure dropping earlier windows hpc server 2008 r2 based windows server 2008 r2 released 20 september 2010 windows hpc server 2008 r2 microsoft released hpc pack 2008 r2 four flavors express enterprise workstation cycle harvesting later simplified offer releasing hpc pack 2012 combined capabilities four versions hpc pack 2008 r2 hpc pack 2012 installed top windows server 2012 standard datacenter
|
Operating systems
|
rpl programming language /ref rpl derived reverse polish lisp according original developers whilst short 1987 hp marketing attempted coin backronym rom-based procedural language handheld calculator operating system application programming language used hewlett-packard scientific graphing rpn reverse polish notation calculators hp 28 48 49 50 series also usable non-rpn calculators 38 39 40 series rpl structured programming language based rpn equally capable processing algebraic expressions formulae implemented threaded interpreter rpl many similarities forth languages stack-based well list-based lisp contrary previous hp rpn calculators fixed four-level stack stack used rpl limited available calculator ram rpl originated hp corvallis oregon development facility 1984 replacement previous practice implementing operating systems calculators assembly language last pocket calculator supporting rpl hp 50g discontinued 2015 however multiple emulators emulate hp rpl calculators exist run range operating systems devices including ios android smartphones internal low- medium-level variant rpl called system rpl sysrpl used earlier hp calculators well aforementioned ones part operating system implementation language hp 48 series variant rpl accessible calculator user without use external tools hp 49/50 series compiler built rom use sysrpl possible cause serious crash coding sysrpl caution must used using high-level user rpl userrpl version language available said graphing calculators developing textual well graphical application programs userrpl programs internally represented sysrpl programs use safe subset available sysrpl commands error checking part userrpl commands however makes userrpl programs noticeably slower equivalent sysrpl programs userrpl command syseval tells calculator process designated parts userrpl program sysrpl code rpl control blocks strictly postfix although notable exceptions control block structures appear would standard infix language calculator manages allowing implementation blocks skip ahead program stream necessary rpl supports basic conditional testing if/then/else structure basic syntax block following example tests see number bottom stack 1 replaces equal one construct evaluates condition tests bottom stack result result rpl optionally support forth-style blocks allowing condition determined block leaving condition empty statement make changes stack condition execution use existing result bottom stack test postfix conditional testing may accomplished using ift if-then ifte if-then-else functions ift ifte pop two three commands stack respectively topmost value evaluated boolean true second topmost value pushed back stack ifte allows third else value pushed back stack boolean false following example uses ift function pop object bottom stack equal 1 replaces one following example uses ifte function pop object bottom stack equal 1 replaces one equal 1 replaces string one ift ifte evaluate program block given one arguments allowing compact form conditional logic if/then/else/end structure following example pops object bottom stack replaces one less depending whether equal less greater 1 support complex conditional logic rpl provides case/then/end structure handling multiple exclusive tests one branches within case statement executed basic syntax block following code illustrates use case/then/end block given letter bottom stack replaces string equivalent unknown letter code identical following nested if/then/else/end block equivalent rpl provides for/next statement looping one index another index loop stored temporary local variable accessed loop syntax for/next block following example uses loop sum numbers 1 10 index variable loop start/next block used simple block runs start index end index unlike for/next loop looping variable available syntax start/next block for/next start/next support user-defined step increment replacing terminating next keyword increment step keyword loop variable incremented decremented different value default +1 instance following loop steps back 10 2 decrementing loop index 2 while/repeat/end block rpl supports indefinite loop condition test start loop syntax while/repeat/end block do/until/end block rpl supports indefinite loop condition test end loop syntax do/until/end block
|
Programming language topics
|
nokia 5530 xpressmusic nokia 5530 xpressmusic smartphone nokia announced june 15 2009 part xpressmusic series phones emphasizes music multimedia playback nokia third touchscreen phone 5800 n97 based symbian os s60 5th edition platform terms specifications rests lower nokia 5230 higher 5800 bearing much lower price tag lacks 5800 3g capability gps receiver compact sleek design models well stereo speakers
|
Operating systems
|
volatility memory forensics volatility open-source memory forensics framework incident response malware analysis written python supports microsoft windows mac os x linux version 2.5 volatility created computer scientist entrepreneur aaron walters drawing academic research memory forensics volatility supports investigations following memory images windows mac osx linux volatility supports variety sample file formats ability convert formats
|
Computer security
|
alisa shevchenko alisa shevchenko also known alisa esage шевченко russian hacker recognised working companies find vulnerabilities systems self-described “ offensive security researcher ” 2014 profile national geographic says shevchenko 'she drawn hacking programming dropping school worked virus analytics expert kaspersky labs five years 2009 founded company esage labs later known цои security russian acronym stands цифровое оружие и защита “ digital weapons defense. ” shevchenko company цои security placed list us sanctioned agents accused helping vladimir putin bid swing 2016 election trump regarding white house accusations shevchenko stated record authorities either misinterpreted facts deceived shevchenko winner phdays iv critical infrastructure attack contest successfully hacking fake smart city detecting several zero-day vulnerabilities indusoft web studio 7.1 schneider electric alisa also awarded zero day initiative zdi owned u.s. tech giant hp uncovering two vulnerabilities microsoft products 2014 work featured security industry publication virus bulletin regarding driving motivations alisa shevchenko said kinda ironic still aspiring inspire women obvious anti-hero wonder google government- ltd global player big gov'ts clashing absurdity show private security firm wapack labs part corporate/cyber intelligence sharing community red sky alliance claim former employee shevchenko company цои security responsible blackenergy virus blackenergy virus used targets georgia ukraine prior russian invasions nations poland belgium also targeted malware attacks using blackenergy virus malware thought created person persons connected persons linked using security services codename sandworm connections made instagram shevchenko software industry developer peter david carter
|
Computer security
|
juliana mickwitz juliana mickwitz 1889-1976 finnish-born russian became naturalized american citizen employed american military later national security agency translator linguist cryptanalyst inducted cryptologic hall honor 2012 juliane charlotte ernestine von mickwitz born elisabeth marie caroline née von dittmann ernst theodor leopold von mickwitz aka mikvits minckwitz 15 may 1889 vyborg grand duchy finland russian empire grandfather estate called halila oldest two children brother alexander would later join united states learning english german russian home tutor entered st ann gymnasium saint petersburg 1903 graduated gold medal excellence 1907 tutored students 1909 year began working secretary michael lazareff president russian unified oil company continued working widow eugenia lazareff death 1919 rise bolsheviks russian civil war mickwitz managed hide assets lazareff turn secured passage poland story mickwitz engaged polish doctor 15 april 1920 two women arrived warsaw mickwitz began trying preserve lazareff assets outside soviet union protect confiscation worked translator various organizations including american consulate warsaw british embassy canadian us timber corporation 1925 year began working foreign correspondent polish agricultural syndicate kooprolna cooperative year applied full-time position american military attaché office 1926 mickwitz became employed us military attaché office warsaw working major general william h. colbern colonel r. i. mckenney colonel john winslow general emer yeager thirteen years worked warsaw nazi invasion poland december 1939 transferred rest office hague netherlands taking lazareff aunt months germans invaded low countries office evacuated berlin three months august 1940 relocated athens germans followed july 1941 mickwitz lazareff fled lisbon assistance former employers able secure travel visas united states march 1942 arriving u.s. mickwitz began working war department military intelligence directorate translating german polish russian documents october 1946 released service awarded meritorious civilian service medal month hired army security agency stationed arlington hall 1952 transferred national security agency nsa founded linguistic unit managed translate plaintext voice remained agency 1963 retired receiving second meritorious service award continued consult nsa 1966 inducted cryptologic hall honor 2012 mickwitz member russian orthodox church helped founding construction russian orthodox cathedral st. john baptist washington dc served head parish many years worked establish congress russian americans virginia help russian immigrants became naturalized american citizen mickwitz died 21 august 1976 sacred heart nursing home hyattsville maryland suffering stroke previous november priest greece father nicolas pekatoros officiated funeral
|
Computer security
|
active hard-drive protection computer hardware active hard-drive protection refers technology attempts avoid reduce mechanical damage hard disk drives preparing disk prior impact approach mainly used laptop computers frequently carried around prone impacts desktop computers usually system consists accelerometers alert system excess acceleration vibration detected software tells hard disk unload heads prevent coming contact platter thus potentially preventing head crash many laptop vendors implemented technology different names hard-disk drives also include technology needing cooperation system
|
Computer security
|
sokoban sokoban created 1981 hiroyuki imabayashi published december 1982 thinking rabbit software house based takarazuka japan game played board squares square floor wall floor squares contain boxes floor squares marked storage locations player confined board may move horizontally vertically onto empty squares never walls boxes player also move box pushes square beyond boxes may pushed boxes walls pulled number boxes equal number storage locations puzzle solved boxes storage locations 1988 sokoban published us spectrum holobyte soko-ban ibm-pc compatible computers commodore 64 apple ii series game title screen text copyright 1984 ascii corp. reference copyrights publishing date review computer gaming world praised game pure simple playable mentally challenging citing addictive qualities also reviewed dragon giving 4½ 5 stars sokoban hit japan sold 400,000 units country time spectrum holobyte imported united states implementations sokoban written numerous computer platforms including almost home computer personal computer systems versions also exist video game consoles mobile phones graphic calculators digital cameras electronic organizers sokoban studied using theory computational complexity problem solving sokoban puzzles proven np-hard work showed significantly difficult np problems pspace-complete also interesting artificial intelligence researchers solving sokoban compared automated planning needs done robot moves boxes warehouse sokoban difficult due branching factor comparable chess also enormous search tree depth levels extended indefinitely iteration requiring exponentially growing number moves pushes skilled human players rely mostly heuristics usually able quickly discard futile redundant lines play recognize patterns subgoals drastically cutting amount search sokoban puzzles solved automatically using single-agent search algorithm ida* enhanced several techniques make use domain-specific knowledge method used rolling stone sokoban solver developed university alberta games group complex sokoban levels however reach even best automated solvers several puzzles considered variants original sokoban game sense make use controllable character pushes boxes around maze alternative tilings standard game mazes laid square grid several variants apply rules sokoban mazes laid tilings hexoban uses regular hexagons trioban uses equilateral triangles multiple pushers variants multiban interlock player control multiple characters alternative goals several variants adjust requirements completing level example block-o-mania boxes different colours goal push onto squares matching colours sokomind plus implements similar idea boxes target squares uniquely numbered interlock sokolor boxes also different colours goal move similarly coloured boxes adjacent cyberbox level designated exit square goal reach exit variant called beanstalk elements level must pushed onto goal fixed sequence additional game elements push crate sokonex xsok cyberbox block-o-mania add new elements basic puzzle examples include holes teleports moving blocks one-way passages character actions pukoban character pull boxes addition pushing destructible walls early sokoban 1982 nec pc-8801 game featured levels destructible walls order solve levels player make destructible wall elements disappear walking wall push certain side unwalkable targets variants make empty target tiles unwalkable becoming walkable occupied crate common sokoban-type levels lasertank chip challenge reverse mode player solves puzzle backwards end initial position pulling instead pushing boxes standard sokoban puzzles played reverse mode reverse mode solutions converted solutions standard-mode puzzles therefore reverse mode also instrumental solving standard sokoban puzzles
|
Computer architecture
|
data protection act 2018 data protection act 2018 c 12 united kingdom act parliament updates data protection laws uk national law complements european union general data protection regulation gdpr updates data protection act 1998 data protection act 2018 achieved royal assent 23 may 2018 applies eu gdpr standards whereas gdpr gives member states limited opportunities make provisions applies country one element dpa 2018 details applying national law dpa 2018 however limited uk gdpr provisions act seven parts outlined section 1 act introduces new offences include knowingly recklessly obtaining disclosing personal data without consent data controller procuring disclosure retaining data obtained without consent selling offering sell personal data knowingly recklessly obtained disclosed would also offence essentially act implements eu law enforcement directive implements parts gdpr 'are determined member state law creates framework similar gdpr processing personal data outside scope gdpr includes intelligence services processing immigration services processing processing personal data held unstructured form public authorities section 3 european union withdrawal act 2018 gdpr incorporated directly domestic law immediately uk exits european union
|
Computer security
|
smudge attack smudge attack method discern password pattern touchscreen device cell phone tablet computer method investigated team university pennsylvania researchers reported 4th usenix workshop offensive technologies smudge attack relies detecting oily smudges left behind user fingers operating device using simple cameras image processing software proper lighting camera settings finger smudges easily detected heaviest smudges used infer frequent user input pattern password researchers able break password 68 time proper conditions research widely covered technical press including reports pc pro zdnet engadget threat recognized least one product introduced whisper systems mitigate risk
|
Computer security
|
goguardian goguardian founded 2014 based los angeles ca offer four core products including goguardian admin web filtering goguardian teacher classroom management goguardian fleet chrome device management goguardian beacon suicide self harm alerting services enable school administrators monitor student activity online filter potentially harmful distracting content help students need june 2018 goguardian claimed active 10,150 schools protect five million students 2018 goguardian named fastest growing education company inc 500 goguardian founded 2014 based los angeles ca feature set includes chromebook filtering monitoring management well usage analytics activity flagging theft recovery device running chrome operating system chrome os goguardian also offers filtering functionality third-party tools youtube services enable school administrators monitor student activity online filter potentially harmful distracting content recover lost stolen devices june 2015 goguardian claimed active 1,600 estimated 15,000 school districts united states january 2015 los angeles unified school district lausd chose goguardian support 1:1 device rollout program 661,000 students chromebooks one device options lausd 1:1 rollout partnership provides lausd device tracking grade-level-specific filtering capabilities facilitates compliance children internet protection act cipa september 2015 company unveiled goguardian teachers tool designed help teachers manage chromebook usage classrooms monitor student activity device goal tool help keep students on-task away inappropriate content january 2016 goguardian announced launch google classroom integration goguardian teachers january 2016 two company co-founders aza steel advait shinde named forbes magazine annual 30 30 list education category 2018 goguardian launched beacon suicide prevention tool aimed help school counselors discover students silently suffering based online activity behavior 2018 goguardian acquired private equity firm sumeru equity partners appointed tony miller board directors afsp 2018 goguardian partnered american foundation suicide prevention provide free prevention training schools https //www.businesswire.com/news/home/20180904005255/en/american-foundation-suicide-prevention-partners-goguardian-provide aas 2017 goguardian announced partnership american association suicidology help tackle youth suicide crisis every school purchases beacon receive on-site sad training free charge http //www.businesswire.com/news/home/20170911005211/en/goguardian-american-association-suicidology-join-forces-tackle google education partner https //edu.google.com/products/classroom/apps/ modal_active=none story-card_activeel=connect-with-school-systems global educator institute endorsed goguardian teacher http //geiendorsed.com/products/goguardian/
|
Computer security
|
cups cups formerly acronym common unix printing system modular printing system unix-like computer operating systems allows computer act print server computer running cups host accept print jobs client computers process send appropriate printer cups consists print spooler scheduler filter system converts print data format printer understand backend system sends data print device cups uses internet printing protocol ipp basis managing print jobs queues also provides traditional command line interfaces system v berkeley print systems provides support berkeley print system line printer daemon protocol limited support server message block smb protocol system administrators configure device drivers cups supplies editing text files adobe postscript printer description ppd format number user interfaces different platforms configure cups built-in web-based interface cups free software provided apache license michael sweet owned easy software products started developing cups 1997 first public betas appeared 1999 original design cups used line printer daemon protocol lpd protocol due limitations lpd vendor incompatibilities internet printing protocol ipp chosen instead cups quickly adopted default printing system linux distributions march 2002 apple inc. adopted cups printing system mac os x 10.2 february 2007 apple inc. hired chief developer michael sweet purchased cups source code cups provides mechanism allows print jobs sent printers standard fashion print-data goes scheduler sends jobs filter system converts print job format printer understand filter system passes data backend —a special filter sends print data device network connection system makes extensive use postscript rasterization data convert data format suitable destination printer cups offers standard modularised printing system process numerous data formats print server cups difficult find standard printer management system would accommodate wide variety printers market using printer languages formats instance system v berkeley printing systems largely incompatible required complicated scripts workarounds convert program data format printable format often could detect file format sent printer thus could automatically correctly convert data stream additionally data conversion performed individual workstations rather central server cups allows printer manufacturers printer-driver developers easily create drivers work natively print server processing occurs server allowing easier network-based printing unix printing systems samba installed users address printers remote windows computers generic postscript drivers used printing across network cups scheduler implements internet printing protocol ipp http/1.1 helper application cups-lpd converts line printer daemon protocol lpd requests ipp scheduler also provides web-based interface managing print jobs configuration server documentation cups authorization module controls ipp http messages pass system ipp/http packets authorized sent client module listens processes incoming connections client module also responsible executing external cgi programs needed support web-based printers classes job status monitoring administration module processed requests sends ipp module performs uniform resource identifier uri validation prevent client sidestepping access controls authentication http server uri text string indicates name address used refer abstract physical resource network scheduler allows classes printers applications send requests groups printers class allowing scheduler direct job first available printer class jobs module manages print jobs sending filter backend processes final conversion printing monitoring status messages processes cups scheduler utilizes configuration module parses configuration files initializes cups data structures starts stops cups program configuration module stop cups services configuration file processing restart service processing complete logging module handles logging scheduler events access error page log files main module handles timeouts dispatch i/o requests client connections watching signals handling child process errors exits reloading server configuration files needed modules used scheduler include cups process variety data formats print server converts print-job data final language/format printer via series filters uses mime types identifying file formats cups system assigned print job scheduler passed cups filter system converts data format suitable printer start-up cups daemon loads two mime databases codice_1 defines known file types cups accept data codice_2 defines programs process particular mime type codice_1 file syntax codice_4 example detect html file following entry would applicable codice_5 second line matches file contents specified mime type determining first kilobyte text file holds printable characters characters include html markup pattern matches filter system would mark file mime type text/html codice_2 file syntax codice_8 source field designates mime type determined looking codice_1 file destination field lists type output requested determines program used also retrieved codice_1 cost field assists selection sets filters converting file last field program determines filter program use perform data conversion examples filtering process works taking input data pre-formatted six arguments determines type data input filter used use mime databases instance image data detected processed particular filter html data detected processed another filter cups convert supplied data either postscript data directly raster data converted postscript data additional filter applied called prefilter runs postscript data another postscript converter add printer specific options like selecting page ranges print setting n -up mode device-specific things pre-filtering done data either sent directly cups backend using postscript printer passed another filter like foomatic linuxprinting.org alternatively passed ghostscript converts postscript intermediary cups-raster format intermediary raster format passed onto final filter converts raster data printer-specific format default filters included cups include however several alternatives integrate cups hplip previously known hp-ijs provides linux+cups drivers hp printers gutenprint previously known gimp-print range high-quality printer drivers mostly inkjet printers turboprint linux another range quality printer drivers wide range printers backends ways cups sends data printers several backends available cups parallel serial usb ports cups-pdf pdf virtual printing well network backends operate via ipp jetdirect appsocket line printer daemon lpd smb protocols new codice_11 backend cups 1.4 provides bonjour dns-sd based printer discovery cups 1.6 bonjour printer discovery sharing using avahi also supported cups provides system v berkeley printing commands users continue traditional commands printing via cups cups uses port 631 tcp udp standard ipp port optionally port 515 inetd launchd solaris service management facility xinetd use cups-lpd helper program support lpd printing cups installed codice_12 system v printing system command codice_13 berkeley printing system commands installed compatible programs allows standard interface cups allows maximum compatibility existing applications rely printing systems several tools exist help set cups platforms cups web-based administration interface runs port 631 particularly helps organisations need monitor print jobs add print queues printers remotely cups 1.0 provided simple class job printer-monitoring interface web browsers cups 1.1 replaced interface enhanced administration interface allows users add modify delete configure control classes jobs printers cups 1.2 later provide revamped web interface features improved readability design support automatically discovered printers better access system logs advanced settings gnome print settings formerly called cups manager add new cups printers manage cups printers queues gnome widget toolkit gtk+ included integrated printing support based cups version 2.10 released 2006 ubuntu accessed graphical menu system administration printing kdeprint framework kde contains various gui-tools act cups front-ends allows administration classes print queues print jobs includes printer wizard assist adding new printers amongst features kdeprint first appeared kde 2.2 kdeprint supports several different printing platforms cups one best-supported replaced previous version printing support kde qtcups backwards compatible module kde kprinter dialogue-box program serves main tool sending jobs print device also started command line kdeprint includes system pre-filter jobs handed cups handle jobs converting files pdf filters described pair desktop/xml files kdeprint main components include mac os x 10.5 printers configured print fax panel system preferences printer proxy applications display print queues allow additional configuration printers set earlier versions mac os x also included printer setup utility supplied configuration options missing earlier versions print fax preference pane printersetup system manage cups queues takes approach assigning text file describe print queue 'printersetupfiles may added text files called 'printersetuplists allows logical grouping printers printersetup project remains infancy starting red hat linux 9 red hat provided integrated print manager based cups integrated gnome allowed adding printers via user interface similar one microsoft windows uses new printer could added using add new printer wizard along changing default printer-properties window containing list installed printers jobs could also started stopped using print manager printer could paused using context menu pops printer icon right-clicked eric raymond criticised system piece luxury ignorance raymond attempted install cups using fedora core 1 print manager found non-intuitive criticised interface designers designing user point-of-view mind found idea printer queues obvious users create queues local computer queues actually created cups server also found plethora queue type options confusing could choose networked cups ipp networked unix lpd networked windows smb networked novell ncp networked jetdirect found help file singularly unhelpful largely irrelevant user needs raymond used cups general topic show user interface design linux desktops needs rethinking careful design stated meta-problem configuration wizard approved rituals gui standardized clicky buttons help popping browser etc etc n't central attribute supposed achieve discoverability quality every point interface prompts actions attached learn next project quality easy software products original creators cups created gui provided support many printers implemented postscript rip esp print pro ran windows unix linux longer available support product ended december 31 2007 cups initially called common unix printing system name shortened cups beginning cups 1.4 due legal concerns unix trademark
|
Operating systems
|
expression computer science expression programming language combination one constants variables operators functions programming language interprets according particular rules precedence association computes produce return stateful environment another value process mathematical expressions called evaluation simple settings resulting value usually one various primitive types numerical string logical complex data type many others example codice_1 arithmetic programming expression evaluates codice_2 variable expression denotes value memory codice_3 expression example relational expression codice_4 evaluates codice_5 c c-derived languages call function void return type valid expression type void values type void used value expression always thrown away many programming languages function hence expression containing function may side effects expression side effects normally property referential transparency many languages e.g c++ expressions may ended semicolon codice_6 turn expression expression statement asks implementation evaluate expression side-effects disregard result expression e.g x+1 unless part expression statement induces side-effects e.g y=x+1 func1 func2 note formal notion side effect change abstract state running program another class side effects changes concrete state computational system loading data cache memories languages often described side effect–free generally still concrete side effects exploited example side-channel attacks furthermore elapsed time evaluating expression even one apparent side effects sometimes essential correct operation system behaviour time easily visible outside evaluation environment parts system interacts might even regarded primary effect performing benchmark testing depends particular programming language specification whether expression abstract side effects legally eliminated execution path processing environment expression evaluated
|
Programming language topics
|
cloudify cloudify open source software cloud nfv orchestration product originally created gigaspaces technologies spun company cloudify uses oasis tosca technology written python programming language licensed apache license version 2.0 source files found forked github built yaml dsl domain specific language configuration files called blueprints define application configurations services tier dependencies cloudify automates deployment phases applications cloud computing virtualization infrastructure blueprints describe application interacts data center apis execute defined blueprint configurations blueprint files describe execution plans lifecycle application installing starting terminating orchestrating monitoring application stack cloudify uses blueprint input describes deployment plan responsible executing cloud environments blueprint also employs cloud driver configuration files well describe machines images chosen cloud making possible manage infrastructure code component describes location binaries installation monitoring configurations creating abstraction layer isolates code underlying infrastructure cloudify able support cloud cloudify also supports configuration management tools like chef puppet ansible application deployment phase method deploying configuring application services cloudify mentioned marketing publications including venturebeat cloudbeat showdown 2011 crn 20 coolest cloud platforms development vendors 2012 2014 2018 2012 sd times 100 software development superfecta cloud leader recognized frost sullivan 2015 global frost sullivan award new product innovation cloudify together vmware athonet 2016 “ best show ” award tokyo interop event demonstration fastest simplest cloud-based deployment virtualized lte mobile packet core volte service cloudify featured breakdown nfv orchestration platforms mirantis emerged mature orchestration solution among reviewed platforms agile reference implementation automation aria open source mano group spawned cloudify “ mano software year ” network virtualization industry 2016 awards cloudify awarded 2017 layer123 network transformation award best vcpe/ucpe enterprise service cloud carrier service category cloudify member various collaborative projects open source communities cloudify used open-o vmware deutsche telekom orange within opnfv metaswitch proximus telstra partner communications mavenir among others cloudify also founding platinum member onap
|
Distributed computing architecture
|
windows runtime xaml framework 'windows runtime xaml framework code name jupiter user interface api part windows runtime winrt programming model forms backbone windows store apps formerly known metro-style immersive windows 8 windows 8.1 windows phone 8.1 operating systems enables declaring user interfaces using extensible application markup language xaml technology xaml framework one multiple ui apis windows runtime others html5 e.g. via winjs directx windows phone 8.0 windows runtime xaml framework supported xaml applications based silverlight xaml framework deployed xap format windows phone 8.1 windows runtime xaml available along improved windows runtime support convergence platforms enable universal apps target windows 8.1 windows phone 8.1 sharing code including user interface windows phone 8.1 still capable running silverlight based xaml apps new features api also added framework called silverlight 8.1 xaml framework related windows presentation foundation wpf silverlight—similar xaml-based ui frameworks used desktop applications portable applications respectively xaml framework uses lot names apis older technologies—especially silverlight use limited windows os specifically windows 8 later wpf major difference silverlight wpf largely based common language runtime clr require using programming languages c visual basic xaml framework part windows runtime written native code also available tools development c++ c++/cx
|
Operating systems
|
roger hui roger hui born 1953 computer scientist codeveloper programming language j 1953 born hong kong 1966 immigrated canada whole family 1973 hui entered university alberta second year took course probability statistics students expected learn programming language apl little formal instruction used time could muster heavily-burdened computer benefited apl\360 user manual book apl language published march 1975 manual written adin falkoff kenneth e. iverson hui thinks reasonable say learned apl falkoff iverson summer student 1975 1976 hui worked i. p. sharp associates ipsa calgary workspaces statistical probability calculations major attraction job unrestricted computer time access apl receiving b.sc degree first class honors computer science 1977 hui worked two years full-time programmer analyst new edmonton office ipsa main duty support clients use apl time-sharing attended apl79 conference rochester new york iverson gave two papers role operators apl derivative operator way hui stopped ipsa toronto obtained copy operators functions ibm research report 7091 1978 studying paper successors ever since september 1979 hui entered department computer science university toronto received m.sc may 1981 thesis complexity decompositions matrix algebra completing master degree hui worked 1981 1985 apl systems analyst programmer alberta energy company edmonton february 1982 hui purchased source book apl 1981 memorable papers design apl 1973 evolution apl 1978 notation tool thought 1980 hui work described apl85 conference paper design financial modelling system written jointly supervisor fred appleyard basic objects system direct definition iverson 1976 1980 falkoff iverson design apl cited hui left alberta energy shortly promoted non-apl non-programming position work access computers september 1985 april 1986 gave plenty time intense study iverson rationalized apl 1983 dictionary apl language named early 1990s ken iverson hui began collaborating advanced continuation apl-like language named j improvements intended fix persistent character set issues plagued apl since inception add new advanced features support parallel multiple instruction multiple data mimd operations intended j language improvement extant apl j interpreter language continue evolve 1996 received kenneth e. iverson award outstanding contribution apl
|
Programming language topics
|
list arm microarchitectures list microarchitectures based arm family instruction sets designed arm holdings 3rd parties sorted version arm instruction set release name arm provides summary numerous vendors implement arm cores design keil also provides somewhat newer summary vendors arm based processors arm provides chart displaying overview arm processor lineup performance functionality versus capabilities recent arm core families dhrystone synthetic benchmark developed 1980s longer representative prevailing workloadsuse caution cores implement arm instruction set developed independently companies architectural license arm following table lists core year announced cores arm7 n't included table
|
Computer architecture
|
path analysis computing path analysis analysis path portrayal chain consecutive events given user cohort performs set period time using website online game ecommerce platform subset behavioral analytics path analysis way understand user behavior order gain actionable insights data path analysis provides visual portrayal every event user cohort performs part path set period time possible track user ’ path site even show path visual representation real question gain actionable insights path analysis simply outputs pretty graph may look nice provide anything concrete act upon order get path analysis first step would determine needs analyzed goals analysis company might trying figure site running slow certain types users interested certain pages products user interface set logical way goal set ways performing analysis large percentage certain cohort people ages 18-25 logs online game creates profile spends next 10 minutes wandering around menu page may user interface logical seeing group users following path developer able analyze data realize creating profile “ play game ” button appear thus path analysis able provide actionable data company act fix error ecommerce path analysis help customize shopping experience user looking products customers certain cohort looked buying one company suggest “ items may also like ” next customer increase chances making purchase also path analysis help solve performance issues platform example company looks path realizes site freezes certain combinations events analyzing path progression events led error company pinpoint error fix historically path analysis fell broad category website analytics related analysis paths websites path analysis website analytics process determining sequence pages visited visitor session prior desired event visitor purchasing item requesting newsletter precise order pages visited may may important may may specified practice analysis done aggregate ranking paths sequences pages visited prior desired event descending frequency use idea determine features website encourage desired result fallout analysis subset path analysis looks black holes site paths lead dead end frequently paths features confuse lose potential customers advent big data along web-based applications online games ecommerce platforms path analysis come include much web path analysis understanding users move app game web platform part modern-day path analysis real world visit shop shelves products placed random order shop owner carefully analyzes visitors path walk shop especially selecting buying products next shop owner reorder shelves products optimize sales putting everything logical order visitors supermarket typically result wine shelf next variety cookies chips nuts etc simply people drink wine eat nuts web sites logic applied visitors questions product go product information support section web site make logical step frequently asked questions page specific question web site owner also wants analyze visitor behavior example web site offers products sale owner wants convert many visitors completed purchase sign-up form multiple pages web site owners want guide visitors final sign-up page path analysis answers typical questions like visitors go enter home page strong visitor relation product product b web site questions ca n't answered page hits unique visitors statistics google analytics provides path function funnels goals predetermined path web site pages specified every visitor walking path goal approach helpful analyzing many visitors reach certain destination page called end point analysis paths visitors walk web site lead endless number unique paths result point analyzing path look strongest paths strongest paths typically shown graphical map text like page -- page b -- page -- exit
|
Web technology
|
teslacrypt teslacrypt ransomware trojan defunct master key released developers early forms teslacrypt targeted game-play data specific computer games newer variants malware also affect file types original game-player campaign upon infection malware searched 185 file extensions related 40 different games include call duty series world warcraft minecraft world tanks encrypted files files targeted involve save data player profiles custom maps game mods stored victim hard drives newer variants teslacrypt focused computer games alone also encrypted word pdf jpeg files cases victim would prompted pay ransom 500 worth bitcoins order obtain key decrypt files although resembling cryptolocker form function teslacrypt shares code cryptolocker developed independently malware infected computers via angler adobe flash exploit even though ransomware claimed teslacrypt used asymmetric encryption researchers cisco talos group found symmetric encryption used developed decryption tool deficiency changed version 2.0 rendering impossible decrypt files affected teslacrypt-2.0 november 2015 security researchers kaspersky quietly circulating new weakness version 2.0 carefully keeping knowledge away malware developer could fix flaw january 2016 new version 3.0 discovered fixed flaw full behavior report shows behaviorgraphs executiongraphs published joesecurity may 2016 developers teslacrypt shut ransomware released master decryption key thus bringing end ransomware days eset released public tool decrypt affected computers charge
|
Computer security
|
attribute grammar attribute grammar formal way define attributes productions formal grammar associating attributes values evaluation occurs nodes abstract syntax tree language processed parser compiler attributes divided two groups synthesized attributes inherited attributes synthesized attributes result attribute evaluation rules may also use values inherited attributes inherited attributes passed parent nodes approaches synthesized attributes used pass semantic information parse tree inherited attributes help pass semantic information across instance constructing language translation tool compiler may used assign semantic values syntax constructions also possible validate semantic checks associated grammar representing rules language explicitly imparted syntax definition attribute grammars also used translate syntax tree directly code specific machine intermediate language one strength attribute grammars transport information anywhere abstract syntax tree anywhere else controlled formal way attribute grammars invented donald knuth peter wegner donald knuth credited overall concept peter wegner invented inherited attributes conversation knuth embryonic ideas trace back work edgar t. ned irons author imp following simple context-free grammar describe language made multiplication addition integers following attribute grammar used calculate result expression written grammar note grammar uses synthesized values therefore s-attributed grammar synthesized attribute computed values attributes children since values children must computed first example bottom-up propagation formally define synthesized attribute let formula_1 formal grammar given string nonterminal symbols formula_6 attribute name formula_7 formula_8 synthesized attribute three conditions met inherited attribute node parse tree defined using attribute values parent siblings inherited attributes convenient expressing dependence programming language construct context appears example use inherited attribute keep track whether identifier appears left right side assignment order decide whether address value identifier needed contrast synthesized attributes inherited attributes take values parent and/or siblings following production get values b c. b take values c. likewise c take values b
|
Programming language topics
|
acoustic cryptanalysis acoustic cryptanalysis type side channel attack exploits sounds emitted computers devices modern acoustic cryptanalysis focuses sounds produced computer keyboards internal computer components historically also applied impact printers electromechanical deciphering machines victor marchetti john d. marks eventually negotiated declassification cia acoustic intercepts sounds cleartext printing encryption machines technically method attack dates time fft hardware cheap enough perform task—in case late 1960s mid-1970s however using primitive means acoustical attacks made mid-1950s book spycatcher former mi5 operative peter wright discusses use acoustic attack egyptian hagelin cipher machines 1956 attack codenamed engulf 2004 dmitri asonov rakesh agrawal ibm almaden research center announced computer keyboards keypads used telephones automated teller machines atms vulnerable attacks based sounds produced different keys attack employed neural network recognize key pressed analyzing recorded sounds able recover text data entered techniques allow attacker using covert listening devices obtain passwords passphrases personal identification numbers pins information entered via keyboards 2005 group uc berkeley researchers performed number practical experiments demonstrating validity kind threat also 2004 adi shamir eran tromer demonstrated may possible conduct timing attacks cpu performing cryptographic operations analyzing variations acoustic emissions analyzed emissions ultrasonic noise emanating capacitors inductors computer motherboards electromagnetic emissions human-audible humming cooling fan shamir tromer along new collaborator daniel genkin others went successfully implement attack laptop running version gnupg rsa implementation using either mobile phone located close laptop laboratory-grade microphone located 4 away published experimental results december 2013 acoustic emissions occur coils capacitors small movements current surge passes capacitors particular change diameter slightly many layers experience electrostatic attraction/repulsion piezoelectric size change coil capacitor emits acoustic noise conversely also microphonic high-end audio industry takes steps coils capacitors reduce microphonics emissions muddy hi-fi amplifier sound march 2015 made public inkjet printers using ultrasonic heads read back using high frequency mems microphones record unique acoustic signals nozzle using timing reconstruction known printed data confidential 12-point font thermal printers also read using similar methods less fidelity signals bursting bubbles weaker hack also involved implanting microphone chip storage ic burst transmitter long-life li+ battery doctored cartridges substituted genuine ones sent post target typically bank retrieved garbage using challenge-response rfid chip similar work reconstructing printouts made dot-matrix printers publicized 2011 kind cryptanalysis defeated generating sounds spectrum form keypresses sounds actual keypresses randomly replayed may possible totally defeat kinds attacks advisable use least 5 different recorded variations 36 x 5 180 variations keypress get around issue fft fingerprinting alternatively white noise sufficient volume may simpler generate playback also mask acoustic emanations individual keypresses
|
Computer security
|
enterprise interoperability enterprise interoperability ability enterprise—a company large organization—to functionally link activities product design supply chains manufacturing efficient competitive way research interoperability enterprise practised various domains enterprise modelling ontologies information systems architectures platforms question positioning enterprise architecture ea presents high level design enterprise capabilities defines successful projects coherence enterprise principals business related requirements ea covers mainly business capabilities analysis validation ii development business application data technical architectures solutions finally iii control programme project implementation governance application ea methodology feeds enterprise repository reference frame sets building blocks used compose targeted system interoperability considered either principal requirement constraint impact definition patterns compose building blocks definition targeted architectural roadmap scope ea within togaf perspective aims reconcile interoperability requirements potential solutions make developed systems interoperable maintain interoperability challenge quite present next steps system ’ lifecycle several models frameworks developed topic enterprise interoperability preserve interoperability several enterprise interoperability frameworks identified literature majority frameworks considers enterprise several aspects viewpoints abstraction levels business process knowledge application technology data technic etc proposes guidelines support modeling connection capabilities levels semantic challenge considered transversal abstraction levels setting applying guidelines methodologies developed within frameworks requires modeling efforts identify connect artifacts evolution technologies aims outsource capabilities vendors manage use demand evolution pathway starts form packaged solutions goes infrastructure service iaas platform service paas software service saas recently cloud interoperability efforts still mainly expected among levels dealing business process definition alignment collaboration interoperability several international standards propose methodologies guidelines perspectives addition recent standards bpmn bpel etc implementation technologies propose relevant integration capabilities furthermore model driven-engineering provides capabilities connect transform refine models support interoperability following approaches propose metrics assess interoperability maturity several interoperability aspects identified previously listed maturity approaches define interoperability categories dimensions propose qualitative well qualitative cross cutting issues assess interoperability aspects covered single maturity approach propositions go deeply definition metric dimensions one interoperability aspect business interoperability measurement proposed aneesh
|
Computer architecture
|
aventri aventri formerly known etouches cloud-based event management software company based norwalk connecticut best known integrated events management saas solutions company 1,200 users spanning 35 countries worldwide large corporations like coca-cola mastercard dell part client mix aventri five-time honoree inc. magazine inc. 5,000 ranking fastest-growing private companies america 2012 – 2016 annual ranking also places aventri among top companies connecticut aventri founded global executive business service 1998 leonora valvo tim cummins business operated fee-for-service event managing company 2008 company relaunched etouches year etouches introduced first event management solution 2010 company raised 2.5 million first round venture capital investments lead investor greycroft partners investors connecticut innovations cava capital growth continued 2012 company launched mobile application emobile enabling users create manage event scheduling smartphones application integrates etouches modules including ereg esocial also year etouches received 7.75 million series b financing led level equity etouches raised 6 million series c round investments 2013 september year company appointed oni chukwu president chief executive officer veteran software industry executive sits board directors connecticut technology council board governors university new haven.the momentum continued throughout 2015. etouches expanded operations middle east opening headquarters office dubai company raised 14 million series c funding investors including argentum group also year etouches expanded platform acquisition tapcrowd company creates mobile applications provides marketing data businesses associations worldwide new partnership integrated ingo social media marketing suite etouches event management platform company also acquired inevention venue sourcing platform estimating tool help planners manage cost offsite meetings events rapid growth earned etouches spot deloitte 2015 technology fast 500 list fastest-growing technology companies north america also year smartceo magazine honored chukwu new york future 50 award recognizing region fastest-growing mid-sized companies etouches continued develop end-to-end event management platform enterprise market throughout 2016 company closed 20 million funding round later year acquired venue sourcing booking platform zentila etouches also introduced event roi product etouches also integrates directly popular software including salesforce passkey march 2 2017 etouches acquired loopd leading onsite data-drive technology acquisition complements etouches focus data-driven approach enhance clients event success positions etouches full enterprise solution two months later may 9 2017 etouches acquired hggc leading middle market private equity firm hggc ’ investment helped etouches expand business invest market-leading cloud platform win greater share 6 billion event management software ems venue sourcing market july 12 2018 company rebranded aventri aventri headquartered norwalk connecticut offices throughout north america europe middle east asian pacific company offers multilingual multi-currency product versions accommodate global customer base
|
Distributed computing architecture
|
openfog consortium openfog consortium sometimes stylized open fog consortium consortium high tech industry companies academic institutions across world aimed standardization promotion fog computing various capacities fields consortium founded cisco systems intel microsoft princeton university dell arm holdings 2015 57 members across north america asia europe including forbes 500 companies noteworthy academic institutions openfog consortium merged industrial internet consortium january 31 2019 openfog created november 19 2015 arm holdings cisco systems dell intel microsoft princeton university idea consortium centered advancement dissemination fog computing thought helder antunes cisco executive history iot mung chiang princeton university professor dean purdue university college engineering tao zhang cisco distinguished engineer cio ieee communications society openfog released reference architecture fog computing 13 february 2017 fog world congress 2017 hosted october 2017 openfog conjunction ieee communications society first congress devoted fog computing openfog consortium governed board directors chaired cisco senior director helder antunes board directors made 11 seats representing one following companies institutions arm cisco dell intel microsoft princeton university ieee ge zte shanghai tech university consortium general membership currently comprises 13 academic members aalto university arizona state university california institute technology georgia state university national chiao tung university national taiwan university shanghai research centre wireless communication chinese university hong kong university colorado boulder university southern california university pisa vanderbilt university wayne state university 20 additional members hitachi internet initiative japan itochu kii nebbiolo prismtech nec ngd systems ntt communications osisoft real-time innovations relayr sakura internet stichting imec nederland toshiba ttt tech fujitsu foghorn systems tttech marsec february 2016 openfog consortium published white paper openfog reference architecture outlined eight pillars openfog architecture security scalability open autonomy programmability ras reliability availability serviceability agility hierarchy february 2017 openfog consortium published openfog reference architecture discusses eight technical pillars fog computing 2017 openfog consortium published industry glossary fog computing terms july 2018 ieee standards association announced adopted openfog reference architecture first standard fog computing
|
Distributed computing architecture
|
darkhotel darkhotel darkhotel targeted spear-phishing spyware malware-spreading campaign appears selectively attacking business hotel visitors hotel in-house wifi network characterized kaspersky lab advanced persistent threat attacks specifically targeted senior company executives using forged digital certificates generated factoring underlying weak public keys real certificates convince victims prompted software downloads valid uploading malicious code hotel servers attackers able target specific users guests luxury hotels primarily asia united states zetter 2014 explains group dubbed darkhotel tapaoux also actively infecting users spear-phishing peer-to-peer networks since 2007 key logging reverse engineering targets aimed primarily executives investments development government agencies defense industries electronic manufacturers energy policy makers large number victims located korea china russia japan attackers victim computer sensitive information passwords intellectual property quickly stolen attackers erase tools hopes getting caught july 2017 bitdefender published new research inexsmar another version darkhotel malware used target political figures instead business targets
|
Computer security
|
next laser printer next laser printer next pn n2000 400 dpi postscript laser printer sold next late nextstation nextcube workstations manufactured canon inc included adjustable paper tray enabled print several paper sizes including a4 letter-size legal envelope varieties similar printers based canon sx engine apple laserwriter ii series hp laserjet ii/iii although printers printed 300x300 dpi parts toner cartridge input paper tray interchangeable laserjet ii/iii printer used proprietary high-speed serial interface essence predecessor software-rendering approach used displaypostscript renderer nextstep rather hardware postscript renderer regardless lack dedicated rendering hardware usually achieved close rated speed 8 ppm nextstation much faster cpu 25 33mhz 68040 greater memory capacity 128 mb turbo models rendering engines contemporary printers nextstep used displaypostscript extensively windowing system postscript rendering path optimized thus printed documents true output wysiwyg corresponding screen next also produced color inkjet printer scsi-i-connected tabloid-capable 360 dpi color bubblejet model next pn n2004 us n2005 uk based technology canon bubblejet
|
Operating systems
|
frequency grid frequency grid table central frequencies corresponding wavelengths channels allowed communications system common frequency grid used fiber-optic communication used channel spacing dense wavelength division multiplexing dwdm wavelengths around 1550 nm defined itu-t g.694.1 grid defined relative 193.1 thz extends 191.7 thz 196.1 thz 100 ghz spacing defined frequency grid often expressed terms wavelength case covers wavelength range 1528.77 nm 1563.86 nm approximately 0.8 nm channel spacing practical purposes grid extended cover 186 thz 201 thz subdivided provide 50 ghz 25 ghz spaced grids
|
Internet protocols
|
flexiscale flexiscale utility computing platform launched xcalibre communications summer 2007 subsequently acquired flexiant launched shortly amazon ec2 service europe first world second cloud computing platform users able create start stop servers require allowing rapid deployment needed windows linux supported flexiscale platform flexiscale uses open source xen hypervisor backend storage comes highly redundant san although level redundancy called question august 2008 2 days downtime resulting engineer mistake storage system previously consisted dual head netapp storage array disk shelves connected heads replaced launch flexiscale 2.0 june 2010 amber road based storage solution sun microsystems revisions flexiscale platform publicly available information first version based virtual iron vm management software second revision called flexiscale v1.5 platform based in-house developed vm control system known extility recent release called flexiscale v2.0 contributed extensively revised user interface
|
Web technology
|
mod n cryptanalysis cryptography mod n cryptanalysis attack applicable block stream ciphers form partitioning cryptanalysis exploits unevenness cipher operates equivalence classes congruence classes modulo n method first suggested 1999 john kelsey bruce schneier david wagner applied rc5p variant rc5 m6 family block ciphers used firewire standard attacks used properties binary addition bit rotation modulo fermat prime rc5p analysis conducted modulo 3 observed operations cipher rotation addition 32-bit words somewhat biased congruence classes mod 3 illustrate approach consider left rotation single bit follows thus left rotation single bit simple description modulo 3 analysis operations data dependent rotation modular addition reveals similar notable biases although theoretical problems analysing operations combination bias detected experimentally entire cipher kelsey et al. 1999 experiments conducted seven rounds based conjecture many 19 20 rounds rc5p distinguished random using attack also corresponding method recovering secret key m6 attacks mod 5 mod 257 even effective
|
Computer security
|
cookie stuffing world wide web cookie stuffing also cookie dropping affiliate marketing technique result visiting website user receives third-party cookie website unrelated visited user usually without user aware user later visits target website completes qualifying transaction making purchase cookie stuffer paid commission target stuffer actually encouraged user visit target technique considered illegitimate many affiliate schemes websites run affiliate program pay commission affiliates introducing visitors complete one qualifying transactions website owners often join affiliate programs earn commission usually simply sending visitors site running affiliate program via special link advertisement user clicks special link single cookie usually placed user computer considered normal practice way affiliate marketers generate genuine income definition cookies considered stuffed one placed user computer purely result viewing page one added time result single click taken extreme dozens cookies stuffed scattergun approach hope user visit one several target affiliate sites complete qualifying transaction cookie stuffing often referred blackhat online marketing technique potential generate fraudulent affiliate income cookie stuffer may also overwrite legitimate affiliate cookies essentially stealing commission another affiliate perfectly normal user visit website click link directed target affiliate site complete qualifying transaction time user may revisit target affiliate website later time complete qualifying transaction original referring affiliate would credited transaction make commission however many affiliate programs award commission recent referring affiliate original referring affiliate problem occurs cookie stuffing site stuffs visitors batch cookies scattergun approach genuine affiliate cookie may get overwritten user visits target affiliate site completes qualifying transaction cookie stuffer gets credit instead original affiliate brought first genuine visit target site operators websites allow user-generated content forums allow users post content aware various cookie stuffing techniques combat order protect visitors type activity cookie stuffing accomplished something simple including image forum post signature image link compromised purpose cookie stuffer made simulate click forum visitors affiliate link techniques used accomplish cookie stuffing similar used cross-site request forgery csrf attacks pop-ups actually method cookie stuffing accepted affiliate networks pop-up gets website visitor visit site course gives affiliate cookie common place find happening review sites affiliate “ reviews ” product companies pay commission customers interested product still wanted information purchasing probably innocent form cookie stuffing still stuffing none-the-less method defeated utilizing pop-up blocking software iframes way embedding page within page webmaster embeds web page one simple line code affiliate embeds iframe onto page loads affiliate url frames work similar fashion frames deprecated modern browsers techniques longer prevalent codice_1 html tag suggests browser attempt retrieve image url ’ matter url supplied n't extension like .jpg .gif .png end instance codice_2 would actually get anyone visits page send visit google affiliate links put directly creating redirect .htaccess javascript used force user visit url end result visiting affiliate url cascading style sheets define web page displayed retrieved like image would – browser instructed visit url affiliate could put direct affiliate url style sheet image loaded way one harder methods detect adobe flash commonly used create interactive media web contains functionality allows developers force website user visit affiliate link removing spoofing referrer information affiliate network wo n't know traffic came common tactic spoofed referring site legitimate white hat affiliate site mask fact cookie stuffing carried 2008 ebay sued four successful affiliate marketers platform used cookie stuffing techniques brian dunning host skeptoid podcast sentenced fifteen months prison 100 fine five months prison 25,000 fine pleading guilty wire fraud
|
Computer security
|
codeplay codeplay software limited privately owned software tools developer based edinburgh scotland codeplay produces compilers debuggers runtimes testing systems specialized tools aid software development heterogeneous systems special purpose processor architectures including gpus dsps codeplay contributing member multicore association khronos group hsa foundation codeplay founded 2002 andrew richards experienced games developer formerly head software development eutechnyx initial funding company provided jez san obe founder argonaut games arc international codeplay began business developing compilers aimed games programmers releasing vectorc compiler playstation 2 x86 windows pc 2005 codeplay shifted focus developing bespoke c/c++ compilers processor designers since expanded services include development debuggers runtimes testing tools 2011 codeplay announced provided real-time car damage system utilising offload technology 2013 codeplay formed r division received investors people accreditation 2014 codeplay announced working implementation khronos group new provisional standard heterogeneous computing sycl codeplay ceo andrew richards currently chairs working group standard within khronos group computeaorta codeplay multi-target multi-platform toolkit rapidly enabling delivery opencl spir vulkan compute standards currently supporting linux windows android operating systems across x86 arm powerpc mips targets computeaorta also easily customized support new novel hardware architectures opencl standard widely adopted programming model gpus cpus dsps fpgas used extensively professional graphics applications adobe photoshop premiere well wide range open-source software codeplay built proprietary bespoke implementations opencl several customers well significantly contributing development opencl related standards within khronos group codeplay computecpp implementation sycl open standard enabling single source c++ software high-level object-oriented programming codeplay extensive participation standards bodies ensure industry benefits extensive varied knowledge codeplay chairs following standards codeplay contributed following eu-funded research projects
|
Computer architecture
|
pike programming language pike interpreted general-purpose high-level cross-platform dynamic programming language syntax similar c. unlike many dynamic languages pike statically dynamically typed requires explicit type definitions features flexible type system allows rapid development flexible code dynamically typed languages still providing benefits statically typed language pike features garbage collection advanced data types first-class anonymous functions support many programming paradigms including object-oriented functional imperative programming pike free software released gpl lgpl mpl licenses pike roots lpc language developed muds programmers lysator linköping sweden notably fredrik hübinette per hedbor separated language virtual machine rest mud driver used rapid prototyping language various applications calling lpc4 lpc license allow use commercial purposes new gpl implementation written 1994 called µlpc micro lpc 1996 µlpc renamed pike order provide commercially viable name although name company changed years company known roxen internet software employed many pike developers provided resources pike development roxen also name web server developed company pike 2002 programming environment laboratory linköping university took maintenance pike roxen several pike programmers found way linköping office opera software language plays central role server/gateway parts opera mini application int main syntax requires explanation familiar c c++ pick right away following list shows standard data types pike provides advanced data types sequences queues heaps stacks etc available adt module included pike basic data types container types types pike requires explicit type definitions variables uses information report type errors compile time following code cause compile error value variable number must integer code attempting assign floating point string values int number // integer variable accepts integers number 5.5 // 5.5 floating point value error number 5 // 5 string integer value 5 error kind behavior traditionally considered restrictive limiting proponents dynamically typed languages however unlike c c++ java pike uses flexible type system—specifically system tagged unions system allows programmers declare variables may contain values multiple types something impossible c-family languages without straying bounds safe usage following demonstrates variable hold either integer floating point number int|float number // integer float variable number 5 // legal number 5.5 // also legal variable declared holding many different data types functions provided determine type data currently stored functions form typenamep intp floatp stringp etc int|float number number 5 intp number // returns true number holds int floatp number // returns false number 5.5 floatp number // returns true number holds float additionally special mixed data type definition allows variable hold kind data type mixed anything anything 5 // anything integer value 5 anything 5.5 // anything float value 5.5 anything 5 // anything string value 5 order convert value one type another pike use explicit cast mixed anything anything int 5.5 // anything integer value 5 anything string anything // anything string value 5
|
Programming language topics
|
vesa enhanced video connector vesa enhanced video connector vesa standard intended reduce number cables around computer incorporating video audio firewire usb single cable system intention system make monitor central point connection although specific idea find favour computer manufacturers evolved somewhat popular vesa plug display standard vesa evc connector capable carrying analog video vga-based output video input composite firewire audio analogue stereo usb signals pinout somewhat similar newer vesa plug display distinguished plug display connector shell shaped like isosceles trapezoid similar shell d-subminiature instead -shaped shell dvi connector
|
Computer architecture
|
global address space programming interface global address space programming interface gpi application programming interface api development scalable asynchronous fault tolerant parallel applications implementation partitioned global address space programming model gpi developed fraunhofer institute industrial mathematics itwm since 2005 initially known fvm fraunhofer virtual machine 2009 name changed global address programming interface gpi 2011 fraunhofer itwm partners fraunhofer scai tud t-systems sfr dlr kit fzj dwd scapos initiated launched gaspi project define novel specification api gaspi based gpi make novel specification reliable scalable universal tool hpc community gpi-2 first open source implementation standard software freely available application developers researchers licenses commercial use available scapos ag gpi completely replaced mpi fraunhofer itwm products research based new gpi-2 modern hardware typically involves hierarchy memory respect bandwidth latency read write accesses within hierarchy non-uniform memory access numa partitions solid state devices ssds graphical processing unit gpu memory many integrated cores mic memory memory segments supposed map variety hardware layers software layer spirit pgas approach gpi segments may globally accessible every thread every gpi process gpi segments also used leverage different memory models within single application even run different applications group subset ranks group members common collective operations collective operation group restricted ranks forming group initial group gaspi_group_all ranks members forming group involves 3 steps creation addition commit operations must performed ranks forming group creation performed using codice_1 operation successful ranks added created group using codice_2 able use created group ranks added must commit group performed using codice_3 collective operation ranks group one-sided asynchronous communication basic communication mechanism provided gpi-2 one-sided communication comes two flavors read write operations single list allocated segments moreover write operations extended notifications enable remote completion events remote rank react one-sided operations non-blocking asynchronous allowing program continue execution along data transfer mechanisms communication gpi-2 following codice_4 possibility use different queues communication requests request submitted one queues queues allow scalability used channels different types requests similar types requests queued get synchronised together independently ones separation concerns gpi-2 provides atomic operations variables manipulated atomically two basic atomic operations codice_5 codice_6 values used global shared variables synchronise processes events failure tolerant parallel programs require non-blocking communication calls gpi-2 provides timeout mechanism potentially blocking procedures timeouts procedures specified milliseconds instance gaspi_block pre-defined timeout value blocks procedure call completion gaspi_test another predefined timeout value blocks procedure shortest time possible i. e. time procedure call processes atomic portion work
|
Operating systems
|
trucluster trucluster closed-source high-availability clustering solution tru64 unix operating system originally developed digital equipment corporation dec transferred compaq 1998 digital acquired company later merged hewlett-packard hp
|
Computer architecture
|
network model network model database model conceived flexible way representing objects relationships distinguishing feature schema viewed graph object types nodes relationship types arcs restricted hierarchy lattice hierarchical database model structures data tree records record one parent record many children network model allows record multiple parent child records forming generalized graph structure property applies two levels schema generalized graph record types connected relationship types called set types codasyl database generalized graph record occurrences connected relationships codasyl sets cycles permitted levels chief argument favour network model comparison hierarchical model allowed natural modeling relationships entities although model widely implemented used failed become dominant two main reasons firstly ibm chose stick hierarchical model semi-network extensions established products ims dl/i secondly eventually displaced relational model offered higher-level declarative interface early 1980s performance benefits low-level navigational interfaces offered hierarchical network databases persuasive many large-scale applications hardware became faster extra productivity flexibility relational model led gradual obsolescence network model corporate enterprise usage network model original inventor charles bachman developed standard specification published 1969 conference data systems languages codasyl consortium followed second publication 1971 became basis implementations subsequent work continued early 1980s culminating iso specification little influence products bachman influence recognized term bachman diagram diagrammatic notation represents database schema expressed using network model bachman diagram named rectangles represent record types arrows represent one-to-many relationship types records codasyl set types well-known database systems use network model include
|
Databases
|
penguin wars player controls one five animals choose cow rabbit bat rat penguin plays games animals nintendo entertainment system arcade editions game five animals penguin bear panda koala beaver game participating animals find opposite sides square table five balls side object game roll balls table soon ten balls one player side player loses game game also time limit 60 seconds reached player fewest balls side wins player hit one balls knocked unconscious certain amount time thus could also said part object game hit opponent otherwise would possible get ten balls side opponent roll back arrived different animals different strengths weaknesses trade-off example rat one move left right fastest return roll balls slowly cow hand slow walker return regains consciousness quickly thirty seconds playing jellybean-like obstacle appears middle table moves left right different kinds obstacles cause varying effects trajectory balls deflect start rolling diagonally players roll parallel sides table whereas others simply ball bounce straight back remake penguin wars announced nintendo switch july 25 2017 game released japan september 21 2017 playstation 4 xbox one versions announced november nintendo switch version released june 27 2019 north america europe
|
Computer architecture
|
traffic analysis traffic analysis process intercepting examining messages order deduce information patterns communication performed even messages encrypted general greater number messages observed even intercepted stored inferred traffic traffic analysis performed context military intelligence counter-intelligence pattern-of-life analysis concern computer security traffic analysis tasks may supported dedicated computer software programs advanced traffic analysis techniques may include various forms social network analysis traffic analysis method used break anonymity anonymous networks e.g. tors two methods traffic-analysis attack passive active military context traffic analysis basic part signals intelligence source information intentions actions target representative patterns include close relationship traffic analysis cryptanalysis commonly called codebreaking callsigns addresses frequently encrypted requiring assistance identifying traffic volume often sign addressee importance giving hints pending objectives movements cryptanalysts traffic-flow security use measures conceal presence properties valid messages network prevent traffic analysis done operational procedures protection resulting features inherent cryptographic equipment techniques used include traffic-flow security one aspect communications security communications metadata intelligence comint metadata term communications intelligence comint referring concept producing intelligence analyzing technical metadata hence great practical example traffic analysis intelligence traditionally information gathering comint derived intercepting transmissions tapping target communications monitoring content conversations metadata intelligence based content technical communicational data non-content comint usually used deduce information user certain transmitter locations contacts activity volume routine exceptions example certain emitter known radio transmitter certain unit using direction finding df tools position emitter locatable hence changes locations monitored way 're able understand certain unit moving one point another without listening orders reports know unit reports back command certain pattern know another unit reports pattern command two units probably related conclusion based metadata two units transmissions content transmissions using much metadata available commonly used build electronic order battle eob – mapping different entities battlefield connections course eob could built tapping conversations trying understand unit using metadata automatic analysis tool enables much faster accurate eob build-up alongside tapping builds much better complete picture traffic analysis also concern computer security attacker gain important information monitoring frequency timing network packets timing attack ssh protocol use timing information deduce information passwords since interactive session ssh transmits keystroke message time keystroke messages studied using hidden markov models song et al claim recover password fifty times faster brute force attack onion routing systems used gain anonymity traffic analysis used attack anonymous communication systems like tor anonymity network adam back ulf möeller anton stiglic present traffic analysis attacks anonymity providing systems steven j. murdoch george danezis university cambridge presented research showing traffic-analysis allows adversaries infer nodes relay anonymous streams reduces anonymity provided tor shown otherwise unrelated streams linked back initiator remailer systems also attacked via traffic analysis message observed going remailing server identical-length anonymized message seen exiting server soon traffic analyst may able automatically connect sender ultimate receiver variations remailer operations exist make traffic analysis less effective difficult defeat traffic analysis without encrypting messages masking channel actual messages sent channel masked hard hide information size timing messages known solutions require alice send continuous stream messages maximum bandwidth ever use ... might acceptable military applications civilian applications military-versus-civilian problems applies situations user charged volume information sent even internet access per-packet charge isps make statistical assumption connections user sites busy 100 time user simply increase bandwidth link since masking would fill well masking often built end-to-end encryptors becomes common practice isps change traffic assumptions
|
Computer security
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.