外文翻译-Internet的历史

0外文原文TheHistoryoftheInternetTheBeginning-ARPAnetTheInternetstartedasaprojectbytheUSgovernment.Theobjectoftheprojectwastocreateameansofcommunicationsbetweenlongdistancepoints,intheeventofanationwideemergencyor,morespecifically,nuclearwar.TheprojectwascalledARPAnet,anditiswhattheInternetstartedas.Fundedspecificallyformilitarycommunication,theengineersresponsibleforARPANethadnoideaofthepossibilitiesofanInternet.Bydefinition,anInternetisfourormorecomputersconnectedbyanetwork.ARPAnetachieveditsnetworkbyusingaprotocolcalledTCP/IP.Thebasicsaroundthisprotocolwasthatifinformationsentoveranetworkfailedtogetthroughononeroute,itwouldfindanotherroutetoworkwith,aswellasestablishingameansforonecomputertotalktoanothercomputer,regardlessofwhetheritwasaPCoraMacintosh.Bythe80sARPAnet,justyearsawayfrombecomingthemorewellknownInternet,had200computers.TheDefenseDepartment,satisfiedwithARPAnetsresults,decidedtofullyadoptitintoservice,andconnectedmanymilitarycomputersandresourcesintothenetwork.ARPAnetthenhad562computersonitsnetwork.Bytheyear1984,ithadover1000computersonitsnetwork.In1986ARPAnet(supposedly)shutdown,butonlytheorganizationshutdown,andtheexistingnetworksstillexistedbetweenthemorethan1000computers.ItshutdownduetoafailiedlinkupwithNSF,whowantedtoconnectits5countywidesupercomputersintoARPAnet.WiththefundingofNSF,newhighspeedlinesweresuccessfullyinstalledatlinespeedsof56k(anormalmodemnowadays)throughtelephonelinesin1988.Bythattime,therewere28,174computersonthe(bythendecided)Internet.In1989therewere80,000computersonit.By1989,therewere290,000.1Anothernetworkwasbuilttosupporttheincrediblenumberofpeoplejoining.Itwasconstructedin1992.Today-TheInternetToday,theInternethasbecomeoneofthemostimportanttechnologicaladvancementsinthehistoryofhumanity.EveryonewantstogetonlinetoexperiencethewealthofinformationoftheInternet.MillionsofpeoplenowusetheInternet,anditspredictedthatbytheyear2003everysinglepersonontheplanetwillhaveInternetaccess.TheInternethastrulybecomeawayoflifeinourtimeandera,andisevolvingsoquicklyitshardtodeterminewhereitwillgonext,ascomputerandnetworktechnologyimproveeveryday.HOWITWORKS:Itsastandardthing.PeopleusingtheInternet.Shopping,playinggames,conversinginvirtualInternetenvironments.TheInternetisnotathingitself.TheInternetcannotjustcrash.Itfunctionsthesamewayasthetelephonesystem,onlythereisnoInternetcompanythatrunstheInternet.TheInternetisacollectionofmillioinsofcomputersthatareallconnectedtoeachother,orhavethemeanstoconnecttoeachother.TheInternetisjustlikeanofficenetwork,onlyithasmillionsofcomputersconnectedtoit.ThemainthingabouthowtheInternetworksiscommunication.HowdoesacomputerinHoustonknowhowtoaccessdataonacomputerinTokyotoviewawebpage?Internetcommunication,communicationamongcomputersconnectedtotheInternet,isbasedonalanguage.ThislanguageiscalledTCP/IP.TCP/IPestablishesalanguageforacomputertoaccessandtransmitdataovertheInternetsystem.ButTCP/IPassumesthatthereisaphysicalconnecetionbetweenonecomputerandanother.Thisisnotusuallythecase.TherewouldhavetobeanetworkwirethatwenttoeverycomputerconnectedtotheInternet,butthatwouldmaketheInternetimpossibletoaccess.Thephysicalconnectionthatisrequireedisestablishedbywayofmodems,phonelines,andothermodemcableconnections(likecablemodemsorDSL).Modemsoncomputers2readandtransmitdataoverestablishedlines,whichcouldbephonelinesordatalines.Theactualhardcoreconnectionsareestablishedamongcomputerscalledrouters.Arouterisacomputerthatservesasatrafficcontrollerforinformation.Toexplainthisbetter,letslookathowastandardcomputermightviewawebpage.1.TheuserscomputerdialsintoanInternetServiceProvider(ISP).TheISPmightinturnbeconnectedtoanotherISP,orastraightconnectionintotheInternetbackbone.2.TheuserlaunchesawebbrowserlikeNetscapeorInternetExplorerandtypesinaninternetlocationtogoto.3.Hereswherethetrickypartcomesin.First,thecomputersendsdataaboutitsdatarequesttoarouter.Arouterisaveryhighspeedpowerfulcomputerrunningspecialsoftware.Thecollectionofroutersintheworldmakewhatiscalledabackbone,onwhichallthedataontheInternetistransferred.Thebackbonepresentlyoperatesataspeedofseveralgigabytesper-second.Suchaspeedcomparedtoanormalmodemislikecomparingtheheatofthesuntotheheatofanice-cube.Routershandledatathatisgoingbackandforth.Arouterputssmallchunksofdataintopackagescalledpackets,whichfunctionsimilarlytoenvelopes.So,whentherequestforthewebpagegoesthrough,itusesTCP/IPprotocolstotelltherouterwhattodowiththedata,whereitsgoing,andoverallwheretheuserwantstogo.4.Theroutersendsthesepacketstootherrouters,eventuallyleadingtothetargetcomputer.Itslikewhisperdownthelane(onlytheinformationremainsintact).5.Whentheinformationreachesthetargetwebserver,thewebserverthenbeginstosendthewebpageback.Awebserveristhecomputerwherethewebpageisstoredthatisrunningaprogramthathandlesrequestsforthewebpageandsendsthewebpagetowhoeverwantstoseeit.6.Thewebpageisputinpackets,sentthroughrouters,andarriveattheuserscomputerwheretheusercanviewthewebpageonceitisassembled.Thepacketswhichcontainthedataalsocontainspecialinformationthatletsroutersandothercomputersknowhowtoreassemblethedataintherightorder.3Withmillionsofwebpages,andmillionsofusers,usingtheInternetisnotalwayseasyforabeginninguser,especiallyforsomeonewhoisnotentirelycomfortalewithusingcomputers.BelowyoucanfindtipstricksandhelponhowtousemainservicesoftheInternet.Beforeyouaccesswebpages,youmusthaveawebbrowsertoactuallybeabletoviewthewebpages.MostInternetAccessProvidersprovideyouwithawebbrowserinthesoftwaretheyusuallygivetocustomers;you.Thefactthatyouareviewingthispagemeansthatyouhaveawebbrowser.ThetoptwousebrowsersareNetscapeCommunicatorandMicrosoftInternetExplorer.NandMSIE/ie.Thefactthatyourereadingthisrightnowmeansthatyouhaveawebbrowser.Nextyoumustbefamiliarwithactuallyusingwebpages.Awebpageisacollectionofhyperlinks,images,text,forms,menus,andmultimedia.Tonavigateawebpage,simplyclickthelinksitprovidesorfollowitsowninstructions(likeifithasaformyouneedtouse,itwillprobablyinstructyouhowtouseit).Basically,everythingaboutawebpageismadetobeself-explanetory.Thatisthenatureofawebpage,tobeeasilynavigatable.Ohno!a404error!Cannotfindwebpage?isacommonremarkmadebynewweb-users.Sometimeswebsiteshaveerrors.Butanerroronawebsiteisnottheusersfault,ofcourse.A404errormeansthatthepageyoutriedtogotodoesnotexist.Thiscouldbebecausethesiteisstillbeingconstructedandthepagehasntbeencreatedyet,orbecausethesiteauthormadeatypointhepage.Theresnothingmuchtodoabouta404errorexceptfore-mailingthesiteadministrator(ofthepageyouwantedtogoto)antellinghim/herabouttheerror.AJavascripterroristheresultofaprogrammingerrorintheJavascriptcodeofawebsite.NotallwebsitesutilizeJavascript,butmanydo.JavascriptisdifferentfromJava,andmostbrowsersnowsupportJavascript.Ifyouareusinganoldversionofawebbrowser(Netscape3.0forexample),youmightgetJavascripterrorsbecausesitesutilizeJavascript4versionsthatyourbrowserdoesnotsupport.So,youcantrygettinganewerversionofyourwebbrowser.E-mailstandsforElectronicMail,andthatswhatitis.E-mailenablespeopletosendletters,andevenfilesandpicturestoeachother.Tousee-mail,youmusthaveane-mailclient,whichisjustlikeapersonalpostoffice,sinceitretrievesandstorese-mail.Secondly,youmusthaveane-mailaccount.MostInternetServiceProvidersprovidefreee-mailaccount(s)forfree.Someservicesofferfreee-mail,likeHotmail,andGeocities.Afterconfiguringyoure-mailclientwithyourPOP3andSMTPserveraddress(youre-mailproviderwillgiveyouthatinformation),youarereadytoreceivemail.Anattachmentisafilesentinaletter.Ifsomeonesendsyouanattachmentandyoudontknowwhoitis,dontrunthefile,ever.Itcouldbeavirusorsomeotherkindofnastyprograms.Youcantgetavirusjustbyreadinge-mail,youllhavetophysicallyexecutesomeformofprogramforavirustostrike.Asignatureisafeatureofmanye-mailprograms.Asignatureisaddedtotheendofeverye-mailyousendout.Youcanputatextgraphic,yourbusinessinformation,anythingyouwant.ImaginethatacomputerontheInternetisanislandinthesea.Theseaisfilledwithmillionsofislands.ThisistheInternet.Imagineanislandcommunicateswithotherislandbysendingshipstootherislandsandreceivingships.Theislandhasportstoacceptandsendoutships.AcomputerontheInternethasaccessnodescalledports.Aportisjustasymbolicobjectthatallowsthecomputertooperateonanetwork(ortheInternet).Thismethodissimilartotheisland/oceansymbolismabove.Telnetreferstoaccessingportsonaserverdirectlywithatextconnection.AlmosteverykindofInternetfunction,likeaccessingwebpages,chatting,ande-mailingisdoneoveraTelnetconnection.TelnettingrequiresaTelnetclient.AtelnetprogramcomeswiththeWindowssystem,soWindowsuserscanaccesstelnetbytypingintelnet(withoutthes)intherundialog.5Linuxhasitbuiltintothecommandline;telnet.ApopulartelnetprogramforMacintoshisNCSAtelnet.Anyserversoftware(webpagedaemon,chatdaemon)canbeaccessedviatelnet,althoughtheyarenotusuallymeanttobeaccessedinsuchamanner.Forinstance,itispossibletoconnectdirectlytoamailserverandcheckyourmailbyinterfacingwiththee-mailserversoftware,butitseasiertouseane-mailclient(ofcourse).TherearemillionsofWebPagesthatcomefromallovertheworld,yethowwillyouknowwhattheaddressofapageyouwantis?Searchenginessavetheday.Asearchengineisaverylargewebsitethatallowsyoutosearchitsowndatabaseofwebsites.Forinstance,ifyouwantedtofindawebsiteondogs,youdsearchfordogordogsordoginformation.Hereareafewsearch-engines.1.Altavista()-Webspider&Indexed2.Yahoo()-Webspider&IndexedCollection3.Excite()-Webspider&Indexed4.Lycos()-Webspider&Indexed5.Metasearch()-MultiplesearchAwebspiderisaprogramusedbysearchenginesthatgoesfrompagetopage,followinganylinkitcanpossiblyfind.ThismeansthatasearchenginecanliterallymapoutasmuchoftheInternetasitsowntimeandspeedallowsfor.Anindexedcollectionuseshand-addedlinks.Forinstance,onYahoossite.YoucanclickonComputers&theInternet.ThenyoucanclickonHardware.ThenyoucanclickonModems,etc.,andalongthewaythroughsections,therearesitesavailablewhichrelatetowhatsectionyourein.Metasearchsearchesmanysearchenginesatthesametime,findingthetopchoicesfromabout10searchengines,makingsearchingalotmoreeffective.Onceyouareabletousesearchengines,youcaneffectivelyfindthepagesyouwant.Withthearrivalofnetworkingandmultiusersystems,securityhasalwaysbeenonthemindofsystemdevelopersandsystemoperators.SincethedawnofAT&Tanditsphonenetwork,hackershavebeenknownbymany,hackerswhofindwaysallthetimeofbreaking6intosystems.Itusedtonotbethatbigofaproblem,sincenetworkingwaslimitedtobigcorporatecompaniesorgovernmentcomputerswhocouldaffordthenecessarycomputersecurity.Thebiggestproblemnow-a-daysispersonalinformation.Whyshouldyoubecarefulwhilemakingpurchasesviaawebsite?Letslookathowtheinternetworks,quickly.Theuseristransferringcreditcardinformationtoawebpage.Lookssafe,right?Notnecessarily.Astheusersubmitstheinformation,itisbeingstreamedthroughaseriesofcomputersthatmakeuptheInternetbackbone.Theinformationisinlittlechunks,inpackagescalledpackets.Herestheproblem:Whiletheinformationisbeingtransferredthroughthisbigbackbone,whatispreventingahackerfrominterceptingthisdatastreamatoneofthebackbonepoints?Big-brotherisnotwatchingyouifyouaccessawebsite,butusersshouldbeawareofpotentialthreatswhiletransmittingprivateinformation.Therearemethodsofenforcingsecurity,likepasswordprotection,anmostimportantly,encryption.Encryptionmeansscramblingdataintoacodethatcanonlybeunscrambledontheotherend.BrowserslikeNetscapeCommunicatorandInternetExplorerfeatureencryptionsupportformakingon-linetransfers.Someencryptionsworkbetterthanothers.ThemostadvancedencryptionsystemiscalledDES(DataEncryptionStandard),anditwasadoptedbytheUSDefenseDepartmentbecauseitwasdeemedsodifficulttocrackthattheyconsidereditasecurityriskifitwouldfallintoanothercountrieshands.ADESusesasinglekeyofinformationtounlockanentiredocument.Theproblemis,thereare75trillionpossiblekeystouse,soitisahighlydifficultsystemtobreak.Onedocumentwascrackedanddecoded,butitwasacombinedeffortof14,000computersnetworkedovertheInternetthattookawhiletodoit,somosthackersdonthavethatmanyresourcesavailable.TheInternethashadarelativelybrief,butexplosivehistorysofar.Itgrewoutofanexperimentbeguninthe1960sbytheU.S.DepartmentofDefense.TheDoDwantedtocreateacomputernetworkthatwouldcontinuetofunctionintheeventofadisaster,suchasanuclearwar.Ifpartofthenetworkweredamagedordestroyed,therestofthesystemstillhad7towork.ThatnetworkwasARPANET,whichlinkedU.S.scientificandacademicresearchers.ItwastheforerunneroftodaysInternet.In1985,theNationalScienceFoundation(NSF)createdNSFNET,aseriesofnetworksforresearchandeducationcommunication.BasedonARPANETprotocols,theNSFNETcreatedanationalbackboneservice,providedfreetoanyU.S.researchandeducationalinstitution.Atthesametime,regionalnetworkswerecreatedtolinkindividualinstitutionswiththenationalbackboneservice.NSFNETgrewrapidlyaspeoplediscovereditspotential,andasnewsoftwareapplicationswerecreatedtomakeaccesseasier.CorporationssuchasSprintandMCIbegantobuildtheirownnetworks,whichtheylinkedtoNSFNET.AscommercialfirmsandotherregionalnetworkprovidershavetakenovertheoperationofthemajorInternetarteries,NSFhaswithdrawnfromthebackbonebusiness.NSFalsocoordinatedaservicecalledInterNIC,whichregisteredalladdressesontheInternetsothatdatacouldberoutedtotherightsystem.ThisservicehasnowbeentakenoverbyNetworkSolutions,Inc.,incooperationwithNSF.HowtheWebWorksTheWorldWideWeb,thegraphicalportionoftheInternet,isthemostpopularpartoftheInternetbyfar.OnceyouspendtimeontheWebyouwillbegintofeellikethereisnolimittowhatyoucandiscover.TheWeballowsrichanddiversecommunicationbydisplayingtext,graphics,animation,photos,soundandvideo.Sojustwhatisthismiraculouscreation?TheWebphysicallyconsistsofyourpersonalcomputer,webbrowsersoftware,aconnectiontoanInternetserviceprovider,computerscalledserversthathostdigitaldataandroutersandswitchestodirecttheflowofinformation.TheWebisknownasaclient-serversystem.Yourcomputeristheclient;theremotecomputersthatstoreelectronicfilesaretheservers.Hereshowitworks:LetssayyouwanttopayavisittotheLouvremuseumwebsite.FirstyouentertheaddressorURLofthewebsiteinyourwebbrowser(moreaboutthisshortly).ThenyourbrowserrequeststhewebpagefromthewebserverthathoststheLouvressite.TheLouvres8serversendsthedataovertheInternettoyourcomputer.Yourwebbrowserinterpretsthedata,displayingitonyourcomputerscreen.TheLouvreswebsitealsohaslinkstothesitesofothermuseums,suchastheVaticanMuseum.Whenyouclickyourmouseonalink,youaccessthewebserverfortheVaticanMuseum.ThegluethatholdstheWebtogetheriscalledhypertextandhyperlinks.ThisfeatureallowelectronicfilesontheWebtobelinkedsoyoucaneasilyjumpbetweenthem.OntheWeb,younavigatethroughpagesofinformationbasedonwhatinterestsyouatthatparticularmoment,commonlyknownasbrowsingorsurfingtheNet.ToaccesstheWebyouneedwebbrowsersoftware,suchasNetscapeNavigatororMicrosoftInternetExplorer.HowdoesyourwebbrowserdistinguishbetweenwebpagesandotherfilesontheInternet?WebpagesarewritteninacomputerlanguagecalledHypertextMarkupLanguageorHTML.SomeWebHistoryTheWorldWideWeb(WWW)wasoriginallydevelopedin1990atCERN,theEuropeanLaboratoryforParticlePhysics.ItisnowmanagedbyTheWorldWideWebConsortium,alsoknownastheWorldWideWebInitiative.TheWWWConsortiumisfundedbyalargenumberofcorporatemembers,includingAT&T,AdobeSystems,Inc.,MicrosoftCorporationandSunMicrosystems,Inc.ItspurposeistopromotethegrowthoftheWebbydevelopingtechnicalspecificationsandreferencesoftwarethatwillbefreelyavailabletoeveryone.TheConsortiumisrunbyMITwithINRIA(TheFrenchNationalInstituteforResearchinComputerScience)actingasEuropeanhost,incollaborationwithCERN.TheNationalCenterforSupercomputingApplications(NCSA)attheUniversityofIllinoisatUrbana-Champaign,wasinstrumentalinthedevelopmentofearlygraphicalsoftwareutilizingtheWorldWideWebfeaturescreatedbyCERN.NCSAfocusesonimprovingtheproductivityofresearchersbyprovidingsoftwareforscientificmodeling,analysis,andvisualization.TheWorldWideWebwasanobviouswaytofulfillthatmission.9NCSAMosaic,oneoftheearliestwebbrowsers,wasdistributedfreetothepublic.ItleddirectlytothephenomenalgrowthoftheWorldWideWeb.UnderstandingWebAddressesYoucanthinkoftheWorldWideWebasanetworkofelectronicfilesstoredoncomputersallaroundtheworld.Hypertextlinkstheseresourcestogether.UniformResourceLocatorsorURLsaretheaddressesusedtolocatethesefiles.TheinformationcontainedinaURLgivesyoutheabilitytojumpfromonewebpagetoanotherwithjustaclickofyourmouse.WhenyoutypeaURLintoyourbrowserorclickonahypertextlink,yourbrowserissendingarequesttoaremotecomputertodownloadafile.WhatdoesatypicalURLlooklike?Herearesomeexamples:/Thehomepageforstudyenglish./pub/AdirectoryoffilesatMIT*availablefordownloading.news:rec.gardens.rosesAnewsgrouponrosegardening.ThefirstpartofaURL(beforethetwoslashes*tellsyouthetypeofresourceormethodofaccessatthataddress.Thesecondpartistypicallytheaddressofthecomputerwherethedataorserviceislocated.Additionalpartsmayspecifythenamesoffiles,theporttoconnectto,orthetexttosearchforinadatabase.YoucanentertheURLofasitebytypingitintotheLocationbarofyourwebbrowser,justunderthetoolbar.MostbrowsersrecordURLsthatyouwanttouseagain,byaddingthemtoaspecialmenu.InNetscapeNavigator,itscalledBookmarks.InMicrosoftExplorer,itscalledFavorites.OnceyouaddaURLtoyourlist,youcanreturntothatwebpagesimplybyclickingonthenameinyourlist,insteadofretypingtheentireURL.10MostoftheURLsyouwillbeusingstartwithhttpwhichstandsforHypertextTransferProtocol*.httpisthemethodbywhichHTMLfilesaretransferredovertheWeb.HerearesomeotherimportantthingstoknowaboutURLs.IfyouenteraURLincorrectly,yourbrowserwillnotbeabletolocatethesiteorresourceyouwant.Shouldyougetanerrormessageorthewrongsite,makesureyoutypedtheaddresscorrectly.YoucanfindtheURLbehindanylinkbypassingyourmousecursoroverthelink.ThepointerwillturnintoahandandtheURLwillappearinthebrowsersstatusbar,usuallylocatedatthebottomofyourscreen.DomainNamesWhenyouthinkoftheInternet,.JustwhatdothosethreelettersattheendofaWorldWideWebaddressmean?Everycomputertha