《计算机专业英语》课件第4章

教学目标教学内容Unit4NetworkTechnique教学目标了解计算机网络的发展史理解网络安全的相关理论了解虚拟化技术掌握电子商务的相关技术了解目前已经广泛使用的局域网技术教学内容Text1EvolutionofcomputernetworksText2NetworkSecurityText3VirtualizationTechnologyText4ElectronicCommerceText5LAN-CruisingText1EvolutionofcomputernetworksMainContentsWordsandExpressionsExercisesThetermnetworkcanmeanmanydifferentthings.Itcanimplyaninterconnectionofrailwaytracksfortherailnetwork;highwaysandstreetsfortransportationnetworks;telephonelinesandswitchingcentersforthephonenetwork;coaxiallinesforthecabletelevisionnetwork;fiberlinesforcablecommunicationsnetworks;ortheinterconnectionofservicecenters,businesses,andsoontoformanetwork.Alloftheseconfigurationsrefertothemeanstotietogethervariousresourcessothattheymayoperateasagroup,realizingthebenefitsofnumbers,sharing,andcommunicationsinsuchagroup.Text1EvolutionofcomputernetworksText1EvolutionofcomputernetworksIncomputersystemsterminologyofanetworkisacombinationofinterconnectedcomputingequipmentandprogramsusedformovinginformation(andcomputations)betweenpoints(nodes)inthenetworkwhereitmaybegenerated,processed,stored,orusedinwhatevermannerisdeemedappropriate.Theinterconnectionmaytakeonmanyforms,suchasdedicatedlinks,sharedlinks,telephonelines,microwavelinks,andsatellitelinks.Networksinthissenseformaloosecoalitionofdevicesthatshareinformation.Thiswasoneofthefirstusesofanetwork,althoughitwasnotthelast.Usersfoundthatthenetworkcouldoffermorethanjustinformationsharing;itcouldofferotherservicesforremotejobexecutionandultimatelydistributedcomputing.Text1EvolutionofcomputernetworksTheearliestconceptofanetworkwasofaloosebindingtogetherofdevicesorresourcesforsharing.AnearlycomputernetworkthatexhibitedthesetraitswastheARPANET.ARPANETwasfirstbroughton-linein1969asaresearchtooltoinvestigatelong-haulnetworkissuesandtoprovideatoolforresearchanddevelopmentsolutions.IthasevolvedintotheInternet,connectingmillionsofcomputersoverlocalareanetworks,metropolitanareanetworks,andotherwideareanetworks.ARPANETprovidedthevehicleforearlyresearchintocommunicationsprotocolsdealingwithcongestion,control,routing,addressing,remoteinvocation,distributedcomputing,distributedoperatingsystemsandservices,andmanyotherareas.ThereasonsforusingnetworkssuchasARPANETweretoprovidegreateravailabilityandaccesstoawiderrangeofdevices.Earlyapplicationsofcomputersdealtwithperformingengineeringtasksandmajordataprocessingfunctions.Asthetechnologyofcomputerschanged,andasresearchersandusersalikeaddedmoreandmoreapplications,informationaccessandmanipulationtookongreateremphasis.Earliernetworksprovidedthenecessaryinformationexchangeservicesbutwerelimitedtobasicallyjustthisservice.Theinformationavailabilitystimulatedmoreimaginativeusesofthisinformation.Asthisoccurredandthetechnologyofnetworksimproved,newapplicationsarose.Thesenewapplicationsnotonlyusedinformationexchangebutalsoremotejobexecution.Itbegansimplyassendingabatchjobdownthelinktoalessbusyhost,havingthejobcompletedthere,andthenshippingtheresultsbacktotheoriginator.Text1EvolutionofcomputernetworksText1EvolutionofcomputernetworksThissufficedforawhile,butitstilldidnotprovidethereal-timeorinteractiveenvironmentsthatuserswerebeginningtobecomeaccustomedto,includingmoreadvancedprotocolsandnetworkoperatingsystemstoprovidefurtherservicesforremotejobinvocationandsynchronization.Theeraofthelocalareanetworkwascoming.Thewideareanetworks'biggestshortfallwasinthroughputorturnaroundtimeforjobsandinterprocessorcommunications.Becauseofthewidedistances,delaysofsecondswerecommonplaceandcausedaddedoverheadinperformingotherwisesimpletasks.Networkdesignerssawtheneedtoprovideanotherlinkinthenetwork:thelocalareanetwork.Localareanetworksbeganshowinguponthenetworkinglandscapeintheearlytomid1970sasmostlyresearchactivitiesinuniversitiesandgovernmentlaboratories.ItwasnotuntilEthernetwasreleasedinthemid1970sthatLANsbecamemorewidelyavailable.Sincethattime,numerousLANdesignshavebeenproducedtofitanextremelywidespectrumofuserrequirements-forexample,thefiberring.Additionally,standardshaveevolved,providingbasicLANtopologiesandtheirservicestoagreaternumberofusers.Text1EvolutionofcomputernetworksText1EvolutionofcomputernetworksLocalareanetworksarefindingtheirwayintoallaspectsofmodernsociety.Wefindtheminourhomesthroughcablemodemsandphonemodems,automobilesviawirelesstechnologies,banking(e.g.,ATMs),schoolsviaInternetconnections,businesses,government,andindustry.TherearenottoomanyaspectsofinformationexchangeanddataprocessinginwhichaLANcannotbefound.Localareanetworksandtheirassociatedtechnologiesrepresentoneofthegreatgrowthareasofthe1990sandearly2000s.AsmoreandmoreLANsbecomeavailable,sowillnewproductsandusesforthem.LANsareusedtoconnectallpersonalcomputersinoffices,classrooms,factoryfloors,retailestablishments,andnowevenmanyhomes.Theyareusedintheseenvironmentstosendmemoranda,issuedirectives,schedulemeetings,transmitdocuments,sende-mail,discovernewinformation,andprocesslargevolumesofdataconcurrentlyatmanysites.Text1EvolutionofcomputernetworksLANsareusedtolinkfactoryrobotstogetherwithareaandfactorycontrollers.Theyprovidesensordata,controldata,andfeedbacktothecontrolcenters,whileatthesametimeprovidingavehicletoissueproductionchangesandnoticestousersandrobotsalike.AfineexampleofalocalareanetworkprovidingdiverseservicestotheusersisseeninWaltDisneyWorld.DisneyusesLANsandcomputerstomonitorallaspectsofservices,includingfireprotection,scheduling,ridemanagement,on-lineinformation,security,personnelservices,andaplethoraofotherparkmanagementfunctions.Largebanks,suchastheWorldBank,haveadoptedLANsasthemeanstointerconnecttheirvariouslocalsitesintosmallernetworkslinkedtogetherbywideareanetworks.However,theLANisnotforeveryone.Text1EvolutionofcomputernetworksNetworkevolutionhasnotstoppedthere.Aswirelesstechnologyhasimproved,sohastheinterestinnetworkingvendorstoprovidetheirservicestousersofthesedomains.Wirelessnetworksbeganfairlyquietlyinthe1970swiththeAlohanetasthefoundation.Sincethen,wirelessphonenetworkdevelopmenthasopenedthedoorforcomputernetworks.TodayoneofthegreatgrowthareasinnetworkingwillbeinfurtherdevelopingwirelessnetworksandintegratingtheseintoexistingLANandWANnetworkstoprovideanevenwiderarrayofapplicationstothewirelesscellphonecommunity.WordsandExpressionsinterconnection[intəkə'nekʃən]n.网络互连track[træk]n.【计算机】数据磁道cable['keibl]n.电缆coaxial['kəu'æksəl]adj.同轴传输线的transportation[trænspɔ:'teiʃən]n.运输，运输系统，运输工具fiber['faibə]n.光纤configuration[kənfigju'reiʃən]n.【计算机】配置terminology[tə:mi'nɔlədʒi]n.用辞，术语microwave['maikrəuweiv]n.微波dedicated['dedikeitid]adj.【计算机】(装置、程序、系统等)专用的coalition[kəuə'liʃən]n.结合，合并，联合distributed[dis'tribju:tid]vt.分布的，分布式的loose[lu:s]adj.宽松的，不牢固的，不精确的WordsandExpressionsbinding['baindiŋ]n.1.捆绑；束缚；粘合；连接2.捆缚物；束缚物；连接物3.(滑雪屐上的)扣栓，(滑雪板上的)皮靴固定装置4.(如桌布、毯子等的)镶边，滚带5.(书籍的)装订；装帧；活页封面和封底、封皮ARPANET阿帕网investigate[in'vestigeit]v.【计算机】研究long-haul['lɔŋ'hɔ:l;'lɔ:ŋ-]adj.长远距的metropolitan[metrə'pɔlit(ə)n]n.大都市的居民，大主教，母国的居民adj.大都市的vehicle['vi:ikl]n.传播媒介，工具，手段，交通工具，车辆congestion[kən'dʒestʃən]n.【计算机】拥挤routing['ru:tiŋ;'rau-]n路由选择，路径选择invocation[invəu'keiʃən]【计算机】调用availability[əveilə'biliti]n.有效，有用，有益.WordsandExpressionsmanipulation[mə，nipju'leiʃən]n.处理emphasi['emfəsis]n.强调，重点stimulate['stimjuleit]vt.刺激，激励，鼓舞batch[bætʃ]n.批，成批，分批originator[ə'ridʒəneitə(r)]n.创始人，发起人sufficed[sə'fais]v.足够，使...满足，合格synchronization[siŋkrənai'zeiʃən]同步化shortfall['ʃɔ:tfɔ:l]n.不足之量，差额throughput['θru:put]n.【计算机】(计算机输入输出信息的)吞吐量，通过量，总处理能力turnaround[‘tɜ:nəraʊnd]n.转变，突然好转WordsandExpressionslandscape['lændskeip]n.风景，山水，风景画LANsabbr.局域网(localareanetworks)spectrum['spektrəm]n.光谱，（比喻）范围，系列fiber['faibə]n.纤维memoranda[memə'rændə]n.备忘录(便条)21世纪大英汉词典》

concurrently[kən'kʌrəntli]adv.同时(兼)plethora['pleθərə]n.过量，过剩vendor['vendɔ:]n.厂商Aloha[ɑ:'ləuhɑ:]int.哈罗，欢迎，再见21世纪大英汉词典》

WAN[wɔn](wideareanetwork)广域网ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Thetermnetworkcanmeanasamething.（）2.Usersfoundthatthenetworkcouldofferinformationsharingonly.（）3.Theearliestconceptofanetworkwasofaloosebindingtogetherofdevicesorresourcesforsharing.（）4.AnearlycomputernetworkthatexhibitedthesetraitswastheInternet.（）5.Becauseofthewidedistances，delaysofminuteswerecommonplaceandcausedaddedoverheadinperformingotherwisesimpletasks.（）6.Localareanetworksbeganshowinguponthenetworkinglandscapeintheearlytomid1960sasmostlyresearchactivitiesinuniversitiesandgovernmentlaboratories.（）7.Wefindwideareanetworksinourhomesthroughcablemodemsandphonemodems，automobilesviawirelesstechnologies，banking(e.g.，ATMs)，schoolsviaInternetconnections，businesses，government，andindustry.（）8.TherearetoomanyaspectsofinformationexchangeanddataprocessinginwhichaLANcannotbefound.（）9.LANsareusedtoconnectallpersonalcomputersinoffices，classrooms，factoryfloors，retailestablishments，andnowevenmanyhomes.（）10.Largebanks，suchastheWorldBank，haveadoptedLANsasthemeanstointerconnecttheirvariouslocalsitesintosmallernetworkslinkedtogetherbywideareanetworks.ExercisesII.Fillintheblankswithproperwords.1.__________wasfirstbroughton-linein1969asaresearchtooltoinvestigatelong-haulnetworkissuesandtoprovideatoolforresearchanddevelopmentsolutions.2.__________hasevolvedintotheInternet，connectingmillionsofcomputersoverlocalareanetworks，metropolitanareanetworks，andotherwideareanetworks.3.__________arefindingtheirwayintoallaspectsofmodernsociety.4.Largebanks，suchastheWorldBank，haveadopted__________asthemeanstointerconnecttheirvariouslocalsitesintosmallernetworkslinkedtogetherbywideareanetworks.Text2NetworkSecurityMainContentsWordsandExpressionsExercisesSecurityisabroadtopicandcoversamultitudeofsins.Initssimplestform,itisconcernedwithmakingsurethatnosypeoplecannotread,orworseyet,secretlymodifymessagesintendedforotherrecipients.Itisconcernedwithpeopletryingtoaccessremoteservicesthattheyarenotauthorizedtouse.ItalsodealswithwaystotellwhetherthatmessagepurportedlyfromtheIRSsaying:PaybyFridayorelseisreallyfromtheIRSandnotfromtheMafia.Securityalsodealswiththeproblemsoflegitimatemessagesbeingcapturedandreplayed,andwithpeopletryingtodenythattheysentcertainmessages.Text2NetworkSecurityText2NetworkSecurityNetworksecurityproblemscanbedividedroughlyintofourcloselyintertwinedareas:secrecy,authentication,nonrepudiation,andintegritycontrol.Secrecy,alsocalledconfidentiality,hastodowithkeepinginformationoutofthehandsofunauthorizedusers.Thisiswhatusuallycomestomindwhenpeoplethinkaboutnetworksecurity.Authenticationdealswithdeterminingwhomyouaretalkingtobeforerevealingsensitiveinformationorenteringintoabusinessdeal.Nonrepudiationdealswithsignatures:Howdoyouprovethatyourcustomerreallyplacedanelectronicorderfortenmillionleft-handeddoohickeysat89centseachwhenhelaterclaimsthepricewas69cents?Ormaybeheclaimsheneverplacedanyorder.Finally,howcanyoubesurethatamessageyoureceivedwasreallytheonesentandnotsomethingthatamaliciousadversarymodifiedintransitorconcocted?Inthedatalinklayer,packetsonapoint-to-pointlinecanbeencryptedastheyleaveonemachineanddecryptedastheyenteranother.Allthedetailscanbehandledinthedatalinklayer,withhigherlayersoblivioustowhatisgoingon.Thissolutionbreaksdownwhenpacketshavetotraversemultiplerouters,however,becausepacketshavetobedecryptedateachrouter,leavingthemvulnerabletoattacksfromwithintherouter.Also,itdoesnotallowsomesessionstobeprotected(e.g.,thoseinvolvingon-linepurchasesbycreditcard)andothersnot.Nevertheless,linkencryption,asthismethodiscalled,canbeaddedtoanynetworkeasilyandisoftenuseful.Text2NetworkSecurityText2NetworkSecurityInthenetworklayer,firewallscanbeinstalledtokeepgoodpacketsandbadpacketsout.IPsecurityalsofunctionsinthislayer.Inthetransportlayer,entireconnectionscanbeencrypted,endtoend,thatis,processtoprocess.Formaximumsecurity,end-to-endsecurityisrequired.Finally,issuessuchasuserauthenticationandnonrepudiationcanonlybehandledintheapplicationlayer.Sincesecuritydoesnotfitneatlyintoanylayer,itdoesnotfitintoanychapterofthisbook.Forthisreason,itratesitsownchapter.Text2NetworkSecurityItiswelldocumentedthatmostsecurityfailuresatbanks,forexample,areduetoincompetentemployees,laxsecurityprocedures,orinsiderfraud,ratherthanclevercriminalstappingphonelinesandthendecodingencryptedmessages.IfapersoncanwalkintoarandombranchofabankwithanATMsliphefoundonthestreetclaimingtohaveforgottenhisPINandgetanewoneonthespot(inthenameofgoodcustomerrelations),allthecryptographyintheworldwillnotpreventabuse.Inthisrespect,RossAnderson'sbookisarealeye-opener,asitdocumentshundredsofexamplesofsecurityfailuresinnumerousindustries,nearlyallofthemduetowhatmightpolitelybecalledsloppybusinesspracticesorinattentiontosecurity.Nevertheless,weareoptimisticthatase-commercebecomesmorewidespread,companieswilleventuallydebugtheiroperationalprocedures,eliminatingthisloopholeandbringingthetechnicalaspectsofsecuritytocenterstageagain.Exceptforphysicallayersecurity,nearlyallsecurityisbasedoncryptographicprinciples.WordsandExpressionsRossAnderson安德森，剑桥大学资讯安全工程讲师loom[lu:m]n.织布机v.朦胧地出现，隐约可见horizon[hə'raizn]n.地平线；视野；眼界.pitfall['pitfɔ:l]n.陷阱，诱惑，阴谋algorithm['ælgəriðəm]算法sin[sin]n.罪，罪孽v.犯罪nosy['nəuzi]adj.鼻子大的，好管闲事的，爱追问的recipient[ri'sipiənt]n.接受者authorized['ɔ:θəraizd]adj.经认可的，审定的，经授权的21世纪大英汉词典》

purportedly[pə:'pɔ:tidli，'pə:p-，'pə:pət-]ad.据称IRSabbr.InternalRevenueService美国国税局Mafia['mɑ:fiə]n.黑手党，秘密政党legitimate[li'dʒitimit]a.合法的，正当的v.使合法malicious[mə‘liʃəs]a.怀恶意的，恶毒的WordsandExpressionsperpetrator[pə:pi'treitə]n.犯人，作恶之人outsmart[aut'smɑ:t]v.比...更聪明，打败adversary['ædvəsəri]n.敌手，对手well-funded资金充足的thwart[θwɔ:t]a.横坐板v.反对，阻碍ad.横过perpetrate['pə:pitreit]v.做，犯tapping['tæpiŋ]n.开孔(导出液体，放液，流出口，浇铸，抽头)insider[in'saidə(r)]n.内部的人，会员，知道内情的人grudge[grʌdʒ]n.怨恨，恶意v.怀恨，嫉妒，吝惜intertwined[intə:'waind]a.互相缠结的，缠绕在一起的secrecy['si:krisi]n.秘密(保密，隐蔽)authentication[ɔ:，θenti'keiʃən]n.证明，鉴定.nonrepudiation认可confidentiality[‘kɔnfi，denʃi’æləti]n.秘而不宣，保密WordsandExpressionsunauthorized['ʌn'ɔ:θəraizd]非法的，越权的doohickey['du:，hiki]n.小玩意，装置，窍门malicious[mə'liʃəs]a.怀恶意的，恶毒的adversary['ædvəsəri]n.敌手，对手transit['trænsit]n.经过，运输v.横越concoct[kən'kɔkt]vt.调制，配制photocopy['fəutəu，kɔpi]n.影印v.影印tampering['tæmpəriŋ]a.干预的，干涉的sealed[si:ld]a.封口的，密封的wiretapping['waiə，tæpiŋ]vt.wiretap的变形n.搭线窃听adj.搭线窃听的tube[‘tju:b]n.地铁，电子管，显像管，管，软管WordsandExpressionspacke[pækt]adj.挤满的；塞满的压结实的；压紧的encrypt[in'kript]vt.把…编码decrypt[di:'kript]v.译，解释oblivious[ə'bliviəs]a.没注意到，或不知道vulnerable['vʌlnərəb(ə)l]a.易受伤害的，有弱点的lax[læks]a.松的，松懈的，不严的slip[slip]n.滑，错误，下跌v.滑倒，犯错，减退cryptography[krip'tɔgrəfi]密码术，密码系统sloppy['slɔpi]a.被泼水弄湿的，泥泞的，多阴雨的inattention[inə'tenʃən]n.不注意，粗心，疏忽debug[di:'bʌɡ]vt.【计算机】调试；排除(程序)中的错误，排除故障loophole['lu:phəʊl]n.枪眼，小窗，换气孔ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Networksecurityproblemscanbedividedroughlyintothreecloselyintertwinedareas:secrecy,authentication,andintegritycontrol.（）2.Alltheseissues(secrecy,authentication,nonrepudiation,andintegritycontrol)donotoccurintraditionalsystems.（）3.Integrityandsecrecyareachievedbyusingregisteredmailandlockingdocumentsup.（）4.Withelectronicchecks,theoriginalandthecopyaredistinguishable.（）5.Tamperingcanusuallybedetectedbyhandwriting,ink,andpaperexperts.Noneoftheseoptionsareavailableelectronically.（）6.Inthetransportlayer,firewallscanbeinstalledtokeepgoodpacketsandbadpacketsout.（）7.Issuessuchasuserauthenticationandnonrepudiationcannotbehandledintheapplicationlayer.ExercisesII.Fillintheblankswithproperwords.1.Forthefirstfewdecadesoftheirexistence,__________wereprimarilyusedbyuniversityresearchersforsendinge-mailandbycorporateemployeesforsharingprinters.2.__________,alsocalledconfidentiality,hastodowithkeepinginformationoutofthehandsofunauthorizedusers.3.__________dealswithdeterminingwhomyouaretalkingtobeforerevealingsensitiveinformationorenteringintoabusinessdeal.4.Inthe__________layer,entireconnectionscanbeencrypted,endtoend,thatis,processtoprocess.Text3VirtualizationTechnologyMainContentsWordsandExpressionsExercisesVirtualizationVirtualization-thetechniqueofmanagingsystemsandresourcesfunctionally,regardlessoftheirphysicallayoutorlocation-representsapowerfulbreakthroughinITefficiency,responsivenessandagility.

Since2005,virtualizationsoftwarewasadoptedfasterthananyoneimagined,includingtheexperts.TherearethreeareasofITwherevirtualizationismakingheadroads,networkvirtualization,storagevirtualizationandservervirtualization.ServervirtualizationServervirtualizationisthemaskingofserverresources(includingthenumberandidentityofindividualphysicalservers,processors,andoperatingsystems)fromserverusers.Theintentionistosparetheuserfromhavingtounderstandandmanagecomplicateddetailsofserverresourceswhileincreasingresourcesharingandutilizationandmaintainingthecapacitytoexpandlater.Ingeneral,servervirtualizationsoftwarerunsbetweentheoperatingsystemandthehardware.Servervirtualizationproductsareavailablefromanumberofvendors.VMwareisthemajorsoftwarevendorprovidingservervirtualizationforWindowsandLinuxsystemswithIntel-poweredservers.MicrosoftoffersitsownVirtualServerproduct.Networkvirtualization

Networkvirtualizationisamethodofcombiningtheavailableresourcesinanetworkbysplittinguptheavailablebandwidthintochannels,eachofwhichisindependentfromtheothers,andeachofwhichcanbeassigned(orreassigned)toaparticularserverordeviceinrealtime.Eachchannelisindependentlysecured.Everysubscriberhassharedaccesstoalltheresourcesonthenetworkfromasinglecomputer.StoragevirtualizationStoragevirtualizationisthepoolingofphysicalstoragefrommultiplenetworkstoragedevicesintowhatappearstobeasinglestoragedevicethatismanagedfromacentralconsole.Storagevirtualizationiscommonlyusedinastorageareanetwork(SAN).Themanagementofstoragedevicescanbetediousandtime-consuming.Storagevirtualizationhelpsthestorageadministratorperformthetasksofbackup,archiving,andrecoverymoreeasily,andinlesstime,bydisguisingtheactualcomplexityoftheSAN.VirtualizationcanbeviewedaspartofanoveralltrendinenterpriseITthatincludesautonomiccomputing,ascenarioinwhichtheITenvironmentwillbeabletomanageitselfbasedonperceivedactivity,andutilitycomputing,inwhichcomputerprocessingpowerisseenasautilitythatclientscanpayforonlyasneeded.Theusualgoalofvirtualizationistocentralizeadministrativetaskswhileimprovingscalabilityandworkloads.WordsandExpressionsVirtualization虚拟化技术layout['lei,aut]n.布局,安排,设计breakthrough['breikθru:]n.突破responsiveness[ri'spɔnsivnis]n.响应性(反应性)agility[ə'dʒiliti]n.敏捷,灵活,轻快complicate['kɔmplikeit]v.弄复杂,使错综,使起纠纷masking['mɑ:skiŋ]n.遮蔽spare[spєə]n.剩余,备用零件,备用轮胎a.多余的,备用的,简陋的utilization[ju:tilai'zeiʃən]n.利用multiple['mʌltipl]a.多样的,多重的n.倍数VMware虚拟机虚拟电脑,虚拟主机WordsandExpressionsscale-out全面地legacy['legəsi]n.祖先传下来之物,遗赠物simulate['simjuleit]vt.模拟；装作distribute[dis'tribju:tid]vt.分布的,分布式的consolidation[kən,sɔli'deiʃən]n.巩固,团结,合并splittingupn.分裂bandwidth['bændwidθ]n.频带宽度(通带宽度)subscriber[sʌbs'kraibə]n.签署者,捐献者,订户tedious['ti:diəs]adj.沉闷的,单调乏味的satisfaction[,sætis'fækʃən]n.满意optimize['ɔptimaiz]v.使...完美,乐观,使...完善v.优化scalability[,skeilə‘biliti]n.可扩充性延展性WordsandExpressionssudden['sʌdn]n.突然,忽然a.突然的,快速的surge[sə:dʒ]n.巨涌,汹涌,澎湃v.汹涌,澎湃complexity[kəm'pleksiti]n.复杂(性),复杂的事物administrator[əd'ministreitə]n.管理人,行政官administrative[əd'ministrətiv]a.行政的,管理的automatically[ɔ:tə'mætikli]a.不经思索的ad.自动地storageareanetwork(SAN)存储区域网络archiving[ɑ:'kəviŋ]n.【计算机】归档，胶片保管hybrid['haibrid]n.混血儿,杂种,混合物a.混合的,杂种的,混合语的centralize['sentrəlaiz]v.集聚,集中,施行中央集权autonomic[ɔ:tə'nɔmik]adj.自治的,自律的scenario[si'nɑ:riəu]n.情节,剧本ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Theintentionofservervirtualizationistolettheuserfromhavetounderstandandmanagecomplicateddetailsofserverresourceswhileincreasingresourcesharingandutilizationandmaintainingthecapacitytoexpandlater.（）2.Vendorssuggestthatservervirtualizationallowsacompanyto“scale-out”withmultiplesmallercomputersasitsprocessingneedsgrowratherthanhavingtoscaleuptoamoreexpensivemulti-processorcomputer.（）3.Servervirtualizationisfrequentlyusedtomaskthecomplexitiesofserverconsolidationandisunrelatedtotheconceptofthevirtualmachine,whichusesacopyofanoperatingsystemtocreatetheappearanceofafullsetofstorageandotherresourcestoeachuser.（）4.Networkvirtualizationisintendedtooptimizenetworkspeed,reliability,flexibility,scalability,andsecurity.（）5.Servervirtualizationisthepoolingofphysicalstoragefrommultiplenetworkstoragedevicesintowhatappearstobeasinglestoragedevicethatismanagedfromacentralconsole.（）6.Userscannotimplementvirtualizationwithsoftwareapplicationsorbyusinghardwareandsoftwarehybridappliances.ExercisesII.Fillintheblankswithproperwords.1.__________isthetechniqueofmanagingsystemsandresourcesfunctionally,regardlessoftheirphysicallayoutorlocation.2.__________virtualizationisthemaskingofserverresources(includingthenumberandidentityofindividualphysicalservers,processors,andoperatingsystems)fromserverusers.3.__________virtualizationisintendedtoimproveproductivity,efficiency,andjobsatisfactionoftheadministratorbyperformingmanyofthesetasksautomatically,therebydisguisingthetruecomplexityofthenetwork.4.Storagevirtualizationiscommonlyusedina__________.5.__________virtualizationhelpsthestorageadministratorperformthetasksofbackup,archiving,andrecoverymoreeasily,andinlesstime,bydisguisingtheactualcomplexityoftheSAN.Text4ElectronicCommerceMainContentsWordsandExpressionsExercisesElectronicCommerceElectronicCommerce,commonlyknownase-commerceoreCommerce,consistsofthebuyingandsellingofproductsorservicesoverelectronicsystemssuchastheInternetandothercomputernetworks.TheamountoftradeconductedelectronicallyhasgrownextraordinarilywithwidespreadInternetusage.Theuseofcommerceisconductedinthisway,spurringanddrawingoninnovationsinelectronicfundstransfer,supplychainmanagement,Internetmarketing,onlinetransactionprocessing,electronicdatainterchange(EDI),inventorymanagementsystems,andautomateddatacollectionsystems.ModernelectroniccommercetypicallyusestheWorldWideWebatleastatsomepointinthetransaction'slifecycle,althoughitcanencompassawiderrangeoftechnologiessuchase-mailaswell.Earlydevelopment

Themeaningofelectroniccommercehaschangedoverthelast30years.Originally,electroniccommercemeantthefacilitationofcommercialtransactionselectronically,usingtechnologysuchasElectronicDataInterchange(EDI)andElectronicFundsTransfer(EFT).Thesewerebothintroducedinthelate1970s,allowingbusinessestosendcommercialdocumentslikepurchaseordersorinvoiceselectronically.Thegrowthandacceptanceofcreditcards,automatedtellermachines(ATM)andtelephonebankinginthe1980swerealsoformsofelectroniccommerce.Anotherformofe-commercewastheairlinereservationsystemtypifiedbySabreintheUSAandTravicomintheUK.Duringthe1980s,onlineshoppingwasusedextensivelyparticularlybyautomanufacturerssuchasFord,Peugeot-Talbot,GeneralMotorsandNissan.Fromthe1990sonwards,electroniccommercewouldadditionallyincludeenterpriseresourceplanningsystems(ERP),datamininganddatawarehousing.Businessapplications

Somecommonapplicationsrelatedtoelectroniccommercearethefollowing:E-mail

Enterprisecontentmanagement

Instantmessaging

Newsgroups

OnlineshoppingandordertrackingOnlinebanking

Onlineoff