教學(xué)目標(biāo)教學(xué)內(nèi)容Unit4NetworkTechnique教學(xué)目標(biāo)了解計(jì)算機(jī)網(wǎng)絡(luò)的發(fā)展史理解網(wǎng)絡(luò)安全的相關(guān)理論了解虛擬化技術(shù)掌握電子商務(wù)的相關(guān)技術(shù)了解目前已經(jīng)廣泛使用的局域網(wǎng)技術(shù)教學(xué)內(nèi)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[int?k?'nek??n]n.網(wǎng)絡(luò)互連track[tr?k]n.【計(jì)算機(jī)】數(shù)據(jù)磁道cable['keibl]n.電纜coaxial['k?u'?ks?l]adj.同軸傳輸線的transportation[tr?nsp?:'tei??n]n.運(yùn)輸，運(yùn)輸系統(tǒng)，運(yùn)輸工具fiber['faib?]n.光纖configuration[k?nfigju'rei??n]n.【計(jì)算機(jī)】配置terminology[t?:mi'n?l?d?i]n.用辭，術(shù)語(yǔ)microwave['maikr?uweiv]n.微波dedicated['dedikeitid]adj.【計(jì)算機(jī)】(裝置、程序、系統(tǒng)等)專用的coalition[k?u?'li??n]n.結(jié)合，合并，聯(lián)合distributed[dis'tribju:tid]vt.分布的，分布式的loose[lu:s]adj.寬松的，不牢固的，不精確的WordsandExpressionsbinding['baindi?]n.1.捆綁；束縛；粘合；連接2.捆縛物；束縛物；連接物3.(滑雪屐上的)扣栓，(滑雪板上的)皮靴固定裝置4.(如桌布、毯子等的)鑲邊，滾帶5.(書(shū)籍的)裝訂；裝幀；活頁(yè)封面和封底、封皮ARPANET阿帕網(wǎng)investigate[in'vestigeit]v.【計(jì)算機(jī)】研究long-haul['l??'h?:l;'l?:?-]adj.長(zhǎng)遠(yuǎn)距的metropolitan[metr?'p?lit(?)n]n.大都市的居民，大主教，母國(guó)的居民adj.大都市的vehicle['vi:ikl]n.傳播媒介，工具，手段，交通工具，車輛congestion[k?n'd?est??n]n.【計(jì)算機(jī)】擁擠routing['ru:ti?;'rau-]n路由選擇，路徑選擇invocation[inv?u'kei??n]【計(jì)算機(jī)】調(diào)用availability[?veil?'biliti]n.有效，有用，有益.WordsandExpressionsmanipulation[m?，nipju'lei??n]n.處理emphasi['emf?sis]n.強(qiáng)調(diào)，重點(diǎn)stimulate['stimjuleit]vt.刺激，激勵(lì)，鼓舞batch[b?t?]n.批，成批，分批originator[?'rid??neit?(r)]n.創(chuàng)始人，發(fā)起人sufficed[s?'fais]v.足夠，使...滿足，合格synchronization[si?kr?nai'zei??n]同步化shortfall['??:tf?:l]n.不足之量，差額throughput['θru:put]n.【計(jì)算機(jī)】(計(jì)算機(jī)輸入輸出信息的)吞吐量，通過(guò)量，總處理能力turnaround[‘t?:n?ra?nd]n.轉(zhuǎn)變，突然好轉(zhuǎn)WordsandExpressionslandscape['l?ndskeip]n.風(fēng)景，山水，風(fēng)景畫(huà)LANsabbr.局域網(wǎng)(localareanetworks)spectrum['spektr?m]n.光譜，（比喻）范圍，系列fiber['faib?]n.纖維memoranda[mem?'r?nd?]n.備忘錄(便條)21世紀(jì)大英漢詞典》

concurrently[k?n'k?r?ntli]adv.同時(shí)(兼)plethora['pleθ?r?]n.過(guò)量，過(guò)剩vendor['vend?:]n.廠商Aloha[ɑ:'l?uhɑ:]int.哈羅，歡迎，再見(jiàn)21世紀(jì)大英漢詞典》

WAN[w?n](wideareanetwork)廣域網(wǎng)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，劍橋大學(xué)資訊安全工程講師loom[lu:m]n.織布機(jī)v.朦朧地出現(xiàn)，隱約可見(jiàn)horizon[h?'raizn]n.地平線；視野；眼界.pitfall['pitf?:l]n.陷阱，誘惑，陰謀algorithm['?lg?rie?m]算法sin[sin]n.罪，罪孽v.犯罪nosy['n?uzi]adj.鼻子大的，好管閑事的，愛(ài)追問(wèn)的recipient[ri'sipi?nt]n.接受者authorized['?:θ?raizd]adj.經(jīng)認(rèn)可的，審定的，經(jīng)授權(quán)的21世紀(jì)大英漢詞典》

purportedly[p?:'p?:tidli，'p?:p-，'p?:p?t-]ad.據(jù)稱IRSabbr.InternalRevenueService美國(guó)國(guó)稅局Mafia['mɑ:fi?]n.黑手黨，秘密政黨legitimate[li'd?itimit]a.合法的，正當(dāng)?shù)膙.使合法malicious[m?‘li??s]a.懷惡意的，惡毒的WordsandExpressionsperpetrator[p?:pi'treit?]n.犯人，作惡之人outsmart[aut'smɑ:t]v.比...更聰明，打敗adversary['?dv?s?ri]n.敵手，對(duì)手well-funded資金充足的thwart[θw?:t]a.橫坐板v.反對(duì)，阻礙ad.橫過(guò)perpetrate['p?:pitreit]v.做，犯tapping['t?pi?]n.開(kāi)孔(導(dǎo)出液體，放液，流出口，澆鑄，抽頭)insider[in'said?(r)]n.內(nèi)部的人，會(huì)員，知道內(nèi)情的人grudge[gr?d?]n.怨恨，惡意v.懷恨，嫉妒，吝惜intertwined[int?:'waind]a.互相纏結(jié)的，纏繞在一起的secrecy['si:krisi]n.秘密(保密，隱蔽)authentication[?:，θenti'kei??n]n.證明，鑒定.nonrepudiation認(rèn)可confidentiality[‘k?nfi，den?i’?l?ti]n.秘而不宣，保密WordsandExpressionsunauthorized['?n'?:θ?raizd]非法的，越權(quán)的doohickey['du:，hiki]n.小玩意，裝置，竅門(mén)malicious[m?'li??s]a.懷惡意的，惡毒的adversary['?dv?s?ri]n.敵手，對(duì)手transit['tr?nsit]n.經(jīng)過(guò)，運(yùn)輸v.橫越concoct[k?n'k?kt]vt.調(diào)制，配制photocopy['f?ut?u，k?pi]n.影印v.影印tampering['t?mp?ri?]a.干預(yù)的，干涉的sealed[si:ld]a.封口的，密封的wiretapping['wai?，t?pi?]vt.wiretap的變形n.搭線竊聽(tīng)adj.搭線竊聽(tīng)的tube[‘tju:b]n.地鐵，電子管，顯像管，管，軟管WordsandExpressionspacke[p?kt]adj.擠滿的；塞滿的壓結(jié)實(shí)的；壓緊的encrypt[in'kript]vt.把…編碼decrypt[di:'kript]v.譯，解釋oblivious[?'blivi?s]a.沒(méi)注意到，或不知道vulnerable['v?ln?r?b(?)l]a.易受傷害的，有弱點(diǎn)的lax[l?ks]a.松的，松懈的，不嚴(yán)的slip[slip]n.滑，錯(cuò)誤，下跌v.滑倒，犯錯(cuò)，減退cryptography[krip't?gr?fi]密碼術(shù)，密碼系統(tǒng)sloppy['sl?pi]a.被潑水弄濕的，泥濘的，多陰雨的inattention[in?'ten??n]n.不注意，粗心，疏忽debug[di:'b?ɡ]vt.【計(jì)算機(jī)】調(diào)試；排除(程序)中的錯(cuò)誤，排除故障loophole['lu:ph??l]n.槍眼，小窗，換氣孔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虛擬化技術(shù)layout['lei,aut]n.布局,安排,設(shè)計(jì)breakthrough['breikθru:]n.突破responsiveness[ri'sp?nsivnis]n.響應(yīng)性(反應(yīng)性)agility[?'d?iliti]n.敏捷,靈活,輕快complicate['k?mplikeit]v.弄復(fù)雜,使錯(cuò)綜,使起糾紛masking['mɑ:ski?]n.遮蔽spare[sp??]n.剩余,備用零件,備用輪胎a.多余的,備用的,簡(jiǎn)陋的utilization[ju:tilai'zei??n]n.利用multiple['m?ltipl]a.多樣的,多重的n.倍數(shù)VMware虛擬機(jī)虛擬電腦,虛擬主機(jī)WordsandExpressionsscale-out全面地legacy['leg?si]n.祖先傳下來(lái)之物,遺贈(zèng)物simulate['simjuleit]vt.模擬；裝作distribute[dis'tribju:tid]vt.分布的,分布式的consolidation[k?n,s?li'dei??n]n.鞏固,團(tuán)結(jié),合并splittingupn.分裂bandwidth['b?ndwidθ]n.頻帶寬度(通帶寬度)subscriber[s?bs'kraib?]n.簽署者,捐獻(xiàn)者,訂戶tedious['ti:di?s]adj.沉悶的,單調(diào)乏味的satisfaction[,s?tis'f?k??n]n.滿意optimize['?ptimaiz]v.使...完美,樂(lè)觀,使...完善v.優(yōu)化scalability[,skeil?‘biliti]n.可擴(kuò)充性延展性WordsandExpressionssudden['s?dn]n.突然,忽然a.突然的,快速的surge[s?:d?]n.巨涌,洶涌,澎湃v.洶涌,澎湃complexity[k?m'pleksiti]n.復(fù)雜(性),復(fù)雜的事物administrator[?d'ministreit?]n.管理人,行政官administrative[?d'ministr?tiv]a.行政的,管理的automatically[?:t?'m?tikli]a.不經(jīng)思索的ad.自動(dòng)地storageareanetwork(SAN)存儲(chǔ)區(qū)域網(wǎng)絡(luò)archiving[ɑ:'k?vi?]n.【計(jì)算機(jī)】歸檔，膠片保管hybrid['haibrid]n.混血兒,雜種,混合物a.混合的,雜種的,混合語(yǔ)的centralize['sentr?laiz]v.集聚,集中,施行中央集權(quán)autonomic[?:t?'n?mik]adj.自治的,自律的scenario[si'nɑ:ri?u]n.情節(jié),劇本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