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1、UNIT18CloudComputing18-1TechnicalPart18-2ReadingMaterial18-1TechnicalPart18-1-1DefinitionCloudcomputingisInternet-basedcomputing,wherebysharedresources,softwareandinformation,areprovidedtocomputersandotherdeviceson-demand,liketheelectricitygrid.18-1-2Introductions1.D
2、evelopmentofCloudComputingCloudcomputingisthenextrevolutionofcomputingtechnologiesfollowingmainframesandPCs.Thisrevolutionisbothfromstandaloneserver-basedcomputingtodistributedcomputingintermsoftechnology,andfrom“box”toserviceintermsofbusinessmodel.IPhaschanged
3、thecommunicationsindustry.Thecloudcomputingtechnologymaychangetheinformationandcommunicationstechnology(ICT)industry.Figure18-1showsthedevelopmentofcloudcomputing.Andnowwearefacingthenexttechnologyrevolutionwhichiscloudcomputing,thisisnotonlythetechnologyrevoluti
4、on,butalsoabusinessmodelrevolutioninICTindustry.Andwecanseethehugepotentialofthismarketwhichhas500billionUSdollarscloudservicesrevenues.Figure18-1Thedevelopmentofcloudcomputing2.CategoriesofCloudComputingCloudcomputingisageneraltermforanythingthatinvolves
5、deliveringhostedservicesovertheInternet.Theseservicesarebroadlydividedintothreecategories:Infrastructure-as-a-Service(IaaS),Platform-as-a-Service(PaaS)andSoftware-as-a-Service(SaaS).Acloudcanbeprivateorpublic.ApubliccloudsellsservicestoanyoneontheInternet.(Currently,Amaz
6、onWebServicesisthelargestpubliccloudprovider.)Aprivatecloudisaproprietarynetworkoradatacenterthatsupplieshostedservicestoalimitednumberofpeople.Whenaserviceproviderusespubliccloudresourcestocreatetheirprivatecloud,theresultiscalledavirtualprivatecloud.P
7、rivateorpublic,thegoalofcloudcomputingistoprovideeasy,scalableaccesstocomputingresourcesandITservices.BelowFigure18-2showsthecategoryofcloudcomputing.Figure18-2Thecategoryofcloudcomputing3.CharacteristicsandMainFunctionofCloudComputingDeviceandlocationindepen
8、denceenableuserstoaccesssystemsusingawebbrowserregardlessoftheirlocationorwhatdevicestheyareusing(e.g.,PC,mobilephone).Asinfrastructureisoff-site(typicallyprovidedbyathird-party)andaccessedviatheInternet,userscanconnectfromanywhere.Virtualizationtechnologyallows
9、serversandstoragedevicestobesharedandutilizationbeincreased.Applicationscanbeeasilymigratedfromonephysicalservertoanother.Centralizationofinfrastructureinlocationswithlowercosts(suchasrealestate,electricity,etc.).Peak-loadcapacityincreases(usersneednotengineerfor
10、highestpossibleload-levels).Utilizationandefficiencyimprovementsforsystemsthatareoftenonly1020%utilized.Reliabilityisimprovedifmultipleredundantsitesareused,whichmakeswell-designedcloudcomputingsuitableforbusinesscontinuityanddisasterrecovery.ScalabilityandElasticity
11、viadynamic(“on-demand”)provisioningofresourcesonafine-grained,self-servicebasisnearreal-time,withoutusershavingtoengineerforpeakloads.Performanceismonitoredandconsistentandlooselycoupledarchitecturesareconstructedusingwebservicesasthesysteminterface.Maintenanceofc
12、loudcomputingapplicationsiseasier,becausetheydonotneedtobeinstalledoneachuserscomputerandcanbeaccessedfromdifferentplaces.4.PerspectivesontheCloudJustasintheearlydaysoftheInternet,theclouddefinitionisbest-suitedtoincludeapubliccloud(external,liketheInterne
13、t)andprivateclouds(internal,likeintranets).PrivatecloudswillbeusedbycompaniesthatdonotwanttohavetheirIT-relatedservicesavailabletoexternalcustomersbutthatdowanttoleveragethedeliveryandacquisitionmodelthecloudenables.Thishasseveralimplications:Thecloudisamec
14、hanismthatsupportsalternativedeliveryandacquisitionmodels(ADMs)ofmultipletypes(forexample,grid,utilityandSaaS)inthatanythingandeverythingcanbeofferedasaservice.ThecloudismorethanjustSaaSinthateverythingasaservice(XaaS)wouldbeamoreappropriateappellation.Through
15、thecloud,wecangetservicesthatareprimarilyhardwarebasedwherethesoftwareisanintegralpartofthedelivery,notaspecificvaluepropositioninitself.Storageasaserviceisanexampleofthis.SaaSisanADMandcanbedeliveredthroughthecloudjustasanyotherservicecan.Tosaythat
16、SaaSandthecloudwerethesamewouldbealimitedview.TheInternetandpotentiallytheWebarenecessaryfortheexistencetodayofthecloudbutarenotsolelydefinitiveofit.Theremustbeadeliberatedeliveryofservicetoconstitutecloudcomputing.(Inthefuture,someothergloballydistri
17、butednetworkmaysupplanttheInternetinthiscapacitytosupportcloudcomputing.)InternalcloudscanexistusingInternet/WebtechnologiesbutmustalsoincludetheintentionalADMofXaaStointernalcustomersandprivatepartners.Thisiswhatdistinguishedtheseinternalcloudsfromtheonepu
18、bliccloud.18-1-3ApplicationCaseorExample1.Case1:ApplicationofvirtualDesktopOnetypicalapplicationscenarioistoprovidevirtualdesktopCloudchoice.ThiscanbeprovidedtoLargeEnterprise/SME/Orindividuals.TheFigure18-3showsthetypicalapplicationofthevirtualdesktop.Figure18-
19、3TheapplicationofvirtuedesktopComparingwiththetraditionaldesktop:PCprocessingcapability(includingCPUandharddisk)iscentralizedtothedatacenter.PCsarereplacedwithTCs,whichdonotrequirestrongprocessingandstoragecapabilities.TheclouddatacenterprovideseachTCwithavi
20、rtualcomputer.ResourcesaresharedbyallTCs.AnyidleresourcesallocatedtoaTCcanbeusedbyotherTCs.ResourceallocationisperformedaccordingtoactualrequirementsbasedontheuniformmanagementplatformofcloudcomputingsharedbyallTCs.AnyidleresourcesallocatedtoaTCcanbeuse
21、dbyotherTCs.Dataondesktopsarerunandstoredonthedatacenter.Userscanremotelyaccesstheirdesktopsovervariousterminals.Therefore,usersdonotneedtostoptherunningapplicationsandcanreplaceterminalsinhotswappingmodesharedbyallTCs.AnyidleresourcesallocatedtoaTCcan
22、beusedbyotherTCs.Terminalsandinformationareseparated.Dataarestoredandprocessedatthebackground.Thedatatransmittedtotheterminalisonlytheresultrefreshedonthescreen.TerminalNo-hard-diskdesigningterminals,sotheycannotstoreserverdata.Blockphysicalinterfacesforpossi
23、bledatadisclosureontheuserside,whichactuallysupportonlyinputandoutputofmouseandkeyboardinstructions(otherapplicationscanbeenabledbytheenvironmentsystemadministratorforspecialrequirements).AccessControlTCauthenticationeffectivelypreventsillegalTCsfromaccessingth
24、esystem.EachhostandtheIDofeachROMcardareboundtogether.ThisensuresuniquenessoftheTClegality.Useridentitycanbeauthenticatedwiththehelpofthemulti-factorauthenticationmethod,suchasusinguserfingerprintanduserpasswordforauthenticationDataTransferVirtualchannelss
25、upportapplicationcontrolandmanagement,suchasPrintcontrol,Filesharingmanagement,USBportmapping,management,Flowmediaapplicationmanagement.Usercomputingnodehasautomaticbackupandrestorationfunctions.Thisensuresseamlessswitchoverwhenhardwareisfaulty.Datafragmentsarebacked
26、upindifferentphysicalareasandautomaticrestorationfunctioncanbeimplementedforanyphysicalstoragefaults.2.Case2:ApplicationofPrivateCloudCurrentSituationisthattheITserverisdeployedinsilomode,resourceneedtobeconfiguredaccordingtomax-use;serverutilizationislowan
27、dthecostishigh,andthestandalonesystemreliabilityislow.BySPC(ServicePrivateCloud)mode,allapplicationsandservicescanbedeployedinaUnifiedhardwareplatform.OneVMisallocatedtoApplications.HardwareresourcecanbesharedandtheresourcecanbeautomaticallyswitchedbetweenAp
28、plications.Costonhardwarewouldbesavedandthesystemreliabilityandavailabilitybasedonthewholeplatformwouldbehigh.WecantakeHeathcloudbuiltinShanghaiasanexample,whichisthefirsthealthcloudinChina.SeebelowFigure18-4showsthestructureofShanghaiheathcloud.Figure1
29、8-4ThedeploymentofShanghaiHealthCloud18-2ReadingMaterial18-2-1ReadingComprehensionCloudComputingCloudcomputingisastyleofcomputinginwhichdynamicallyscalableandoftenvirtualizedresourcesareprovidedasaserviceovertheInternet.Usersneednothaveknowledgeof,expertisei
30、n,orcontroloverthetechnologyinfrastructureinthe“cloud”thatsupportsthem.Cloudcomputingcanbeconfusedwithgridcomputing(“aformofdistributedcomputingwherebyasuperandvirtualcomputeriscomposedofaclusterofnetworked,loosely-coupledcomputers,actinginconcerttoperformveryl
31、argetasks”),utilitycomputing(the“packagingofcomputingresources,suchascomputationandstorage,asameteredservicesimilartoatraditionalpublicutilitysuchaselectricity”)andautonomiccomputing(“computersystemscapableofself-management”).Indeed,manycloudcomputingdeploymentsasof2
32、009dependongrids,haveautomaticcharacteristics,andbilllikeutilitiesbutcloudcomputingtendstoexpandwhatisprovidedbygridsandutilities.Somesuccessfulcloudarchitectureshavelittleornocentralizedinfrastructureorbillingsystemswhatsoever,includingpeer-to-peernetworkssucha
33、sBitTorrentandSkype,andvolunteercomputingsuchasSETLhome.Furthermore,manyanalysisaretakentostresstheevolutionary,incrementalpathwaybetweengridtechnologyandcloudcomputing,tracingrootsbacktoApplicationServiceProviders(APIs)intheyear1990sandtheparallelstoSaaS,oftenr
34、eferredtoasapplicationonthecloud.Someareofthepersuasionthatthetruedifferencebetweenthesetermsismarketingandbranding;thatthetechnologyevolutionwasincrementalandmarketingevolutiondiscrete.Words&Expressionscloudcomputing云计算scalableadj.可升级的，可扩展的infrastructuren.基础设施，基础结
35、构confusedadj.混淆的，混乱的gridcomputing网格计算loosely-coupledadj.松散耦合的capableadj.有能力的，有技能的deploymentn.展开，部署，调度whatsoeverpron.无论什么analystn.分析家，化验员SaaSn.软件服务化persuasionn.信仰，说服，劝说incrementaladj.增加discreteadj.离散expertisen.专门知识或技能18-2-2ExercisesI.MultipleChoices1.Usersofcloudcomputing
36、shouldhavethequalitiesincluding_.A.Knowledgeofthetechnologyinfrastructure.B.Expertiseinthetechnologyinfrastructure.C.Controloverthtechnologyinfrastructure.D.Noneoftheaboveisnecessary.2.WhichoftheFollowingwouldNOTbeconfusedwithcloudcomputingA.Gridcomputing.B.Utility
37、computing.C.Autonomiccomputing.D.Parallelcomputing.3.WhichofthefollowingisnotanexampleofcentralizedinfrastructureorbillingsystemsnotfoundinsomesuccessfularchitecturesA.BitTorrent.B.Skype.C.SETIhome.D.MS.4.Accordingtothepassage,whatisstressedbymanyanalysesA.Thediffere
38、ncebetweencloudcomputingandutilitycomputing.B.Whycloudcomputingdependongrids.C.Thepathwaybetweencloudcomputingandgridtechnology.D.Thedifferencebetweencloudcomputingandgridcomputing.5.WhatisthetruedifferencebetweenthetermsmentionedinthelastparagraphA.Thearchitec
39、ture.B.Thetheory.C.Theprocess.D.Themarkingandbranding.II.Read&Translate.1.CloudcomputingisastyleofcomputinginwhichdynamicallyscalableandoftenvirtualizedresourcesareprovidedasaserviceovertheInternet.2.Cloudcomputingcanbeconfusedwithgridcomputing(“aformofdistribute
40、dcomputingwherebyasuperandvirtualcomputeriscomposedofaclusterofnetworked,loosely-coupledcomputers,actinginconcerttoperformverylargetasks”),utilitycomputing(the“packagingofcomputingresources,suchascomputationandstorage,asameteredservicesimilartoatraditionalpublicutilitysuchaselectricity”)andautonomiccomputing(“computersystemscapableofself-management”).3.Someareofthepersuasionthatthetruedifferencebetweenthesetermsismarketingandbranding;thatthetechnologyevolutionwasincrementalandmarketingevolutiondiscrete.