IT专业英语UNIT18 Cloud Computing.ppt

UNIT18CloudComputing,18-1TechnicalPart18-2ReadingMaterial,18-1TechnicalPart18-1-1DefinitionCloudcomputingisInternet-basedcomputing,wherebysharedresources,softwareandinformation,areprovidedtocomputersandotherdeviceson-demand,liketheelectricitygrid.,18-1-2Introductions1.DevelopmentofCloudComputingCloudcomputingisthenextrevolutionofcomputingtechnologiesfollowingmainframesandPCs.Thisrevolutionisbothfromstandaloneserver-basedcomputingtodistributedcomputingintermsoftechnology,andfrom“box”toserviceintermsofbusinessmodel.IPhaschangedthecommunicationsindustry.Thecloudcomputingtechnologymaychangetheinformationandcommunicationstechnology(ICT)industry.Figure18-1showsthedevelopmentofcloudcomputing.,Andnowwearefacingthenexttechnologyrevolutionwhichiscloudcomputing,thisisnotonlythetechnologyrevolution,butalsoabusinessmodelrevolutioninICTindustry.Andwecanseethehugepotentialofthismarketwhichhas500billionUSdollarscloudservicesrevenues.,Figure18-1Thedevelopmentofcloudcomputing,2.CategoriesofCloudComputingCloudcomputingisageneraltermforanythingthatinvolvesdeliveringhostedservicesovertheInternet.Theseservicesarebroadlydividedintothreecategories:Infrastructure-as-a-Service(IaaS),Platform-as-a-Service(PaaS)andSoftware-as-a-Service(SaaS).Acloudcanbeprivateorpublic.ApubliccloudsellsservicestoanyoneontheInternet.(Currently,AmazonWebServicesisthelargestpubliccloudprovider.),Aprivatecloudisaproprietarynetworkoradatacenterthatsupplieshostedservicestoalimitednumberofpeople.Whenaserviceproviderusespubliccloudresourcestocreatetheirprivatecloud,theresultiscalledavirtualprivatecloud.Privateorpublic,thegoalofcloudcomputingistoprovideeasy,scalableaccesstocomputingresourcesandITservices.BelowFigure18-2showsthecategoryofcloudcomputing.,Figure18-2Thecategoryofcloudcomputing,3.CharacteristicsandMainFunctionofCloudComputingDeviceandlocationindependenceenableuserstoaccesssystemsusingawebbrowserregardlessoftheirlocationorwhatdevicestheyareusing(e.g.,PC,mobilephone).Asinfrastructureisoff-site(typicallyprovidedbyathird-party)andaccessedviatheInternet,userscanconnectfromanywhere.,Virtualizationtechnologyallowsserversandstoragedevicestobesharedandutilizationbeincreased.Applicationscanbeeasilymigratedfromonephysicalservertoanother.Centralizationofinfrastructureinlocationswithlowercosts(suchasrealestate,electricity,etc.).,Peak-loadcapacityincreases(usersneednotengineerforhighestpossibleload-levels).Utilizationandefficiencyimprovementsforsystemsthatareoftenonly1020%utilized.Reliabilityisimprovedifmultipleredundantsitesareused,whichmakeswell-designedcloudcomputingsuitableforbusinesscontinuityanddisasterrecovery.,ScalabilityandElasticityviadynamic(“on-demand”)provisioningofresourcesonafine-grained,self-servicebasisnearreal-time,withoutusershavingtoengineerforpeakloads.Performanceismonitoredandconsistentandlooselycoupledarchitecturesareconstructedusingwebservicesasthesysteminterface.Maintenanceofcloudcomputingapplicationsiseasier,becausetheydonotneedtobeinstalledoneachuserscomputerandcanbeaccessedfromdifferentplaces.,4.PerspectivesontheCloudJustasintheearlydaysoftheInternet,theclouddefinitionisbest-suitedtoincludeapubliccloud(external,liketheInternet)andprivateclouds(internal,likeintranets).PrivatecloudswillbeusedbycompaniesthatdonotwanttohavetheirIT-relatedservicesavailabletoexternalcustomersbutthatdowanttoleveragethedeliveryandacquisitionmodelthecloudenables.Thishasseveralimplications:,Thecloudisamechanismthatsupportsalternativedeliveryandacquisitionmodels(ADMs)ofmultipletypes(forexample,grid,utilityandSaaS)inthatanythingandeverythingcanbeofferedasaservice.,ThecloudismorethanjustSaaSinthateverythingasaservice(XaaS)wouldbeamoreappropriateappellation.Throughthecloud,wecangetservicesthatareprimarilyhardwarebasedwherethesoftwareisanintegralpartofthedelivery,notaspecificvaluepropositioninitself.Storageasaserviceisanexampleofthis.SaaSisanADMandcanbedeliveredthroughthecloudjustasanyotherservicecan.TosaythatSaaSandthecloudwerethesamewouldbealimitedview.,TheInternetandpotentiallytheWebarenecessaryfortheexistencetodayofthecloudbutarenotsolelydefinitiveofit.Theremustbeadeliberatedeliveryofservicetoconstitutecloudcomputing.(Inthefuture,someothergloballydistributednetworkmaysupplanttheInternetinthiscapacitytosupportcloudcomputing.),InternalcloudscanexistusingInternet/WebtechnologiesbutmustalsoincludetheintentionalADMofXaaStointernalcustomersandprivatepartners.Thisiswhatdistinguishedtheseinternalcloudsfromtheonepubliccloud.,18-1-3ApplicationCaseorExample1.Case1:ApplicationofvirtualDesktopOnetypicalapplicationscenarioistoprovidevirtualdesktopCloudchoice.ThiscanbeprovidedtoLargeEnterprise/SME/Orindividuals.TheFigure18-3showsthetypicalapplicationofthevirtualdesktop.,Figure18-3Theapplicationofvirtuedesktop,Comparingwiththetraditionaldesktop:PCprocessingcapability(includingCPUandharddisk)iscentralizedtothedatacenter.PCsarereplacedwithTCs,whichdonotrequirestrongprocessingandstoragecapabilities.TheclouddatacenterprovideseachTCwithavirtualcomputer.ResourcesaresharedbyallTCs.AnyidleresourcesallocatedtoaTCcanbeusedbyotherTCs.,ResourceallocationisperformedaccordingtoactualrequirementsbasedontheuniformmanagementplatformofcloudcomputingsharedbyallTCs.AnyidleresourcesallocatedtoaTCcanbeusedbyotherTCs.Dataondesktopsarerunandstoredonthedatacenter.Userscanremotelyaccesstheirdesktopsovervariousterminals.Therefore,usersdonotneedtostoptherunningapplicationsandcanreplaceterminalsinhotswappingmodesharedbyallTCs.AnyidleresourcesallocatedtoaTCcanbeusedbyotherTCs.,Terminalsandinformationareseparated.Dataarestoredandprocessedatthebackground.Thedatatransmittedtotheterminalisonlytheresultrefreshedonthescreen.TerminalNo-hard-diskdesigningterminals,sotheycannotstoreserverdata.Blockphysicalinterfacesforpossibledatadisclosureontheuserside,whichactuallysupportonlyinputandoutputofmouseandkeyboardinstructions(otherapplicationscanbeenabledbytheenvironmentsystemadministratorforspecialrequirements).,AccessControlTCauthenticationeffectivelypreventsillegalTCsfromaccessingthesystem.EachhostandtheIDofeachROMcardareboundtogether.ThisensuresuniquenessoftheTClegality.Useridentitycanbeauthenticatedwiththehelpofthemulti-factorauthenticationmethod,suchasusinguserfingerprintanduserpasswordforauthentication,DataTransferVirtualchannelssupportapplicationcontrolandmanagement,suchasPrintcontrol,Filesharingmanagement,USBportmapping,management,Flowmediaapplicationmanagement.Usercomputingnodehasautomaticbackupandrestorationfunctions.Thisensuresseamlessswitchoverwhenhardwareisfaulty.Datafragmentsarebackedupindifferentphysicalareasandautomaticrestorationfunctioncanbeimplementedforanyphysicalstoragefaults.,2.Case2:ApplicationofPrivateCloudCurrentSituationisthattheITserverisdeployedinsilomode,resourceneedtobeconfiguredaccordingtomax-use;serverutilizationislowandthecostishigh,andthestandalonesystemreliabilityislow.,BySPC(ServicePrivateCloud)mode,allapplicationsandservicescanbedeployedinaUnifiedhardwareplatform.OneVMisallocatedtoApplications.HardwareresourcecanbesharedandtheresourcecanbeautomaticallyswitchedbetweenApplications.Costonhardwarewouldbesavedandthesystemreliabilityandavailabilitybasedonthewholeplatformwouldbehigh.WecantakeHeathcloudbuiltinShanghaiasanexample,whichisthefirsthealthcloudinChina.SeebelowFigure18-4showsthestructureofShanghaiheathcloud.,Figure18-4ThedeploymentofShanghaiHealthCloud,18-2ReadingMaterial18-2-1ReadingComprehensionCloudComputingCloudcomputingisastyleofcomputinginwhichdynamicallyscalableandoftenvirtualizedresourcesareprovidedasaserviceovertheInternet.Usersneednothaveknowledgeof,expertisein,orcontroloverthetechnologyinfrastructureinthe“cloud”thatsupportsthem.,Cloudcomputingcanbeconfusedwithgridcomputing(“aformofdistributedcomputingwherebyasuperandvirtualcomputeriscomposedofaclusterofnetworked,loosely-coupledcomputers,actinginconcerttoperformverylargetasks”),utilitycomputing(the“packagingofcomputingresources,suchascomputationandstorage,asameteredservicesimilartoatraditionalpublicutilitysuchaselectricity”)andautonom