UNIT18

CloudComputing

18-1TechnicalPart

18-2ReadingMaterial

18-1TechnicalPart

18-1-1Definition

CloudcomputingisInternet-basedcomputing,wherebysharedresources,softwareandinformation,areprovidedtocomputersandotherdeviceson-demand,liketheelectricitygrid.18-1-2Introductions

1.?DevelopmentofCloudComputing

CloudcomputingisthenextrevolutionofcomputingtechnologiesfollowingmainframesandPCs.Thisrevolutionisbothfromstandaloneserver-basedcomputingtodistributedcomputingintermsoftechnology,andfrom“box”toserviceintermsofbusinessmodel.IPhaschangedthecommunicationsindustry.Thecloudcomputingtechnologymaychangetheinformationandcommunicationstechnology(ICT)industry.Figure18-1showsthedevelopmentofcloudcomputing.

Andnowwearefacingthenexttechnologyrevolutionwhichiscloudcomputing,thisisnotonlythetechnologyrevolution,butalsoabusinessmodelrevolutioninICTindustry.Andwecanseethehugepotentialofthismarketwhichhas500billionUSdollarscloudservicesrevenues.Figure18-1Thedevelopmentofcloudcomputing

2.?CategoriesofCloudComputing

CloudcomputingisageneraltermforanythingthatinvolvesdeliveringhostedservicesovertheInternet.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.?CharacteristicsandMainFunctionofCloudComputing

Deviceandlocationindependenceenableuserstoaccesssystemsusingawebbrowserregardlessoftheirlocationorwhatdevicestheyareusing(e.g.,PC,mobilephone).Asinfrastructureisoff-site(typicallyprovidedbyathird-party)andaccessedviatheInternet,userscanconnectfromanywhere.

Virtualizationtechnologyallowsserversandstoragedevicestobesharedandutilizationbeincreased.Applicationscan

beeasilymigratedfromonephysicalservertoanother.

Centralizationofinfrastructureinlocationswithlowercosts(suchasrealestate,electricity,etc.).

Peak-loadcapacityincreases(usersneednotengineerforhighestpossibleload-levels).

Utilizationandefficiencyimprovementsforsystemsthatareoftenonly10–20%utilized.

Reliabilityisimprovedifmultipleredundantsitesareused,whichmakeswell-designedcloudcomputingsuitableforbusinesscontinuityanddisasterrecovery.

ScalabilityandElasticityviadynamic(“on-demand”)provisioningofresourcesonafine-grained,self-servicebasisnearreal-time,withoutusershavingtoengineerforpeakloads.

Performanceismonitoredandconsistentandlooselycoupledarchitecturesareconstructedusingwebservicesasthesysteminterface.

Maintenanceofcloudcomputingapplicationsiseasier,becausetheydonotneedtobeinstalledoneachuser'scomputerandcanbeaccessedfromdifferentplaces.

4.?PerspectivesontheCloud

JustasintheearlydaysoftheInternet,theclouddefinitionisbest-suitedtoincludeapubliccloud(external,liketheInternet)andprivateclouds(internal,likeintranets).PrivatecloudswillbeusedbycompaniesthatdonotwanttohavetheirIT-relatedservicesavailabletoexternalcustomersbutthatdowanttoleveragethedeliveryandacquisitionmodelthecloudenables.Thishasseveralimplications:

Thecloudisamechanismthatsupportsalternativedeliveryandacquisitionmodels(ADMs)ofmultipletypes(forexample,grid,utilityandSaaS)inthatanythingandeverything

canbeofferedasaservice.

ThecloudismorethanjustSaaSinthateverythingasaservice(XaaS)wouldbeamoreappropriateappellation.Throughthecloud,wecangetservicesthatareprimarilyhardwarebasedwherethesoftwareisanintegralpartofthedelivery,notaspecificvaluepropositioninitself.Storageasaserviceisanexampleofthis.SaaSisanADMandcanbedeliveredthroughthecloudjustasanyotherservicecan.TosaythatSaaSandthecloudwerethesamewouldbealimitedview.

TheInternetandpotentiallytheWebarenecessaryfortheexistencetodayofthecloudbutarenotsolelydefinitiveofit.Theremustbeadeliberatedeliveryofservicetoconstitutecloudcomputing.(Inthefuture,someothergloballydistributednetworkmaysupplanttheInternetinthiscapacitytosupportcloudcomputing.)

InternalcloudscanexistusingInternet/WebtechnologiesbutmustalsoincludetheintentionalADMofXaaStointernalcustomersandprivatepartners.Thisiswhatdistinguishedtheseinternalcloudsfromtheonepubliccloud.18-1-3ApplicationCaseorExample

1.?Case1:ApplicationofvirtualDesktop

OnetypicalapplicationscenarioistoprovidevirtualdesktopCloudchoice.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.

Terminal

No-hard-diskdesigningterminals,sotheycannotstoreserverdata.

Blockphysicalinterfacesforpossibledatadisclosureontheuserside,whichactuallysupportonlyinputandoutputofmouseandkeyboardinstructions(otherapplicationscanbeenabledbytheenvironmentsystemadministratorforspecialrequirements).

AccessControl

TCauthenticationeffectivelypreventsillegalTCsfromaccessingthesystem.EachhostandtheIDofeachROMcardareboundtogether.ThisensuresuniquenessoftheTClegality.

Useridentitycanbeauthenticatedwiththehelpofthemulti-factorauthenticationmethod,suchasusinguserfingerprintanduserpasswordforauthentication

DataTransfer

Virtualchannelssupportapplicationcontrolandmanagement,suchasPrintcontrol,Filesharingmanagement,USBportmapping,management,Flowmediaapplicationmanagement.

Usercomputingnodehasautomaticbackupandrestorationfunctions.Thisensuresseamlessswitchoverwhenhardwareisfaulty.

Datafragmentsarebackedupindifferentphysicalareasandautomaticrestorationfunctioncanbeimplementedforanyphysicalstoragefaults.

2.?Case2:ApplicationofPrivateCloud

CurrentSituationisthattheITserverisdeployedinsilomode,resourceneedtobeconfiguredaccordingtomax-use;serverutilizationislowandthecostishigh,andthestandalonesystemreliabilityislow.

BySPC(ServicePrivateCloud)mode,allapplicationsandservicescanbedeployedinaUnifiedhardwareplatform.OneVMisallocatedtoApplications.HardwareresourcecanbesharedandtheresourcecanbeautomaticallyswitchedbetweenApplications.Costonhardwarewouldbesavedandthesystemreliabilityandavailabilitybasedonthewholeplatformwouldbehigh.WecantakeHeathcloudbuiltinShanghaiasanexample,whichisthefirsthealthcloudinChina.SeebelowFigure18-4showsthestructureofShanghaiheathcloud.Figure18-4ThedeploymentofShanghaiHealthCloud18-2ReadingMaterial

18-2-1ReadingComprehension

CloudComputing

CloudcomputingisastyleofcomputinginwhichdynamicallyscalableandoftenvirtualizedresourcesareprovidedasaserviceovertheInternet.Usersneednothaveknowledgeof,expertisein,orcontroloverthetechnologyinfrastructureinthe“cloud”?thatsupportsthem.

Cloudcomputingcanbeconfusedwithgridcomputing(“aformofdistributedcomputingwherebya‘superandvirtualcomputer’iscomposedofaclusterofnetworked,loosely-coupledcomputers,actinginconcerttoperformverylargetasks”),utilitycomputing(the“packagingofcomputingresources,suchascomputationandstorage,asameteredservicesimilartoatraditionalpublicutilitysuchaselectricity”)andautonomiccomputing(“computersystemscapableofself-management”).

Indeed,manycloudcomputingdeploymentsasof2009dependongrids,haveautomaticcharacteristics,andbilllikeutilities—butcloudcomputingtendstoexpandwhatisprovidedbygridsandutilities.Somesuccessfulcloudarchitectureshavelittleornocentralizedinfrastructureorbillingsystemswhatsoever,includingpeer-to-peernetworkssuchasBitTorrentandSkype,andvolunteercomputingsuchasSETL@home.

Furthermore,manyanalysisaretakentostresstheevolutionary,incrementalpathwaybetweengridtechnologyandcloudcomputing,tracingrootsbacktoApplicationServiceProviders(APIs)intheyear1990sandtheparallelstoSaaS,oftenreferredtoasapplicationonthecloud.Someareofthepersuasionthatthetruedifferencebetweenthesetermsismarketingandbranding;thatthetechnologyevolutionwasincrementalandmarketingevolutiondiscrete.

Words&Expressions

cloudcomputing云計算

scalableadj.可升級的，可擴展的

infrastructuren.基礎(chǔ)設(shè)施，基礎(chǔ)結(jié)構(gòu)

confusedadj.混淆的，混亂的

gridcomputing網(wǎng)格計算

loosely-coupledadj.松散耦合的

capableadj.有能力的，有技能的

deploymentn.展開，部署，調(diào)度

whatsoeverpron.無論什么

analystn.分析家，化驗員

SaaSn.軟件服務(wù)化

persuasionn.信仰，說服，勸說

incrementaladj.增加

discreteadj.離散

expertisen.專門知識或技能18-2-2Exercises

I.?MultipleChoices

1.Usersofcloudcomputingshouldhavethequalitiesincluding______.

A.?Knowledgeofthetechnologyinfrastructure.

B.?Expertiseinthetechnologyinfrastructure.

C.?Controloverthtechnologyinfrastructure.

D.?Noneoftheaboveisnecessary.

2.?WhichoftheFollowingwouldNOTbeconfusedwithcloudcomputing?

A.?Gridcomputing.

B.?Utilitycomputing.

C.?Autonomiccomputing.

D.?Parallelcomputing.

3.?Whichofthefollowingisnotanexampleofcentralizedinfrastructureorbillingsystemsnotfoundinsomesuccessfularchitectures?

A.?BitTorrent.

B.?Skype.

C.?SETI@home.

D.?MS.

4.?Accordingtothepassage,whatisstressedbymanyanalyses