2.面向服务与面向服务的体系架构概述

1面向服务与面向服务的体系架构概述北京大学信息科学技术学院2010年2010-9-252Outline†SOAdefinitionanditsbusinessandtechnologyvalues†Service-orientationvs.object-orientation†Service-orientedarchitecturevs.distributedobjectarchitecture22010-9-253WhatisSOA?†Justlikeobjectagenerationago,servicesisnowthekillerbuzzword.However,SOAisaoftenmisunderstoodtopicinITtoday.“Myarchitectthinksit’sservice-oriented,mydevelopersinsistit’sobject-oriented,andmyanalystswishitwouldbemorebusiness-oriented.AllIcantellyouisthatitisn’twhatitwasbeforewestartedbuildingWebservices.”2010-9-254WhatareServices?†Servicesmaymeandifferentthingstodifferentpeople:„LooselycoupledsoftwarecomponentsthatinteractwithoneanotherdynamicallyviastandardInternettechnologies(Gartner,1996).„AsoftwareapplicationidentifiedbyaURI,whoseinterfacesandbindingarecapableofbeingdefined,described,anddiscoveredbyXMLartifactsandsupportsdirectinteractionswithothersoftwareapplicationsusingXML-basedmessagesviaInternet-basedprotocols(W3C).32010-9-255WhatareServices?„ApieceofbusinesslogicaccessibleviatheInternetusingopenstandards(Microsoft).„Encapsulated,looselycoupled,contractedsoftwarefunctions,offeredviastandardprotocolsovertheWeb(DestiCorp).„Servicesareself-contained,reusablesoftwaremodulesthatareindependentofapplicationsandthecomputingplatformsonwhichtheyrun.Serviceshavewithwell-definedinterfacesandallowa1:1mappingbetweenbusinesstasksandtheexactITcomponentsneededtoexecutethetask.(IBM)2010-9-256WhatisSOA?†SOAdefinitionisstillevolving.„Asetofcomponentswhichcanbeinvoked,andwhoseinterfacedescriptioncanbepublishedanddiscovered(W3C).„Service-orientedarchitectureisaclient/serverdesignapproachinwhichanapplicationconsistsofsoftwareservicesandsoftwareserviceconsumers(alsoknownasclientsorservicerequesters).SOAdiffersfromthemoregeneralclient/servermodelinitsdefinitiveemphasisonloosecouplingbetweensoftwarecomponents,andinitsuseofseparatelystandinginterfaces(Gartner).42010-9-257WhatisSOA?„Service-OrientedArchitectureisabusiness-drivenITarchitectureapproachthatsupportsintegratingyourbusinessaslinked,repeatablebusinesstasks,orservices.SOAhelpstoday’sbusinessinnovatebyensuringthatITsystemscanadaptquickly,easilyandeconomicallytosupportrapidlychangingbusinessneeds.SOAhelpscustomersincreasetheflexibilityoftheirbusinessprocesses,strengthentheirunderlyingITinfrastructureandreusetheirexistingITinvestmentsbycreatingconnectionsamongdisparateapplicationsandinformationsources.(IBM)ANewWayofThinking2010-9-258ACDPlayerExample†TakeaCDforinstance.Ifyouwanttoplayit,youputyourCDintoaCDplayerandtheplayerplaysitforyou.TheCDplayeroffersaCDplayingservice.WhichisnicebecauseyoucanreplaceoneCDplayerwithanother.YoucanplaythesameCDonaportableplayeroronyourexpensivestereo.TheybothofferthesameCDplayingservice,butthequalityofserviceisdifferent.52010-9-259ServicebrokerRegistrationOrganizationXOrganizationZOrganizationYComponentLibraryServicesFoundAuto-searchableApplication1Application2BusinessProcessTheSOAStoryRegistrationRegistration2010-9-2510WhyService-Orientation?MarketingManufacturingAccountingResearch&DevelopmentCustomerServiSalesDistributedBusinessRequiresDistributedComputingDistributedDataDistributedComputationDistributedusers…..DistributedDataDistributedComputationDistributedusers…..MarkeManufaAccouReseaDeveloCustomerSaMarkeManufaAccouReseaDeveloCustomerSaMarketingManufacturingAccountingResearch&DevelopmentCustomerServiceSales62010-9-2511WhyService-Orientation?†Interoperationissues„Heterogeneousnetworkprotocols„Heterogeneoushardwareplatforms„Heterogeneousoperatingsystems„Heterogeneousapplicationformats„……TheremustbeconsensusOnInteroperability!2010-9-2512ChangingMarketDynamicsCollaborative,integratedvaluenetsDynamic,adaptive,learningUnpredictablefluctuationsShorteningproductlifecycleProactiveriskmanagementIncreasedfocusonprivacyandsecurityFixedCostsProprietarysystemsLabor-intensiveUsersadapttotechnologyVariablecostsOpen,integratedsystemsSelf-healing,self-managingsystemsTechnologyadaptstousersBusinessTechnologyBusinessprocessdecision-makingRigidorganizationalstructureSlowandsteadyeconomicgrowthLong-termproductlifecyclePassiveoperationalriskmanagementStaticOnDemandWhyService-Orientation?72010-9-2513WhyService-Orientation?2010-9-2514BusinessDrivers†Newopportunities„Innovativeproductsandservicesfromthekeydifferentiatortogaincompetitiveedge.„Abilitytoleveragetechnologytoadoptnewerbusinessmodels,thusenablingmorechannelstoearnrevenue.†CostSavings„CostreductionthroughreducedTotalCostofOwnershipaddstothebottom-line.†BusinessAgility„Withcut-throatcompetition,everymissedbusinessopportunitypositionsanenterprisebelowitscompetitors.Theabilityofanenterprisetoquicklyrespondtovariousbusinessstimuliwillbekeytosurvival.„Fastertimetomarketincreasescustomersatisfactionandalsocustomerloyalty.Thisresultsinincreasedbusinessandhigherrevenues.„Abilitytoprovideondemandservice,inreal-time24/7.„Seamlesscollaborationwithpartnersandcustomershelpstoimproveservicequalityandtimetomarket.82010-9-2515SOABusinessValuestoITManagement†Makeinteroperabilityaninnatecharacteristico