企业级应用系统体系架构SOA概述课件

企业级应用系统体系架构（八）

SOA概述ChenHaopengTuesday,November22,2022References：IBMRedbook:PatternsServiceOrientedArchitectureandWebServices1企业级应用系统体系架构（八）

SOAThebusinessdriversforanewapproachWhileITexecutiveshavebeenfacingthechallengeofcuttingcostsmaximizingtheutilizationofexistingtechnologyAtthesametimetheyhavetocontinuouslystrivetoservecustomersbetterbemorecompetitivebemoreresponsivetothebusiness’sstrategicpriorities.Therearetwounderlyingthemesbehindallofthesepressures:HeterogeneityandchangeThebusinessdriversforanewThebusinessdriversforanewapproachHeterogeneity

Mostenterprisestodaycontainarangeofdifferentsystems,applications,andarchitecturesofdifferentagesandtechnologies.Integratingproductsfrommultiplevendorsandacrossdifferentplatformswerealmostalwaysanightmare.Butwealsocannotaffordtotakeasingle-vendorapproachtoIT,becauseapplicationsuitesandthesupportinginfrastructurearesoinflexible.ChangeGlobalizationande-businessareacceleratingthepaceofchange.Improvementsintechnologycontinuetoaccelerate,feedingtheincreasedpaceofchangingcustomerrequirements.ThebusinessdriversforanewThebusinessdriversforanewapproachAsaresult,businessorganizationsareevolvingfromthevertical,isolatedbusinessdivisionsofthe1980’sandearliertothehorizontalbusiness-process-focusedstructuresofthe1980’sand1990’stowardsthenewecosystembusinessparadigm.Businessservicesnowneedtobecomponentizedanddistributed.Thereisafocusontheextendedsupplychain,enablingcustomerandpartneraccesstobusinessservices.ThebusinessdriversforanewThebusinessdriversforanewapproachQuestions:HowdoImakemyITenvironmentmoreflexibleandresponsivetotheeverchangingbusinessrequirements?Howcanwemakethoseheterogeneoussystemsandapplicationscommunicateasseamlesslyaspossible?Howcanweachievethebusinessobjectivewithoutbankruptingtheenterprise?CurrentlymanyITexecutivesandprofessionalsalikebelievethatnowwearegettingreallyclosetoprovidingasatisfactoryanswerwithservice-orientedarchitecture.ThebusinessdriversforanewThebusinessdriversforanewapproachInordertoalleviatetheproblemsofheterogeneity,interoperabilityandeverchangingrequirements,suchanarchitectureshouldprovideaplatformforbuildingapplicationserviceswiththefollowingcharacteristics:LooselycoupledLocationtransparentProtocolindependentBasedonsuchaservice-orientedarchitecture,aserviceconsumerdoesnotevenhavetocareaboutaparticularserviceitiscommunicatingwithbecausetheunderlyinginfrastructure,orservice“bus”,willmakeanappropriatechoiceonbehalfoftheconsumer.Theinfrastructurehidesasmanytechnicalitiesaspossiblefromarequestor.ParticularlytechnicalspecificitiesfromdifferentimplementationtechnologiessuchasJ2EEor.NETshouldnotaffecttheSOAusers.Weshouldalsobeabletoreconsiderandsubstitutea“better”serviceimplementationifoneisavailable,andwithbetterqualityofservicecharacteristics.ThebusinessdriversforanewService-orienteddesignimportantservice-orientedterminology:Services:Logicalentities,thecontractsdefinedbyoneormorepublishedinterfaces.Serviceprovider:Thesoftwareentitythatimplementsaservicespecification.Serviceconsumer(orrequestor):Thesoftwareentitythatcallsaserviceprovider.Traditionally,thisistermeda“client”.Aserviceconsumercanbeanend-userapplicationoranotherservice.Servicelocator:Aspecifickindofserviceproviderthatactsasaregistryandallowsforthelookupofserviceproviderinterfacesandservicelocations.Servicebroker:Aspecifickindofserviceproviderthatcanpassonservicerequeststooneormoreadditionalserviceproviders.Service-orienteddesignimportaInterface-baseddesignInbothcomponentandservicedevelopment,thedesignoftheinterfacesisdonesuchthatasoftwareentityimplementsandexposesakeypartofitsdefinition.Therefore,thenotionandconceptof“interface”iskeytosuccessfuldesigninbothcomponent-basedandservice-orientedsystems.Thefollowingaresomekeyinterface-relateddefinitions:Interface:Definesasetofpublicmethodsignatures,logicallygroupedbutprovidingnoimplementation.Aninterfacedefinesacontractbetweentherequestorandproviderofaservice.Anyimplementationofaninterfacemustprovideallmethods.Publishedinterface:Aninterfacethatisuniquelyidentifiableandmadeavailablethrougharegistryforclientstodynamicallydiscover.Publicinterface:Aninterfacethatisavailableforclientstousebutisnotpublished,thusrequiringstaticknowledgeonthepartoftheclient.Dualinterface:Frequentlyinterfacesaredevelopedaspairssuchthatoneinterfacedependsonanother;forexample,aclientmustimplementaninterfacetocallarequestorbecausetheclientinterfaceprovidessomecallbackmechanism.Interface-baseddesignInbothInterface-baseddesignThefollowingfigureshowstheUMLdefinitionofacustomerrelationshipmanagement(CRM)service,representedasaUMLcomponent,thatimplementstheinterfacesAccountManagement,ContactManagement,andSystemsManagement.Onlythefirsttwoofthesearepublishedinterfaces,althoughthelatterisapublicinterface.NotethattheSystemsManagementinterfaceandManagementServiceinterfaceformadualinterface.Interface-baseddesignThefollLayeredapplicationarchitecturesObject-orientedtechnologyandlanguagesaregreatwaystoimplementcomponents.Whilecomponentsarethebestwaytoimplementservices,thoughonehastounderstandthatagoodcomponent-basedapplicationdoesnotnecessarilymakeangoodservice-orientedapplication.Theterm“theapplicationedge”reflectsthefactthataserviceisagreatwaytoexposeanexternalviewofasystem,withinternalreuseandcompositionusingtraditionalcomponentdesign.LayeredapplicationarchitectuAcloserlookatservice-orientedarchitectureService-orientedarchitecturepresentsanapproachforbuildingdistributedsystemsthatdeliverapplicationfunctionalityasservicestoeitherend-userapplicationsorotherservices.Itiscomprisedofelementsthatcanbecategorizedintofunctionalandqualityofservice.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureFunctionalaspectsinclude:Transportisthemechanismusedtomoveservicerequestsfromtheserviceconsumertotheserviceprovider,andserviceresponsesfromtheserviceprovidertotheserviceconsumer.ServiceCommunicationProtocolisanagreedmechanismthattheserviceproviderandtheserviceconsumerusetocommunicatewhatisbeingrequestedandwhatisbeingreturned.ServiceDescriptionisanagreedschemafordescribingwhattheserviceis,howitshouldbeinvoked,andwhatdataisrequiredtoinvoketheservicesuccessfully.Servicedescribesanactualservicethatismadeavailableforuse.BusinessProcessisacollectionofservices,invokedinaparticularsequencewithaparticularsetofrules,tomeetabusinessrequirement.Notethatabusinessprocesscouldbeconsideredaserviceinitsownright,whichleadstotheideathatbusinessprocessesmaybecomposedofservicesofdifferentgranularities.TheServiceRegistryisarepositoryofserviceanddatadescriptionswhichmaybeusedbyserviceproviderstopublishtheirservices,andserviceconsumerstodiscoverorfindavailableservices.Theserviceregistrymayprovideotherfunctionstoservicesthatrequireacentralizedrepository.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureQualityofserviceaspectsinclude:Policyisasetofconditionsorrulesunderwhichaserviceprovidermakestheserviceavailabletoconsumers.Thereareaspectsofpolicywhicharefunctional,andaspectswhichrelatetoqualityofservice;thereforewehavethepolicyfunctioninbothfunctionalandqualityofserviceareas.Securityisthesetofrulesthatmightbeappliedtotheidentification,authorization,andaccesscontrolofserviceconsumersinvokingservices.Transactionisthesetofattributesthatmightbeappliedtoagroupofservicestodeliveraconsistentresult.Forexample,ifagroupofthreeservicesaretobeusedtocompleteabusinessfunction,allmustcompleteornonemustcomplete.Managementisthesetofattributesthatmightbeappliedtomanagingtheservicesprovidedorconsumed.Acloserlookatservice-orienSOAcollaborationsThefollowingfigureshowsthecollaborationsinaservice-orientedarchitecture.Thecollaborationsfollowsthe“find,bindandinvoke”paradigm.Aserviceconsumerperformsdynamicservicelocationbyqueryingtheserviceregistryforaservicethatmatchesitscriteria.Iftheserviceexists,theregistryprovidestheconsumerwiththeinterfacecontractandtheendpointaddressfortheservice.SOAcollaborationsThefollowinSOAcollaborationsTherolesinaservice-orientedarchitectureare:Serviceconsumer:Theserviceconsumerisanapplication,asoftwaremoduleoranotherservicethatrequiresaservice.Itinitiatestheenquiryoftheserviceintheregistry,bindstotheserviceoveratransport,andexecutestheservicefunction.Theserviceconsumerexecutestheserviceaccordingtotheinterfacecontract.Serviceprovider:Theserviceproviderisanetwork-addressableentitythatacceptsandexecutesrequestsfromconsumers.Itpublishesitsservicesandinterfacecontracttotheserviceregistrysothattheserviceconsumercandiscoverandaccesstheservice.Serviceregistry:Aserviceregistryistheenablerforservicediscovery.Itcontainsarepositoryofavailableservicesandallowsforthelookupofserviceproviderinterfacestointerestedserviceconsumers.Eachentityintheservice-orientedarchitecturecanplayone(ormore)ofthethreerolesofserviceprovider,consumerandregistry.SOAcollaborationsTherolesinSOAcollaborationsTheoperationsinaservice-orientedarchitectureare:Publish:Tobeaccessible,aservicedescriptionmustbepublishedsothatitcanbediscoveredandinvokedbyaserviceconsumer.Find:Aservicerequestorlocatesaservicebyqueryingtheserviceregistryforaservicethatmeetsitscriteria.Bindandinvoke:Afterretrievingtheservicedescription,theserviceconsumerproceedstoinvoketheserviceaccordingtotheinformationintheservicedescription.Theartifactsinaservice-orientedarchitectureare:Service:Aservicethatismadeavailableforusethroughapublishedinterfacethatallowsittobeinvokedbytheserviceconsumer.Servicedescription:Aservicedescriptionspecifiesthewayaserviceconsumerwillinteractwiththeserviceprovider.Itspecifiestheformatoftherequestandresponsefromtheservice.Thisdescriptionmayspecifyasetofpreconditions,postconditionsand/orqualityofservice(QoS)levels.SOAcollaborationsTheoperatioSOAcollaborationsInadditiontodynamicservicediscoveryanddefinitionofaserviceinterfacecontract,aservice-orientedarchitecturehasthefollowingcharacteristics:Servicesareself-containedandmodular.Servicessupportinteroperability.Servicesarelooselycoupled.Servicesarelocation-transparent.Servicesarecompositemodules,comprisedofcomponents.Thesecharacteristicsarealsocentraltofulfillingtherequirementsforane-businessondemand™operationalenvironment.Finally,service-orientedarchitectureisnotanewnotion.SOAcollaborationsInadditionSponentsAserviceisacoarse-grainedprocessingunitthatconsumesandproducessetsofobjectspassed-by-value.Itisnotthesameasanobjectinprogramminglanguageterms.Instead,itisperhapsclosertotheconceptofabusinesstransactionsuchasaCICS®orIMS™transactionthantoaremoteCORBAobject.Aserviceconsistsofacollectionofcomponentsthatworkinconcerttodeliverthebusinessfunctionthattheservicerepresents.Thus,incomparison,componentsarefiner-grainedthanservices.Inaddition,whileaservicemapstoabusinessfunction,acomponenttypicallymapstobusinessentitiesandthebusinessrulesthatoperateonthem.Asanexample,letuslookatthePurchaseOrdercomponentmodelfortheWS-ISupplyChainManagementsample.SponentsAserviSponentsInacomponent-baseddesign,componentsarecreatedtocloselymatchbusinessentities(suchasCustomer,PurchaseOrder,OrderItem)andencapsulatethebehaviorthatmatchestheentities’expectedbehavior.PurchaseOrdercomponentprovidesfunctionstoobtaininformationaboutthelistofproductsorderedandthetotalamountoftheorderItemcomponentprovidesfunctionstoobtaininformationaboutthequantityandpriceoftheproductordered.Inaservice-orienteddesign,servicesarenotdesignedbasedonbusinessentities.Instead,eachserviceisaholisticunitthatmanagesoperationsacrossasetofbusinessentities.Forexample,acustomerservicewillrespondtoanyrequestfromanyothersystemorservicethatneedstoaccesscustomerinformation.Thecustomerservicecanprocessarequesttoupdatecustomerinformation;add,update,deleteinvestmentportfolios;andenquireaboutthecustomer’sorderhistory.Thecustomerserviceownsallthedatarelatedtothecustomersitismanagingandiscapableofmakingotherserviceinquiriesonbehalfofthecallingpartyinordertoprovideaunifiedcustomerserviceview.Thismeansaserviceisamanagerobjectthatcreatesandmanagesitssetcomponents.SponentsInacoService-orientedarchitecturebenefitsWithaservice-orientedarchitecture,wecanrealizeseveralbenefitstohelporganizationssucceedinthedynamicbusinesslandscapeoftoday:Leverageexistingassets.Easiertointegrateandmanagecomplexity.Moreresponsiveandfastertime-to-market.Reducecostandincreasereuse.Bereadyforwhatliesahead.Service-orientedarchitectureisbynomeansasilverbullet,andmigrationtoSOAisnotaneasytask.Ratherthanmigratingthewholeenterprisetoaservice-orientedarchitectureovernight,therecommendedapproachistomigrateanappropriatesubsetofbusinessfunctionsasthebusinessneedarisesorisanticipated.Service-orientedarchitectureSOA的疑问在我的系统中，所有的功能都包装成了Web

Service，现在我的系统是否就是SOA架构了？协议独立、位置透明、松散耦合高度动态性SOA的疑问在我的系统中，所有的功能都包装成了WebSerSOA的疑问Services与

Components的差异是什么？问题域vs.解决域集成方式我们的机遇SOA的疑问Services与Components的差异863计划信息技术领域

2007年度专题课题申请指南（节选）专题一：智能感知与先进计算技术专题WhatisSoftwareArchitecture探索导向类课题8．服务计算技术主要研究内容（可从以下内容中选择其一申请课题）：（1）服务描述与发现、可信的服务资源组织与管理；（2）可靠的服务组合方法与验证；（3）动态的服务组合。说明与要求：要求完成相应的软件原型系统；获得软件著作权和申请专利，或以开放源码形式发布。863计划信息技术领域

2007年度专题课题申请指南（节选）ClassicSOALayersClassicSOALayers企业级应用系统体系架构SOA概述课件企业级应用系统体系架构SOA概述课件企业级应用系统体系架构SOA概述课件ModelsofSOADJBI（JavaBusinessIntegration）2005.8JSR208为JBI组件（包括服务引擎和绑定组件）的开发者建立一套标准的服务提供者接口SPI。抽象的协议无关的消息交换和规格化消息。提供一套标准的JBI组件间消息交换机制。建立一个标准来封装JBI组件，并为这些组件部署服务。定义一些管理监控挂钩（hooks），用于以后开发针对各种特定问题域的标准工具。提供服务引擎和绑定组件实现的复杂性和多样性。允许不同的供应商发布JBI组件，这些组件之间能够可靠地互操作，由这些组件（在JBI基础设施之上）构建的系统可以集中管理。28ModelsofSOADJBI（JavaBusinesModelsofSOADJBI（JavaBusinessIntegration）29ModelsofSOADJBI（JavaBusinesModelsofSOADSCA(ServiceComponentArchitecture)/SDO(ServiceDataObject)SCA定义了如何创建服务组件以及如何将服务组件组装成业务解决方案的通用方法。SCA由一系列规范组成,包括说明如何用某种具体语言（如Java、C++、Spring、BPEL等）实现业务服务组件的组件实现(ComponentImplementation)规范；如何定义组合服务组件结构的装配(Assembly)模型；如何使用各种访问方法（如Webservices、JMS、RMI-IIOP、REST等）的绑定(Binding)规范；如何将基础设施服务（如安全、事务、可靠消息等）加到解决方案的策略框架(PolicyFramework)SDO(ServiceDataObject)提供了一种通用的数据编程架构和API，SCA组件可以通过传递服务数据对象来交换数据。SDO体系结构中的基本概念主要有数据对象（DataObject）、数据图（datagraph）和数据访问服务DAS(DataAccessServices)。30ModelsofSOADSCA(ServiceCompModelsofSOADSCA(ServiceComponentArchitecture)/SDO(ServiceDataObject)31ModelsofSOADSCA(ServiceCompModelsofSOADWindowsServer2003+.NETFramework3.0+BizTalkServer2006R2BizTalkServerMessageroutingMessagevalidationMessagetransformation)CentralizedexceptionmanagementExtensibleadapterframeworkServiceorchestrationBusinessrulesengineBusinessactivitymonitoring32ModelsofSOADWindowsServer2ModelsofSOADWindowsServer2003+.NETFramework3.0+BizTalkServer2006R233ModelsofSOADWindowsServer2TypicalSOAAPPLICATIONS34TypicalSOAAPPLICATIONS34EndTobecontinued35EndTobecontinued35企业级应用系统体系架构（八）

SOA概述ChenHaopengTuesday,November22,2022References：IBMRedbook:PatternsServiceOrientedArchitectureandWebServices36企业级应用系统体系架构（八）

SOAThebusinessdriversforanewapproachWhileITexecutiveshavebeenfacingthechallengeofcuttingcostsmaximizingtheutilizationofexistingtechnologyAtthesametimetheyhavetocontinuouslystrivetoservecustomersbetterbemorecompetitivebemoreresponsivetothebusiness’sstrategicpriorities.Therearetwounderlyingthemesbehindallofthesepressures:HeterogeneityandchangeThebusinessdriversforanewThebusinessdriversforanewapproachHeterogeneity

Mostenterprisestodaycontainarangeofdifferentsystems,applications,andarchitecturesofdifferentagesandtechnologies.Integratingproductsfrommultiplevendorsandacrossdifferentplatformswerealmostalwaysanightmare.Butwealsocannotaffordtotakeasingle-vendorapproachtoIT,becauseapplicationsuitesandthesupportinginfrastructurearesoinflexible.ChangeGlobalizationande-businessareacceleratingthepaceofchange.Improvementsintechnologycontinuetoaccelerate,feedingtheincreasedpaceofchangingcustomerrequirements.ThebusinessdriversforanewThebusinessdriversforanewapproachAsaresult,businessorganizationsareevolvingfromthevertical,isolatedbusinessdivisionsofthe1980’sandearliertothehorizontalbusiness-process-focusedstructuresofthe1980’sand1990’stowardsthenewecosystembusinessparadigm.Businessservicesnowneedtobecomponentizedanddistributed.Thereisafocusontheextendedsupplychain,enablingcustomerandpartneraccesstobusinessservices.ThebusinessdriversforanewThebusinessdriversforanewapproachQuestions:HowdoImakemyITenvironmentmoreflexibleandresponsivetotheeverchangingbusinessrequirements?Howcanwemakethoseheterogeneoussystemsandapplicationscommunicateasseamlesslyaspossible?Howcanweachievethebusinessobjectivewithoutbankruptingtheenterprise?CurrentlymanyITexecutivesandprofessionalsalikebelievethatnowwearegettingreallyclosetoprovidingasatisfactoryanswerwithservice-orientedarchitecture.ThebusinessdriversforanewThebusinessdriversforanewapproachInordertoalleviatetheproblemsofheterogeneity,interoperabilityandeverchangingrequirements,suchanarchitectureshouldprovideaplatformforbuildingapplicationserviceswiththefollowingcharacteristics:LooselycoupledLocationtransparentProtocolindependentBasedonsuchaservice-orientedarchitecture,aserviceconsumerdoesnotevenhavetocareaboutaparticularserviceitiscommunicatingwithbecausetheunderlyinginfrastructure,orservice“bus”,willmakeanappropriatechoiceonbehalfoftheconsumer.Theinfrastructurehidesasmanytechnicalitiesaspossiblefromarequestor.ParticularlytechnicalspecificitiesfromdifferentimplementationtechnologiessuchasJ2EEor.NETshouldnotaffecttheSOAusers.Weshouldalsobeabletoreconsiderandsubstitutea“better”serviceimplementationifoneisavailable,andwithbetterqualityofservicecharacteristics.ThebusinessdriversforanewService-orienteddesignimportantservice-orientedterminology:Services:Logicalentities,thecontractsdefinedbyoneormorepublishedinterfaces.Serviceprovider:Thesoftwareentitythatimplementsaservicespecification.Serviceconsumer(orrequestor):Thesoftwareentitythatcallsaserviceprovider.Traditionally,thisistermeda“client”.Aserviceconsumercanbeanend-userapplicationoranotherservice.Servicelocator:Aspecifickindofserviceproviderthatactsasaregistryandallowsforthelookupofserviceproviderinterfacesandservicelocations.Servicebroker:Aspecifickindofserviceproviderthatcanpassonservicerequeststooneormoreadditionalserviceproviders.Service-orienteddesignimportaInterface-baseddesignInbothcomponentandservicedevelopment,thedesignoftheinterfacesisdonesuchthatasoftwareentityimplementsandexposesakeypartofitsdefinition.Therefore,thenotionandconceptof“interface”iskeytosuccessfuldesigninbothcomponent-basedandservice-orientedsystems.Thefollowingaresomekeyinterface-relateddefinitions:Interface:Definesasetofpublicmethodsignatures,logicallygroupedbutprovidingnoimplementation.Aninterfacedefinesacontractbetweentherequestorandproviderofaservice.Anyimplementationofaninterfacemustprovideallmethods.Publishedinterface:Aninterfacethatisuniquelyidentifiableandmadeavailablethrougharegistryforclientstodynamicallydiscover.Publicinterface:Aninterfacethatisavailableforclientstousebutisnotpublished,thusrequiringstaticknowledgeonthepartoftheclient.Dualinterface:Frequentlyinterfacesaredevelopedaspairssuchthatoneinterfacedependsonanother;forexample,aclientmustimplementaninterfacetocallarequestorbecausetheclientinterfaceprovidessomecallbackmechanism.Interface-baseddesignInbothInterface-baseddesignThefollowingfigureshowstheUMLdefinitionofacustomerrelationshipmanagement(CRM)service,representedasaUMLcomponent,thatimplementstheinterfacesAccountManagement,ContactManagement,andSystemsManagement.Onlythefirsttwoofthesearepublishedinterfaces,althoughthelatterisapublicinterface.NotethattheSystemsManagementinterfaceandManagementServiceinterfaceformadualinterface.Interface-baseddesignThefollLayeredapplicationarchitecturesObject-orientedtechnologyandlanguagesaregreatwaystoimplementcomponents.Whilecomponentsarethebestwaytoimplementservices,thoughonehastounderstandthatagoodcomponent-basedapplicationdoesnotnecessarilymakeangoodservice-orientedapplication.Theterm“theapplicationedge”reflectsthefactthataserviceisagreatwaytoexposeanexternalviewofasystem,withinternalreuseandcompositionusingtraditionalcomponentdesign.LayeredapplicationarchitectuAcloserlookatservice-orientedarchitectureService-orientedarchitecturepresentsanapproachforbuildingdistributedsystemsthatdeliverapplicationfunctionalityasservicestoeitherend-userapplicationsorotherservices.Itiscomprisedofelementsthatcanbecategorizedintofunctionalandqualityofservice.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureFunctionalaspectsinclude:Transportisthemechanismusedtomoveservicerequestsfromtheserviceconsumertotheserviceprovider,andserviceresponsesfromtheserviceprovidertotheserviceconsumer.ServiceCommunicationProtocolisanagreedmechanismthattheserviceproviderandtheserviceconsumerusetocommunicatewhatisbeingrequestedandwhatisbeingreturned.ServiceDescriptionisanagreedschemafordescribingwhattheserviceis,howitshouldbeinvoked,andwhatdataisrequiredtoinvoketheservicesuccessfully.Servicedescribesanactualservicethatismadeavailableforuse.BusinessProcessisacollectionofservices,invokedinaparticularsequencewithaparticularsetofrules,tomeetabusinessrequirement.Notethatabusinessprocesscouldbeconsideredaserviceinitsownright,whichleadstotheideathatbusinessprocessesmaybecomposedofservicesofdifferentgranularities.TheServiceRegistryisarepositoryofserviceanddatadescriptionswhichmaybeusedbyserviceproviderstopublishtheirservices,andserviceconsumerstodiscoverorfindavailableservices.Theserviceregistrymayprovideotherfunctionstoservicesthatrequireacentralizedrepository.Acloserlookatservice-orienAcloserlookatservice-orientedarchitectureQualityofserviceaspectsinclude:Policyisasetofconditionsorrulesunderwhichaserviceprovidermakestheserviceavailabletoconsumers.Thereareaspectsofpolicywhicharefunctional,andaspectswhichrelatetoqualityofservice;thereforewehavethepolicyfunctioninbothfunctionalandqualityofserviceareas.Securityisthesetofrulesthatmightbeappliedtotheidentification,authorization,andaccesscontrolofserviceconsumersinvokingservices.Transactionisthesetofattributesthatmightbeappliedtoagroupofservicestodeliveraconsistentresult.Forexample,ifagroupofthreeservicesaretobeusedtocompleteabusinessfunction,allmustcompleteornonemustcomplete.Managementisthesetofattributesthatmightbeappliedtomanagingtheservicesprovidedorconsumed.Acloserlookatservice-orienSOAcollaborationsThefollowingfigureshowsthecollaborationsinaservice-orientedarchitecture.Thecollaborationsfollowsthe“find,bindandinvoke”paradigm.Aserviceconsumerperformsdynamicservicelocationbyqueryingtheserviceregistryforaservicethatmatchesitscriteria.Iftheserviceexists,theregistryprovidestheconsumerwiththeinterfacecontractandtheendpointaddressfortheservice.SOAcollaborationsThefollowinSOAcollaborationsTherolesinaservice-orientedarchitectureare:Serviceconsumer:Theserviceconsumerisanapplication,asoftwaremoduleoranotherservicethatrequiresaservice.Itinitiatestheenquiryoftheserviceintheregistry,bindstotheserviceoveratransport,andexecutestheservicefunction.Theserviceconsumerexecutestheserviceaccordingtotheinterfacecontract.Serviceprovider:Theserviceproviderisanetwork-addressableentitythatacceptsandexecutesrequestsfromconsumers.Itpublishesitsservicesandinterfacecontracttotheserviceregistrysothattheserviceconsumercandiscoverandaccesstheservice.Serviceregistry:Aserviceregistryistheenablerforservicediscovery.Itcontainsarepositoryofavailab