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基于Java代理和HTTP协议的RMI框架的实现.docx

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基于Java代理和HTTP协议的RMI框架的实现 Introduction RemoteMethodInvocation(RMI)isadistributedcomputingmechanisminJavathatenablesobjectstocallmethodsoneachotheracrossmultipleJVMs(JavaVirtualMachines)ondifferentsystemsoveranetwork.RMIisavitalpartofJava'sinfrastructureforbuildingdistributedsystems.However,thetraditionalRMIarchitecturehasitsdrawbacksconcerningsecurityandscalability.Therefore,researchersandpractitionershavebeenworkingtocreatemoreadvancedRMIframeworkstoaddresstheseissues.Inthispaper,wewillintroduceaJavaRMIframeworkbasedonJavaproxiesandHTTPprotocol,whichovercomesscalabilityandsecuritylimitationsoftraditionalRMI. JavaRMI JavaRMIallowsremoteobjectstocommunicateoversystemsinadistributedsystem.Generally,therearetwotypesofRMIarchitecture:client-servermodelandthepeer-to-peermodel.Intheclient-servermodel,theserverrunstheapplicationandexposesservices,andtheclientcallsthoseservices.IntheP2Pmodel,multiplenodesareconnected,andeverynodeactsasaclientandaserver. TraditionalRMIhastwomaindrawbacks:scalabilityandsecurityissues.Thefirewallcanblockallinboundnetworktraffic,makingitimpossibleforaservertoinitiateconnectionswithclients.Additionally,RMIoverHTTPdoesnotsupportobjectsthatimplementtheRemoteinterface.ThetraditionalRMIprotocolisbasedonTCP/IP,whichmaybeblockedbyfirewallsormaynotbeavailableinsomenetworks. TheRMIarchitectureisdividedintothreelayers:remotereferencelayer,transportlayer,andsterilizationlayer.ClientsandobjectscommunicatethroughremotereferencesthatarepassedbetweenvariouscomponentsoftheRMIsystem.Thetransportlayerpassesremotereferencesoverthenetwork,whilethesterilizationlayerserializesobjectstotransferthemoverthesystemcorrectly.Typically,RMIencodesthemethodparameters,whichmakesitefficientbutlimitsthesupportforcomplexdatatypes. JavaProxies Javaproxyisanobjectthatrepresentsaninterfaceandcanhandleallmethodinvocationsstoredbytheproxy.Itinterceptsmethodinvocationsanddelegatesthemtothetargetobject.JavaproxywasintroducedinJDK1.6.ItisapowerfulmechanismforcreatingdynamicproxiesinJava.