RMICORBA

Matt

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RMI VS CORBA

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J2EE

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Sample Application

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RMI-IIOP

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Tools

• New rmic compilerConverts Java Interfaces to IDLGenerates IIOP Stubs and tie classes

• New idlj compilerMaps IDL to JavaGenerates IIOP Stubs and tie classes

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RMI to RMI-IIOP

IIOP

RMI Java Client

RMI JavaServer

tie class

rmic -iiopComplier

stub class

RMIImplementation

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RMI to RMI-IIOP

1. Converting Server Extend your implementation class from PortableRemot

eObject rather than UnicastRemoteObject: Use JNDI naming service rather than rmiregistry.

2. Converting Client Use JNDI naming service to locate object Use PortableRemoteObject.narrow() method rather tha

n Java type cast.

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IDL to RMI-IIOP• Write Java IDL

• Use idlj compiler Generates Java MappingsGenerates stubs and skeletons

• Implement Server

• Run Server and register with JNDI service

• Develop Client and test

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RMI-IIOP• With RMI and CORBA, programmers face a cruel choice: they must deci

de between RMI, with its easy programming features, and CORBA, with its broad interoperability.

• With RMI-IIOP, programmers can create applications in RMI that include CORBA connections

• RMI over IIOP (RMI-IIOP hereafter), developed jointly by IBM and Sun, is a new version of RMI (Remote Method Invocation) for IIOP (Internet Inter-ORB Protocol) that combines RMI's easy programming features with CORBA's interoperability.

• RMI and CORBA have developed independently as distributed-objects programming models. RMI, a foundation of the EJB and Jini technologies, was introduced as a Java-based, easy-to-use programming model for distributed objects. CORBA (the Common Object Request Broker Architecture), defined by the OMG (Object Management Group), is a well-known distributed-object programming model that supports a number of languages. The IIOP protocol connects CORBA products from different vendors, ensuring interoperability among them. RMI-IIOP is, in a sense, a marriage of RMI and CORBA.

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RMI-IIOP

• 與 J2EE 1.3相容的 server都有 RMI-IIOP實作功能，可以協助處理各種網路問題

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Before RMI-IIOP

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• It used to be difficult to choose between RMI (JRMP) and CORBA when starting a new project. If you selected RMI (JRMP), you got easy programming, but lost interoperability across multiple languages.

• If you selected CORBA, you got interoperability, but faced a more daunting programming task.

Please connect the two Please connect the two

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Java RMI clients can access RMI/IIOP objects through ordinary RMI interfaces. CORBA clients need equivalent interfaces in IDL.

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Java RMI clients can access RMI/IIOP objects implemented as CORBA objects through ordinary RMI interfaces. CORBA clients

and RMI/IIOP object implementations need equivalent interfaces in IDL.

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• Example of interoperability scenario between different vendors of EJB

containers.

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RMI/IIOP architecture.

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RMI

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RMI Architecture

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Java IDL

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CORBA

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CORBA• CORBA (Common Object Request Broker Architecture) 是在 1992年由 OM

G(Open Management Group) 組織提出的。那時的分佈式應用環境都採用 Client/Server架構， CORBA的應用很大程度的提高了分佈式應用軟體的開發效率。

• CORBA的 IDL採用類 C++的定義，是公開的規範

• IIOP是 Internet CORBA互換性的通訊協定

• Object Request Broker (ORB)是 CORBA之間網路傳遞的基礎， ORB負責找到服務方法的物件，負責處理參數傳遞與傳回結果

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CORBA

• IDL用來發展與整合 CORBA物件的服務， IDL是一個可攜型的規格語言。使用 IDL編譯器可以產生前面所提到的 Stub和 Skeleton程式碼，並且可以對應許多高階程式語言（如：Java、 Smalltalk、 C++等等）

• 有了 IDL， CORBA應用程式可以是由不同程式語言撰寫的

• IDL與 Java結合