Transcript RMI-IIOP
RMI CORBA Matt RMI VS CORBA 2 3 J2EE 4 Sample Application 5 6 RMI-IIOP 7 Tools • New rmic compiler Converts Java Interfaces to IDL Generates IIOP Stubs and tie classes • New idlj compiler Maps IDL to Java Generates IIOP Stubs and tie classes 8 RMI to RMI-IIOP tie class RMI Implementation rmic -iiop Complier RMI Java Server IIOP stub class RMI Java Client 9 RMI to RMI-IIOP 1. Converting Server Extend your implementation class from PortableRemoteObject 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 than Java type cast. 10 IDL to RMI-IIOP • Write Java IDL • Use idlj compiler Generates Java Mappings Generates stubs and skeletons • Implement Server • Run Server and register with JNDI service • Develop Client and test 11 RMI-IIOP • With RMI and CORBA, programmers face a cruel choice: they must decide 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. 12 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 13 Before RMI-IIOP 14 • 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 15 Java RMI clients can access RMI/IIOP objects through ordinary RMI interfaces. CORBA clients need equivalent interfaces in IDL. 16 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. 17 • Example of interoperability scenario between different vendors of EJB containers. 18 RMI/IIOP architecture. 19 RMI 20 RMI Architecture 21 22 Java IDL 23 24 CORBA 25 CORBA • CORBA (Common Object Request Broker Architecture) 是在1992年由 OMG(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 26 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 27