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Sun Microsystems Inc.

Support for Distribution and Interoperability

Enterprise JavaBeans 2.0, Public Draft

Interoperability overview

18.1.1 Client-side objects in distributed environment

When the RMI-IIOP protocol or similar distribution protocols are used, the client communicates with the enterprise bean using stubs for the server-side objects. The stubs implement the home and remote interfaces.

Figure 75 Location of EJB Client Stubs.

client address space (i.e. JVM)

container address space (i.e. JVM)

EJB home stub

container

EJB home object

 

remote client

EJB object stub

EJB object

enterprise Bean

 

The communication stubs used on the client side are artifacts generated at enterprise Bean’s deployment time by the EJB Container provider tools. The stubs used on the client are specific to the wire protocol used for the remote invocation.

18.2 Interoperability overview

Session beans and entity beans that are deployed in one vendor’s server product often need to be accessed from J2EE client components that are deployed in another vendor’s product. EJB 2.0 defines a standard interoperability protocol based on CORBA/IIOP to address this need.

The interoperability protocols described here must be supported by compatible EJB products. Additional vendor-specific protocols may also be supported.

The figure below shows a heterogeneous environment that includes systems from several vendors to illustrate the interoperability enabled by EJB 2.0.

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Sun Microsystems Inc

Interoperability overview

Enterprise JavaBeans 2.0, Public Draft

Support for Distribution and Interoperability

Figure 76 Heterogeneous EJB Environment

JSP/

 

 

 

 

 

Servlet

 

 

 

 

 

client

IIOP

Enterprise

 

 

Enterprise

 

 

 

 

 

JavaBeans

 

 

JavaBeans

vendor1

 

 

 

 

 

 

 

 

 

IIOP

 

 

 

 

Application

EJB

IIOP

EJB

 

client

IIOP

server

 

 

server

 

 

 

 

 

 

 

vendor 2

vendor 4

 

 

vendor 5

 

 

 

 

 

 

 

 

 

 

 

 

 

CORBA

 

 

 

 

 

client

 

 

 

 

 

 

 

 

 

 

 

vendor 3

 

 

 

 

 

The following sections of this chapter describe the goals for EJB invocation interoperability, illustrative scenarios, and the interoperability requirements for remote invocations, transactions, naming and security.

18.2.1 Interoperability goals

The goals of the interoperability requirements specified in this chapter are as follows:

To allow clients in one application deployed in J2EE containers from one server provider to access services from session and entity beans in another application that is deployed in an EJB container from a different server provider. For example, web components (JavaServer Pages and Servlets) that are deployed on a J2EE compliant web server provided by one server provider must be able to invoke the business methods of enterprise beans that are deployed on a J2EE compliant EJB server from another server provider.

To achieve interoperability without any new requirements on the J2EE application developer.

To ensure out-of-the-box interoperability between compliant J2EE products. It must be possible for an enterprise customer to install multiple J2EE server products from different server

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