Enterprise Bean Clients
Overview
Enterprise beans can be accessed by a variety of client applications:
· J2EE components (J2EE application clients, Web components, other enterprise beans)
Typically, session beans serve as clients for the entity beans in an EJB application.
· Non-J2EE Java applications (J2EE Engine libraries, WebDynpro applications, Enterprise Portal applications, standalone Java applications, and so on)
· Non-Java applications (ABAP applications, CORBA clients, and so on).
Local and Remote Client View
The session and entity enterprise beans provide either a local, or a remote client view, or both. The differences between local and remote access to the enterprise beans are:
Local Access |
Remote Access |
The clients must reside in the same Java Virtual Machine (JVM) |
The clients may reside in a different Java Virtual Machine (JVM) |
The bean must have a local and a local home interface |
The bean must have a remote and a remote home interface |
Provides better performance |
May generate a significant overhead if the bean is frequently accessed |
Beans that provide local view can be accessed by: · Web components · Other enterprise beans · Non-J2EE Java programs that are deployed and run in the same JVM as the beans. These beans cannot be accessed by J2EE application clients. |
Beans that provide remote view can be accessed by: · J2EE application clients · Web components · Other enterprise beans · Non-J2EE Java applications · Non-Java applications |
The arguments of the methods of the bean’s interfaces are passed by reference. |
The arguments of the methods of the bean’s interfaces are passed by value. |
There are no restrictions for the type of the objects that are passed as parameters of the bean’s methods |
The objects that are passed as parameters of the bean’s methods must be correct RMI-IIOP types |
Fine-grained objects (usually entity beans) are typically accessed locally |
Coarse-grained objects (usually session beans) are typically accessed remotely |
Entity beans with container-managed persistence, which are in relationships with other container-managed beans, must provide a local view |
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For more information how to access session and entity enterprise beans, see Looking Up Enterprise Beans.
Message-driven beans are not accessed through interfaces. For more information about access to message-driven beans, see Developing Message-Driven Beans.