The Enterprise JavaBeans 3. The purpose of the Enterprise JavaBeans 3.
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The focus will be on the core session bean and message-driven bean component models and their client API. Aspects that should be considered by the Expert Group for inclusion in this work include, but are not limited to, the following: Removal of the requirement for a separate local business interface.
Support for direct use of EJBs in the servlet container, including simplified packaging options. Singleton beans. Support for asynchronous session bean invocation.
Support for stateful web services via stateful session bean web service endpoints. Specification of concurrency options for stateful session beans. Although EJB makes application development much simpler, it's still a complex and ambitious technology that requires a great deal of time to study and master.
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But now, thanks to Enterprise JavaBeans 3. Now you can harness the complexity of EJB with just a single resource by your side. You can also simply name the injected variable exactly the same as the persistence unit you want injected into the variable; in this case, you no longer need to specify the unitName attribute, but the EJB container still deploys the persistence unit and sets its JNDI name to the persistence unit name.
See Invoking a 3. When you inject a persistence context into a variable using either javax.
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PersistenceUnit , the standard data type of the injected variable is EntityManager. If your persistence provider provides a subinterface of the EntityManager such as KodoEntityManager in the case of BEA Kodo then as a convenience you can simply set the data type of the injected variable to that subinterface, rather than use the more complicated lookup mechanisms as described in the EJB 3.
For example:. See Simple Enterprise JavaBeans 3.
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The sections in this guide reference these examples extensively. These examples are meant to simply show how to use the new EJB 3.
This guide describes how to program 3. It does not describe how to actually program and configure a 3. This script outputs the product breadcrumb required for edocs documentation. Understanding EJB 3. You are no longer required to create the EJB deployment descriptor files such as ejb-jar.
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You can now use metadata annotations in the bean file itself to configure metadata. You are still allowed, however, to use XML deployment descriptors if you want; in the case of conflicts, the deployment descriptor value overrides the annotation value.
Note: In this release, WebLogic-specific features can only be configured in the WebLogic deployment descriptors, such as weblogic-ejb-jar. SessionBean or javax. As a result of not having to implement javax. MessageDrivenBean , the bean file no longer has to implement the lifecycle callback methods, such as ejbCreate , ejbPassivate , and so on.