EJB 3.0 specification: What is new
Enterprise JavaBeans 3.0 is a major enhancement to the EJB specification, introducing a new plain old Java object (POJO)-based programming model that greatly simplifies development of Java EE applications. The main features are as follows:
| EJBs are now POJOs that expose regular business interfaces (plain old Java interfaces: POJI), and there is no requirement for home interfaces.
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| Deployment descriptor information is replaced by annotations.
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| A complete new persistence model, Java Persistence API (JPA), is provided, which supersedes EJB 2.x entity beans.
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| Interceptor facility invokes user methods at the invocation of business services or at life cycle events.
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| Adopts a annotation-based dependency injection pattern to obtain Java EE resources (JDBC data sources, JMS factories and queues, and EJB references).
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| Default values are provided whenever possible ("configuration by exception" approach).
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| Usage of checked exceptions are reduced.
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| All life cycle methods are optional now.
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More information about EJB 3.0 and JPA can be found in the IBM Redbooks publication, WebSphere Application Server V6.1 Feature Pack for EJB 3.0, SG24-7611, in Chapter | 2, Persistence using the Java Persistence API (JPA), in Chapter | 4, Developing EJB applications, and here:
http://java.sun.com/products/ejb