Chapter 9 Creating J2EE Applications for IBM WebSphere 5.0
Enterprise JavaBean (EJB) is a component model for Java.
There are several types of EJBs: Entity Bean, Session Bean, and Message Driven Bean.
Entity Bean is used for persistent objects. There are two types of persistence management: Container Managed Persistence (CMP) and Bean Managed Persistence (BMP). In CMP mode, the persistence is handled by the application server. An EJB deployer has to define the O/R mapping information to allow the application server to manage the persistence. In BMP mode, the persistence management code is defined in the EJB implementation class.
J2EE 1.3 has a new EJB 2.0 component model. The EJB 2.0 specification introduces a number of improvements: better definition for CMP, local interfaces, EJB Query Language (EJB-QL), and ejbSelect methods.
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