EJB 2.0 enhances the Container Managed Persistence (CMP) model for entity beans as follows:
The deployment descriptor more fully describes the persistent fields in the bean and the required database queries, making for less work after deploying an EJB JAR file that contains CMP entity beans.
CMP entity beans in the same EJB JAR (which maps to an EAServer module) can have container-managed relationships. For example, an Order bean may have an items field that consists of a collection of Inventory bean instances representing the items being purchased. Or, an Employee bean may be related to itself, with manager and employees fields that contain Employee instances.
