The material in this section applies only to session and entity beans, not to message-driven beans. Because they have a different programming model, message-driven beans do not have interfaces that define client access.
A client may access a session or an entity bean only through the methods defined in the bean’s interfaces. These interfaces define the client’s view of a bean. All other aspects of the bean—method implementations, deployment descriptor settings, abstract schemas, and database access calls—are hidden from the client.
Well-designed interfaces simplify the development and maintenance of J2EE applications. Not only do clean interfaces shield the clients from any complexities in the EJB ...