Enterprise JavaBeans, Second Edition

Implementing a Common Interface

This book discourages implementing the remote interface in the bean class. This makes it a little more difficult to enforce consistency between the business methods defined in the remote interface and the corresponding methods on the bean class. There are good reasons for not implementing the remote interface in the bean class, but there is also a need for a common interface to ensure that the bean class and remote interface define the same business methods. This section describes a design alternative that allows you to use a common interface to ensure consistency between the bean class and the remote interface.

Why the Bean Class Shouldn’t Implement the Remote Interface

There should be no difference, other than the missing java.rmi.RemoteException, between the business methods defined in the ShipBean and their corresponding business methods defined in the Ship interface. EJB requires you to match the method signatures so that the remote interface can accurately represent the bean class on the client. Why not implement the remote interface com.titan.Ship in the ShipBean class to ensure that these methods are matched correctly?

EJB allows a bean class to implement its remote interface, but this practice is discouraged for a couple of very good reasons. First, the remote interface is actually an extension of the javax.ejb.EJBObject interface, which you learned about in Chapter 5. This interface defines several methods that are implemented by the EJB ...