Enterprise bean developers are required to provide a bean class, component interfaces, and, for entity beans, a primary key. Only the component interfaces and primary key class are visible to the client; the bean class is not. The component interfaces and primary key contribute to the client-side API in EJB.
In EJB 1.1, all clients, whether they are in the same container system or not, must use the Remote Client API, which means they must use the remote interface, the remote home interface, and Java RMI in all their interactions. In EJB 2.0, remote clients still must use the Remote Client API, but enterprise beans that are located in the same EJB container system have the option of using the Local Client API. The Local Client API provides local component interfaces and avoids the restrictions and overhead of the Remote Client API.
This section examines in more detail the remote component interfaces and the primary key, as well as other Java types that make up EJB’s remote client-side API, which is used in both EJB 2.0 and EJB 1.1. This will provide you with a better understanding of how the remote client-side API is used and its relationship with the bean class on the EJB server. At the end of this chapter, in Section 5.3, we will examine the use of local component interfaces for EJB 2.0 readers.
Enterprise JavaBeans 2.0 and 1.1 define an enterprise bean’s remote interfaces in terms of Java RMI-IIOP, which enforces compliance with CORBA. This means ...