In object-oriented analysis and design a control class encapsulates business logic for a use case. Session beans are used to implement such control classes. Check credit card details, transfer funds, and book reservation are examples of potential session bean candidates. Session beans are transient and relatively short lived. In particular, session beans are not persistent; they are not stored in a database or other permanent file system. Session beans can create and update entities, which are persistent, as we shall see in the following chapters.

A client interacts with a session bean by invoking one or more methods defined in the bean. This sequence of method calls we call a session, hence the name session beans. The client can be a web-tier client such as a servlet or JSP page, or a standalone Java application program.

Like EJB 2.x, EJB 3 session beans are a component technology. In EJB 3 a session bean component consists of a bean interface and a bean class. The bean interface...