Understanding Session Beans

Oct 7, 2002

📄 Contents

␡

What Is Conversational State?
What Are Session Beans?
Session Bean Files
Characteristics of Session Beans
Types of Session Beans
Session Bean Methods
Life Cycle of Session Beans
Comparing Stateless and Stateful Session Beans
Best Practices
Summary
Q&A
Quiz
Exercises

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Session beans were first introduced in March of 1998 when Sun Microsystems published the EJB 1.0 specification.

A session bean is one type of enterprise bean that resides in EJB container. Session beans model business processes. They provide a robust way for handling sessions in a J2EE application.

Today's road map:

Learn the fundamentals of session beans, and their characteristics and types
Learn how the concepts of instance pooling, activation, and passivation are applicable to session beans
Learn session bean methods and examine their life cycle diagrams

What Is Conversational State?

Client/server interaction typically involves multiple request/response roundtrips. A session is a single client's interaction with a server. The session state is client-specific data that is accumulated during the session. This session state is also known as conversational state.

The conversational state can be maintained in the client, the server, or split between them. For example, the contents of the temporary shopping cart can be maintained in the client side or in the server object's instance variables. The division of responsibility is based on factors such as performance, security, and so on.

The use of session beans to maintain client interactions is the standard method in any J2EE application. As their name implies, session beans were designed with this purpose in mind. Services such as security, concurrency, and transactions are provided to session beans by the container.

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