Using Session Beans

This section provides guidelines for creating session beans in the Enterprise Server environment. This section addresses the following topics:

• About the Session Bean Containers

• Session Bean Restrictions and Optimizations

Information on session beans is contained in the Enterprise JavaBeans Specification, v3.1.

About the Session Bean Containers

Like an entity bean, a session bean can access a database through Java Database Connectivity (JDBC) calls. A session bean can also provide transaction settings. These transaction settings and JDBC calls are referenced by the session bean’s container, allowing it to participate in transactions managed by the container.

Stateless Container

The stateless container manages stateless session beans, which, by definition, do not carry client-specific states. All session beans (of a particular type) are considered equal.

A stateless session bean container uses a bean pool to service requests. The Enterprise Server specific deployment descriptor file, sun-ejb-jar.xml, contains the properties that define the pool:

• steady-pool-size

• resize-quantity

• max-pool-size

• pool-idle-timeout-in-seconds

For more information about sun-ejb-jar.xml, see The sun-ejb-jar.xml File in Sun GlassFish Enterprise Server v3 Prelude Application Deployment Guide.

The Enterprise Server provides the wscompile and wsdeploy tools to help you implement a web service endpoint as a stateless session bean. For more information about these tools, see the Sun GlassFish Enterprise Server v3 Prelude Reference Manual.

Session Bean Restrictions and Optimizations

This section discusses restrictions on developing session beans and provides some optimization guidelines.

Restricting Transactions

The following restrictions on transactions are enforced by the container and must be observed as session beans are developed:

• A session bean can participate in, at most, a single transaction at a time.

• If a session bean is participating in a transaction, a client cannot invoke a method on the bean such that the trans-attribute element (or @TransactionAttribute annotation) in the ejb-jar.xml file would cause the container to execute the method in a different or unspecified transaction context or an exception is thrown.

• If a session bean instance is participating in a transaction, a client cannot invoke the remove method on the session object’s home or business interface object, or an exception is thrown.