What Is a Session Bean
What Is a Session Bean
that is deployed on the server, the client invokes the session bean's methods. The session bean
performs work for its client, shielding the client from complexity by executing business tasks
inside the server.
shared; it can have only one client, in the same way that an interactive session can have only one
user. Like an interactive session, a session bean is not persistent. (That is, its data is not saved to
a database.) When the client terminates, its session bean appears to terminate and is no longer
associated with the client.
the instance variables represent the state of a unique client-bean session. Because the client
interacts ("talks") with its bean, this state is often called the conversational state.
terminates, the session ends and the state disappears. This transient nature of the state is not a
problem, however, because when the conversation between the client and the bean ends there is
no need to retain the state.
invokes the methods of a stateless bean, the bean's instance variables may contain a state specific
to that client, but only for the duration of the invocation. When the method is finished, the
client-specific state should not be retained. Clients may, however, change the state of instance
variables in pooled stateless beans, and this state is held over to the next invocation of the
pooled stateless bean. Except during method invocation, all instances of a stateless bean are
equivalent, allowing the EJB container to assign an instance to any client. That is, the state of a
stateless session bean should apply accross all clients.
applications that require large numbers of clients. Typically, an application requires fewer
stateless session beans than stateful session beans to support the same number of clients.