Java Persistance Application Stateless vs. Stateful

Question

I am new in JPA and I can't understand the use and the difference between stateless and stateful.

Any experiences?

regards, Haythem

Answer 1

Stateless and Stateful are EJB Session Bean concept, not of JPA.

Nota bene: JPA is part of EJB specification, but can be used separately and outside of an EJB container. This is what usually causes the confusion.

Edited: A useful SO thread, Why Use Stateful Session Beans.

Answer 2

"Stateful" and "Stateless" are attributes for session beans.

A session bean (in brief) provides a way to call methods on an application server. The bean is an instance of a java class. Usually, a bean is destroyed after the remote method terminates (and returns a result). Those bean are "stateless".

It is possible (but rather unusual) to add fields and attributes to the bean so that a client can "create" this instance on the server and use it for more then one operation. Those beans are "stateful" (and should be avoided).