stateful-session-bean

I'm learning EJB3 and I'm just curious when it's convenient to use SFSB? I can't find any nice example when SFSB realy solve easily some complex problem. Actually I see that SLSB can be used as web-services and this is convenient. But I don't know when to use SFSB. I see only problems with it, because we should learn something about it, we should write code which consists of annotations a bit less then completely, we should use annoying lookup ... and we don't get anything good in return. For example, we can't use SFSB from SLSB, because stateful objects can be used only from stateful context.

I have a Stateful Session Bean (SFSB) which acts as authentication module. In the SFSB I store the current user that is logged in. Moreover I have some facades (which are Stateless Session Beans (SLSB)) that handles the JPA/SQL stuff for my entities. In order to check the access permissions of the current user, I try to call the SFSB out of the SLSB. But the current user field is always "null" when called from SLSB. When calling the SFSB directly, the current user field is set correctly... For calling I use the @EJB annotation. Any ideas what the problem might be? Is that somehow a context

A stateful session bean is defined as follows: Stateful Session Beans The state of an object consists of the values of its instance variables. In a stateful session bean, 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. A stateless session bean is defined as follows: Stateless Session Beans A stateless session bean does not maintain a conversational state with the client. When a client invokes the methods of a stateless bean, the bean’s instance variables may

Is it possible to access a stateful session bean inside a stateless bean? My problem is that I have a session bean called User and I want to access user info inside a stateless bean... I am trying like this: Ejb Side: @Stateless public class OfferManagerBean implements OfferManagerLocal, OfferManager { @Resource private SessionContext context; @EJB private ro.project.ejb.interfaces.User user; public String getUsername() { user = (ro.project.ejb.interfaces.User) context.lookup("java:global/project/projectEJB/User!ro.project.ejb.interfaces.User"); return user.getUsername(); } Client side User