Same stateless session bean working different in same application

Question

I have created a stateless session bean(SLSB) and doing a local call from the same JVM. I have a BO local variable in the SLSB when initializing i am setting this value and in the next call i am performing some business function but in the next call i am unable to get the value which i have set in prev. call. which seems to be according to the SLSB functionality but there is a similar fucntionality which is working in another part of our application. I have confirmed both are SLSB and no connection pooling is done in the ejb-jar.xml and weblogic-ejb-jar.xml(also both are same) also i have debugged both the class but no clue how it is working in the other class.

I am wondering is there any other way in which we can do the state full behaviour of stateless session bean apart from connection pooling.

Answer 1

The important (if slightly obvious) lesson here is: Don't store state in stateless session beans. If you want to store conversational state, use a stateful bean, if you want shared state use a singleton bean. You could also use an entity bean to persist the state.

The reason this is working elsewhere is most likely to do with bean pooling. EJB containers mostly use bean pools to store their stateless beans, as this gives the best performance and scalability. When a request comes in, the container chooses a bean from the pool to service it, takes it out of the pool, the bean handles the request, then is placed back in the pool. Which bean gets chosen is up to the container, since in theory they are all interchangeable.

If you're setting a member variable in your bean then finding (some of the time) later calls find the variable set to your value, this shows that the container has given you the same bean instance back. This is non-deteministic - it depends on server load, pool size and the container's strategy.