I have a simple question but i can't find a answer for Java EE 6!
Should a stateful session bean implements Serializable or not?
I tested with and without implementing java.io.Serializable and there is no different and no errors.
My feeling tells me, that a stateful session bean MUST implements Serializable because it can be persisted in a long term session...
No, it doesn't need to as the specification does not require that.
You may download and check the EJB specification from: https://jcp.org/en/jsr/detail?id=318