I was trying to use the thread local pattern for my hibernate application, and I am unconfortable with the following facts. (note: I am using j2ee transaction semantics-CMT)

Case1: If the tread local is handled at the servlet(presentation tier). That means the sevlet is responsible for calling the closeSession.

* If the application is deployed in a cluster,one of your ejb can call another ejb which resides in the second node. The transaction flow in this case would be for instance Container1Servlet1---->Container1EJB1---->Container2EJB2. Since Thread Local won't be propagated across containers, the Container2EJB2 will create a new session and use that. And now Container1Servlet1 is not aware of that session and it closes only the first session created by him.

Case2: If the thread local is handled by each of the EJBs. That means that each EJB method is responsible for calling the closeSession at the end of the execution.

* If the transaction flows is like Container1Servlet1---->Container1EJB1(M1-TXRequiresNew) ---->Container1EJB1(M2-TXRequired) In this scenario, I cannot implement the session-per-request or not even session-per-transaction and results in poor performance. Because M1 and M2 has to open and close the session by its own.

Any input would be appreciated.

In the case of using SLSBs, I wrap the unit-of-work by the SLSB and CMT. There is never any calls to another SLSB from within the unit-of-work. The unit-of-work can be built using a rich Domain Model or DAO structure which makes use of the Thread local pattern. If modeled like this then there are no clustering issues. It also allows reliable and easy testing outside of the container.