EJB : Two stateless objects use two different transaction

Question

I would like to ask question regarding EJB. I am using eclipselink of JPA.

There is two stateless objects in a stateless object in my code.

Is that possible this two stateless object use two different transactions?

Answer 1

Absolutely. You may find it useful to read about the transaction attributes.

If the called method in your first class (say StatelessFirst) has a transaction type REQUIRED (the default) or REQUIRES_NEW, when it is called it will initiate a new transaction. If this then calls a method in your second class (say StatelessSecond) with transaction type REQUIRES_NEW, the first transaction is suspended and a second transaction is initiated while the second method executes. When the method in StatelessSecond completes, the second transaction commits, the first transaction is reinstated, and control is passed back to StatelessFirst.

To make the first transaction commit before StatelessSecond is called, you can use bean-managed transactions. This gives you full control over the transaction management, so in StatelessFirst you can begin a transaction, then commit then call StatelessSecond. If you go with this approach, note that you can't perform nested transactions in BMT.

One other option which allows you to stay within CMT would be to pull the transactional behaviour out of StatelessFirst into a third EJB, with REQUIRES_NEW. Then the pattern is:

• Client calls StatelessFirst, which initiates transaction A
• StatelessFirst calls NewBean, which initiates transaction B, and performs some work
• NewBean commits transaction B and returns
• StatelessFirst calls StatelessSecond, which initiates transaction C, and performs its work
• StatelessSecond commits transaction C and returns
• StatelessFirst completes, and commits transaction A (which doesn't have any changes anyway)