Actually, I there was an error in my earlier e-mail. Session Bean A
(The Stateless Front End) should have transaction attribute
"NotSupported". There's no such transaction attribute as "NotRequired".
I'm drawing attention to this because I don't want anyone to mistake my
use of "NotRequired" for the transaction attribute "Supports".
"Supports" won't do because there must never be a transaction in place
when you go to create and remove your stateful session bean and
"Supports" still allows existing transactions to be propogated into the
method call.
Also, since Stateful Session Beans are pooled, you should probably put
the call to sfsb.remove() inside a finally block to provide
deterministic cleanup of the stateful session bean, allowing it to be
immediately returned to the pool. Yes, the garbage collector should
eventually reclaim the resource, but it's non-deterministic when that
runs.
So, for the record, the solution should be like the following.
----------------------------------------------------------------------
--------------- STATELESS FRONT END ------------------
/**
* @ejb:interface-method
* @ejb:transaction="NotSupported" <<<<<<
*/
public void someMethod(String arg1)
{
try
{
StatefulEJBLocal sfsb =
StatefulEJBUtil.getLocalHome().create();
StatelessEJBLocal slsb =
StatelessEJBUtil.getLocalHome.create();
slsb.anotherMethod(sfsb,arg1);
}
finally
{
Helper.remove(sfsb);
//Helper.remove() should simply call sfsb.remove() and catch
any exceptions thrown.
//It's a very bad thing to allow finally blocks to throw
exceptions of their own.
}
}
slsb.anotherMethod() MUST have transactional scope, and it MUST do ALL
the transactional stuff required in someMethod()!!! someMethod()'s only
responisbility is creating sfsb!
-------------------------------------------------------
I definitely prefer this stateless front end design to all the others
discussed.
Doug
P.S. The Transaction.registerSychronization(sync) method is on
javax.transaction.Transaction but not javax.transaction.UserTransaction.
Since UserTransaction is all that you're required to have access to in
the application server (EJB 2.0 Spec Sec. 24.1.1, p. 494), I'll have to
get back to you regarding using regular Java objects implementing
javax.transaction.Synchronization after I ask around a little.
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