Can't understand the answer

[Sergey Kozmin]

Hi All,
I'm prepearing to take 310-090 exam next week and have unresolved questions. I read ejb 2.0 spec and still can�t find answer on my question. Any answers will be so much appreciated.
Here it is:

Which three, of a session bean that implements SessionSynchronization, are called with an
unspecified transaction context? (Choose three.)

A. constructor
B. afterBegin
C. afterCompletion
D. beforeCompletion
E. setSessionContext

Answer: A, C, E

That means that if the session bean was called with unspecified context (but not without it) then I won�t be able to rollback the transaction in beforeCompletion method. I tried to find any references in ejb spec about circumstances when do SessionSynchronization callback methods won�t be called but I couldn�t find anything.
Can anyone explain it for me why does B and D are not correct.

[Ali Gohar]

Hi,

SessionSynchronization can only be implemented by a stateful session bean with bean managed transaction demarcation. It is not possible that session bean is called with an unspecified transaction context because your bean's (which implements SessionSynchronization) methods should use the transaction's attribute as REQUIRED, REQUIRES_NEW or MANDATORY otherwise container will raise error.

Hope it clarifies