Sorry that i bother this list, but for the moment i can't send anything
to the EJB-INTEREST list. Everything is coming back to me as unsent...
...
Reading the EJB 1.1 spec about exception handling and can't really
figure out what happens in a situation like this one:
If an EntityBean (CMP) has changed some of its persistent fields but
then decides to throw an appl. exception (that is before any update in
db has been made), what happens with the changed fields in the bean
instance?
Case 1: The tx is started in the EntityBean method and the method calls
on setRollbackOnly() before throwing the exception. I guess that the
container rollbacks the ongoing tx and rethrows the exception. The bean
instance in intact and can be used again. What about the fields?
Case 2: Same as 1 but there is no call on setRollbackOnly(). Here i
guess that the container will attempt to commit the tx, the changed
fields will be stored in db, and then rethrows the exception. The bean
instance is intact and will have 'correct' field values. At least they
are the same as in db.
Case 3: The tx is already started by the caller and the caller retries
the call within the same tx. Here i guess that the container will
rethrow the exception to the caller. The bean instance is intact. The
caller calls the method again - but what value have the field then?
Case 4: Like 3 but the caller calls setRollbackOnly() and rethrows the
exception. Here i guess that the container will rollback the tx. The
bean instance is intact. But what about the field values?
Case 5: Like 3 but the caller just rethrows the exception without
calling setRollbackOnly(). Here i guess that the container will attempt
to commit the tx, the changed fields will be stored in db, and then
rethrows the exception. The bean instance is intact and will have
'correct' field values like in case 2.
My problem: I'm really worried about what values the entity fields will
have, especially in the cases where the tx has been rolled back and no
update done in database! Do i have to manually reset the fields to its
originally value before throwing the appl. exception? It's the cases 1,
3 and 4 that bother me most. Cases 2 and 5 i think is quit clear, the
bean has to undo changes of the fields or they will be stored in db with
wrong values.
Any comments to this rather basic EJB question? Maybe i'm stupid but for
the moment when i reads the spec i think that everything is a bit messy.
Thanks,
/Lennart
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