Carlos,
1- Please restrain from sending formated text, send plain text when you can
2- I just came back from a deep dive in the current TM package. To be
honest it is not really up to snuff and I am considering nipping it
altogether. I have put stop gap fixes in there just to get the
TxInterceptor and the container behaving properly.
You seem a fellow keen on JTS/JTA do you have spare cycles for the
integration of a TM?
When I integrated Jonas' TM it took me a day (most the code is simple) heck
I'll do it.
marc
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Carlos Pita
Sent: Thursday, July 27, 2000 5:44 PM
To: [EMAIL PROTECTED]
Subject: [jBoss-Dev] TransactionImpl
Hi!
I have a question (it could be an observation if already had more
self-confidence) about enlisting/delisting xa resources in the Transaction
implementation. Here are the sources of both methods as they were in last
week CVS repository (remember that resources is a Vector):
public boolean delistResource(XAResource xaRes, int flag)
{
try {
xaRes.end(xid, Status.STATUS_ACTIVE);
// resources.removeElement(xaRes);
return true;
} catch(XAException e) {
e.printStackTrace();
return false;
}
}
public boolean enlistResource(XAResource xaRes)
throws RollbackException
{
// Check rollback only
if (status == Status.STATUS_MARKED_ROLLBACK)
{
throw new RollbackException();
}
// Add resource
try {
xaRes.start(xid, Status.STATUS_ACTIVE);
resources.addElement(xaRes);
return true;
} catch(XAException e) {
e.printStackTrace();
return false;
}
}
When the transaction commits (or rollback) the algorithm is:
[...]
for (int i = 0; i < resources.size(); i++)
{
try
{
((XAResource)resources.elementAt(i)).commit(xid, false);
} catch (XAException e)
{
try {
((XAResource)resources.elementAt(i)).forget(xid);
} catch(XAException another) {}
e.printStackTrace();
// TODO: what to do here?
}
}
So the question is:
What if we have more than one xa resource enlisted in the transaction
corresponding to the same resource manager? I think that in this scenario
the algorithm will run the 2 phase protocol against the same resource
manager and for the same transaction more than once.
Regard this, the JTA spec says:
"
The enlistResource request results in the Transaction Manager informing the
resource manager to start associating the transaction with the work
performed through
the corresponding resource�by invoking the XAResource.start method. The
Transaction Manager is responsible for passing the appropriate flag in its
XAResource.start method call to the resource manager. The XAResource
interface
is described in section 3.4.
If the target transaction already has another XAResource object
participating in the
transaction, the Transaction Manager invokes the XAResource.isSameRM method
to
determine if the specified XAResource represents the same resource manager
instance.
This information allows the TM to group the resource managers who are
performing
work on behalf of the transaction.
1.Transaction Branch is defined in the X/Open XA spec [1] as follows: 'A
global transaction has one or
more transaction branches. A branch is a part of the work in support of a
global transaction for which the
TM and the RM engage in a separate but coordinated transaction commitment
protocol. Each of the RM�s
internal units of work in support of a global transaction is part of exactly
one branch. .. After the TM begins
the transaction commitment protocol, the RM receives no additional work to
do on that transaction branch.
The RM may receive additional work on behalf of the same transaction, from
different branches. The differ-ent
branches are related in that they must be completed atomically. Each
transaction branch identifier (or
XID) that the TM gives the RM identifies both a global transaction and a
specific branch. The RM may use
this information to optimise its use of shared resources and locks.'
"
That's all for now.
Thank you,
Carlos
