Andreas
Now that work has started on JTA support inside Synapse and the
transports, I have a general question. The model used in JTA is to
bind the transaction to the current thread. With all the asynchronous
and non blocking features we have in Synapse this is obviously not the
most appropriate model.
Not really.. even with the non-blocking http/s or any other transport, a
'worker' thread that performs the mediation on a message will only be a
transport thread, or a Synapse thread (for tasks and/or iterate/split
mediators etc). This does not have any impact on the performance, as we
can only process messages bound by the limitations of the host system,
as configured via the thread pools.
Instead, transactions should be bound to the
MessageContext (either Axis2's or Synapse's one, TBD). Of course JTA
transactions can be detached from one thread and resumed in another
thread (assuming that a reference to the underlying TransactionManager
is available).
Well.. we actually do send the transaction along with the message, in a
very un-disruptive manner, so that elements aware of its presence (e.g.
DB mediators) could join the same transaction. The ability to detach a
JTA transaction is limited, and bound by the support/limitations of
typical app servers - for example, JBoss does not allow you to access
the Transaction manager from outside its app server JVM
However that leaves us with two options:
1. Detach the transaction from the thread when it stops doing work
related to the MessageContext and resume the transaction when a thread
starts working on a MessageContext.
Yes, I prefer to keep this 'optional' and triggered by the mediators
proposed to deal with these. In addition, we could consider a fault as a
criteria for a default rollback, like with JEE servers
2. When the transaction is started, immediately detach it from the
thread and put it into the MessageContext. Whenever a mediator or
transport needs the transaction, resume it and detach it again
immediately afterwards.
This does not give an advantage, or cause an overhead, since its just
bound typically via a thread local. Since people will only use
transactional services where they are needed, and explicitly requested,
the most natural thing is to let the transaction flow by default - and
detach if required *and* supported by the underlying implementations.
asankha
--
Asankha C. Perera
http://adroitlogic.org
http://esbmagic.blogspot.com
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
