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| Problem with JMS/MQSeries transacted session |
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| jjversa |
 Posted: Fri Oct 24, 2003 12:01 pm Post subject: Problem with JMS/MQSeries transacted session |
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Newbie
Joined: 24 Oct 2003
Posts: 3
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I'm executing Java code on an IBM mainframe running z/OS and MQSeries 5.3, and am using a transacted session to send/receive messages. When no errors occur, naturally all's well--my sender writes the message in an uncommitted state, and I can commit it/roll it back as the situation warrants. When a handled exception occurs, things are still OK, in that I can catch the exception and yell for rollback() to bring us back to where we were before the message was sent.
My problem is what happens when an unhandled error condition stops the client application. In my shop, this scenario is usually tested by placing an unhandled zero-divide bomb in the code immediately after the message.send(). The client naturally blows up, and I would expect the theoretically uncommitted message to roll back. Instead, it commits. Can someone tell me why?
Thanks.
JJ |
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| RogerLacroix |
| Posted: Fri Oct 24, 2003 8:50 pm Post subject: |
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Jedi Knight
Joined: 15 May 2001
Posts: 3264
Location: London, ON Canada
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Hi,
On your PUT, add the following pmo option: MQC.MQPMO_SYNCPOINT
Then on your abend, the message will be rollback.
later
Roger...
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| jjversa |
| Posted: Sat Oct 25, 2003 4:31 am Post subject: |
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Newbie
Joined: 24 Oct 2003
Posts: 3
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| I'm familiar with the syncpoint MQPutMessageOption. Humor me for a moment, as our documentation is a bit sketchy here, but weren't the JMS message writes supposed to be done with send() rather than put()? Maybe we're barking up the wrong tree. |
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| RogerLacroix |
| Posted: Sat Oct 25, 2003 9:07 pm Post subject: |
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Jedi Knight
Joined: 15 May 2001
Posts: 3264
Location: London, ON Canada
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Hi,
I used "PUT" as a figure of speech. For Java, send() is the correct method.
Even if you are using a transactional client, you still need to set the syncpoint option. Otherwise the "PUT" is considered to be outside of the Unit Of Work.
later
Roger...
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| jjversa |
| Posted: Mon Nov 03, 2003 12:19 pm Post subject: Follow-up |
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Newbie
Joined: 24 Oct 2003
Posts: 3
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Since we had already been setting up a PutMessageOption containing SYNCPOINT, we knew that wasn't the trouble, so we had to dig a bit. Finally, someone found the following in an old IBM FAQ:
PartnerWorldibm.com <!-- Home | Products & services | Support & downloads | My accountIBM PartnerWorld > <!-- <!-- PartnerWorld for DevelopersTechnical > FAQs Frequently Asked Questions FAQ help Search tips Can you use Java programming with MQSeries to have a two-phase commit via RRS? A: MQSeries Java stubs are linked to the MVS batch stubs, not with the RRS stubs. Therefore, Java calls to MQSeries do not invoke RRS recovery routines. You would probably have to link to the C/C++ stubs which have been linked with the RRS stubs. Reference: 20839 / 22352 Date: 12 Sep 2002 Keyword: Java/JMS programming [ Return to main page ] About IBM | Privacy | Terms of use | Contact
Bottom line: Only a proper JMS to RRS (Resource Recovery Services) to MVS traversal will give you the automatic rollback support granted by full MVS abend, and the mainframe batch JVM (at least ours) is rigged to bypass RRS.
The two ways around this are either to:
1. Relay upward and catch all Throwables in all application main() methods, then call session.rollback() manually from within such catch blocks.
2. Relay upward and catch all Throwables in all application main() methods, then call an "abender" program written in C (which does have hooks into the RRS layer that handles abend-triggered rollback). This has the benefit of triggering all rollbacks (MQ, DB2, etc.) that MVS full abend can grant, not just solving the MQ problem.
JJ |
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