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| CICS bridge and the CSAC transaction |
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| royr |
 Posted: Mon Aug 16, 2004 1:07 am Post subject: CICS bridge and the CSAC transaction |
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Acolyte
Joined: 30 Jun 2001
Posts: 65
Location: Israel
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Hi,
I have a question regarding the CICS bridge.
We are running CICS TS 1.3. We have our own implementation of the CICS bridge monitor and exit, which uses MQ for transport. It's sort of a hybrid between DPL and 3270, which is able to start a separate transaction per request, without using 3270 datastream.
Our bridge monitor program duplicates IBM's CKBR logic. It sits on its own request queue, waits for requests and starts the bridge transactions. If an error occurs while trying to EXEC CICS START the bridge transaction, it sends back an error message with the MQ CICS Header.
In the last few days I noticed that extra reply messages are being generated by the CICS transaction CSAC. It seems that our bridge monitor program tries to execute an "EXEC CICS START BREXIT TRANSID(id)". The request fails with TRANSIDERR. Then, out of nowhere, the CICS-supplied transaction CSAC starts and sends its own MQ reply (with higher MQ priority!). This client apps expect only one reply - ours. The extra reply messages clutter up the reply queues and create a mess.
This did not happen until a few days ago. It may have started due to some PTFs installed in the CICS but I'm not sure.
Can anyone tell me why is CSAC "interfering" with the bridge mechanism and where is this behaviour documented?
Thanks in advance,
Roy. |
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| bob_buxton |
| Posted: Mon Aug 16, 2004 2:08 am Post subject: |
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Master
Joined: 23 Aug 2001
Posts: 266
Location: England
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CSAC is not generating MQ messages - there is very little CICS supplied code that is MQ aware.
CSAC is the CICS abnormal condition processor I can only surmise that it is being driven as part of CICS error handling and is somehow invoking your brexit routine. Does the message look like one that your exit might have built?
I am not aware of any recent changes to CICS that might have caused a change in behaviour or of problem reports from users of the real CKBR.
You may need to run a CICS trace to see if that sheds any light on the problem and if necessary raise a problem with IBM service.
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Bob Buxton
Ex-Websphere MQ Development |
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| royr |
| Posted: Mon Aug 16, 2004 5:46 am Post subject: |
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Acolyte
Joined: 30 Jun 2001
Posts: 65
Location: Israel
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Hi Bob,
Thanks for the reply.
I ran a trace, and you're right: When there's an error STARTing the bridge transaction, CSAC runs instead - under the bridge exit. The bridge exit thinks it's running normally, under the bridge transaction, and sends back a reply. This is in addition to the bridge monitor's error reply.
My question is now: What changed in the last few days that makes CSAC execute? Is its activation controlled by some system parameters, or is it fixed? If CSAC is guarateed to run when the START command fails, I can disable the bridge monitor's error checking for the START command. If CSAC's activation is not guaranteed, I need to add some logic to the bridge exit, which skips processing when running under CSAC.
TIA,
Roy. |
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| bob_buxton |
| Posted: Mon Aug 16, 2004 7:06 am Post subject: |
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Master
Joined: 23 Aug 2001
Posts: 266
Location: England
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I don't know what changed in CICS - it may be worth raising a PMR asking if it is intended behaviour that the bridge exit gets control when CSAC runs?
In CKBR if a Start fails we do a destructive get for the message prior to issuing the error reply message so either the bridge exit or the monitor will suceed in getting the message and issuing a reply but not both.
I have never seen the case where the bridge exit runs when the intended transaction fails to start
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Bob Buxton
Ex-Websphere MQ Development |
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