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Message
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| jasmin |
 Posted: Thu Dec 08, 2005 7:06 am Post subject: Problems with accessing the queue several times in a row |
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Novice
Joined: 04 Nov 2005
Posts: 15
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Hi.
I use the com.ibm.mq.jar library to access a message queue with my java application.
When I try to get a single message from the queue, my program works fine.
| Code: |
int openOptionsGET = MQC.MQOO_INPUT_SHARED|MQC.MQOO_FAIL_IF_QUIESCING;
MQQueue MyQueue = qMgr.accessQueue(qQueue,openOptionsGET);
MQMessage MyMessage = new MQMessage();
MyQueue.get(MyMessage);
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But as soon as I try to get more than one message in a loop, I receive a "Completion code 2 Reason code 2033" - error.
Example:
| Code: |
int openOptions = MQC.MQOO_BROWSE | MQC.MQOO_INQUIRE;
MQQueue MyQueue_STATG = qMgr.accessQueue(qQueue, openOptions,null,null, null);
while (MyQueue_STATG.getCurrentDepth() > 0) {
MyQueue.get(MyMessage);
}
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The error occurs though the condition in the while-statement is definetly true. (I've checked that.)
Does anybody know, what might went wrong?
Thanks. |
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| jefflowrey |
| Posted: Thu Dec 08, 2005 7:13 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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What went wrong is that you are trying to tell if the queue is empty by using the unreliable current queue depth message, instead of by whether or not you got a return code from the Get that was a 2033.
Also, it is fairly unlikely that you should be using MQC.MQOO_BROWSE.
Among other things, using BROWSE means that your queue depth won't go down when you GET a message.
_________________
I am *not* the model of the modern major general. |
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| jasmin |
| Posted: Thu Dec 08, 2005 7:22 am Post subject: |
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Novice
Joined: 04 Nov 2005
Posts: 15
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Actually the queue depth does go down with BROWSE, as it shows when you have a System.out.println() before and after the get.
Anyway, I've got know idea how else I could request all messages in a loop. Apart from that, I don't know exactely what messageid and corellid is?
Does anybody have sample code for such a case? |
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| jasmin |
| Posted: Thu Dec 08, 2005 7:27 am Post subject: |
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Novice
Joined: 04 Nov 2005
Posts: 15
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| Besides, what exactely means error code 2033? |
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| bower5932 |
| Posted: Thu Dec 08, 2005 7:29 am Post subject: |
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Jedi Knight
Joined: 27 Aug 2001
Posts: 3023
Location: Dallas, TX, USA
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You can use mqrc to get return code descriptions:
C:\Documents and Settings\Administrator>mqrc 2033
2033 0x000007f1 MQRC_NO_MSG_AVAILABLE
As far as sample code is concerned, there is some here and some more at:
http://www.developer.ibm.com/isv/tech/sampmq.html |
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| jefflowrey |
| Posted: Thu Dec 08, 2005 7:40 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| jasmin wrote: |
| Actually the queue depth does go down with BROWSE, as it shows when you have a System.out.println() before and after the get. |
Ahh. That's because you opened the queue for BROWSING, but aren't specifying the BROWSE options on your get (MQGMO_BROWSE_FIRST or MQGMO_BROWSE_NEXT).
So you're not browsing, you're doing a destructive get.
Regardless, trying to use the queue depth is not the right way to find out when the queue is empty - for a lot of reasons. The right way is to keep getting messages until you get back MQRC_NO_MORE_MESSAGES... which is 2033! Or until you get some other exception/bad return code, that indicates something else is not right.
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I am *not* the model of the modern major general. |
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| jasmin |
| Posted: Thu Dec 08, 2005 7:46 am Post subject: |
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Novice
Joined: 04 Nov 2005
Posts: 15
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| Quote: |
Regardless, trying to use the queue depth is not the right way to find out when the queue is empty - for a lot of reasons. The right way is to keep getting messages until you get back MQRC_NO_MORE_MESSAGES... which is 2033! Or until you get some other exception/bad return code, that indicates something else is not right.
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Why's that?
I found out the problem was, that I didn't close the queue before I started the next get. Now it works, with the BROWSE. Isn't this more consistent than waiting for an exception? |
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| wschutz |
| Posted: Thu Dec 08, 2005 8:32 am Post subject: |
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Jedi Knight
Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)
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Two reason why curdepth isn't reliable:
1. curdepth includes uncommitted messages that have been "put" but wouldn't be available to your application
2. if some other process is reading messages from the queue, they might have gotten the message between your inquiry for curdepth and your "get" of the message,
Also, I don't see how your code works since you didn't specify a MQOO_INPUT* option.
_________________
-wayne |
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| PeterPotkay |
| Posted: Thu Dec 08, 2005 1:44 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| wschutz wrote: |
Two reason why curdepth isn't reliable:
1. curdepth includes uncommitted messages that have been "put" but wouldn't be available to your application
2. if some other process is reading messages from the queue, they might have gotten the message between your inquiry for curdepth and your "get" of the message,
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Reason #3, messages that are expired count towards q depth, but you can't get them.
_________________
Peter Potkay
Keep Calm and MQ On |
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| jasmin |
| Posted: Thu Dec 08, 2005 11:36 pm Post subject: |
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Novice
Joined: 04 Nov 2005
Posts: 15
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| Ok, you've convinced me. Could you post a sample code for doing it the other way? |
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| wschutz |
| Posted: Fri Dec 09, 2005 2:39 am Post subject: |
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Jedi Knight
Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)
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