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| Can you use a GET command in a loop ? |
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| AlexeiSkate |
 Posted: Thu Apr 18, 2002 12:31 pm Post subject: |
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Centurion
Joined: 10 Apr 2002
Posts: 123
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Hi,
Is there a way to get all of the messages off the queue by using a 'while loop' or a 'for loop' ? What would the test condition be to terminate the loop, e.g. while (queue has more messages) ... ?
thanks,
Alex |
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| StefanSievert |
| Posted: Thu Apr 18, 2002 12:43 pm Post subject: |
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Partisan
Joined: 28 Oct 2001
Posts: 333
Location: San Francisco
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Alex,
of course this is possible, that's the recommended way of processing: drain the queue until empty.
Your loop condition could be as simple as:
while( CompCode != MQCC_FAILED )
But it depends on what non MQCC_OK conditions you might treat as OK, for example it might be tolerable to continue processing on certain MQCC_WARNING conditions. It depends on what your business logic is.
Remember to test for reason code MQRC_NO_MSG_AVAILABLE (2033) before you report an error condition, because this reason code will be reported as MQCC_FAILED.
One other thing to make sure, when you drain the queue: Reset your messageID/correlID to MQMI_NONE/MQCI_NONE before each MQGET.
The sample program amqsget0.c may help you to get started, along with the Application Programming Guide and Reference.
Cheers,
Stefan
_________________
Stefan Sievert
IBM Certified * MQSeries
In the end everything is right. If not, it's not the end.
[ This Message was edited by: StefanSievert on 2002-04-18 13:44 ] |
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| AlexeiSkate |
| Posted: Thu Apr 18, 2002 1:08 pm Post subject: |
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Centurion
Joined: 10 Apr 2002
Posts: 123
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Stephan,
I see that you can reference the CompCode directly when using MQI and code statement like "if (CompCode == MQCC_FAILED)", but how can you do similar logic when using the MQSeries for Java ? In Java, the completion code is an attribute of the MQException object. If I try to do a GET and there is no more message to be read, an exception is thrown to the catch block of the program and any remaining logic within the try-catch block is not executed. Do you have any idea on how I duplicate the MQI logic when using the Java API ?
thanks,
Alex |
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| StefanSievert |
| Posted: Thu Apr 18, 2002 1:51 pm Post subject: |
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Partisan
Joined: 28 Oct 2001
Posts: 333
Location: San Francisco
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Alex,
you didn't mention that you were referring to Java.
In that case your logic probably looks like
| Quote: |
try
{
while(true)
{
reset messageID/CorrelID (or create new MQMessage object)
get
do your OK processing
}
}
catch( MQException mqe )
{
if( mqe.Reason == MQC.MQRC_NO_MSG_AVAILABLE )
{
probably OK, do nothing
}
else
{
probably not OK, do your error processing
}
}
catch( other exceptions )
{
...
}
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I am not a Java expert so the code above might be totally wack-o, plus I did it from the top of my head.
Yes, you will leave your try block when an exception occurs, but isn't that what you want anyway?
Maybe I don't really understand your question, so please correct me if you meant something different.
Stefan
_________________
Stefan Sievert
IBM Certified * MQSeries
In the end everything is right. If not, it's not the end.
[ This Message was edited by: StefanSievert on 2002-04-18 14:52 ] |
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| AlexeiSkate |
| Posted: Fri Apr 19, 2002 6:29 am Post subject: |
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Centurion
Joined: 10 Apr 2002
Posts: 123
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Stephan,
Thanks for your help. I guess I just have always look at the catch block as a place to catch and issue error and that any actual programming logic takes place only with the try block. But now if I need to do some other processing logic in my program after retrieving all of the msgs off the queue, I will do that in the catch block. Thanks again for your help.
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