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Message
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| mitoiuv |
 Posted: Wed Jul 21, 2010 6:51 am Post subject: Can't catch the messages |
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Novice
Joined: 06 Jul 2010
Posts: 20
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Hi,
I have a little problem regarding reading messages from a queue, I modified the MQget sample and I am able to read (print on the screen) the messages read from a queue in BROWSE mode .
The problem appears on a queue that is consumed by another application when the message was delivered.
The problem is like this.
I send a message to a queue, I stay with my "sniffer" on the queue(the destination) but the message is consumed by the external APP before I read it.
Is this a problem redarging speed or the APP could be locking the queue in some "special" manner.
If I stop the APP I can see the message in the queue and read it.
Thank you
Last edited by mitoiuv on Wed Jul 21, 2010 7:09 am; edited 1 time in total |
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| mqjeff |
| Posted: Wed Jul 21, 2010 7:08 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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If there are two applications with an open handle and sitting in an MQGET-with-wait and a new message appears that matches the criteria that *both* are expecting, it is *undefined* which one will get the message.
There's no good reason to do what you are actually doing. There may be a good reason to fulfill the requirement you are trying to make, but you will have to do it in an entirely different way. |
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| mitoiuv |
| Posted: Wed Jul 21, 2010 7:10 am Post subject: |
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Novice
Joined: 06 Jul 2010
Posts: 20
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Hmm....that just rocked my world  , what way would be that ? Have any suggestions ?
Thank you |
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| mqjeff |
| Posted: Wed Jul 21, 2010 7:23 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| What are you *trying* to do, other than read the exact same message from two separate applications? |
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| Vitor |
| Posted: Wed Jul 21, 2010 7:23 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| mitoiuv wrote: |
| what way would be that ? Have any suggestions ? |
Any number of ways & suggestions depending on why you're doing this, i.e. your requirement. Why exactly do you have 2 applications trying to read the same message from the same queue?
Details please.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| mitoiuv |
| Posted: Wed Jul 21, 2010 9:52 pm Post subject: |
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Novice
Joined: 06 Jul 2010
Posts: 20
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I need two APP's for the following reasons:
- i have one APP that is always connected and doing it's job on the queue(that is reading/consuming the messages from that queue after they arrive)
- and I need another APP that I start only when I want to investigate a specific problem regarding some errors/issues that are in the messages.
So I need/have to able to use both in the same time without interfering with each other. |
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| mitoiuv |
| Posted: Wed Jul 21, 2010 9:54 pm Post subject: |
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Novice
Joined: 06 Jul 2010
Posts: 20
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| mqjeff wrote: |
| What are you *trying* to do, other than read the exact same message from two separate applications? |
That is exactly what I want to do |
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| zpat |
| Posted: Wed Jul 21, 2010 11:14 pm Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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One of the main benefits of MQ is that is does not allow more than one application to get the same message. One time delivery is useful.
If you want two applicationss to read the same message, send a copy to two different queues. |
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| mitoiuv |
| Posted: Thu Jul 22, 2010 12:31 am Post subject: |
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Novice
Joined: 06 Jul 2010
Posts: 20
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| I was thinking at using MirrorQ to mirror that queue and read from the mirrored queue instead of the business queue. |
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| zpat |
| Posted: Thu Jul 22, 2010 1:11 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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| mqjeff |
| Posted: Thu Jul 22, 2010 2:37 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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Generally if an MQ application has trouble processing a specific message, it will turn around and put it back to another queue - an error queue or a backout queue.
It can then be investigated from there.
Keeping a separate copy of every single message for this purpose is usually seen as large overkill. |
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| Vitor |
| Posted: Thu Jul 22, 2010 4:12 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| mitoiuv wrote: |
| I was thinking at using MirrorQ to mirror that queue and read from the mirrored queue instead of the business queue. |
As has been said many times, mirrorq is a piece of sample code and a) is not considered production strength & b) will be your problem to maintain & fix going forward
<plug>Though Cressida does sell something that does this & supports it </plug>
Also as my most worthy associate points out, if there are errors or issues the application should reject the message and write to an error queue for your investigiation.
If you do use mirrorq or similar to keep a copy of each message, how will you a) identify the failing message in among the (presumably) large number of successful ones and b) clear unwanted messages out of this copy queue?
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| mitoiuv |
| Posted: Thu Jul 22, 2010 4:40 am Post subject: |
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Novice
Joined: 06 Jul 2010
Posts: 20
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This APP is for testing, it is going to be developed only for this, now the problem is different...I tried to setup mirrorq to "clone" the queue and then use the first APP for reading messages from it but it seems that i'm doing something wrong.
I compiled mirrorq, put it in the /bin/ folder of MQ, but it is not trigerring... this is the config file that I used.
What am I doing wrong here ?
| Code: |
* Queue to mirror business application queue
DEFINE QLOCAL('RD92.XML.SYNC1.MIRROR') REPLACE +
DESCR('Mirror queue for EXPLODE')
* Staging queue used by explodeMirror
* Set application up to put to this queue rather
* than business application queue
DEFINE QLOCAL('RD92.XML.SYNC1.STAGEQ') REPLACE +
DESCR('Staging queue for EXPLODE') +
* Shareable
SHARE +
* Trigger control on
TRIGGER +
* Trigger on first message
TRIGTYPE (EVERY) +
INITQ('RD92.EVTINITQ') +
PROCESS('RD92.PROCESS')
* Process definition to load explodeMirror
DEFINE PROCESS('RD92.PROCESS') REPLACE +
DESCR('Trigger process for EXPLODE') +
USERDATA('RD92.XML.SYNC1 RD92.XML.SYNC1.MIRROR') +
APPLICID('mirrorq')
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I started the trigger monitor to see what's happening but can't see any activity.
| Code: |
runmqtrm -m RD92.MANAGER -q RD92.EVTINITQ
5724-H72 (C) Copyright IBM Corp. 1994, 2005. ALL RIGHTS RESERVED.
WebSphere MQ trigger monitor started.
__________________________________________________
Waiting for a trigger message
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| Vitor |
| Posted: Thu Jul 22, 2010 4:51 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| mitoiuv wrote: |
I compiled mirrorq, put it in the /bin/ folder of MQ, but it is not trigerring... this is the config file that I used.
What am I doing wrong here ?
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Believing that mirrorq is a triggered app. It's a exit that's called by the internal WMQ process.
It's on this basis I warned you about it being non-production strength & your responsibility going forward. An exit with inefficient (i.e. sample) code or a minor problem with adversly affect queue manager performance. An exit with a bug will bring the queue manager crashing down.
Exits (even sample ones) are an advanced topic. Read some of the threads in here (especially Roger's) and the notes for the mirrorq sample.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| mqjeff |
| Posted: Thu Jul 22, 2010 5:34 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| Vitor wrote: |
| mitoiuv wrote: |
I compiled mirrorq, put it in the /bin/ folder of MQ, but it is not trigerring... this is the config file that I used.
What am I doing wrong here ?
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Believing that mirrorq is a triggered app. It's a exit that's called by the internal WMQ process. |
There's an older version that was a triggered app, I believe.
But that's the far back reaches of my memory, and it's really fuzzy in there. |
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