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| MQClients - Can they lose a message? |
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| PeterPotkay |
 Posted: Thu Jun 07, 2001 9:22 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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If an application does a client connect to a Queue Manager on a MQ server,
and that connection includes going over a network, does that application
risk losing messages?
For instance, the client issues a GET call to the QM. The QM proceeds to
pull the message off of the queue and send it down the channel. What happens
if the network goes down before the app gets the message, but after the QM
pulled it off the queue? As I understand it, there are no MCAs in this
situation to insure that the receiving side (the client app) got the
message.
Also, what if the message did make it across the channel but the app
terminates abnormally while processing the message? Does the message get put
back somehow? Does the syncpoint option make a diff here? If the message
DOES make it back somehow, what if " the app terminates abnormally " means
the box that the app is running on gets unplugged?
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Peter Potkay
Keep Calm and MQ On |
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| kolban |
| Posted: Thu Jun 07, 2001 12:15 pm Post subject: |
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Grand Master
Joined: 22 May 2001
Posts: 1072
Location: Fort Worth, TX, USA
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Messages can indeed be lost using the MQClient. If a message is got from a queue without syncpoint, the queue manager can flag the message as obtained even if the client crashes during or immediately after getting the message. If this is undesirable, consider using the Syncpoint coordination of the gets and puts.
If a client application has performed gets/puts under syncpoint and either crashes or loses network connection to the queue manager, the queue manager will roll-back all transactional work performed by the application.
Neil |
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| rajesh_avrs |
| Posted: Sun Feb 20, 2005 3:36 pm Post subject: |
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Apprentice
Joined: 18 May 2001
Posts: 31
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I have noticed another wierd scenario.
When I was working in Win2K environment, I have shutdown the queue manager thru MMC in 'Controlled' mode. Once the queue manager is down, I had issued an MQPUT request from the client to this Queue manager.
Surprisingly, the client application did not receive any error messages. After digging around a bit, I have noticed that even though I have shut down the queue manager, the listener process 'runmqlsr' was still running in the background and is accepting the client connections... but, the message is lost since the queue manager is not available.
Wierd, isn't it???
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| jefflowrey |
| Posted: Sun Feb 20, 2005 10:27 pm Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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Why are you responding to several messages that are several years old?
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| EddieA |
| Posted: Sun Feb 20, 2005 10:54 pm Post subject: |
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Jedi
Joined: 28 Jun 2001
Posts: 2453
Location: Los Angeles
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To "pad" his rating and look like he's helping. 
Yeah, that's another one for me. 
Cheers,
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Eddie Atherton
IBM Certified Solution Developer - WebSphere Message Broker V6.1
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| rajesh_avrs |
| Posted: Sun Feb 20, 2005 11:19 pm Post subject: |
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Apprentice
Joined: 18 May 2001
Posts: 31
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Sorry about that... I have no 'bad' intentions to improve my rating or what so ever...
Today I had a chance to look at mqseries.net after a long time and thought i would respond to some postings that are interesting...
I spend a lot of time at orkut.com where messages are sorted by date in descending order... so i generally go to the last page and start posting my messages... I did the samething here without bothering to look at the date... i only realized that i am responding to old topics after doing couple of other postings...
Anyways, apologies for posting reply to an old thread, and what to make it clear that mqseries.net rating is gonna increase my salary... 
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