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| smvineed |
 Posted: Sun Jun 05, 2016 9:51 pm Post subject: Possiblity of Message lost in MQ |
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Apprentice
Joined: 24 Jul 2011
Posts: 34
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In what scenario MQ messages will be lost, can any of experts explain the scenarios ?
Thanks in Advance
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SMV
If you want it,work for it. it's that simple |
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| exerk |
| Posted: Mon Jun 06, 2016 2:05 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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MQ does not 'lose' messages, period!
There may be circumstances where MQ discards messages however - and those are all explained in the Knowledge Centre (KC).
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It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| smvineed |
| Posted: Mon Jun 06, 2016 7:09 pm Post subject: Possiblity of Message lost in MQ |
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Apprentice
Joined: 24 Jul 2011
Posts: 34
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Hi exerk,
Thanks for your reply.
Regards
SMV |
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| zpat |
| Posted: Tue Jun 07, 2016 9:50 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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There is a chance a message was not actually accepted (e.g. queue full or message length too large) and the putting application did not handle the MQRC correctly.
So the application must be coded correctly to handle conditions when the MQPUT does not succeed. Once it does succeed MQ will keep the message in accordance with the documented behaviour.
Depending how resilient your storage hardware is, it's possible to lose both data and log filesystems, but very unlikely if well designed and spread over fault tolerant SAN.
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Well, I don't think there is any question about it. It can only be attributable to human error. This sort of thing has cropped up before, and it has always been due to human error. |
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| Vitor |
| Posted: Tue Jun 07, 2016 10:07 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| zpat wrote: |
| There is a chance a message was not actually accepted (e.g. queue full or message length too large) and the putting application did not handle the MQRC correctly. |
I always use the post box analogy - if you post a letter and don't see it go through the slot & hit the bottom, you can't expect the postal service to deliver it. If you just throw the message at the slot, miss, see it fall to the ground and then just leave it laying there, the postal service is not going to pick up all the letters scattered round close to the post box.
Once it's in the post box, you can rely on it being delivered. You can't rely on when, and you can't expect the postal service to make the recipient read the letter, just to deliver it.
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Honesty is the best policy.
Insanity is the best defence. |
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| mqjeff |
| Posted: Tue Jun 07, 2016 10:14 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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And if you see a lorry plow over the post box just after you've put your letter in...
Err. Sorry. I'm American. A "truck" and a "mailbox".
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| Vitor |
| Posted: Tue Jun 07, 2016 12:21 pm Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| mqjeff wrote: |
| And if you see a lorry plow over the post box just after you've put your letter in... |
In American, that would be the large blue things you see standing around, not the weird shaped objects outside your house. Going to the blue thing is analogous to making a client connection. If you're using a binding connection (i.e. the thing by your house) you'll easily detect the problem from your window and resend.
| mqjeff wrote: |
| Err. Sorry. I'm American. A "truck" and a "mailbox". |
I'm keeping in practice with British terms in case the next President makes my position dodgy by tearing up the 14th Amendment so he can "remove" undocumented chosen classes of people, even those who are raising native born US citizens (who without the protection of the 14th Amendment are just children of undocumented parents).
I'm not "American" in the sense of "my family has been here for n generations" and I'm certainly not as cute as the children in question.
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Honesty is the best policy.
Insanity is the best defence. |
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| vsathyan |
| Posted: Tue Jun 07, 2016 10:57 pm Post subject: |
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Centurion
Joined: 10 Mar 2014
Posts: 121
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What happens when a non-persistent message is posted on the sending side through a remote queue, and the destination queue manager does not have the destination queue defined, and no dead letter queue on destination queue manager...
"Will the post man throw those mails on the road and return home, rather than taking them back to the post office and keep it?" LOL  
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Custom WebSphere MQ Tools Development C# & Java
WebSphere MQ Solution Architect Since 2011
WebSphere MQ Admin Since 2004 |
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| mqjeff |
| Posted: Wed Jun 08, 2016 4:00 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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Fortunately, MQ does not support the model of "what if the postal employee goes nuts and decides to hoard all mail they are handling in their apartment or home".
Nor the more violent methods that postal employees have occasionally gone nuts...
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| Vitor |
| Posted: Wed Jun 08, 2016 4:45 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| vsathyan wrote: |
| "Will the post man throw those mails on the road and return home, rather than taking them back to the post office and keep it?" LOL |
Strangely yes....
| exerk wrote: |
There may be circumstances where MQ discards messages however - and those are all explained in the Knowledge Centre (KC). |
Your use case is one such circumstance.
Analogy only goes so far.
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Honesty is the best policy.
Insanity is the best defence. |
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| bruce2359 |
| Posted: Wed Jun 08, 2016 5:56 am Post subject: Re: Possiblity of Message lost in MQ |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| smvineed wrote: |
In what scenario MQ messages will be lost, can any of experts explain the scenarios ?
Thanks in Advance |
This subject has been discussed here many, many times. It is frequently a job-interview and certification test question.
Have you used the Search option at the top of this page to answer your own question? What were the results of your search?
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