| Author |
Message
|
| crowne |
 Posted: Wed Mar 10, 2010 3:41 am Post subject: Can I replace local queue with a distribution list? |
 |
|
Newbie
Joined: 08 Jan 2010
Posts: 4
|
Hi,
I have a local queue which is the target of a remote queue, however I want to replicate each message that lands on the local queue to several other local queues for consumption by separate test environments that share the same queue manager.
Is it possible to do this using only definitions without changing application code of the sender?
I.E. define a namelist, and set some properties the local queues i.e. DISTL=ENABLED, define a Queue Alias pointing to the name list, which lists the underlying replicated queues. |
|
| Back to top |
|
 |
| exerk |
| Posted: Wed Mar 10, 2010 3:56 am Post subject: |
|
|
Jedi Council
Joined: 02 Nov 2006
Posts: 6339
|
If you're using WMQ V7.0, look at setting up pub/sub QA's/QL. Somewhere on the site is a very precise description of how by PeterPotkay.
Found it HERE. The abstract is below, but the whole thread is worth a read...
| PeterPotkay wrote: |
App A is putting to a local q called Q1. App B is pulling from Q1. You have MQ 7 and want to duplicate the messages but do not want to change the sending or receiving app code.
Define a topic called Q1T, with a topic string of Q1
Define a sub to topic object Q1T, with a destination of Q1
Define a Q Alias called Q1Alias, target type topic with a target of Q1T
A put to Q1Alias will now produce a message to the Q1 local queue
Define another sub to topic object Q1T, this time with a destination of Q2
A put to Q1Alias will now produce 2 messages, one to Q1 and one to Q2.
The only change in the original setup is that App A puts to Q1Alias instead of Q1. App A and App B don't know they are using Pub Sub. The subscriptions are created by the MQ Admin using admin commands. |
_________________
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. |
|
| Back to top |
|
|
| mqdogsbody |
| Posted: Thu May 12, 2011 5:12 am Post subject: |
|
|
Acolyte
Joined: 01 Jun 2010
Posts: 71
|
| exerk wrote: |
| If you're using WMQ V7.0, look at setting up pub/sub. QA's/QL. |
And if one is using MQ6 and no pub/sub? The impression I get from R'ing the FMs is that there is no way of doing distribution lists that is transparent to apps. MQ supports the abillity for one "put" call putting to several queues but the queues have to be opened in a special way (by setting RecsPresent and ObjectRecPtr in the MQOD). Ideally the "put" call needs to be different too. (Not sure if this is required or not.)
Have I understood the situation correctly or have I missed something?
Does MQ6 support application-transparent distribution lists?
_________________
-- mqDB -- |
|
| Back to top |
|
|
| exerk |
| Posted: Thu May 12, 2011 5:17 am Post subject: |
|
|
Jedi Council
Joined: 02 Nov 2006
Posts: 6339
|
WMQ V6.0 also has a Pub/Sub engine.
_________________
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. |
|
| Back to top |
|
|
| mqdogsbody |
| Posted: Thu May 12, 2011 5:26 am Post subject: |
|
|
Acolyte
Joined: 01 Jun 2010
Posts: 71
|
| exerk wrote: |
| WMQ V6.0 also has a Pub/Sub engine. |
Yes, but does MQ6 support the DEFINE SUB, DEFINE TOPC and the queue TARGTYPE(TOPIC) facilities that (IIUIC) Peter Potkay's solution seems to rely on? I suspect not. |
|
| Back to top |
|
|
| exerk |
| Posted: Thu May 12, 2011 5:34 am Post subject: |
|
|
Jedi Council
Joined: 02 Nov 2006
Posts: 6339
|
| mqdogsbody wrote: |
| Yes, but does MQ6 support the DEFINE SUB, DEFINE TOPC and the queue TARGTYPE(TOPIC) facilities that (IIUIC) Peter Potkay's solution seems to rely on? |
No, it doesn't, which is why I stated "...If you're using WMQ V7.0, look at setting up pub/sub QA's/QL..." and not "...If you're using WMQ V6.0 or above, look at setting up pub/sub QA's/QL..."
_________________
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. |
|
| Back to top |
|
|
| mqjeff |
| Posted: Thu May 12, 2011 5:37 am Post subject: |
|
|
Grand Master
Joined: 25 Jun 2008
Posts: 17447
|
| mqdogsbody wrote: |
| Does MQ6 support application-transparent distribution lists? |
No version of MQ supports application-transparent distribution lists.
Distribution lists are application level objects.
Using Pub/Sub in v7 IS NOT THE SAME THING as using a distribution list. It's using pub/sub. It happens that MQ v7 makes using pub/sub transparent at the application level...
Using a distribution list ensures that every destination gets an exact copy of the same message. Using pub/sub ensures that every destination gets a unique copy of the same message.
For v6, the smartest approach is to configure a new application that can forward messages to more than one queue (whether using a distribution list or not), and then put this application IN FRONT of the existing application.
It should merely require altering the application's configuration to point it at a new queue and then restarting it.
If you believe that would require "a production change" and thus an outage, well, sorry, but all of your other choices (aka mirror queue) ALSO REQUIRE that.
Please migrate to v7, as well. |
|
| Back to top |
|
|
| mqdogsbody |
| Posted: Thu May 12, 2011 6:35 am Post subject: |
|
|
Acolyte
Joined: 01 Jun 2010
Posts: 71
|
Thanks Jeff. You've told me pretty much what I needed to know.
| mqjeff wrote: |
| It happens that MQ v7 makes using pub/sub transparent at the application level... Using a distribution list ensures that every destination gets an exact copy ... |
OK, I can see the differences, but the transparent pb/sub would be sufficient for the immediate need, if only we had MQ7.
| mqjeff wrote: |
| For v6, the smartest approach is to configure a new application that can forward messages to more than one queue |
I told them they might have to do that, but I wanted to be sure I hadn't missed something.
| mqjeff wrote: |
| If you believe that would require "a production change" and thus an outage, well, sorry, but all of your other choices (aka mirror queue) ALSO REQUIRE that. |
It's a question on minimizing the work required. Resources are more than usually limited at the moment.
| mqjeff wrote: |
| Please migrate to v7, as well. |
I wish... and it's not just MQ we are behind with!
_________________
-- mqDB -- |
|
| Back to top |
|
|
| PeterPotkay |
| Posted: Thu May 12, 2011 6:46 am Post subject: |
|
|
Poobah
Joined: 15 May 2001
Posts: 7722
|
| mqjeff wrote: |
Using a distribution list ensures that every destination gets an exact copy of the same message. Using pub/sub ensures that every destination gets a unique copy of the same message.
|
Jeff, you're talking about Message IDs and Correlation IDs, right?
_________________
Peter Potkay
Keep Calm and MQ On |
|
| Back to top |
|
|
| mqjeff |
| Posted: Thu May 12, 2011 7:15 am Post subject: |
|
|
Grand Master
Joined: 25 Jun 2008
Posts: 17447
|
| PeterPotkay wrote: |
| mqjeff wrote: |
Using a distribution list ensures that every destination gets an exact copy of the same message. Using pub/sub ensures that every destination gets a unique copy of the same message.
|
Jeff, you're talking about Message IDs and Correlation IDs, right? |
 |
|
| Back to top |
|
|
| mqjeff |
| Posted: Thu May 12, 2011 7:17 am Post subject: |
|
|
Grand Master
Joined: 25 Jun 2008
Posts: 17447
|
| mqdogsbody wrote: |
| mqjeff wrote: |
| If you believe that would require "a production change" and thus an outage, well, sorry, but all of your other choices (aka mirror queue) ALSO REQUIRE that. |
It's a question on minimizing the work required. Resources are more than usually limited at the moment. |
it'd be a ten minute hack on amqsput0.c to change it to support a large message buffer and write to two queues rather than one. |
|
| Back to top |
|
|
| mqdogsbody |
| Posted: Thu May 12, 2011 7:42 am Post subject: |
|
|
Acolyte
Joined: 01 Jun 2010
Posts: 71
|
| mqjeff wrote: |
| it'd be a ten minute hack on amqsput0.c to change it to support a large message buffer and write to two queues rather than one. |
It would! But such a service would be one more service for people to not know about, to document in a a support card, to configure, to add to system start/stop scripts etc etc :-( Plus the build/release/test time.
And I'd have to hack in our standard framework stuff too.
Of course, a transparent DL would also require a change request, test evidence, approvals etc, but probably less than adding a brand new service.
But, that all said, I suspect I will find myself doing that 10-minute hack some time soon. |
|
| Back to top |
|
|
| mqdogsbody |
| Posted: Thu May 12, 2011 7:43 am Post subject: |
|
|
Acolyte
Joined: 01 Jun 2010
Posts: 71
|
| exerk wrote: |
| No, it doesn't |
So I am left wondering how your comment helps me. |
|
| Back to top |
|
|
| mqjeff |
| Posted: Thu May 12, 2011 7:51 am Post subject: |
|
|
Grand Master
Joined: 25 Jun 2008
Posts: 17447
|
| mqdogsbody wrote: |
| mqjeff wrote: |
| it'd be a ten minute hack on amqsput0.c to change it to support a large message buffer and write to two queues rather than one. |
It would! But such a service would be one more service for people to not know about, to document in a a support card, to configure, to add to system start/stop scripts etc etc  Plus the build/release/test time.
And I'd have to hack in our standard framework stuff too.
Of course, a transparent DL would also require a change request, test evidence, approvals etc, but probably less than adding a brand new service.
But, that all said, I suspect I will find myself doing that 10-minute hack some time soon. |
You'd again have most of the same issues using mirrorq, but it's worth a review. |
|
| Back to top |
|
|
| mqdogsbody |
| Posted: Thu May 12, 2011 8:01 am Post subject: |
|
|
Acolyte
Joined: 01 Jun 2010
Posts: 71
|
| mqjeff wrote: |
| You'd again have most of the same issues using mirrorq, but it's worth a review. |
mirrorq?
_________________
-- mqDB -- |
|
| Back to top |
|
|
|
|
