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| Distribution Lists: How it works |
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| sumeet |
 Posted: Wed May 26, 2004 11:11 pm Post subject: Distribution Lists: How it works |
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Novice
Joined: 16 Mar 2004
Posts: 16
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Hello everyone,
I have recently started work on distribution lists and am not sure as to how it works.
I understand that it saves me the effort / code by allowing me to do a put to multiple destinations in one shot. What I am trying to understand is that does it allow me to save on network traffic also? 
If I am sending the same message to multiple destinations on the same queue manager, then DL will send only one message over the network and @ destination, it will replicate the message for the multiple queues. (I hope that understanding is correct.)
If I am sending message to multiple queue managers (one queue per queue manager), and all support distribution lists, then how does distribution list works. To quantify the scenario, say source is QM1 and destinations are Q2@QM2, Q3@QM3, Q4@QM4, Q5@QM5.
Does it still help me by saving on network traffic (sending one message only)?
My understanding here is that since there are multiple destinations, it will send out multiple messages (from source QM1), one for each queue manager (replication occurs only if at the same queue manager there are multiple queues).
Any clarifications on the above would be greatly appreciated.
If you could provide pointers to documentation on distribution lists, that would also be of great help.
Thanks & Regards,
Sumeet |
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| EddieA |
| Posted: Thu May 27, 2004 8:27 am Post subject: |
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Jedi
Joined: 28 Jun 2001
Posts: 2453
Location: Los Angeles
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As far as I remember, you are correct. When the Channel connection is made, both ends agree on certain settings. One of these is Distribution Lists. If the receiving end doesn't understand them, then the sending QM will break the list down and send out individual messages.
| Quote: |
| If I am sending the same message to multiple destinations on the same queue manager, then DL will send only one message over the network and @ destination, it will replicate the message for the multiple queues. (I hope that understanding is correct.) |
Absolutely.
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| If I am sending message to multiple queue managers (one queue per queue manager) |
Then the sending QM will send a copy to each, as you describe. So, you are not saving any network traffic. However, you have only done ONE Open and ONE PUT to achieve this. Instead of oner per Queue.
Cheers,
_________________
Eddie Atherton
IBM Certified Solution Developer - WebSphere Message Broker V6.1
IBM Certified Solution Developer - WebSphere Message Broker V7.0 |
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| mqonnet |
| Posted: Thu May 27, 2004 11:09 am Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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Just out of curiousity though, i have a question.
Why did you go this route at all. I mean, why do you think you need to consider "network traffic" as part of your design/discussion of distribution list puts(messages).
Unless you are doing like 100's and 1000's of MB of data transfer, which incidently is the same accross all recipients, and you have to cater to the need of handling network traffic. I dont see any specific reason why you would want to even look at this.
Is this a business requirement or you playing with DL's.
Reason i am asking all this is, i havent seen many customers using DL's. And you seem to be discussing network traffic with DL's. Just got me curious. :)
Cheers
Kumar
_________________
IBM Certified WebSphere MQ V5.3 Developer
IBM Certified WebSphere MQ V5.3 Solution Designer
IBM Certified WebSphere MQ V5.3 System Administrator |
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| sumeet |
| Posted: Thu May 27, 2004 8:37 pm Post subject: |
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Novice
Joined: 16 Mar 2004
Posts: 16
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Thanks for the clarification Eddie.
Hi Kumar,
To elaborate on my question. I had read in one of the guides that DL allows me to save code by enabling me to send out a message to multiple destinations in one shot only. It also mentioned that it sends out one message and creates copies at destination.
We have a network constraint in our project, where we are trying to minimise the amount of messages that flow to multiple systems. We thought that DL would allow us to send one message on the network and it would be replicated at the destination and hence we would save on network traffic also. (instead of sending the same message multiple times to multiple people)
But now we understand that by using DL, all we are doing is saving us some code in the application (opening a queue and putting a message and closing it) but @ network level, we are sending out multiple messages, coz the destinations are different queue managers.
| Quote: |
| Is this a business requirement or you playing with DL's. |
It was from a business perspective that we had to mix the two, network and dl together.
Cheers |
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| fjb_saper |
| Posted: Fri May 28, 2004 4:55 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Depending on your network topology you can still potentially save some network traffic
Let's say you have multiple nodes A B C D E. C D and E are hanging off B.
A being the sender you can use a DL to send to B. B has a local queue for itself and remote queues for C D and E. So your message will ultimately get to B C D and E.
Practical A and B are on different sides of the ocean for examle A is in Europe and B C D E are in the states. This way the message crosses the Atlantic only once.
Hope it helps some.
F.J.  |
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| dnaren |
| Posted: Sun Oct 10, 2004 10:34 am Post subject: |
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Apprentice
Joined: 10 Aug 2001
Posts: 45
Location: Charlotte, NC
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With Distribution lists, there is no way to specify to unique "ReplyToQueue" and "ReplyToQueueManager" for each copy of the message going to different destinations.
If your application is waiting for response messages, all of them end up in one reply queue (assuming connectivity). Your program has to rely on specifying unique MsgId/CorlID for each copy of the message via the MQOMR structure. When reading the response messges, use MsgId/CorlID to match the responses.
I just wanted to add my 2 cents.
I haven't used distribution lists but I read the programming guide hoping to take the certification test  |
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