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Multiple sender channels running to common receiver channel |
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vinay_s_s |
Posted: Wed Apr 20, 2011 8:45 am Post subject: Multiple sender channels running to common receiver channel |
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 Apprentice
Joined: 17 Nov 2008 Posts: 39
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Hi MQ Experts,
Here is a weird situation, which we came across and tried to reproduce it. It worked. Here is the scenario.
1. We have a small MQ cluster with two queue managers on two different nodes. Both the queue managers are full repositories.
2. Each cluster queue manager has a normal sender channel (not cluster sender channel) definition - A.B.1.
3. The sender channel in each of the clustered queue manager is pointed to the same queue manager (B) on the receiving side.
4. Queue manager 'B' has a single definition of the receiver channel A.B.1 (you cannot create a second one with the same name though ).
5. There are 3 queue managers in this integration - A, B, C. A and C send messages to B). A and C are clustered and B is not part of this cluster. On A and C, we have sender definitions - A.B.1 and on B we have the receiver definition - A.B.1
6. Operating system - Windows 2003, Windows 2008 Servers
7. MQ version 6 on Windows 2003 (6.0.2.7), MQ version 7 on Windows 2008 (7.0.1.3).
Here is the issue.
1. When we start the sender channels on both the clustered queue managers, both the channels start and get into 'Running' state successfully.
Question - Why is this happening? (This should not happen).
2. At the receiving side, it is automatically adding a new instance of the receiver channel. If we check the current status of the channel, it displays 2 with different sequence number on each instance. For example, if there are 10 messages sent from 1, 3 messages sent from 2, the receiver channel instances will show these exactly.
Question - Is this how MQ is designed to behave?
3. We tried deleting the receiver channel and define a new one. After we reset the sender sequence numbers, again the sender at both ends just run fine if started.
4. This also worked out on non clustered queue managers with
a. Two queue managers with same name on different nodes having a sender channel pointing to a single receiver channel on a different node.
b. Two queue managers with different names on different nodes having a sender channel pointing to a single receiver channel on a different node.
5. We tried creating 2 more sender channels on different queue managers pointing to the same receiver channel, still it worked. When we checked the status of the receiver channel, there were 4 instances, each instance with different sequence numbers.
The question now is -
Is this a bug in MQ or is it a feature?
Just wanted to check if any one has faced this? You can try out and let us know any feed back, so that we can bring this to IBM's notice.
If required, I can send the screen shots.
Thanks in advance for your responses.
Have a great day,
Vinay S |
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Vitor |
Posted: Wed Apr 20, 2011 8:58 am Post subject: Re: Multiple sender channels running to common receiver chan |
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 Grand High Poobah
Joined: 11 Nov 2005 Posts: 26093 Location: Texas, USA
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vinay_s_s wrote: |
1. When we start the sender channels on both the clustered queue managers, both the channels start and get into 'Running' state successfully.
Question - Why is this happening? (This should not happen). |
So to be clear:
- Queue manager A has a sender channel A.B.1 pointing to queue manager B
- Queue manager C has a sender channel A.B.1 pointing to queue manager B
- Queue manager B has a receiver channel A.B.1
Aside from the naming convention (surely one of the channels should be C.B.1?) there's nothing wrong with this. If the channels were just called B even the naming convention would fit.
So the channels starting should happen. Why should it not?
vinay_s_s wrote: |
2. At the receiving side, it is automatically adding a new instance of the receiver channel. If we check the current status of the channel, it displays 2 with different sequence number on each instance. For example, if there are 10 messages sent from 1, 3 messages sent from 2, the receiver channel instances will show these exactly.
Question - Is this how MQ is designed to behave? |
Yes, because to maintain integrity and prevent message loss the receiver MCA must handshake with both of the sender MCAs.
vinay_s_s wrote: |
3. We tried deleting the receiver channel and define a new one. After we reset the sender sequence numbers, again the sender at both ends just run fine if started. |
They will, because the scenario is valid. There's been a number of discussions in here about how good an idea it is, and IMHO the conclusion was "it depends".
vinay_s_s wrote: |
4. This also worked out on non clustered queue managers with
a. Two queue managers with same name on different nodes having a sender channel pointing to a single receiver channel on a different node.
b. Two queue managers with different names on different nodes having a sender channel pointing to a single receiver channel on a different node. |
What's "nodes" here? Is this some kind of HA setup?
vinay_s_s wrote: |
5. We tried creating 2 more sender channels on different queue managers pointing to the same receiver channel, still it worked. When we checked the status of the receiver channel, there were 4 instances, each instance with different sequence numbers. |
Yes, because each sender channel has it's own MCA. See my comment above.
vinay_s_s wrote: |
Is this a bug in MQ or is it a feature? |
Neither really; it's one valid way of configuring things. It's possibly not the most common way. A feature if you press the point.
vinay_s_s wrote: |
Just wanted to check if any one has faced this? You can try out and let us know any feed back, so that we can bring this to IBM's notice. |
I've seen it done on a number of sites. It has strengths & weaknesses and the search will turn up discussions which expound them.
I'm fairly sure IBM know about this.  _________________ Honesty is the best policy.
Insanity is the best defence. |
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vinay_s_s |
Posted: Thu Apr 21, 2011 8:33 pm Post subject: Re: Multiple sender channels running to common receiver chan |
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 Apprentice
Joined: 17 Nov 2008 Posts: 39
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Vitor wrote: |
What's "nodes" here? Is this some kind of HA setup?
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These are just non-HA, non-MSCS, non-MQ clustered independent windows 2003 and 2008 servers. |
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