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| WAS MDB's and MQ Failover using CCDT |
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| vivica12 |
 Posted: Thu Apr 02, 2009 6:15 am Post subject: WAS MDB's and MQ Failover using CCDT |
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Acolyte
Joined: 13 Jul 2007
Posts: 58
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We are defining our WAS and MQ failover procedures and code examples for the enterprise. In doing this, we have discovered a scenario that goes against the concept of failover, and we end up with stranded messages.
The Scenario is described below, Can anyone assist. Are we doing something wrong, is this an MDB problem?
1. we have 2 queue managers - primary and secondary
2.puts and gets happening on primary
3.primary goes down OR Channel is disabled
4.puts and gets now happening on secondary
5. primary comes up, puts now happening on primary because the MQ connection factory detects an active primary, our gets using MDBs are still listening to the secondary. All responses for all PUTS here on are lost.This is a disaster as we lose state and there is no error recovery. This is even true with a min 0 in the connection pool and waiting 30 mins for no activity.
The limitation here is MDB cannot switch over to primary.
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| fjb_saper |
| Posted: Thu Apr 02, 2009 3:04 pm Post subject: Re: WAS MDB's and MQ Failover using CCDT |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| vivica12 wrote: |
We are defining our WAS and MQ failover procedures and code examples for the enterprise. In doing this, we have discovered a scenario that goes against the concept of failover, and we end up with stranded messages.
The Scenario is described below, Can anyone assist. Are we doing something wrong, is this an MDB problem?
1. we have 2 queue managers - primary and secondary
2.puts and gets happening on primary
3.primary goes down OR Channel is disabled
4.puts and gets now happening on secondary
5. primary comes up, puts now happening on primary because the MQ connection factory detects an active primary, our gets using MDBs are still listening to the secondary. All responses for all PUTS here on are lost.This is a disaster as we lose state and there is no error recovery. This is even true with a min 0 in the connection pool and waiting 30 mins for no activity.
The limitation here is MDB cannot switch over to primary. |
You should not be using MDB for a request / reply model.
The server part in a primary / failover needs to run the MDB on both the primary and the failover. So when one goes down all the admin needs to do when it comes back up is to restart the mdb.
You CANNOT use the CCDT for the MDBs.
Have fun 
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| vivica12 |
| Posted: Thu Apr 02, 2009 5:49 pm Post subject: |
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Acolyte
Joined: 13 Jul 2007
Posts: 58
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You should not be using MDB for a request / reply model.
The server part in a primary / failover needs to run the MDB on both the primary and the failover. So when one goes down all the admin needs to do when it comes back up is to restart the mdb.
You CANNOT use the CCDT for the MDBs
You say that 'you should not be using MDB for request/reply'..i didn't say this was request/reply. We have app A that is putting to Q1 and app B is getting from Q1 using an MDB. So if the primary server for Q1 fails both app A and B are able to switch to secondary via the CCDT configuration.
so first point we can use the CCDT for MDB's, so i wanted to clarify if you are saying you cannot, or you should not -- those are different.
In this scenario with app A and B now using Q1 on secondary, well if primary comes back online and app A now puts to Q1 on primary, app B is listening on secondary and the messages never get processed. So it's not request/reply, it's an app sending a message that needs to get processed.
Any more input with that explanation?
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