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| brgmo |
 Posted: Tue Jun 26, 2007 2:59 am Post subject: Transmission queue and Channel share |
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Master
Joined: 03 Jun 2002
Posts: 227
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Hi All,
Can i share a transmission queue and a channel across various remote queues. If i can share, then what will be the adavantages or disadvantages of that.
Regards
brgmo. |
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| Vitor |
| Posted: Tue Jun 26, 2007 3:08 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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It's typical to do so. All traffic for a given queue manager will flow through the xmitq/channel defined, even though routed via different remote queues. This also allows for automatic name resolution.
The only time you'd usually want to break this pattern is if you're defining multiple routes between 2 queue managers for network load / SLA type issues. The example quoted in the Intercommunication manual (which descibes all this) is high priority request reply over 1 channel that uses high speed fibre while low priority asyncronous work goes over the other channel via copper.
Check out the manual for full details.
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| brgmo |
| Posted: Tue Jun 26, 2007 3:24 am Post subject: |
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Master
Joined: 03 Jun 2002
Posts: 227
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But what if the channel stops and then the entire business comes down because all the remote queues are using the same setup for transmission queue and channel.
Also, if i need to get performance then having a separate channels for each queue makes sense.isn't it?
Also if the same TX queue is used and we have separate channels sharing then will there be any concurrency problems i.e. only one channel will be able to access the queue at one time. |
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| Vitor |
| Posted: Tue Jun 26, 2007 3:35 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| brgmo wrote: |
| But what if the channel stops and then the entire business comes down because all the remote queues are using the same setup for transmission queue and channel. |
This is where you'll both deploy your monitoring and ensure the channels are set for automatic recovery.
| brgmo wrote: |
Also, if i need to get performance then having a separate channels for each queue makes sense.isn't it? |
Only if you have separate routes over the network for the channels to follow, as I described above. Otherwise whatever causes one channel to stop is likely to bring down the others; MCAs don't just stop!
| brgmo wrote: |
Also if the same TX queue is used and we have separate channels sharing then will there be any concurrency problems i.e. only one channel will be able to access the queue at one time. |
You can't share channels and xmitqs. They have a 1-1 relationship.
To answer your "entire business comes crashing down" point; this is why you use MQ. Simple network failures are easier to recover from (try recovering a TCP/IP based system as quickly as you can recover a channel), assuming recovery is not automatic. Also if your business is so vunerable to downtime (a high volume stockbroker for instance), then the business interuption plan will cater for this siutation with failover networks, hardware, this sort of thing. Or should.
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| brgmo |
| Posted: Tue Jun 26, 2007 4:46 am Post subject: |
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Master
Joined: 03 Jun 2002
Posts: 227
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| How aabout sequence of messages on channels. Are channels FIFO based or the messages coming out can be in any order on the other end. |
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| Vitor |
| Posted: Tue Jun 26, 2007 4:53 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| brgmo wrote: |
| How aabout sequence of messages on channels. Are channels FIFO based or the messages coming out can be in any order on the other end. |
Sequence of messages should be irrelevant in any MQ set up. It's called message affinity and is a very bad thing, for reasons that you'll find discussed if you search for the term in here.
AFAIK messages are delivered in batch order, but order within batch is not defined. A common thing is to reduce batch size to 1 to enforce message sequence, which it does. While killing your performance stone dead!! 
Design message affinity out of your system.
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