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| pcelari |
 Posted: Wed May 13, 2015 9:45 am Post subject: MQ Pub/Sub - possible to publish to every node in the tree? |
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Chevalier
Joined: 31 Mar 2006
Posts: 411
Location: New York
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It might sounds a naïve question.
I wonder if it is possible to publish in such a way that every node in the topic tree receives the publication - like a dynamic broadcast to all subscription point.
thanks much.
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pcelari
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| Vitor |
| Posted: Wed May 13, 2015 9:55 am Post subject: Re: MQ Pub/Sub - possible to publish to every node in the tr |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| pcelari wrote: |
| I wonder if it is possible to publish in such a way that every node in the topic tree receives the publication - like a dynamic broadcast to all subscription point. |
It's an odd question - why would you want to send a publication on a topic that the subscriber has not indicated an interest in?
To illustrate:
A subscriber has registered with a topic '/Cricket/WinningTeams/England'. Clearly they're not expecting much trafic, and they're certainly not expecting anything on the topic of Soccer, winning or losing. What would the kind of generic broadcast you're describing do to them, and what are you wishing it would do?
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| pcelari |
| Posted: Wed May 13, 2015 10:09 am Post subject: |
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Chevalier
Joined: 31 Mar 2006
Posts: 411
Location: New York
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Hi Vitor, thanks for responding.
Yes, it might be an odd wish.
What I have in mind is something like an alert sent to every node in the tree declaring something like "the pub/sub system will be down to 20 minutes". I'm not sure if such is a reasonable request after all.
thanks a lot for sharing your insight.
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pcelari
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| Vitor |
| Posted: Wed May 13, 2015 10:15 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| pcelari wrote: |
| What I have in mind is something like an alert sent to every node in the tree declaring something like "the pub/sub system will be down to 20 minutes". I'm not sure if such is a reasonable request after all. |
I did wonder if it was something like that.
Aside from the surmountable problems of having all possible subscribers coded to respond to such an alert, what value does it offer? There isn't a "pub/sub system", there are 1-n queue managers with 1-n subscribers connected to them. If the whole "system" is going down, that's a scheduled outage. If one publisher is going down, that's business as usual. No subscriber should be expecting publications to arrive, and all subscribers should cater by design for the scenario where their queue manager experiences a crisis and/or the network unexpectedly disconnects them.
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| Vitor |
| Posted: Wed May 13, 2015 10:20 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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If you had a real or percieved use case for this (and I can understand your receipt of a "requirement" from a business area to know if "the system is working"), I'd be inclined to set up a topic called "Availability" with a retained publication. Interested applications could then subscribe to it, with alerts as you describe being published to it by your administrators or your monitoring software.
But if someone has a genuine need to be that tightly coupled with their information provider, pub/sub is probably not the best model for them to be using.
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| mqjeff |
| Posted: Wed May 13, 2015 10:38 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| Aside from the slightly confusing requirement, there should be information about how to do this in the KC. |
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| pcelari |
| Posted: Wed May 13, 2015 11:03 am Post subject: |
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Chevalier
Joined: 31 Mar 2006
Posts: 411
Location: New York
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| Vitor wrote: |
| But if someone has a genuine need to be that tightly coupled with their information provider, pub/sub is probably not the best model for them to be using. |
I had a similar, yet vague feeling about such a request. But couldn't state it clearly as yours above.
Appreciate all the insights !
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pcelari
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| rammer |
| Posted: Thu May 14, 2015 1:27 am Post subject: Re: MQ Pub/Sub - possible to publish to every node in the tr |
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Partisan
Joined: 02 May 2002
Posts: 359
Location: England
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[quote="Vitor"]
| pcelari wrote: |
To illustrate:
A subscriber has registered with a topic '/Cricket/WinningTeams/England'. Clearly they're not expecting much trafic |
If at all any the way we are now  |
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| PaulClarke |
| Posted: Thu May 14, 2015 1:41 am Post subject: |
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Grand Master
Joined: 17 Nov 2005
Posts: 1002
Location: New Zealand
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I'm not sure I understand why the KC would need to describe this topic explicitly. If you really wanted to do this would you not just define a TOPIC say PubSubAlerts (or similar) and publish on that. Anyone who is interested in these alerts would just subscribe to it. You could, of course, generate a lot of traffic this way. One thing to consider is using Multicast. Multicast allows you to send data to large numbers of clients without needing to send each individual client it's own separate message. It is also faster. It would seem a pretty good candidate for broadcasting such status messages.
Cheers,
Paul.
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Paul Clarke
MQGem Software
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