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From Gary Tully <gary.tu...@gmail.com>
Subject Re: Understanding the Exclusive Consumer
Date Thu, 22 Apr 2010 09:01:52 GMT
yes, but the consumers all have to be present, they already content for the
lock.

imagine an app that has a hot standby, both the primary and hot standby have
started consumers. The broker delivers messages to the first consumer, the
primary (because it got there first) and when/if it fails, it will deliver
messages to the second consumer (the hot standby). So the broker chooses but
only from among the current active consumers.

On 22 April 2010 09:09, TonyTobin <cavanaghtony@hotmail.com> wrote:

>
> Thank you for your reply Gary,
>
> In the documentation for exclusive Consumer, it states
>
> "The broker will pick a single MessageConsumer to get all the messages for
> a
> queue to ensure ordering. If that consumer fails, the broker will auto
> failover and choose another consumer"
>
> Doesnt this mean that the broker selects the next consumer, rather than the
> consumer going for the lock.
>
> Thanks again for your reply.
>
>
>
> Gary Tully wrote:
> >
> > exclusive consumer is a simple solution to the case where there are many
> > consumers but only one should be active at any time. Rather than some
> > application logic keeping track of which one should be active, they all
> > have
> > a go and the broker ensures exclusive access.
> >
> > So each consumer connects but only one of them gets the exclusive lock
> and
> > gets the messages. When it dies, the next consumer in line gets the
> > messages. If effectively allows consumers to stack waiting for the
> current
> > consumer to die.
> >
> > On 21 April 2010 16:35, TonyTobin <cavanaghtony@hotmail.com> wrote:
> >
> >>
> >> In the ActiveMQ doc http://activemq.apache.org/exclusive-consumer.htmlit
> >> states
> >>
> >> The broker will pick a single MessageConsumer to get all the messages
> for
> >> a
> >> queue to ensure ordering. If that consumer fails, the broker will auto
> >> failover and choose another consumer.
> >>
> >> Is this a consumer master slave relationship, the broker will send all
> >> messages to the designated consumer, and the consumer passes the
> messages
> >> onto the other consumers. Or does the broker send the messages to all
> the
> >> consumers, but only one consumer acknowledges them,  so if that consumer
> >> dies the other consumer can then pick up where the first consumer died.
> >>
> >> If there is a link that covers Queue consumer clusters in more depth, I
> >> would be grateful if you could post it.
> >>
> >> Thanks Tony
> >>
> >> Thanks Tony
> >>
> >>
> >> --
> >> View this message in context:
> >>
> http://old.nabble.com/Understanding-the-Exclusive-Consumer-tp28288049p28288049.html
> >> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
> >>
> >>
> >
> >
> > --
> > http://blog.garytully.com
> >
> > Open Source Integration
> > http://fusesource.com
> >
> >
>
> --
> View this message in context:
> http://old.nabble.com/Understanding-the-Exclusive-Consumer-tp28288049p28325468.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
>


-- 
http://blog.garytully.com

Open Source Integration
http://fusesource.com

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