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From TonyTobin <cavanaght...@hotmail.com>
Subject Re: Understanding the Exclusive Consumer
Date Thu, 22 Apr 2010 09:13:47 GMT

Thanks Gary,

That makes sence.


Are there any decent links on the different strategies for message
persistence within consumers. 

A consumer is building up messages and then falls over, how the other
consumer takes over. Managing failover within the consumer cluster.

Thank you for your help

Tony


Gary Tully wrote:
> 
> 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
> 
> 

-- 
View this message in context: http://old.nabble.com/Understanding-the-Exclusive-Consumer-tp28288049p28326125.html
Sent from the ActiveMQ - User mailing list archive at Nabble.com.


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