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From Dejan Bosanac <de...@nighttale.net>
Subject Re: Automatic recovery when using Message Groups
Date Thu, 12 Feb 2009 16:36:17 GMT
Hi Luis,

I'm not sure this is the correct use case. Consumers don't explicitly know
what groups they will be assigned to when they first subscribe, so there is
usually no difference what consumer is consuming messages from what group.
When your consumer goes down, the other one will take its group and
everything will work fine.

Maybe we should add a feature that would instruct the broker to try to make
an even distribution of groups among consumers. So when the new consumer is
subscribed, the broker will see if it can reassign certain groups to it
depending on the number of groups assigned to existing consumers. I have an
impression, that this would make for you as well?

Cheers
--
Dejan Bosanac

Open Source Integration - http://fusesource.com/
ActiveMQ in Action - http://www.manning.com/snyder/
Blog - http://www.nighttale.net


On Thu, Feb 12, 2009 at 4:03 PM, kalki70 <lrg@pobox.com> wrote:

>
> Hi, Dejan,
>
> My opinion is that the functionality of Message Groups is partially broken
> if there is no automatic recovery. What should the user do? Restart
> ActiveMQ
> ? :-(
> I don't think it is so hard to implement. Upon subscription the consumer
> could be informed its consumer id, which can be an optional parameter for
> subscriptions. It would be responsibility of the consumer, when it
> subscribes again, to provide its previous consumer id, if it wants to
> assume
> the identity of the previous consumer.
> If it doesn't provide it, it will be assigned a new consumer id. Assigned
> consumer ids that are not claimed back could be released based on some
> criteria, for instance, they could have an expiration time.
>
> What do you think?
>
> Best regards,
>
> Luis
>
> Dejan Bosanac wrote:
> >
> > Hi Luis,
> >
> > unfortunately there is no way for the consumer to recover its previous
> > message groups. I'm not sure how this could be implemented, since the
> > consumer will have a new consumer id upon recovery, so it would be
> > impossible to relate it to the previous subscription.
> >
> > Cheers
> > --
> > Dejan Bosanac
> >
> > Open Source Integration - http://fusesource.com/
> > ActiveMQ in Action - http://www.manning.com/snyder/
> > Blog - http://www.nighttale.net
> >
>
> --
> View this message in context:
> http://www.nabble.com/Automatic-recovery-when-using-Message-Groups-tp21938109p21977778.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
>

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