[rabbitmq-discuss] Exclusive consumers via STOMP
simon at rabbitmq.com
Fri Apr 25 14:46:28 BST 2014
On 24/04/2014 12:53, Nagy, Attila wrote:
>> Possibly. In RabbitMQ consumer exclusivity means no more than 1
>> consumer can
>> be added on a given queue. This includes federation links for
>> federated queues.
> Exactly what I need.
It's worth noting that no more than one consumer can be on one
individual queue, not one set of queues that are federated together.
>> I need to run some tests to see how queue federation works in such case.
> How does queue federation consumes from the queue? I mean it's not just
> a normal consumer, because if nobody is on the other side, it won't
> consume. Or it just starts consuming if there are somebody?
> But there are even more conditions need to be true to get messages to it
> (described on the federation page), so this is not so simple.
It is a low priority (http://www.rabbitmq.com/consumer-priority.html)
consumer that starts and stops according to whether the downstream
> Also, if consumer A on broker A consumes from the queue, but broker B
> can't consume from broker A's queue, I assume consumer B on broker B
> will be able to consume from the queue on broker B, so this essentially
> doesn't work in a federated setup.
> Or is there something which disallows this?
No. And really there couldn't be; in order to do that you'd need some
distributed shared state, which would have to be Consistent and
Available, thius not Partition Tolerant, thus not really compatible with
how federation works.
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