[rabbitmq-discuss] Publisher Confirms in mirrored queues

Thu Jul 19 18:43:51 BST 2012

Thank You Tim.

On Wed, Jul 18, 2012 at 4:52 PM, Tim Watson <watson.timothy at gmail.com>wrote:

>
> On 18 Jul 2012, at 20:15, Prashanth <meetprashanth437 at gmail.com> wrote:
>
> Hi all,
>
>
> Hi
>
> I was confused after reading the publisher confirm documentation.
>
> Similarly, messages published by clients using publisher confirms<http://www.rabbitmq.com/extensions.html#confirms> will
> still be confirmed correctly even if the master (or any slaves) fail
> between the message being published and the message being able to be
> confirmed to the publisher. Thus from the point of view of the publisher,
> publishing to a mirrored-queue is no different from publishing to any other
> sort of queue. It is only consumers that need to be aware of the
> possibility of needing to re-consume from a mirrored-queue upon receipt of
> a Consumer Cancellation Notification<http://www.rabbitmq.com/extensions.html#consumer-cancel-notify>
> .
>
>
> So from the publisher's point of view, it looks like just one queue and
> the confirm means every surviving mirror has received and accepted the
> message.
>
> Equally, in the case of publisher confirms, a message will only be
> confirmed to the publisher when it has been accepted by all of the mirrors.
> It is correct to think of the semantics as being the same as a message
> being routed to multiple normal queues, and of a transaction with
> publications within that similarly are routed to multiple queues.
>
> After reading the above lines. Now I am confused about the publisher
> confirms. The first paragraph says that publishing to mirrored queues is
> like publishing to each individual queue.
>
>
> Where does it say that? It says that publishing to mirrored queues is
> atomic with respect to confirms.
>
> Messages are published to all the queues and each queue sends publisher
> confirms.
>
>
> That's not what it says. It says that all queues will have the message
> before a confirm is sent to the publisher from the queue to which it
> originally published.
>
> The publisher knows next to nothing about the mirrors.
>
> In the second paragraph it says a message will only be confirmed to the
> publisher when it has been accepted by all of the mirrors.
> Those two paragraph looks like they say two opposite things.
>
> Please, correct me if I am wrong.
>
>
> Thanks,
> Prashanth.
>
>
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