[rabbitmq-discuss] Using RabbitMQ Beyond Queueing

[Peter Silva]

On Wed, Nov 12, 2008 at 7:36 AM, Ben Hood <0x6e6562 at gmail.com> wrote:

> Peter,
>
> On Wed, Nov 12, 2008 at 11:54 AM, Peter Silva <Peter.A.Silva at gmail.com>
> wrote:
> > read about no_ack=false...
> > you mean there is no window for acknowledgements?
> > you send one, wait for acknowledgment, then send the next?
> >
> > latency will really kill bandwidth on long links.  was hoping that one
> could
> > send a large number of messages, and have them acknowledged later (like
> TCP
> > does.)
> >
> > The AMQP spec seems to allow for that, I took it for granted that rabbit
> did
> > that....
>
> I don't *think* that Dmitriy was implying that there has to be a lock step.
>
> This is what the protocol says about the basic.ack command:
>
> "If set to 1, the delivery tag is treated as "up to and including", so
> that the client can acknowledge multiple
> messages with a single method. If set to zero, the delivery tag refers
> to a single message. If the multiple
> field is 1, and the delivery tag is zero, tells the server to
> acknowledge all outstanding messages. "
>
> HTH,
>

say you have a 5000 km. link.  you can fit oh... several hundred messages in
flight (on the fibre between the two points.)  It would be better to issue
periodic group acknowledgements, but single message acknowledgements would
work.  I don't get how 'acknowledge all outstanding messages'  works.  How
does the receiver know what is in-flight?
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