[rabbitmq-discuss] Using RabbitMQ Beyond Queueing

[Alexis Richardson]

On Wed, Nov 12, 2008 at 12:58 PM, Peter Silva <Peter.A.Silva at gmail.com> wrote:
> On Wed, Nov 12, 2008 at 7:36 AM, Ben Hood <0x6e6562 at gmail.com> wrote:
>
>> 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. "
>
> 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?

It doesn't need to - it is telling the server to do something based on
what the server believes.

Apologies - the spec(s) is (are) not always worded to prevent all
possible misinterpretations.

alexis