[rabbitmq-discuss] a possibility of AMQP/RabbitMQ extension?

Fri Nov 6 10:28:18 GMT 2009

Igor,

Several people have asked about browsing queues, and being able to
read or extract selected messages out of order.

It's an interesting feature because it represents a different way of
thinking about messaging queues: as containers for resources, instead
of as streams of values.  It's not obvious whether this difference is
always fundamental.

As you can see from Paul's post below, our current implementation,
which follows the spirit of AMQP as well as the letter, forces you to
take a streams based view.  This leads to a number of contortions if
you want to reach into the middle of the stream without disrupting
other consumers.

If you have any thoughts on this let us know.

Re your other question about 'modifying AMQP proto': I think the
safest approach is to say a bit more about what you would like to do,
on this list.  We can advise.  I would not want to discourage anyone
from messing with the code or the innards of AMQP... but it's 'at your
own risk' ;-)

alexis

On Fri, Nov 6, 2009 at 9:11 AM, Paul Jones <pauljones23 at gmail.com> wrote:
> Igor,
>
> You can get at the messages, but not in a particularly nice or scalable way.
> If you setup a consumer on the queue without auto-acknowledgment, then
> you'll receive all of the messages. If you then only acknowledge message B,
> and then close the channel, the messages will be returned to the queue (and
> redelivered to other consumers). This probably isn't an approach that is
> recommended however, since it starts to get very messy once you break beyond
> simplified examples such as the one you've just posted.
>
> Paul.
>
> On Fri, Nov 6, 2009 at 8:58 AM, Igor Goryachev <igor at goryachev.org> wrote:
>>
>> Alexis Richardson <alexis.richardson at gmail.com> writes:
>>
>> >> BTW, is it safe to implement i.e. custom methods or some other 'core'
>> >> features?
>> >
>> > I'm not sure what you mean - do you mean modifying the source of the
>> > broker?  Or something else?
>>
>> I meant modifying AMQP proto itself (then of course modifying broker and
>> client source core accordingly).
>>
>>
>> Well, yet another dummy question. Is it possible to get particular
>> message from the queue? I.e. there three messages waiting in queue,
>> 'message_a', 'message_b' and 'message_c'. Is there any chance to get
>> 'message_b' while not even touching other messages? I guess it is
>> impossible, but I want to get sure.
>>
>>
>> --
>>    Igor Goryachev              E-Mail/Jabber: igor at goryachev.org
>>
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>
>
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