[rabbitmq-discuss] question on exchange type

[Ben Hood]

Daniel,

On Tue, Feb 3, 2009 at 12:06 AM, Daniel N <has.sox at gmail.com> wrote:
> Would a selector be able to be applied to things like delayed routing (use
> it after an activation time is reached) or priority queuing?

Interesting concept - TTL based routing :-)

I haven't heard of that one, but I imagine that you could specify some
kind of routing rule that is executed after a TTL expires. There are a
few considerations for this:

- The implementation of TTLs in Rabbit has just kicked off but there
is not ETA on this;
- The current thinking is to just turf the message after expiry, so
we'd need to consider how and why you might want to configure
post-routing;
- TTLs are will probably expire after having been resident in a queue,
i.e. after routing has taken place - so you would have to apply a
second phase of routing;
- Then you would have to think about the types of routing that could
applied here - off the top of my head, I don't see why any routing
algorithm is ruled out per se, but this may require analysis;
- Another approach would be to build some kind of exchange in a
compositional fashion - so that you build an macro-exchange out of a
micro-exchange/binding/queue combination - essentially this would
require AMQP to eat its own dogfood - this might be an application for
an embedded client;

As for combining priority queueing and selectors, I'm not quite sure I
follow this example. Can you elaborate?

Ben