[rabbitmq-discuss] A new exchange type

Alister Morton Alister.Morton at tradition.com
Wed Jan 28 15:30:52 GMT 2009

> Alternatively (and please note that this is purely a
> theoretical speculation on my part), is the broker itself the
> best place to run this extended functionality?
That's a very valid question.

> For example, if core broker could expose AMQP events via AMQP
> (i.e., broker itself will be sending messages to a certain
> protected exchange every time a queue is created, or consumer
> connects, or consumer disconnects, etc) plus have its runtime
> state obtainable via AMQP (again - send a request message to
> a certain exchange, get response), then I could hopefully
> implement last-value-cache scenario totally in user-space.
> (This could also help with monitoring, btw).

In order that last value caching can work, you'd need to be able to ask the broker to notify you (a publisher) whenever a queue was connected to an exchange that you'd flagged as needing last value caching, in order that the last value can be pushed again. But this last value must only be pushed to the newly connecting queue, so it would have to have some kind of flags attached to it to indicate that it was a refresh and was not to be passed to queues that had already seen it. While this is possible, I think it could add as much complexity as adding a new exchange type.

What does everyone else think?


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