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<div class="moz-cite-prefix">On 26/07/13 14:18, Matthias Radestock
wrote:<br>
</div>
<blockquote cite="mid:51F27730.3030203@rabbitmq.com" type="cite">On
26/07/13 13:25, Will Hughes wrote:
<br>
<br>
<blockquote type="cite">Another option I was thinking of to
enforce more a delay was to see if I
<br>
could chain together two queues using dead-letter-exchange
settings:
<br>
<br>
Queue A, no TTL, DLX=Exchange B (with Queue B bound to it).
<br>
Queue B, ttl of (x) seconds, DLX= Exchange A (with Queue A bound
to it).
<br>
<br>
When we NAck the mesage from Queue A, we set requeue=false.
<br>
<br>
I've not seen much discussion so far on whether it's sane to
hook up two
<br>
queues/exchanges in a loop like this.
<br>
</blockquote>
<br>
Yep, that makes perfect sense and should work well.
<br>
</blockquote>
<br>
Implemented exactly as described there, it yields an infinite loop
for unprocessable messages. You might therefore also want to keep a
count of the number of processing attempts in a header on the
message, and more thoroughly reject messages which reach some
maximum number of attempts. I think you could do the final rejection
by setting a routing key on the message when you reject it for the
last time, and having exchange B be a direct exchange which routes
to either queue B or some final deadletter queue.<br>
<br>
If you want exponential backoff in the retries, then life gets more
complicated (multiple timeout queues, selected between by a routing
key set by the consumer of A?). We are currently pussyfooting around
this issue at my company. I will report back here if we ever
implement a good solution!<br>
<br>
tom<br>
<br>
<div class="moz-signature">-- <br>
<p>Tom Anderson | Developer | +44 20 7826 4312 | <a
href="http://timgroup.com/">timgroup.com</a></p>
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