[rabbitmq-discuss] Questions on RabbitMQ

Ralf Kistner ralf.kistner at gmail.com
Sun Oct 3 18:25:49 BST 2010

Thanks for the response.

EventMachine looks perfect for my Ruby script.

I'm already using MongoDB for other parts of my application, so I'll
use it to implement a similar approach to what you suggested.
My messages will mostly be binary data, but that shouldn't make a big

I'll use an additional consumer (on routing key "#") , to ensure that
the messages are all persisted even when my consumer is broken and
silently discards messages (this happened to me in the past).


On Sat, Sep 25, 2010 at 2:59 PM, Jon Brisbin <jon at jbrisbin.com> wrote:
> On Sep 25, 2010, at 6:07 AM, Ralf Kistner wrote:
> 2 a. Are there any recommended practices for running a (Ruby) process
> to consume messages in an infinite loop?
> Check out the AMQP stuff in Ruby. It uses EventMachine. EM will run until
> you tell it to stop, which is what you're looking for.
> 2 b. The Ruby script would occasionally be unable to process a
> message. This could be because of a temporary lock on the database, an
> invalid message from the mobile client, or a bug on the server. The
> ideal would be for these messages to be retried a few times, then
> moved to a different queue if it still fails. The messages in the
> queue could then be inspected manually, and moved back to the original
> queue when the bug was fixed.
> How would this be accomplished? Does RabbitMQ have something like a
> dead letter queue? Or would I have to move the message to a different
> queue myself (in the Ruby script), in case of an error?
> Note that I can't return any messages to the sender, I want to keep it
> on the server in a different queue.
> Redelivery is something I'm working on in my own application. I use it to
> update databases at remote locations that might or might not be online. If I
> get a timeout error, I write my message into a Riak bucket. There is a
> Quartz-based job that runs every five minutes that checks this retry bucket
> and simply deletes the messages and dumps them back into the broker. I
> haven't put it in yet, but I'm planning on implementing a "maxRetries" so
> that when a message exceeds the retry number, it will be either sent to a
> notification queue where it gets emailed, or moved to another Riak bucket
> where I can write an RSS feed over the top of it.
> 3. What is the best way to create a backup of all the message sent to
> the server? Does RabbitMQ automatically do this, or should I write an
> additional consumer to create a backup?
> A NoSQL store where you keep the entire message in JSON format seems to me
> the safest and most performant way to persist messages with enough
> information to be able to resubmit the message at a later time. I have
> security tokens in the headers (I don't use logins but tokens) and of course
> I have to capture the exchange and routing key information. I use JSON data
> for my messages, so this fits nicely together but you could also base64
> encode your data.
> You could use an additional consumer (e.g. on routing key "#") but I let the
> consumer decide whether to persist a message to Riak or not.
> Thanks!
> J. Brisbin
> http://jbrisbin.com/

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