How do I get old messages from RabbitMQ?

Question

I'm publishing RabbitMQ messages using Bunny (Ruby) like this:

x.publish("Message !"+n.to_s, :routing_key => 'mychannel')

and subscribing like this:

    ch   = conn.create_channel
x    = ch.topic('fling',durable: true)
q    = ch.queue("")
q.bind(x, :routing_key => 'mychannel')


puts "Waiting for messages."
q.subscribe( :block => true) do |delivery_info, properties, body|
puts " [x] Received #{body}, message properties are #{properties.inspect}"

Once I start the subscriber, it immediately receives any messages which are sent. However, if I send messages without starting the subscriber, they aren't received when I start the subscriber (whether the sender is still pushing messages, or not).

Is it possible to go back through the queue and receive messages that were sent in the past, when no subscribers were listening?

Muggins

Answer 1

You're making a new queue each time you start the consumer! So when you restart the consumer, the new queue gets new messages, but doesn't have previous ones.

Do this:

q    = ch.queue("myqueue",durable: true)

instead of this:

q    = ch.queue("")

Then, as soon as you restart the consumer, it will immediately get all backed-up messages as fast as it can.

Muggins

How long duration does RabbitMQ do back-up the messages? – Moulin

I don't understand what you mean by "back up." – Muggins

What was the meaning of 'backed-up messages' you used then? – Moulin

Backed-up messages means messages that are delayed. Are you asking "how long does RabbitMQ delay the messages?" It delays them until you collect them! How long is a piece of string... – Muggins

Answer 2

Queue has to be parameter called durable its never losses

ch.queue(queue, {
       durable: true
     });
instead 
q    = ch.queue("")

Girardi

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