Messages on a RabbitMQ Topic Exchange queue

Question

Note: Using RabbitMQ .NET library

I have a Topic Exchange on my RabbitMQ called FXTO.HK and a binding key of FXTO.# The server publishes messages to this queue.

On the client side, the queues have a unique and random name but use the same binding key of FXTO.#

We use the Subscription class from the library on the client side which works fine: ie. the message is received by all clients at the same time.

However, in RabbitMQ management UI, the server queue (FXTO.HK) is showing to have all the messages in the queue (they are not removed from the queue).

Am I doing anything wrong in my setup? When will these messages be removed from the server queue?

Answer 1

This question is better suited to the RabbitMQ Discuss mailing list.

However, in RabbitMQ management UI, the server queue (FXTO.HK) is showing to have all the messages in the queue (they are not removed from the queue).

This strongly suggests you're not ack'ing messages after consuming them. Looking at this example, I see you need to call Subscription.Ack after each call to Subscription.Next (or start the Subscription in NoAck mode)

Answer 2

I'm not quite sure what "client" and "server" mean in your question. RabbitMQ doesn't understand clients and servers other than considering itself a server for everyone. Neither publishers nor consumers are inherently clients or servers.

You say "I have a Topic Exchange on my RabbitMQ called FXTO.HK and a binding key of FXTO.# The server publishes messages to this queue.", but that doesn't make sense. Are messages being published to the FXTO.HK exchange or some other queue? I think that confusion may be at the root of your issue:

• If your messages with FXTO.?? routing keys are being published to an exchange (i.e. you have "exchange" set in the parameters to the publish function) with one or more queues bound to it with the binding key of FXTO.#, those messages will be duplicated into each bound queue. Those messages will remain in each queue until they are consumed in no-ack mode or acknowledged. If you happen to have a queue with the same name as the exchange bound to the exchange (e.g exchange FXTO.HK is bound to queue FXTO.HK with some binding key), no special behavior will occur as a result of their sharing the same name. Messages will be duplicated into each matching bound queue including FXTO.HK, and will sit in that queue until a consumer connects to it and acknowledges them.
• If your messages are being published to a queue (i.e. you don't have "exchange" set in the parameters to publish or you're using the default exchange) called FXTO.HK, your messages will remain in that queue until a consumer connects to that queue and receives them/acknowledges them. No exchange/fanout routing will occur.