使用wso2 / rabbitMq / c＃在主题消息中通配符如何工作？

Question

If I publish a message to a wso2 topic like so:

channel.BasicPublish(someExchangeName,"farm.cow.brown",null,someMessage);

I can retrieve the message if I am listening to the routing key "farm.cow.brown":

channel.QueueBind(someQueueName,someExchangeName,"farm.cow.brown");

I think I should also be able to get the message if I am listening to a variation such as this:

channel.QueueBind(someQueueName,someExchangeName,"farm.cow.*");

Of the two listening examples above the first works, the second never does, regardless of the routing key combinations attempted (farm.cow.* , farm.*.brown , farm.cow.# , farm.# , etc.).

I am connecting to wso2 using rabbitMq and c#.

Thank you.

Answer 1

This is working for me now. It appears that to use a wildcard to listen to multiple topics/routing paths, there need to be existing queues for each topic.

Here is what I mean: consider the topics "farm.cow.brown" and "farm.cow.white" and a listener consuming route "farm.cow.*".

If there is an existing queue on "farm.cow.brown" but not on "farm.cow.white", I will only get messages published to "farm.cow.brown", even though "farm.cow.white" exists and is getting messages published to it.

If there is a queue on "farm.cow.brown" and another on "farm.cow.white", "farm.cow.*" will get all messages published to "farm.cow.brown" and published to "farm.cow.white".

If neither have queues, "farm.cow.*" retries no messages published to "farm.cow.brown" and "farm.cow.white".

(As an aside, the "farm.cow.*" examples above are work equivalently using "farm.#")

To restate, using wildcards only retrieves messages for topics that have existing queues or subscriptions.

This is my experience. I have been testing this for a few days and it appears to be the consistent behavior.