CODEWITHSUNDEEP
rabbitmqamqp
yangmillstheory
yangmillstheory

Reputation: 1065

RabbitMQ - basic reject with metadata

I've got a consumer that rejects messages and knows exactly why those messages were rejected. She'd like to provide the "why" as well as the "what" to the producer when rejecting a message.

What's a good queue architecture for nack'ing messages but also sending back metadata describing why the message failed?

(At a higher level, if the producer isn't doing anything with the 'nacked reason codes, I'm thinking logging the reason codes from the consumer would suffice for visibility, so the question becomes moot. Still, seems like an interesting question assuming otherwise.)

Upvotes: 4

Views: 2834

Answers (2)

Serge
Serge

Reputation: 2006

I fall into similar issue. My solution was to assign unique ID to each message on sending (using properties) and then on rejection save error (associating it with assigned ID) into redis / memcached (I also used time expiration in redis to not overload storage). It is possible in my case, because I quickly handle all these dead messages so errors should not be keeped for a long time.

Probably not so elegant, but I didn't want publish anything manually and preferred rely on native rabbit functionality and I didn't nee many changes to the code.

Upvotes: 0

Gabriele Santomaggio
Gabriele Santomaggio

Reputation: 22682

You can use the RPC model as described here: https://www.rabbitmq.com/tutorials/tutorial-six-java.html In this way you can send-back to the publisher a message with the reason.

You can also considerer Dead Letter Exchanges extension, but you can't change the message, so you are just informed that your message has been rejected.

With a little work, you can create an exchange where you redirect the nack messages, and using the header property message to write the reason, like that:

 Map<String, Object> myHeader = new HashMap<String, Object>();
 myHeader("reason", "can't access to database");//<-- just an example
 AMQP.BasicProperties.Builder bob = new AMQP.BasicProperties.Builder();
 bob.headers(myHeader);

In this way you can maintain the original message and modify only the header. (similar to Dead Letter Message)

hope it helps

Upvotes: 2

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