[rabbitmq-discuss] Java client and Qpid

Fri Jun 14 17:43:17 BST 2013

Hi.

I have a Java application which acts a bit like Shovel plugin - it 
receives messages from one AMQP broker (Apache Qpid) and forwards them 
to another (RabbitMQ). As the RabbitMQ is the "main" broker, I'm using 
its Java library to connect to both.

And it is that Qpid to Rabbit Java client integration point that is 
giving me headache.
I'm not sure what exactly is going on but after some debugging it looks 
to me that scenario is like this:
1. The queue already has some messages at the moment I try to run 
basicConsume() on it (it is a durable queue)
2. ChannelN.basicConsume() begins its RPC call and waits for the reply
3. ChannelN.processAsync() gets invoked with the first message BEFORE 
the reply to that RPC is received
4. As there is no ConsumerTag yet in the _consumers map (it gets there 
when RPC completes), processAsync() throws "Unsolicited delivery" exception.

Unfortunately I do not know the protocol well enough to understand if 
Qpid violates it by sending me a message before sending reply to 
basicConsume request or not. Without reading the specs I would assume 
that this behaviour is a valid one and it is RabbitMQ Java client that 
needs to be more tolerant.

Could you please advise?

Thank you.

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