问题
I want to make my app resilient to connection issues that can happen when sending messages to rabbitmq. I want to get hold of all unsent messages, store them and send them latter, when rabbitmq becomes available.
Looking at the official documentation I didn't manage to figure out what is the difference between return callback and retry callback. I understand that retry callback is invoked when retry template exhausts configured policy but don't find this much useful since context doesn't contain message itself. Based on "replyCode" that is passed in the "returnedMessage" method of ReturnCallback interface one can easily determine further behavior but haven't figured out when this callback is invoked.
One way to go is ConfirmCallback but there is an issue of having additional logic for keeping in sync CorrelationData and messages and statuses of those messages.
So...except ConfirmCallback interface is there any easier way to keep track of messages that are not successfully sent through RabbitMQ using Spring AMQP?
回答1:
Returns are when the broker returns a message because it's undeliverable (no matching bindings on the exchange to which the message was published, and the mandatory bit is set).
Confirms are when the broker sends an ack back to the publisher, indicating that a message was successfully routed.
Retry is outside the broker realm so it is likely what you need for your use case.
来源：https://stackoverflow.com/questions/30034092/spring-amqp-return-callback-vs-retry-callback