Idempotency Barrier for messaging

Question

A recent presentation I saw regarding RabbitMQ mentioned the use of something called an "idempotency barrier" for message de-duplication. Is this just a fancy name for a message conflator or is it something more specific. If so, what exactly is it? A google search yielded results which are mostly related to RabbitMQ, with little explanation of what it was.

Answer 1

Idempotency is the behavior of a function where performing the function on the function's output n times results in the same state as the function being performed once. This is useful in a messaging environment because delayed messages do not cause unexpected behavior. While conflation implies that messages would be concentrated to prevent duplication, idempotency implies that the messaging framework would permit multiple transmissions and executions of duplicate messages, while maintaining that the execution of multiple copies of a message has the same result as execution of one message.