What is RabbitMQ and Celery?

RabbitMQ

key points from Wiki

• Open source message broker software
• AMQP (Advanced Message Queuing Protocol)
• Written in the Erlang Programming Language
• Built on the Open Telecom Platform framework

Celery

words from their official website

Celery is an asynchronous task queue/job queue based on distributed message passing. It is focused on real-time operation, but supports scheduling as well.
The execution units, called tasks, are executed concurrently on a single or more worker servers using multiprocessing, Eventlet, or gavent. Tasks can execute asynchronously (in the background) or synchronously (wait until ready).

RabbitMQ 是一個仲介者角色(broker)，使用AMQP所以開啓port 5672，啟動後開始聽別人分赴的工作。而Celery則是負責規劃工作，且是Multiprocessing，並由多個worker去完全安排的工作。

所以RabbitMQ和Celery是怎麼合作的？

這份stackoverflow的post中提到： Celery is a distributed task queue, which means the only thing that it should do is dispatching tasks/jobs to other servers and get the result back. And, RabbitMQ is a message queue, and nothing more.

由此可見，Celery是安排message怎麼到達RabbitMQ的一個角色，其中甚至可以做排程，而真正處理message的人是RabbitMQ。