RabbitMQ

RabbitMQ follows the AMQP (Advanced Message Queueing Protocol) specification.

AMQP defines 3 components:

• Exchange - components that routes messages to queues
• Queue - stores messages
• Binding - rule that tells the exchange which queue to route a particular message

The flow of data is: Application -> RabbitMQ -> Exchange -> Queue

Binding (also called binding keys) will be used by Exchange to evaluate routing keys of each message and decide the target queue.

Questions:

• can one message directed to multiple queues?

RabbitMQ supports binding of Exchange to Exchange in addition of Exchange to Queue.

All commands in RabbitMQ are sent in a common data structure “Frame”.

A frame has 5 parts:

• Frame type
• Channel number
• Frame size in bytes
• Frame payload
• End-byte marker

Questions:

• what does “channel” means?

There are 5 frame types:

1. Protocol header frame - used only once when connecting to RabbitMQ
2. Method frame - RPC request or response that’s being sent/received from RabbitMQ
3. Content header frame - containers the size and properties for a message
4. Body frames - contain the contents of messages
5. Heartbeat frame - ensure both sides are working

Combinations:

• 1 method
• 1 content
• 1 or more body