Concepts

Before reading

The following slides include channel-oriented AMQP API mechanics you should consider first before reading code samples.

For progressive understanding of the concepts and samples, please consider reading

• the official documentation
• the official tutorials
• the amqplib API reference

Core concepts

• You create a connection over TCP with an URI (optionally containing a virtual host)
• You create a channel (virtual connection) over the connection
• You use the channel API to
  • create exchanges
  • create/bind queues
  • publish on exchange
  • consume queues

Why channels ?

• To reuse connections
• To take advantage of requests into a given channel being serialized
• To be able to have different consuming behaviors over the same connection 

exchanges and queues

Basically, this enables this separation of concerns:

• A message publisher
  • ensures the exchange exists
  • publishes a message once on the exchange
  • -> publishing a message on a exchange without bound queues will be dropped instantly
• A message consumer
  • check if the exchange exists
  • ensures the queue exists and is bound to the exchange with an optional routing key
  • starts a consumer

EXCHANGES AND QUEUES

Publisher

Consumer

Exchange

Queue

routes

publish

consumes

Conventions

URI scheme

• Please consider the RabbitMQ URI Specification
• Also consider this URI builder for NodeJS use
• Pay special attention to encoding URI components

Vhost

• Virtual hosts should be used to implement a strict isolation
  • -> a channel on a vhost is not able to transport requests and messages corresponding to another vhost

Naming

All named things should follow a naming convention

• exchanges
  • the application owning it
  • the message type it transports (if applicable) 
• queues
  • the application owning it
  • the message type it stores (if applicable)
• consumers
  • the application owning it
  • the hostname and pid

Extensions

Extensions

@TODO

Please consider the official protocol extension documentation

Libraries

Amqplib

amqplib github

• is a channel oriented API
• supports callback api and promises

amqp-connection-manager

amqp-connection-manager is a wrapper around amqplib

The main features it adds are:

• automatic reconnection
• round-robin connections between multiple brokers in a cluster
• queues messages in memory until reconnection

Exercises

Exercises

With a RabbitMQ server on your machine:

• create an application producing messages
• create an application consuming these messages