AMQP Simple Pub Sub

A simple Pub Sub system that uses AMQP Messaging to exchange data between services

• develop —
• master —

To Use

You project needs to be using at least Node version 8, and ideally Node 10 (LTS) or later.

npm install amqp-simple-pub-sub

Create a Publisher

const { makePublisher } = require('amqp-simple-pub-sub')
const publisher = makePublisher({ exchange: 'testService' })

Publish a message

await publisher.start()
publisher.publish('test', 'Hello World')

Create a Subscriber

const { makeSubscriber } = require('amqp-simple-pub-sub')

const subscriber = makeSubscriber({
  exchange: 'testService',
  queueName: 'testQueue',
  routingKeys: ['test']
})

Subscribe to a queue and listen for messages

const handler = message => {
  console.log('Message Received', message)
  subscriber.ack(message)
}

subscriber.start(handler)

Other Options

Publisher

The full options object is as follows

{
  type: 'topic' // the default
  url: 'amqp://localhost' // the default
  exchange: 'you must provide this' // it's the name of your service usually
  onError: err => { // optional
    console.error('A connection error happened', err) // or do something clever
  }
  onClose: () => { // optional
    console.log('The connection has closed.') // or do something clever
  }
}

Subscriber

The full options object is as follows

{
  type: 'topic' // the default
  url: 'amqp://localhost' // the default
  exchange: 'you must provide this' // it's the name of your service usually
  queueName: 'you must also provide this' // give your queue a name
  routingKeys: ['an', 'array', 'of', 'routingKeys'] // optional.  Uses [queueName] otherwise.
  onError: err => { // optional
    console.error('A connection error happened', err) // or do something clever
  }
  onClose: () => { // optional
    console.log('The connection has closed.') // or do something clever
  }
}

Examples

See some examples in the tests, and also:

• competing-services-example
• And the associated article: itnext.io/connecting-competing-microservices-using-rabbitmq

Related Projects

• amqp-delegate — A library that simplifies, to the point of triviality, use of AMQP based remote workers.
• ampq-event-tester — A Dockerised and configurable utility to help integration-test your amqp services.

Development

Prerequisites

• NodeJS, version 10.15.1 (LTS) or better (I use nvm to manage Node versions — brew install nvm.)
• Docker (Use Docker for Mac, not the homebrew version)

Initialisation

npm install

To Start the queue server for integration testing.

docker-compose up -d

Runs Rabbit MQ.

Test it

• npm test — runs the unit tests (quick and does not need rabbit mq running)
• npm run test:integration — runs the integration tests (not so quick and needs rabbitmq running)

Lint it

npm run lint

Contributing

Please see the contributing notes.