rabbit-rr v2.0.0

rabbit-rr

A simple rabbitmq module based on amqplib and inspired by rabbit.js meant to provide a simple callback interface for using a req/rep pattern. This is ideal when doing concurrent operations that require the return callback to be properly associated with the data that was sent (and the result then returned)

Goal:

The purpose of this module is to hide all of the dirty async startup needed when connecting to rabbit. When initializing a constructor, we establish a connection to rabbit and begin creating a channel WITH that connection. This channel and connection is used with any socket created with the rabbit instance. We take care of deferring the function calls of connect and send (send is only for the REQ socket) so that you have a clean and simple API to use. Each Rabbit and Socket instance is an EventEmitter with various events associated for gaining insight into the inner workings. The main event to worry about though is the message event on the REP socket which emits any message received from a REQ socket with a callback to reply to it. Please see the example below to understand my ramblings.

Example:

Below shows a simple use case

var Rabbit = require('rabbit-rr');

//
// Remark: This constructor accepts an object or URL string with the
// options you want to pass into `amqplib` to connect (e.g ssl options)
//
var rabbit = new Rabbit()
  .on('ready', function () {
    console.log('We are conected to Rabbit!');
  });

//
// Creates a socket to handle sending requests to Rabbit,
// options are accepted as a second argument
//
var req = rabbit.socket('REQ')
  .on('error', console.error.bind(console))
  .on('ready', function () {
    // Called when channel has been assigned
    console.log('REQ socket Ready!');
  })
  // Connect to the specified Queue, accepts an optional callback
  .connect('made_up_queue')
  .on('connect', function () {
    console.log('REQ has connected to queue');
  })
  // We assume and parse payloads as objects
  .send({ foo: 'bar' }, function (err, msg) {
    if (err) return console.error('application error from REP socket %s', err.message)
    console.log('received msg %j', msg);
  });

var rep = rabbit.socket('REP')
  .on('error', console.error.bind(console))
  .on('ready', function () {

    console.log('REP socket ready');
  })
  .connect('made_up_queue')
  .on('connect', function () {
    console.log('REP has connected');
  })
  // Listen for messages from requester
  .on('message', function (msg, reply) {
    // Reply to them with a particular payload
    // We assume object payloads everywhere
    reply(undefined, { reply: 'wooo' });
  });