Tag Archives: AMQP

Video Part 1: Reliable Messaging With RabbitMQ


This is an introduction to message broker, RabbitMQ and AMQP.

AMQP 0-9-1 library and client for Node.JS


README.md

AMQP 0-9-1 library and client for Node.JS

npm install amqplib

A library for making AMQP 0-9-1 clients for Node.JS, and an AMQP 0-9-1 client for Node.JS v0.8, v0.9, v0.10, and v0.11.

This library does not implement AMQP 1.0 or AMQP 0-10.

Project status:

  • Expected to work
  • Complete high-level and low-level APIs (i.e., all bits of the protocol)
  • A fair few tests
  • Measured test coverage
  • Ports of the RabbitMQ tutorials as examples
  • Used in production

Still working on:

  • Getting to 100% (or very close to 100%) test coverage
  • Settling on completely stable APIs

Callback API example

var q = 'tasks';

function bail(err) {
  console.error(err);
  process.exit(1);
}

// Publisher
function publisher(conn) {
  conn.createChannel(on_open);
  function on_open(err, ch) {
    if (err != null) bail(err);
    ch.assertQueue(q);
    ch.sendToQueue(q, new Buffer('something to do'));
  }
}

// Consumer
function consumer(conn) {
  var ok = conn.createChannel(on_open);
  function on_open(err, ch) {
    if (err != null) bail(err);
    ch.assertQueue(q);
    ch.consume(q, function(msg) {
      if (msg !== null) {
        console.log(msg.content.toString());
        ch.ack(msg);
      }
    });
  }
}

require('./callback_api')
  .connect('amqp://localhost', function(err, conn) {
    if (err != null) bail(err);
    consumer(conn);
    publisher(conn);        
  });

Promise API example

var q = 'tasks';

var open = require('amqplib').connect('amqp://localhost');

// Publisher
open.then(function(conn) {
  var ok = conn.createChannel();
  ok = ok.then(function(ch) {
    ch.assertQueue(q);
    ch.sendToQueue(q, new Buffer('something to do'));
  });
  return ok;
}).then(null, console.warn);

// Consumer
open.then(function(conn) {
  var ok = conn.createChannel();
  ok = ok.then(function(ch) {
    ch.assertQueue(q);
    ch.consume(q, function(msg) {
      if (msg !== null) {
        console.log(msg.content.toString());
        ch.ack(msg);
      }
    });
  });
  return ok;
}).then(null, console.warn);

Running tests

npm test

Best run with a locally-installed RabbitMQ, but you can point it at another using the environment variableURL; e.g.,

URL=amqp://dev.rabbitmq.com npm test

NB You may experience test failures due to timeouts if using the dev.rabbitmq.com instance.

You can run it under different versions of Node.JS using nave:

nave use 0.8 npm test

or run the tests on all supported versions of Node.JS in one go:

make test-all-nodejs

(which also needs nave installed, of course).

Lastly, setting the environment variable LOG_ERRORS will cause the tests to output error messages encountered, to the console; this is really only useful for checking the kind and formatting of the errors.

LOG_ERRORS=true npm test

Test coverage

make coverage
open file://`pwd`/coverage/lcov-report/index.html