mqtt

A library for the MQTT protocol

npm install mqtt
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Introduction

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mqtt.js is a library for the MQTT protocol, written in JavaScript to be used in node.js.

Important notes for existing users

  • v0.3.0 improves connection stability, performance, the reconnection logic and SSL support. See #118 for details. A Connection is a Writable stream, so you can run MQTT.js over any kind of Stream (doc needed). Both the constructors of MqttClient and MqttConnection changed, but not the factory method mqtt.createClient and mqtt.createConnection.

  • v0.2.0 has brough some API breaking changes to mqtt.js. Please consult the migration guide for information or open an issue if you need any help.

Installation

npm install mqtt

Example

First you will need to install and run a broker, such as Mosquitto or Mosca, and launch it.

For the sake of simplicity, let's put the subscriber and the publisher in the same file:

var mqtt = require('mqtt')

client = mqtt.createClient(1883, 'localhost');

client.subscribe('presence');
client.publish('presence', 'Hello mqtt');

client.on('message', function (topic, message) {
  console.log(message);
});

client.end();

output:

Hello mqtt

If you do not want to install a separate broker, you can try using the server/orig example. It implements enough of the semantics of the MQTT protocol to run the example.

Documentation

Detailed documentation can be found in the wiki

Client API usage

See: examples/client

Simple publish client

var mqtt = require('mqtt')
  , client = mqtt.createClient();

client.publish('messages', 'mqtt');
client.publish('messages', 'is pretty cool');
client.publish('messages', 'remember that!', {retain: true});
client.end();

Simple subscribe client

var mqtt = require('mqtt')
  , client = mqtt.createClient();

client.subscribe('messages');
client.publish('messages', 'hello me!');
client.on('message', function(topic, message) {
  console.log(message);
});
client.options.reconnectPeriod = 0;  // disable automatic reconnect

Connect using a URL

Using the connect method, which can create either a normal or secure MQTT client.

var mqtt = require('mqtt')
  , client = mqtt.connect('mqtt://user:pass@localhost?clientId=123abc');

client.subscribe('messages');
client.publish('messages', 'hello me!');
client.on('message', function(topic, message) {
  console.log(message);
});

Supports mqtt:// and tcp:// for normal connections, and mqtts:// or ssl:// for secure connections.

As seen above the clientId can be passed in as a query parameter.

Chainable API!

var mqtt = require('mqtt')
  , client = mqtt.createClient();

client
  .subscribe('messages')
  .publish('presence', 'bin hier')
  .on('message', function(topic, message) {
    console.log(topic);
  });

Server API usage

Broadcast server example

Included in examples/broadcast.js:

var mqtt = require('mqtt');

mqtt.createServer(function(client) {
  var self = this;

  if (!self.clients) self.clients = {};

  client.on('connect', function(packet) {
    client.connack({returnCode: 0});
    client.id = packet.clientId;
    self.clients[client.id] = client;
  });

  client.on('publish', function(packet) {
    for (var k in self.clients) {
      self.clients[k].publish({topic: packet.topic, payload: packet.payload});
    }
  });

  client.on('subscribe', function(packet) {
    var granted = [];
    for (var i = 0; i < packet.subscriptions.length; i++) {
      granted.push(packet.subscriptions[i].qos);
    }

    client.suback({granted: granted, messageId: packet.messageId});
  });

  client.on('pingreq', function(packet) {
    client.pingresp();
  });

  client.on('disconnect', function(packet) {
    client.stream.end();
  });

  client.on('close', function(err) {
    delete self.clients[client.id];
  });

  client.on('error', function(err) {
    client.stream.end();
    console.log('error!');
  });
}).listen(1883);

License

MIT

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