MQTT.DART - MQTT Client Library Encyclopedia

Written by Jean-Noel Guillerme

Category: MQTT MQTT Client MQTT Client Library

Published: October 5, 2015

Short info

MQTT.DART
Language	Dart
Website	github.com/jnguillerme/mqtt.dart

Description

I developed the MQTT Dart library as I was working on the backend of a mobile app in 2013. The backend was developed in Dart but I could not find any MQTT library.

I’ve not been too active on the library recently due to lack of time. But I have plan to review the library with the latest Dart features and include the missing MQTT features before the end of the year.

Features

Feature
MQTT 3.1
MQTT 3.1.1
LWT
SSL/TLS
Automatic Reconnect

Feature
QoS 0
QoS 1
QoS 2
Authentication
Throttling

Usage

Installation

Add this to your package’s pubspec.yaml file:

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dependencies:
  mqtt: "^1.1.0"

You can install packages from the command line:

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$ pub get

In your dart code add:

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import 'package:mqtt/mqtt_shared.dart';

Connect

1.Define a connection Before connecting to the broker you must define a connection. Web socket and socket connections are supported:

websocket:

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var mqttCnx = new MqttConnectionIOWebSocket.setOptions("ws://127.0.0.1/8080");

socket:

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var mqttCnx = new MqttConnectionIOSocket.setOptions(host:127.0.0.1, port: 8083);

2.Create a client

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MqttClient c = new MqttClient(mqttCnx, clientID: "MyClientID", qos: QOS_1);

3.Connect

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c.connect(onConnectionLost) .then( (c)=> onConnected(c) ) .catchError((e) => print("Error: $e"), test: (e) => e is SocketException)
.catchError((mqttErr) => print("Error: $mqttErr") );

Connect with LWT

1. Define a connection Before connecting to the broker you must define a connection. Web socket and socket connections are supported:

websocket:

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var mqttCnx = new MqttConnectionIOWebSocket.setOptions("ws://127.0.0.1/8080");

socket:

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var mqttCnx = new MqttConnectionIOSocket.setOptions(host:127.0.0.1, port: 8083);

2. Create a client

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MqttClient c = new MqttClient(mqttCnx, clientID: "MyClientID", qos: QOS_1);

3. Define the will

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c.setWill("MyWillTopic", "MyWillPayload", QOS_1, 0);

4. Connect

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c.connect(onConnectionLost) .then( (c)=> onConnected(c) ) .catchError((e) => print("Error: $e"), test: (e) => e is SocketException)
.catchError((mqttErr) => print("Error: $mqttErr") ); 

Connect with Username / Password

Create the client as :

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MqttClient c = new MqttClient(mqttCnx, clientID: "MyClientID", qos: QOS_1, userName: “MyUserName”, password: ”MyPassword”);

Publish

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c.publish("MyTopic", "MyMessage")
 	.then( (m) => print("Message ${m.messageID} published"); );

Publish a retained message

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c.publish("MyTopic", "MyMessage", retain: true)
 	.then( (m) => print("Message ${m.messageID} published"); );

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c.subscribe("MyTopic", QOS_1, onMessage) 
.then( (s) => print("Subscription done - ID: ${s.messageID} - Qos: ${s.grantedQoS}") );

Unsubscribe

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c.unsubscribe("MyTopic", s.messageID) 
	.then( (u) => print("Unsubscribed from subscription ${u.messageID}") );

Disconnect

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c.disconnect();

About Jean-Noel Guillerme

Thanks for this guest blog post

Jean-Noel works as an independent software developer in London. He has been working on projects around messaging for more than 10 years. Jean-Noel started working with MQTT a couple of years ago, when he was involved in mobile app projects.

Follow Jean-Noel on Github

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