mqtt-demo on localhost

Requirements

• Node JavaScript Runtime Environment
• Mosquitto MQTT Broker

1. In command line go to the installation directory of mosquitto and run mosquitto in verbose mode so that you can see console messages.By default the broker will start listening on port 1883.

  mosquitto -v

2. Go to the project directory and clone the repository

  git clone https://github.com/erkanina/mqtt-demo.git

3. Install mqtt package

  npm install mqtt

4. You will need two console windows, one for publisher and one for subscriber. Run both scripts as below;

  Node publisher.js

  Node subscriber.js

publisher

const mqtt = require("mqtt");
const client = mqtt.connect('mqtt://localhost');

var counter = 0;

function publishData() {
    client.publish(
        "mqtt/myCounter",
        JSON.stringify(`Timer:${counter}`)
      );

      console.log("Published : " + counter);

      counter++;
}

setInterval(publishData, 3000);

subscriber

const mqtt = require('mqtt')
const client = mqtt.connect('mqtt://localhost')

client.on('connect', () => {
  console.log('Connected to broker');

  client.subscribe('mqtt/myCounter');
  console.log('Subscribed to \"mqtt/myCounter\"');
});

client.on('message', (topic, payload) => {
    switch(topic){
        case 'mqtt/myCounter':
            console.log('Rx message : ' + payload.toString());
        break;
    }
});