Skip to main content

MQTT using Node JS | Node JS Tutorial

This post shows you Simple MQTT Application using Node JS. There are three parts of the application.
For running any MQTT application, we need a 

1. Broker (The broker can be anywhere in the Internet or cloud or a local machine) 
2. Publisher (pub.js is the name of the file)
3. Subscriber (sub.js is the name of the file)

Check the following video for complete instructions.




In this example, we will be using a broker called https://www.hivemq.com

To use the cloud broker (mqtt://broker.hivemq.com) and connect the publisher and subscriber with a topic and a message. To install the Hive MQ software in your local machine (127.0.0.1) and run the same above code locally and make the connectivity between the pub-sub.

  • We open two new .js files called pub.js (publisher) and sub.js (subscriber) in Visual Studio Code. To install the mqtt module in NodeJS, we use the command “npm install mqtt” in C:/ terminal. 
  • We define our client as connecting to “mqtt://broker.hivemq.com”. We connect to the cloud broker in both publisher and subscriber js modules. We have taken temperature and temperature value as our message. The source code is given below. 
  • To execute our code, we open two terminals and use the command “node pub.js” and then in the other one, “node sub.js”. In the left command prompt, we have published, and in the one on the right, we have subscribed. We can see the outputs match each other. 
MQTT using Node JS
MQTT using Node JS

Using cloud broker:

Pub.js:

const mqtt = require("mqtt");

var client = mqtt.connect("mqtt://broker.hivemq.com");


client.on("connect",function()

{

    setInterval(function(){

        var random = Math.random()*50;

        console.log(random);

        if(random<30)

        {

            client.publish("Pradeep","temperature value: "+random.toString());

        }

    }),30000;

});


Sub.js:


const mqtt = require("mqtt");

var client = mqtt.connect("mqtt://broker.hivemq.com");


client.on("connect",function()

{

    client.subscribe("Shirish");

    console.log("Client subscribed ");

});


client.on("message",function(topic, message){

    console.log(message.toString());

});



Using local broker:

  • To run the broker locally, we first install HiveMQ on our system.
HiveMQ for MQTT
HiveMQ for MQTT

Pub.js:


const mqtt = require("mqtt");

var client = mqtt.connect("mqtt://127.0.0.1:1883");


client.on("connect",function()

{

    setInterval(function(){

        var random = Math.random()*50;

        console.log(random);

        if(random<30)

        {

            client.publish("Shirish","temperature value: "+random.toString());

        }

    }),30000;

});



Sub.js:


const mqtt = require("mqtt");

var client = mqtt.connect("mqtt://127.0.0.1:1883");


client.on("connect",function()

{

    setInterval(function(){

        var random = Math.random()*50;

        console.log(random);

        if(random<30)

        {

            client.publish("Shirish","temperature value: "+random.toString());

        }

    }),30000;

});



Comments

Popular posts from this blog

Installing ns-3.34 in Ubuntu 20.04

This post shows how to install ns 3.34 in Ubuntu 20.04 LTS Prerequisites: Fresh installation of Ubuntu Version 20.04 LTS  ns3.34 can be downloaded from here Follow the video link for complete step by step instructions on the installation.  This version fixes the compilation issues of vanet-routing-compare.cc (bug in ns3.33)  Issue the following commands after opening a terminal  $ sudo apt update $ sudo apt install g++ python3 python3-dev python-dev pkg-config sqlite3 python3-setuptools git qt5-default gir1.2-goocanvas-2.0 python3-gi python3-gi-cairo python3-pygraphviz gir1.2-gtk-3.0 ipython3 openmpi-bin openmpi-common openmpi-doc libopenmpi-dev autoconf cvs bzr unrar openmpi-bin openmpi-common openmpi-doc libopenmpi-dev tcpdump wireshark libxml2 libxml2-dev Unzip or untar the ns-allinone-3.34.tar.bz2 in the home folder (in my case its /home/pradeepkumar) $ cd ns-allinone-3.34/ $ ./build.py --enable-examples --enable-tests  Once the installation is completed, you may get an output show

Installation of ns3 in Windows 10 and Windows 11 OS using WSL (Windows Subsystem for Linux)

This post shows how to install ns-3.33 in Windows 10 through WSL (Windows Subsystem for Linux) This posts works for Windows 11 also (I have tested it on a Windows 11 ISO and it works the Same way as mentioned in the following post.) This post will work for ns-3.3x version. Prerequisites : Install Windows Subsystem for Linux with GUI: Please refer the following video  System Information: OS used: Windows 10 and WSL (Ubuntu 20.04) GUI: XServer for Windows NS3 Version: ns-3.33 See the following complete video on how to install ns3 in Windows 10 Step 0 : Open XLaunch Step 1 :  Open WSL using PowerShell and open it as Administrator Command:/  wsl $ xfce4-session The GUI of Ubuntu Opens within Windows 10 OS. Step 2 : Download ns3 from nsnam.org website through Mozilla Firefox browser Step 3: Open a Terminal  $ sudo apt update $ sudo apt install build-essential autoconf automake libxmu-dev python3-pygraphviz cvs mercurial bzr git cmake p7zip-full python3-matplotlib python-tk python3-dev qt5-q

Installing NS-3.32 in Ubuntu 20.04

This is about installing ns version 3.32 in Ubuntu 20.04 LTS. #ns3 #ns3 .32 #networksimulation The commands used in the video are given here. $] sudo apt update $] sudo apt install build-essential autoconf automake libxmu-dev python3-pygraphviz cvs mercurial bzr git cmake p7zip-full python3-matplotlib python-tk python3-dev qt5-qmake qt5-default gnuplot-x11 wireshark Download the ns-allinone-3.32.tar.bz2 package from nsnam.org and copy it to /home/ folder See the full video for detailed instructions Extract it either in GUI or using command $] tar jxvf ns-allinone-3.32.tar.bz2 $] cd ns-allinone-3.32/ $] ./build.py --enable-examples --enable-tests The above command will take some time to install all the packages  You can see the output as shown below ns3 To check whether ns3 installed successfully, use the following commands. $] cd ns-3.32/ $] ./waf --run hello-simulator You should get the output as Hello Simulator $] ./waf --run first This is the example from the ns-3.32/exa