Halo

A simple nodeJS project that uses the socket.io NodeJS module to enable real time communication between clients and the development board via a web browser

This NodeJS application consists of a client side application accessible via a web browser in which users can view the number of connected users, send text messages between users as well as toggle the onboard LED (ON/OFF) of your development board.

You can view this application by inputting your development board's IP address as well as the port number (3000) specified in the main.js within the browser's address bar. For example, http://192.168.1.0:3000.

Note: You can find your board's IP address by typing the ifconfig command in the Linux terminal via a Serial or SSH connection.

####(Intel XDK IoT Edition) Upload & Run project After installing the neccessary node modules, press the: 1. Upload button 2. Run button to execute your project on your board.

####Getting Started with socket.io NodeJS Plug-in #####Design Considerations The necessary information needed for creating a web socket (socket.io) application:

var mraa = require('mraa'); //require mraa
console.log('MRAA Version: ' + mraa.getVersion()); //write the mraa version to the Intel XDK console
//var myOnboardLed = new mraa.Gpio(3, false, true); //LED hooked up to digital pin (or built in pin on Galileo Gen1)
var myOnboardLed = new mraa.Gpio(13); //LED hooked up to digital pin 13 (or built in pin on Intel Galileo Gen2 as well as Intel Edison)
myOnboardLed.dir(mraa.DIR_OUT); //set the gpio direction to output
var ledState = true; //Boolean to hold the state of Led

var express = require('express');
var app = express();
var path = require('path');
var http = require('http').Server(app);
var io = require('socket.io')(http);

In order to setup the client side web page, you will need to identify the path to the index.html:

app.get('/', function(req, res) {
    //Join all arguments together and normalize the resulting path.
    res.sendFile(path.join(__dirname + '/client', 'index.html'));
});

Files required for your client side web page(s) need to be explicitly identified.

//Allow use of files in client folder
app.use(express.static(__dirname + '/client'));
app.use('/client', express.static(__dirname + '/client'));

#####Socket.io EventListeners Handling connection, and custom events

//Socket.io Event handlers
io.on('connection', function(socket) {
    console.log("\n Add new User: u"+connectedUsersArray.length);
    if(connectedUsersArray.length > 0) {
        var element = connectedUsersArray[connectedUsersArray.length-1];
        userId = 'u' + (parseInt(element.replace("u", ""))+1);
    }
    else {
        userId = "u0";
    }
    console.log('a user connected: '+userId);
    io.emit('user connect', userId);
    connectedUsersArray.push(userId);
    console.log('Number of Users Connected ' + connectedUsersArray.length);
    console.log('User(s) Connected: ' + connectedUsersArray);
    io.emit('connected users', connectedUsersArray);
    
    socket.on('user disconnect', function(msg) {
        console.log('remove: ' + msg);
        connectedUsersArray.splice(connectedUsersArray.lastIndexOf(msg), 1);
        io.emit('user disconnect', msg);
    });
    
    socket.on('chat message', function(msg) {
        io.emit('chat message', msg);
        console.log('message: ' + msg.value);
    });
    
    socket.on('toogle led', function(msg) {
        myOnboardLed.write(ledState?1:0); //if ledState is true then write a '1' (high) otherwise write a '0' (low)
        msg.value = ledState;
        io.emit('toogle led', msg);
        ledState = !ledState; //invert the ledState
    });
    
});

Starting the http server listening on port 3000

http.listen(3000, function(){
    console.log('Web server Active listening on *:3000');
});

####(Web Browser) View Client side application Input the IP address of your board plus the port number (3000) For example, http://192.168.1.0:3000

Important App Files

• main.js
• package.json
• icon.png
• README.md