index.js

/*
Load Twilio configuration from .env config file - the following environment
variables should be set:

process.env.TWILIO_ACCOUNT_SID
process.env.TWILIO_API_KEY
process.env.TWILIO_API_SECRET
process.env.TWILIO_IPM_SERVICE_SID

*/
require('dotenv').load();
var http = require('http');
var path = require('path');
var AccessToken = require('twilio').AccessToken;
var IpMessagingGrant = AccessToken.IpMessagingGrant;
var express = require('express');
var randomUsername = require('./randos');

// Create Express webapp
var app = express();
app.use(express.static(path.join(__dirname, 'public')));

/*
Generate an Access Token for a chat application user - it generates a random
username for the client requesting a token, and takes a device ID as a query
parameter.
*/
app.get('/token', function(request, response) {
    var appName = 'TwilioChatDemo';
    var identity = randomUsername();
    var deviceId = request.query.device;

    // Create a unique ID for the client on their current device
    var endpointId = appName + ':' + identity + ':' + deviceId;

    // Create a "grant" which enables a client to use IPM as a given user,
    // on a given device
    var ipmGrant = new IpMessagingGrant({
        serviceSid: process.env.TWILIO_IPM_SERVICE_SID,
        endpointId: endpointId
    });

    // Create an access token which we will sign and return to the client,
    // containing the grant we just created
    var token = new AccessToken(
        process.env.TWILIO_ACCOUNT_SID,
        process.env.TWILIO_API_KEY,
        process.env.TWILIO_API_SECRET
    );
    token.addGrant(ipmGrant);
    token.identity = identity;

    // Serialize the token to a JWT string and include it in a JSON response
    response.send({
        identity: identity,
        token: token.toJwt()
    });
});

// Create http server and run it
var server = http.createServer(app);
var port = process.env.PORT || 3000;
server.listen(port, function() {
    console.log('Express server running on *:' + port);
});