udpUtils.js

var util = require('util')
var EventEmitter = require('events').EventEmitter;

const PORT = 20000;
const MULTICAST_ADDR = "233.255.255.255";

const dgram = require("dgram");
const process = require("process");

const socket = dgram.createSocket({ type: "udp4", reuseAddr: true });

var udpUtils = function(){
    socket.bind(PORT);

    socket.on("listening", function() {
      socket.addMembership(MULTICAST_ADDR);
      var that = this
      const address = socket.address();
      console.log(`UDP socket listening on ${address.address}:${address.port} pid: ${process.pid}`);
    });
    
    var that = this
    socket.on("message", function(message, rinfo) {
      //console.log(message, rinfo)
      console.info(`Message from: ${rinfo.address}:${rinfo.port} - ${message}`);
      var rtnMsg = {
        address: rinfo.address,
        port: rinfo.port,
        message: message.toString()
      }
      that.emit('message',rtnMsg);
    });

    this.sendMessage = function(thisMsg){
      //const message = Buffer.from(`Message from process ${process.pid}`);
      const message = Buffer.from(thisMsg);
      socket.send(message, 0, message.length, PORT, MULTICAST_ADDR, function() {
        console.info(`Sending message "${message}"`);
      }); 
    }
}

util.inherits(udpUtils, EventEmitter);
module.exports = udpUtils;