multicast.js

multicast.js

const PORT = 20000;
const MULTICAST_ADDR = "233.255.255.255";
/*Here, choose the port that we will bind the socket to and the multicast address we will use. The multicast group address must be within the appropriate multicast address space. Much of the space is reserved, but you can still find some unassigned ad-hoc space such as 233.252.18.0-233.255.255.255.*/
const dgram = require("dgram");
const process = require("process");

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

socket.bind(PORT);

socket.on("listening", function() {
  socket.addMembership(MULTICAST_ADDR);
  setInterval(sendMessage, 2500);
  const address = socket.address();
  console.log(
    `UDP socket listening on ${address.address}:${address.port} pid: ${
      process.pid
    }`
  );
});

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

socket.on("message", function(message, rinfo) {
  console.info(`Message from: ${rinfo.address}:${rinfo.port} - ${message}`);
});