client.js

var Cutter = require('cutter');
var net = require('net');

/**
 * must return length of head + body
 */
function packetLength(data) {
  return 4 + data.readInt32BE(0);
}
var cutter = new Cutter(4, packetLength);
cutter.on('packet', function(packet) {
  var serverMsg = parsePacket(packet);
  console.log('got server message: ', serverMsg);
});

var client = net.connect({port: 12345});
client.on('data', function (data) {
  cutter.emit('data', data);
});

client.on('end', function () {
  console.log('client disconnected');
});


var clientPacket = createPacket('hello server');
client.write(clientPacket);

//---------------helpers------------------//

function createPacket(msg) {
  var head = new Buffer(4);
  var body = new Buffer(msg);
  // write body's length into head
  head.writeInt32BE(body.length, 0);
  // concat head and body
  return Buffer.concat([head, body]);
}

function parsePacket(packet) {
  var head = packet.slice(0, 4);
  var body = packet.slice(4, packet.length);
  return body.toString();
}

server.js

var Cutter = require('cutter');
var net = require('net');

/**
 * must return length of head + body
 */
function packetLength(data) {
  return 4 + data.readInt32BE(0);
}

var server = net.createServer(function(socket) {
  var cutter = new Cutter(4, packetLength);
  socket.on('data',function(data) {
    cutter.emit('data', data);
  });

  cutter.on('packet', function(packet) {
    var clientMsg = parsePacket(packet);
    console.log('got client message: ', clientMsg);

    var serverPacket = createPacket('hello client');
    socket.write(serverPacket);
  });
});

server.listen(12345);

//---------------helpers------------------//

function createPacket(msg) {
  var head = new Buffer(4);
  var body = new Buffer(msg);
  // write body's length into head
  head.writeInt32BE(body.length, 0);
  // concat head and body
  return Buffer.concat([head, body]);
}

function parsePacket(packet) {
  var head = packet.slice(0, 4);
  var body = packet.slice(4, packet.length);
  return body.toString();
}