socket.io/server

## 55.js
var fs = require('fs');
var server = require('http').createServer(handler);
var io = require('socket.io').listen(server);

function handler (req, res) {
  if (req.url === '/') {
    res.statusCode = 200;
    res.setHeader('content-type', 'text/html');
    fs.createReadStream('./index.html').pipe(res);
  }
}

io.sockets.on('connection', function (socket) {
  socket.on('echo', function (data) {
    io.sockets.emit('echo', data, socket.username);
  });
  socket.on('setName', function (name) {
    socket.username = name;
    io.sockets.emit('join', name);
  });
});

server.listen(8080);