text: var net = require('net');
  var server = net.createServer(function(connection) { 
     console.log('client connected');
     connection.on('end', function() {
        console.log('客户端关闭连接');
     });
     connection.write('Hello World!\r\n');
     connection.pipe(connection);
  });
  server.listen(8888, function() { 
    console.log('server is listening');
  });