/*server.js*/
  var net=require('net');
  var count=0;
  var users={};
  
  var server=net.createServer(function (conn) {
    conn.setEncoding('utf8');
    conn.write(count+' people are connected'
      +'\nplease write your nickname:');
    count++;
    var nickname;
    conn.on('data',function (data) {
      data=data.replace(/\r\n/,'');
      if(!nickname){
        if(users[data]){
          conn.write('\n nickname already used,try again:');
          return;
        }else {
          nickname=data;
          users[nickname]=conn;//每个客户端对应的conn是不一样的
          for(var i in users){
            users[i].write(nickname+' join the romm\n');
          }
        }
      }else {
        conn.write('发送者nickname: '+nickname+'\n');
        for(var i in users){
          if(i!=nickname){
            users[i].write(nickname+': '+data+'\n');
          }
        }
      }
    });
    conn.on('close',function () {//这里防止连接出错，使用close而非end
      console.log(nickname+' client disconnected\n');
      count--;
      delete users[nickname];
    });
    conn.on('error',function (err) {
      console.log('Error in connection:'+ err+'\n');
    });
  }).listen(3000,function () {
    console.log('server is listenning on 3000');
  });

  /*client.js*/
  var net=require('net');
  var stop = false;
  process.stdin.resume(); 
  
  process.stdin.on('data', function(data){
    if(data.toString().trim().toLowerCase()==='stop'){
      stop=true;
      console.log('connection stop\n');
      client.end();
    }else{
      client.write(data);
    }
  });
  
  var client=net.createConnection(3000,function () {
    console.log('connected to server!\n');
  });
  client.on('data', function(data) {
    console.log(data.toString());//打印服务器发送的数据
  });
  client.on('error', function(err) {
    console.log('Error in connection:'+ err+'\n');
  });
  client.on('close', function() {
    if(! stop) {
      console.log('connection got closed');
    }
  });