如何将node.js客户端连接限制为2？

这是我的服务器代码：

var express = require('express'),app = express(),server = require('http').createServer(app),io = require('socket.io').listen(server);

var osc = require('node-osc');

var client = new osc.Client('127.0.0.1',12345);

server.listen(3000);

app.get('/',function(req,res){

    res.sendfile(__dirname + '/index.html');
});

io.sockets.on('connection',function(socket){
    socket.on('send message',function(data){
        client.send('/oscAddress',parseInt(data));
    });
});