Socket.io监听路由

Question

我正在尝试将socket.io集成到我的Web应用程序中。 socket.io的文件如下所示：

var express = require('express');
var bodyParser = require('body-parser');
var app = express();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var mongoose = require('mongoose');

app.use(express.static(__dirname));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: false}));

var Message = mongoose.model('Message',{
  name : String,
  message : String
})

mongoose.connect('mongodb://localhost/simple');

app.get('/messages', (req, res) => {
  Message.find({},(err, messages)=> {
    res.send(messages);
  });
});

app.post('/messages', function(req, res){
  Message.create(req.body, function(err, message){
    if(err){
      return console.log('error', err);
    }
    io.emit('message', req.body);
  });
});

io.on('connection', () =>{
  console.log('a user is connected');
});

var server = http.listen(process.env.PORT, process.env.IP, function(){
  console.log('server is running');
});

但是，我的主应用程序的app.js文件如下所示：

var   express       = require("express"),
      app           = express(),
      bodyParser    = require("body-parser"),
      mongoose      = require("mongoose");

mongoose.connect("mongodb://localhost/simpleapp");

app.get('/', function(req, res){
    res.render('landing');
});

app.listen(process.env.PORT, process.env.IP, function(){
    console.log("Server is Live!!");
});

我现在遇到的问题是合并这些文件，以便它们可以作为一个文件工作。具体来说，如何创建一条适用于所有代码的app.listen路由？