s1.js

var express = require("express");
var app = express();

app.get('/app1',function(req,res) {
    res.send("Hello world From Server 1");
});

app.listen(8001);

s2.js

var express = require("express");
var app = express();

app.get('/app2',function(req,res) {
    res.send("Hello world From Server 2");
});

app.listen(8002);

server.js

var express  = require('express');
var app      = express();
var httpProxy = require('http-proxy');
var request = require('request');
var apiProxy = httpProxy.createProxyServer();
var serverOne = 'http://localhost:8001',
    ServerTwo = 'http://localhost:8002';
    
 
app.all("/app1/*", function(req, res) {
    console.log('redirecting to Server1');
    apiProxy.web(req, res, {target: serverOne});
});

app.all("/app2/*", function(req, res) {
    console.log('redirecting to Server2');
    apiProxy.web(req, res, {target: ServerTwo});
});

app.all('/getmap',function(req,resp){
    request.get({
        url: 'https://maps.googleapis.com/maps/api/js?key=AIzaSyCCisTmeb2rhu32O7n2M6RF1iS6xWFbEH4',
       
        json: true
      },function(err,res,body){
        if(err)console.log(err);
        else{
          console.log(res);
        resp.send(res);
        }

    });

});

app.listen(8000);