config.json

{
    "httpRoot": "/",
    "httpPort": 8080,
    "serviceRoot": "/api/",
    "serviceHost": "localhost",
    "useLocal": true,
    "staticPath": ["apps", "library"]
}

server.js

var express = require('express');
var path = require('path');
var fs = require('fs');
var bodyParser = require('body-parser');
var request = require('request');

var app = express();
var dataPath = __dirname + '/data/';
var rootPath = __dirname + '/../';
var configFile = require(rootPath + 'apps/config/app.json');

app.use(bodyParser.json());

var run = function(address, file) {
    app.all(configFile.serviceRoot + address, function(req, res) {
        res.json(JSON.parse(fs.readFileSync(dataPath + file + '.json', 'utf8')));
    });
};

if (configFile.useLocal) {
    run('', 'test');
} else {
    app.use(configFile.serviceRoot, function(req, res) {
        var url = configFile.serviceHost + req.url;
        var query = false;
        if (req.method === 'POST') {
            query = request.post({
                uri: url,
                json: req.body
            });
        } else {
            query = request(url);
        }
        req.pipe(query).pipe(res);
    });
}

configFile.staticPath.forEach(function(value) {
    app.use('/' + value, express.static(rootPath + value));
});

app.get('/', function(req, res) {
    res.sendFile(path.join(rootPath + 'index.html'));
});

app.listen(configFile.httpPort);