whether a module or a server

app.js

/**
 * 
 * Created by tommytang on 5/18/15.
 */
  
var express = require("express");
var http = require("http");
var app = express();
var server = http.createServer(app);

app.set('port', 3000);
var boot = function () {
    server.listen(app.get('port'), function () {
        console.log('listening on port ' + app.get('port'));
    });
};
var shutdown = function () {
    server.close();
};
console.log("require\n", require.main);
if (require.main === module) {
    boot();
} else {
  console.log('running as a module');
  exports.boot = boot;
  exports.shutdown = shutdown;
  exports.port = app.get('port');
}