Open API USSD handling (Heroku)

app.js

var http = require('http');

http.createServer(function (req, res) {
  if (req.method !== 'POST') {
    res.writeHead(405, {'Content-Type': 'text/plain'});
    return res.end(req.method + ' not allowed. Use POST instead.');
  }

  var data = '';
  req.setEncoding('utf8');
  req.on('data', processPayload);
  req.on('end', sendResponse);

  function sendResponse () {
    var ussd = JSON.parse(data).api.request['ussd-pull'];
    res.writeHead(200, {'Content-type': 'text/plain'});
    res.end('Hello ' + ussd.callee + ' who sent ' + ussd.code);
  }

  function processPayload (chunk) {
    data += chunk;
  }
}).listen(process.env.PORT || 5000);

package.json

{
  "name": "ussd-heroku",
  "version": "0.0.0",
  "description": "",
  "main": "app.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "BSD"
}

Procfile

web: node app.js