A simple Amazon SNS HTTP endpoint server that subscribe to a topic and show request and response logs related to Amazon SNS activities.

amazon-sns-server.js

// Amazon SNS HTTP Endpoint
// ========================
//
// A simple Amazon SNS HTTP endpoint server that subscribe to a topic and show
// request and response logs related to Amazon SNS activities.
//
// > (c) 2014 Chao Huang <chao@realguess.net>

var http  = require('http');
var https = require('https'); // HTTPS is needed for Amazon SNS subscription.
var port  = process.env.PORT || 3000;
var logs  = []; // Keep a log of all requests/responses from Amazon SNS.

// Simple request.
function request(url, callback) {
  var req = https.request(url, function (res) {
    var body = '';
    res.on('data', function (chunk) { body += chunk; });
    res.on('end' , function (chunk) {
      if (chunk) { body += chunk; }
      callback(null, res, body);
    });
  });
  req.on('error', function (err) { callback(err, null, null); });
  req.end();
}

// Simple response with logs of previous Amazon SNS requests/responses.
function respond(res) {
  // Remove the first item, keep the log small.
  if (logs.length > 20) { logs.shift(); }

  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify(logs));
}

// Log request coming from Amazon SNS.
function logRequest(err, req, body, rawBody) {
  logs.push({
    method : req.method,
    url    : req.url,
    headers: req.headers,
    rawBody: rawBody,
    length : rawBody.length,
    body   : body,
    error  : err,
  });
}

// Log response after requesting resource to Amazon SNS.
function logResponse(err, res, body) {
  logs.push({
    status : res.statusCode,
    headers: res.headers,
    body   : body,
    error  : err,
  });
}

http.createServer(function (req, res) {
  var messageType = req.headers['x-amz-sns-message-type'];
  var rawBody, body;

  // Ignore all requests that are not related to Amazon SNS.
  if (req.url !== '/amazon-sns' || req.method !== 'POST' || !messageType) {
    return respond(res);
  }

  rawBody = '';
  req.on('data', function (chunk) { rawBody += chunk; });
  req.on('end' , function (chunk) {
    if (chunk) { rawBody += chunk; }

    try {
      body = JSON.parse(rawBody);
      logRequest(null, req, body, rawBody);
    } catch (err) {
      logRequest(err , req, null, rawBody);
    }

    switch (messageType) {
      case 'SubscriptionConfirmation':
        // Visiting subscription URL and response to subscription confirmation
        // request can happen at the same time.
        request(body.SubscribeURL, logResponse);
        break;
      case 'Notification':
        // Do something.
        break;
      case 'UnsubscriptionConfirmation':
        // Do something.
        break; 
      default:
        // Unrecognized Amazon SNS messages
    }

    respond(res);
  });
}).listen(port);