Chain.com Webhooks Example

webhooks.js

/*
  Chain's Webhooks system will send an HTTP request
  to our app with an event type of 'address-transaction'.
  The body of the request will contain Chain's transaction
  object. We can use this payload to do whatever we want!
*/
app.post('/', function (req, res) {
  if (req.body['event'] == 'address-transaction') {
    sendSMS(req.body.transaction)
    res.send('OK\n');
  }
});

// Using twilio's Node.js SDK, we can send
// an SMS to our phone alerting us of the change
// to our address.
var sendSMS = function(txn) {
  var b = 'sent=' + txnDiff(txn.outputs) +
      'received=' + txnDiff(txn.inputs);

  twilio.messages.create({
    body: b,
    to: process.env.YOUR_NUMBER,
    from: process.env.TWILIO_NUMBER
  }, function(err, message) {
    process.stdout.write(message.sid);
  });
}

/*
  This function will sum the values of inputs or outputs
  if the particular input or output is related to
  the address we specify in our environment.
*/
var txnDiff = function(col) {
  return _.filter(col, function(x) {
    return _.contains(x['addresses'], process.env.ADDRESS);
  }).reduce(col, function(memo, num) {return memo + num;}, 0);
}