How to avoid polling in Twilio?

Question

I would like to create a Twilio app in python that runs in the background on my mac osx desktop and performs an action whenever a new text message arrives. I'm only interested in processing the most recently received text message.

My current solution is a polling mechanism where I have an infinite loop and in the loop I call TwilioRestClient(...).messages.list() every single time and process the first message in the returned array. I sleep for 1 second in each iteration in order to avoid taxing the processor too much.

The current implementation usually works but sometimes lags at the TwilioRestClient(...).messages.list() call for multiple seconds. I'm assuming this is because I'm using the trial version of Twilio. However, any advice on how to fix this would be greatly appreciated. The other main issue is that the implementation is extremely wasteful. The app should really be sleeping for the vast majority of the time it is running and there should be brief spurts of activity when new messages arrive.

Here's the current implementation:

def run(self):
    last_message = self.get_most_recent_message_body().lower()
    self.is_running = True
    while self.is_running:
        message = self.get_most_recent_message_body().lower()
        if (message != last_message):
            last_message = message
            self.commander.execute(message)
            sleep(1);

def get_most_recent_message_body(self):
    messages = TwilioRestClient(self.TWILIO_ACCOUNT_SID, self.TWILIO_AUTH_TOKEN).messages.list()
    most_recent_message = messages[0]
    return most_recent_message.body

I want the app to be as responsive as possible. The optimal solution would be some kind of Observer pattern or some kind of signal use where Twilio alerts my app to "wake up" whenever a new message arrives. Is there a way to implement this?

Thanks!

Answer 1

Twilio developer evangelist here.

You can absolutely do that without polling. Let me explain.

When you buy a number with Twilio you can set two URLs that point to an application that you build, one for voice and one for messaging. Then, when Twilio receives a call or a text message it will make an HTTP request (a webhook) to the url you set with the details of the call or the message. Your application can respond with some XML (called TwiML) to tell Twilio what to do with the message or call.

I'm guessing you're writing a python application as you tagged this question with Python. Here's a quick guide to getting started receiving SMS messages with Python.