AWS and Dash, Amazon buddies forever!

Amazon don't sell their IoT Button in the UK. But that didn't stop Aran and I from making a pretty sweet hack over the weekend...


...and winning Best Use of AWS, at my first ever international hackathon! (I'm the scared-looking chap on the right, if you must know.)

Our hack was simple, or so it seemed: use the Dash button to make a low-cost, low-effort panic button to rival the overpriced and less-than-sexy alternatives.

Aran's already gone into some of the problems we faced around networking. But I think it's worth talking a little bit about AWS -- after all, that was what we won the prize for!

Here's the best explanation I can give: a hasty scribble of the system architecture in my HackCampus notebook (always reppin'), electronicized by

So there's a local server, listening out for the Dash button sending ARP requests. Or, in our case, just plain UDP packets.

That server sends a POST to Amazon API Gateway whenever a button is registered (more on this later), or pressed.

That gateway is in turn backed by a couple of Lambda functions: one of which handles button-registration and the other of which handles button-pressing.

The button-pressing Lambda reads the GUID of the button that it's been sent, and retrieves some info about who we're gonna be waking up in the middle of the night from a Redis instance.

(Incidentally, this is where the button-registration Lambda comes in: instead of reading that info from the Redis instance, we're writing to it.)

When we've got the info we need -- maybe including a phone number to text, using Twilio's API -- we send a POST request to our Transformer server.

That Transformer server is running Express and it also happens to be the backend of the main site,

So whenever anyone connects to, they'll start a websocket connection with our Transformer server!

That means any time a button relevant to them is pressed, we'll be sending them a "ping" via a websocket connection -- so on the frontend we can flash some warning lights or some other crazy stuff. We chose to keep it simple for the demo, and just update a big heading with the message text.

Maaaaaybe this is a complicated way of doing things. After all, it might have been easier to set up a simple polling system where any client connected to would just ask (over and over again) whether there was a new message.

But where's the fun in that?