So, what do webhooks look like?
Webhooks can be implemented in many ways. Usually a webook is called via a HTTP request to a PHP page. As the technology is already ubiquitous it makes it an almost trivial technology to utilise.Here are some examples of what a call to a webhook looks like:
- http://iotha.co.uk/webhooks.php?com=tx433_on_1&dev=RPI
- http://iotha.co.uk/webhooks.php?com=get&key=zone&val=1&dev=RPI
- http://iotha.co.uk/webhooks.php?com=ir&key=IR_HX_PLAY&dev=RPI&sub=HUMAX
- http://iotha.co.uk/webhooks.php?com=ir&dev=RPI&key=POWER&sub=RPI
- http://iotha.co.uk/webhooks.php?com=inf&dev=RPI&key=com
- https://maker.ifttt.com/trigger/LoungeCamOn/with/key/secretkey
My webhooks are implemented with the file webhooks.php which is on my server and can be called from anywhere in the world.
The usual PHP calling conventions are used:
Anything after the '?' is decoded as a set of parameter names and values.
A parameter name and value are seperated by a '='.
Each parameter name and value pair is seperated by an '&'.
The webhooks that I've implemented through the IOTHA website have the following arguments:
- com - This argument specifies a command to perform
- val - A value for the command to use
- key - An identifier that gives more data about the command
- dev - The device that the webhook is to be sent to
- sub - A sub-device for the webhook
I'll explain more about these later and show you how to implement them on your local network without the need for a website.
IFTTT allows you to set up webhooks and call them as shown in the final example, here it is used to switch on a TP-Link camera in my lounge (only if you know the secret key though).