Being documented is not enough. Implementing a commercial device requires including an Authentication component (before it used to be an actual chip, now it seems it can be done in software), and that can be used to prevent devices from speaking to alternative control apps.
From what I can tell, Homebridge implements Homekit as a device, receiving commands. But can anyone build an app or device to send commands, outside of iOS?
The fact that I can't find an Homekit control app for Android strongly indicates this is not possible.
> Being fully documented means anything can work in any way.
A protocol being fully documented does not mean you can get a device you cannot control (like an Homekit lightbulb) to connect to your server instead of the manufacturer's. If requests are signed and/or encrypted, knowing the protocol won't help if you don't have the keys. See also Tivoization.
> For example, search the web for ‘homebridge alexa’
I had found it. I don't think you realize that there's no Homekit there at all.
The point of Homebridge is to translate from a Homekit-speaking control app/assistant to a non-Homekit-enabled device:
But when you use homebridge-alexa, you're replacing that first link with another protocol (specifically, MQTT+JSON, which is what it uses to connect to https://www.homebridge.ca/).
So you've actually removed all Homekit parts from your smart home system!
From what I can tell, Homebridge implements Homekit as a device, receiving commands. But can anyone build an app or device to send commands, outside of iOS?
The fact that I can't find an Homekit control app for Android strongly indicates this is not possible.