Protokoll

This is an attempt to document the Hemtjänst protocol. You’ll find the specification of how devices and features are encoded as well as the documentation for the service discovery mechanism.

Contrary to many other projects Hemtjänst reuses an existing specification, the Apple HomeKit Accessory Protocol. We use Apple’s Accessories, Services and Characteristic definitions but have extended it with some of our own in places where Apple’s specification falls short. Access to the HAP specification requires an Apple ID but is otherwise free (you don’t have to be a subscriber of the Apple Developer program).

Versions

The current version of the protocol is v0. An update to it, v1, is currently under discussion.

Specifications

Each version contains two specifications. One is for how to represent a device and its features. This is what we call Metadata. The metadata specification also provides the mapping for device features to MQTT topics.

The second specification is the Service Discovery part. This documents how devices can discover each other and how to make yourself discoverable.