I have an Atag One central heating system and the corresponding themostat and want to control and monitor it through openHAB. There is no binding for this device, so in the past, I used a set of rules to connect to this device via this java application. This worked okay but was not a very elegant solution (at least to my opinion).
Now, recently, I have been experimenting with my own ESP8266 devices. In the process, I came along MQTT and the Homie convention, which work very nicely together with openHAB. So I thought, why not make my Atag One available as a Homie device? So that is what I implemented the past week. I created a Python script to read and write from the Atag One and bridge that to MQTT via the Homie convention. Luckily, I could use some building blocks available from Github so I did not have to invent the wheel again. The end result can be found in the atagone-mqtt-bridge project on Github.
I run openHAB via Docker, so for me it as natural to host this bridge also via a Docker container. The Dockerfile to build it can be found in the project. (I still have to find out how to publish these containers). But it should also be possible to run this bridge as a Python service (e.g. in openHABian).
I hope this solution is useful and please comment if you have any question or remarks.