Friday, 31 January 2020

OpenHAB Broadlink Binding situation report

After #dadlife, #newjob and #otherstuff got in the way for a while last year, I got back into my role as maintainer of the OpenHAB Broadlink device binding. My first priority was to create a binding JAR that would actually work with the newly-published OpenHAB version 2.5. As the Broadlink binding is still not part of the official OpenHAB binding repository, it doesn't "automagically" get the necessary changes applied when the upstream APIs change. Luckily, it wasn't too much work.

My priorities for 2020 for this binding remain unchanged; get it to a high-quality state, make it pass the (extremely strict) linter guidelines for OpenHAB code, and get it merged into the official codebase. For me to consider it high-quality, there are still the following tasks to do:

  • Get a solid chunk of it covered by unit tests to prevent regressions; and
  • Redesign the device-discovery and identification areas of the code, to make adding new devices easier
Unit Tests

Prior to OpenHAB 2.5, bindings/addons that wished to define tests had to create an entire second project that shadowed the production code and could only be run via a strange incantation to Maven which did horrible OSGi things to run integration-style tests. Essentially, OpenHAB addons were not unit-testable by conventional means. Which given most addons are developed by unpaid volunteers, naturally meant that hardly any addons had tests.

Fortunately, one of the major changes in the 2.5 architecture has been a move towards more Java-idiomatic unit testing. Finally, classic JUnit-style unit testing with Mockito mocking will be available for fast, reliable testing within the binding. I'll be shooting for at least 60% test coverage before I'll consider submitting a PR to OpenHAB.

Discovery redesign

I've been told that new versions of some popular Broadlink devices will be arriving in 2020. In anticipation of that, I want to make it much easier to add a new device. At the moment it requires defining a new subclass of BroadlinkBaseThingHandler (which is par-for-the-course for OpenHAB, being a pretty standard Java app), but also adding "magic numbers" in a number of places to assist in looking-up and identifying devices during "discovery" and also when they boot up. I want to consolidate this such that everything needed to support a device is located within one .java file - i.e. adding support for a new device will require exactly two changes in Git:

  • The new .java file containing all the required information to support the new device; and
  • Adding a reference to this class somewhere to "pick it up".
I see no technical reason why this can't happen, and consider it only fair if maintenance of the binding will (at least partly) be a burden on the core OpenHAB team. So again, I won't be submitting this binding to become official until that work is complete.

Thanks for all the kind words from users/testers of this binding - it's very rewarding to hear people using it with great success!


  1. Hi there,
    Very happy to find this blog and the Broadlink binding. I purchased and installed a SP3(US). The binding recognised it as a SP2. The main function (PowerOnOff) works perfectly but the unit is also supposed to have a nightlight and there is no control for that.Not a complaint because I am very happy that you have enabled me to have the main function, just a FYI if you have time to improve the binding.

  2. Hi there,
    Thank you for the binding, not seen much support for Broadlink with openhab so much appreciated.
    I've managed to add the binding into openhab and find set up my Broadlink Rm Pro as a thing which gives me a Command channel and a temperature channel.
    I'm new to openhab and only have limited experience with coding so not fully sure in what I'm doing 😁,
    I'm wanting to control my Broadlink TC2 switches via openhab so I can start building rules around them etc. Do you know how I would go about setting up the TC2 switches as things so I can control then in OH and set up rules around them?