In a concerted effort to make the communication between the UFrameIT server and the Unity Plugin more principled, semantic, and scalable, we have fixed a JSON API that describes and standardizes the communicated objects independently of the implementations.
The implementation in the UFrameIT server is mostly complete, work on realizing it in the Unity plugin is well under way.
The API specification is maintained together with the UFrameIT server. It has stabilized for the moment, but will continue to evolve with the FrameIT project.
A side effect of this work is that it will be much easier (and well-defined) to add additional game engine plugins, e.g. for the Unreal Engine.