As promised, I've put together a prototype C++ client. See my github repo for more info: https://github.com/Vivero/KNav The repo includes a general purpose interface library I've named KRPCI, which interacts with the RPC server (I haven't implemented any support for the stream server yet). I then wrote a tool which queries the SpaceCenter service (or any service, for that matter), and generates a header and source file for an auto-generated class, which implements all the procedures/enums/classes provided by that service. Using this tool, I create the KRPCI_SpaceCenter library, which -- as you may have guessed -- provides function calls to all the procedures provided by the SpaceCenter service. Finally, as a use-case example, I created KNav, a small auto-pilot program which currently only has one function: it maintains your craft in a fixed-altitude hover. I'm looking forward to expanding its capabilities. Especially with the new Parts API you've added on! This code is very very new, and I haven't tested a lot of things. Currently it only runs and compiles on Windows. Hopefully any other developers looking to implement their own C++ autopilot programs can take advantage of this code.