Hello,
My idea is making this using .Net and C#, completely managed. Since the TABIO SDK supplies COM object(s), it is really easy to consume it in C#. I have been working and creating COM objects for the past 14+ years, either from C++, or C# and using them for automation, from C++/C#, VBA or other scripts, so I know all of the gotchas to it.
About the http client, there's not much to it. .Net provides wonderful httpclient library for sending/receiving json (and or other protocols) so I do not expect any surprises there.
For the JSON formatting under C#, I'm going to use the NewtonSoft library, which is fast and well established.
If you give me you server code I could start it on my local node.js instance for testing. Or if you prefer to host it yourself, then that is OK, too.
You didn't mentioned if you want this to be just a wrapper, library, a windows app, or maybe a windows server?
If you have any questions, please don't hesitate to ask.
Regards,
Goran.