The socket server only exposes a very small subset of what is available in MHAPI. The sum total of what calls are available can be found inside the *ops.py files here:
https://github.com/makehumancommunity/c ... ver_socket(in the __init__ of each file is an array called "function" where available function calls are specified)
If there is a particular call you would like to add, a pull request or a patch for adding it is welcome.