The client/server protocol?

[HiPhish]

Hello,

I'm a Neovim user and I would like to try porting Geiser to Neovim. From what 
I understand Geiser consists of two parts: the client (Emacs part) and the 
servers (the Scheme part, a separate server for each implementation), similar 
to how Slime works. Obviously the client will have to be rewritten, but I 
would like to reuse the servers.

My question is, how do the client and server communicate? How does the client 
start the server? Which messages do they exchange? I know how to read Scheme 
and Common Lisp, but I don't know Emacs Lisp. The implementations I am most 
familiar with are Guile and Racket.

I want to be able to perform at least a simple handshake for starters, that 
should be enough to nudge me in the right direction. Just running the server 
from the command line and exchanging messages over stdio per hand would be all 
I need, I can figure out the Neovim side of things myself.

Thanks in advance for your answer. I really hope that Geiser can be brought to 
more editors.