There are two modes:
ReDoc for v1.0 - PRIMARY, LTS, RESTful WebAPI
ReDoc for v0.1 - endpoint only for tests
Download CPlugin.WebAPI.Realtime.ts typescript interface file to get all interfaces and classes used.
Feel free to check source code of pages below to get general idea about SignalR/WebSockets connection.
very simple demo page can be found here.
Or move right to MT4 SignalR demo page, download it, put correct settings and run on your own