... out of compatibility Reasons moving up Versions with the Engine used in this project. The new Version is completly undocumented when this was written, but offered a lot of Promises on increasing Performance immensly.
Helpful references: https://socket.io/docs/v4/emit-cheatsheet/ https://socket.io/docs/v3/server-api/index.html#socket-on-eventName-callback https://redis.io/commands