Hello. I did the same. I came up with redis (as phpsession storage), in combination of nginx (as proxy for ssl/wss termination), crossbar.io as websocket router, autobahn.js as ws-js-client and Thruway as Libs. It is not an cake plugin. I wrote my own lib therefore for usage.
I read a lot about this topic. It is a big setup (i know), but necessary. There are so many pitfalls, with this setup, they are all handled.
Greetings!