Ratchet is an alternative to ZeroMQ

I'm new to building WebSockets apps and I'm trying to set up Ratchet (since the back end will be entirely PHP).

Everything worked correctly until I received the "Push notifications" part. It says you can use simple sockets for push notifications, but they prefer to use ZeroMQ. Can you show me an example / point me to some tutorial on how to use these simple sockets? (I don't want to use ZeroMQ due to limited access to the production server, almost no way to install stuff there)

Or if there is a library for it that does not require any extensions to be installed, can you post me to your docs?

Thanks for any help.