Dashboard currently uses a WebSocket commonly called EventStream/event socket, that is a constant stream of Events. It's an unfiltered stream. Every Event, every duplicate is sent.
MakerAPI is another method, it is filtered, it is de-duplicated and it only sends Events that have been subscribed.
There are at least 3 other Dashboard alternatives, perhaps a browse through their code will help.
There's very very little on EventStream, but you can click the hamburger menu on any hub and then Help. Then search for Eventstream. I found 4 references with the one above having the most words.