Asterisk ARI | Websocket

Is there a websocket event that tells me if an endpoint goes online? Or do i have to poll all endpoints using the ARI-Interface?

You can subscribe[1] to receive events about a specific endpoint or you can also subscribe to receive events about all (passing endpoint: as the event source should do it if I recall correctly).

[1] https://wiki.asterisk.org/wiki/display/AST/Asterisk+13+Applications+REST+API#Asterisk13ApplicationsRESTAPI-subscribe