Interesting. I'm writing an application that will control devices over HTTP with a REST-style API (defined in OpenAPI). But we also want those devices to be able to alert the controlling application to events without being polled. This won't be a large datastream, but rather the occasional update of progress or notification of a state change.

I was considering Websockets or MQTT (or both), so server-sent events sound like a direct and possibly superior competitor. But from a design standpoint, what do you do? Just do a GET on some general "status" endpoint to open this SSE stream and then have the server send everything down this pipe indefinitely?