CODEWITHSUNDEEP
httpserver-sent-events
n1try
n1try

Reputation: 1120

Why use Server-Sent Events instead of simple HTTP chunked streaming?

I just read RFC-6202 and couldn't figure out benefits of using SSEs instead of simply requesting a chunked stream. As an example use case imagine you want to implement client and server, where the client wants to "subscribe" to events at the server using pure HTTP technology. What would be a drawback of the server keeping the initial HTTP request open and then occasionally sending new chunks as new events come up? I found some argument against this kind of streaming, which include the following:

However, in my understanding, both arguments also apply to SSEs. Another potential argument I could imagine is that a JavaScript browser client might have no chance to actually get the respective chunks, since re-combining them is handled on a lower level, transparent to the client. But I don't know if that's actually the case, since video streams must work in some kind of similar way, or not?

EDIT: What I've found in the meantime is that SSE basically is exactly just a chunked stream, encapsulated by a easier-to-use API, is that right?

And one more thing. This page first tells that SSE doesn't support streaming binary data (for which technical reason?) and then (at the bottom), they say that it is possible but inefficient. Could somebody please clarify that?

Upvotes: 8

Views: 5874

Answers (2)

Mario
Mario

Reputation: 1791

Yes, SSE is an API that works on top on HTTP for providing you some nice features such as automatic reconnection at client/server side or handling different types of events.

If you want to use it for streaming binary data, for sure it is not the right API. The main fact is that SSE is a text-based protocol (it's delimited by '\n's and every line starts with a text tag. If you still want to experiment with binary over SSE, a quick and dirty hack would be maybe submit the binary data in Base 64.

If you want to know more about SSE, maybe you can have a look to this simple library: https://github.com/mariomac/jeasse

Upvotes: 2

baynezy
baynezy

Reputation: 7066

You are correct SSE is a nice API on top of chunked HTTP. The API is good, and it also has support for reconnection.

With regards to your question about binary over SSE, I've got no experience of doing that. However, you can send binary over HTTP. So I see no reason why you can't do this. Although, you may end up having to convert it in JavaScript.

Upvotes: 2

Related Questions