Use SSE (Server-Sent Events) in the lucky?

[zw963]

Is there a way to launch the SSE in lucky action?

I saw there is a sse shard https://github.com/y2k2mt/sse.cr, following work.

require "sse"

server = HTTP::Server.new [
  HTTP::ServerSentEvents::Handler.new { |es, _|
    es.source {
      # Delivering event data every 1 second.
      sleep 1
      HTTP::ServerSentEvents::EventMessage.new(
        data: ["foo", "bar"],
      )
    }
  },
]

server.bind_tcp "127.0.0.1", 8080
server.listen

How to use it in lucky?

Is there any sample lucky project can refer to?

Thanks

[jwoertink]

You can, but it's up to you to set it up. I did it once, but I don't have any examples laying around. Related

One thing to keep in mind though is without using HTTP2 SSE is pretty useless. You're limited to something like 6 connections total with Crystal's HTTP server. That will change if we manage to get #1981 merged in

[zw963]

Does Crystal official std-lib still not support HTTP2 yet?

[jwoertink]

It does not. Crystal std-lib only supports HTTP1.1

[Blacksmoke16]

Somewhat relevant as I was exploring a similar thing for Athena. Depending on your exact use case, could consider using https://mercure.rocks/docs/mercure. The con is it requires another service running, but the benefit is that the lucky app no longer needs to also be the SSE server. It just has to make POST requests to the mercure hub which inherently does support HTTP/2, along with some other helpful abstractions like JWT auth and such. Also has the benefit of since the hub is centralized, could also emit SSE events via a CLI command or what have you.