http3 breaks SSE

[WeidiDeng]

From the community, apparently, SSE doesn't work with http3.

[francislavoie]

/cc @dunglas since Mercure is SSE, do you happen to know how it interacts with HTTP/3?

[dunglas]

At least at protocols level, HTTP/3 works perfectly well with SSE (SSE is just a standard HTTP connection). If there is a bug, it's definitely an implementation bug.

IIRC I already tried the Mercure hub with HTTP/3 and it was working properly.

[mholt]

That's odd. I've asked for a minimal reproducer in the forum thread.

[jmzwcn]

Yes, I hit the same issue.

[otbutz]

That's odd. I've asked for a minimal reproducer in the forum thread.

https://sse.dev/test

[jmzwcn]

I find browser (sse client) will reconnect when it find server support a HTTP3 and having message come at the same time. The problem is just here, having reconnect, but message data is loss. This is not expected.

[jmzwcn]

#> > That's odd. I've asked for a minimal reproducer in the forum thread.

https://sse.dev/test

Your test not run in HTTP3.

[otbutz]

Your test not run in HTTP3.

I just listed a publicly available SSE endpoint as a basis for a reproducer 😉