Remix: Using Server-Sent Events

1

Hello, all!

I’m trying out Render and it’s not bad so far. Main reason I’m using it is because I’m trying to use Server-Side Events. Unfortunately, the connection hangs and doesn’t seem to send the data from the EventSource. It works in my local build, and it actually worked on here for a bit, but has since stopped.

Can anyone provide insight on this? Thanks.

2

Server-Sent Events definitely work for us on render.

Once a time connection errors (net::ERR_QUIC_PROTOCOL_ERROR 200 (OK)) but event source reconnects just after this.

We worked with both native EventSource and @microsoft/fetch-event-source package.

Few tips:

  • Debug SSE endpoint with curl

  • Make sure that you are setting correct headers in response:

    Connection: keep-alive
Content-Type: text/event-stream
Cache-Control: no-cache

  • Emit retry: 500 event when connection is opened

  • Try to emit ping event every 60 seconds or so to keep connection alive.
    Let me know if this one helped

3

Thanks for the reply.

I think I know what the problem is: my machine is likely blocking the SSE connection. I tried it on other devices and they seem to work. I didn’t think this would be a problem.

Thanks for your help!

4

No problem.

I’d appreciate if you let me know whether Sever-Sent Events work on render.com without pings for long-lived connections.

5

I will try. They probably do. I’m not sure how long a Hobby server stays active for, though.

6

There’s no such thing as a Hobby Server. Limitations of Free tier instances can be seen at https://render.com/docs/free . All paid tiers continue to run as long as they’re paid for and not suspended.