A hapijs server sent event (SSE) example

[wy193777]

Module version

21.3.10

What documentation problem did you notice?

There is no hapijs SSE example. I recently figured it out but don't know where to put it. So I have it here:

'use strict';

const Hapi = require('@hapi/hapi');

const init = async () => {
    const server = Hapi.server({
        port: 3000,
        host: 'localhost'
    });

    // Route using raw.res for direct response handling
    server.route({
        method: 'GET',
        path: '/sse',
        handler: async (request, h) => {
            const res = request.raw.res;
            res.writeHead(200, { "Content-Type": "application/json" });

            const intervalId = setInterval(() => {
                res.write('this is a server sent event message');
            }, 1000);  // send a message every 1 second 
            const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
            await sleep(10000);  // mock a long running request handling

            res.end('This is a raw response using raw.res');
            return h.abandon; // Abandon Hapi's normal response flow because we used raw response
        }
    });

    await server.start();
    console.log('Server running on %s', server.info.uri);
};

process.on('unhandledRejection', (err) => {
    console.log(err);
    process.exit(1);
});

init();

[kanongil]

That is not really a SSE, as it needs to have Content-Type: text/event-stream.

Anyway, you should probably not use raw.res, but rather return a Passthrough stream that you can keep and later write the event data to. The response won’t end until the stream is closed.

Also, a Cache-Control: no-cache header is probably appropriate.

[wy193777]

Contributor

what's the difference between explicitly using res.end() compare to return a PassThrough?

[Marsup]

I just went through the code of susie, it seems pretty close to what kanongil has in mind. It's pretty old but I think it should be mostly functional even on today's hapi, you can always fork it if you find bugs.

[8th-block]

So is there a way to do "text/event-stream" in hapi?

[damusix]

@wy193777 @8th-block Check this out: https://matthewwid.github.io/better-sse/reference/recipes/#hapi

I haven't tried it, but I ran into it and asked the maintainer to add a Hapi example and he did. Perhaps it can fit your needs?

[hashda04]

Hi everyone ,
I noticed there’s some back-and-forth about adding a proper SSE example to the Hapi docs. I’d be happy to help put together a minimal, correct snippet (using text/event-stream, proper headers, and streams) if that would be useful. Could you confirm if a contribution like this would be welcome for the documentation?

Thanks!