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Server-sent events

developer.mozilla.org

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Re: Server-sent events

#11

Post by franky47 »

no_wizard wrote: post #2

I know alot of websites and engineers use Websocket for push only data. SSE is tailored made for real time one sided updates! In fact, I think it made a better chat protocol, when we built a chat system at a previous job, similar to Slack. We ended up leveraging SSE to push updates to channels and traditional HTTP requests to send data to the server, resulting in lower latency and less overhead on the server side. We…

One major issue I encountered with SSE is dealing with reconnection. WebSocket makes it very easy to detect differences between a loss of network connectivity, a server dying, and a client exiting properly (eg: closing the tab), on either side of the socket.

Maybe there are facilities to do so with SSE that I don't know of, but my experience in reliable server-to-client-only comms with it has been a bit rough.

Re: Server-sent events

#12

Post by marcellus23 »

no_wizard wrote: post #2

I know alot of websites and engineers use Websocket for push only data. SSE is tailored made for real time one sided updates! In fact, I think it made a better chat protocol, when we built a chat system at a previous job, similar to Slack. We ended up leveraging SSE to push updates to channels and traditional HTTP requests to send data to the server, resulting in lower latency and less overhead on the server side. We…

What was the challenge in typing indicators? My naive idea is that it's basically sending `typing_started` and `typing_ended` messages.

Re: Server-sent events

#13

Post by pieter »

Note that this really isn’t anything except the agreement to send messages separated by 2 new lines. The SSE object in browsers is old and quirky; for example, it only supports GET requests, which means you’ll hit path length limits if you use it for something like LLM completion with large prompts.

Luckily since there’s nothing special about the browser support, you can very easily replace it with custom implementations. https://www.npmjs.com/package/@microsoft/fetch-event-source for example offers mostly the same API, but does offer POST requests and a bunch of other goodies.

Re: Server-sent events

#15

Post by VWWHFSfQ »

marcellus23 wrote: post #12
no_wizard wrote: post #2

I know alot of websites and engineers use Websocket for push only data. SSE is tailored made for real time one sided updates! In fact, I think it made a better chat protocol, when we built a chat system at a previous job, similar to Slack. We ended up leveraging SSE to push updates to channels and traditional HTTP requests to send data to the server, resulting in lower latency and less overhead on the server side. We…

What was the challenge in typing indicators? My naive idea is that it's basically sending `typing_started` and `typing_ended` messages.

I'm guessing that since it's not a full-duplex connection you have to send those messages out-of-band, ie, with a separate POST request API

Re: Server-sent events

#17

Post by jraph »

no_wizard wrote: post #2

I know alot of websites and engineers use Websocket for push only data. SSE is tailored made for real time one sided updates! In fact, I think it made a better chat protocol, when we built a chat system at a previous job, similar to Slack. We ended up leveraging SSE to push updates to channels and traditional HTTP requests to send data to the server, resulting in lower latency and less overhead on the server side. We…

I used both WebSockets and SSE. In one project, I even support WebSockets and a fallback working like what you describe.

I'm sold on using SSE for pushed updates. But how is regular requests + SSE easier on the server compared to WebSockets? It seems like an open connection to maintain in both cases plus additional http request for the SSE+requests case.

Re: Server-sent events

#18

Post by mr-wendel »

My favorite use of this that I've spotted in the wild is https://nightride.fm (not affiliated, just a fan!). It's a Synthwave music site + community.

In particular, I noticed that EventSource goodies are used to broadcast currently playing songs on each station, as well as to provide anon read access to their IRC server via a simple vanilla javascript webapp.

WAY cleaner and easier than web sockets for this use case, and CDN friendly to boot!

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