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Server Sent Events infamously have low global connection limit per origin[1], so if you have multiple tabs open for a single site you'll run into it pretty quic

by kreetx 3y ago

Server Sent Events infamously have low global connection limit per origin[1], so if you have multiple tabs open for a single site you'll run into it pretty quickly. If it weren't for that, they would be great. [1] https://stackoverflow.com/questions/18584525/server-sent-events-and-browser-limits https://stackoverflow.com/questions/18584525/server-sent-eve...

flaviut 3y ago
I've never worked with Web Workers, but the doc page mentions them at the very top. Isn't that the intended workaround? Have a background thread that receives the events & coordinates, rather than having each page deal with them?
- silverwind 3y ago
  Yes, that's `ShardedWorker`.
  - nikeee 3y ago
    I wanted so use these in a project recently, only to find out that they aren't supported on Chrome for Android. This makes them non-usable for me, since there is no drop-in polyfill available yet.
    - silverwind 3y ago
      If you are doing websocket in there, you could fall back to main thread, but it comes at the cost of code duplication.
VWWHFSfQ 3y ago
Sophisticated services that offer SSE will have many different endpoint domains to get around browser limits on simultaneous connections to the same service. endpoint-00.example.com endpoint-01.example.com endpoint-02.example.com etc. It isn't specific to SSE. It's any HTTP request. SSE is just the most obvious because the connections stay open for long periods.
- paulddraper 3y ago
  And that's an easy workaround, with wildcard DNS entries and certs.
- kreetx 3y ago
  That's what I'm saying: it's not that good for non-sophisticated services, you need workarounds to make this "great technology" work. Might as well switch to websockets and not worry about this.
  - miyuru 3y ago
    Another "workaround" is to enable HTTP/2, which should be already enabled if the system is managed by a competent admin who cares about his work.
    - kreetx 3y ago
      Right, but with websockets you wouldn't have to think about this at all. You'd also need to ensure http2 for local development, proxies in between, etc. You _can_ do all this, but you can also avoid putting any thought into this matter.
toomim 3y ago
This problem is fixed by using HTTP/2.
- silverwind 3y ago
  No, the browser's HTTP connection limits still apply on HTTP2, each `EventSource` per tab counts against this limit of I think 6 (?) connections. Websockets to my knowledge have no such limit because they are not HTTP requests.
  - makkesk8 3y ago
    This is simply not true, it's negotiated between the client and server and defaults to 100 usually. 6 is the limit for http 1.1 not http/2. Source: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events https://developer.mozilla.org/en-US/docs/Web/API/Server-sent...
  - nitwit005 3y ago
    I believe you have it essentially backward. Websockets consume a connection no matter what, as the protocol does not work with HTTP2 (there was an attempt, but I believe it wasn't adopted and abandoned). The SSE requests do work with HTTP2, as do some other old methods like long polling. All the tabs will generally share one connection to that domain.
    - DaiPlusPlus 3y ago
      > Websockets consume a connection no matter what, as the protocol does not work with HTTP2 (there was an attempt, but I believe it wasn't adopted and abandoned). Are you thinking of RFC 8441? https://www.rfc-editor.org/rfc/rfc8441 https://www.rfc-editor.org/rfc/rfc8441 If so, then it's already implemented by Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1434137 https://bugzilla.mozilla.org/show_bug.cgi?id=1434137 ...and by Chrome/Chromium since 91: https://chromestatus.com/feature/6251293127475200 https://chromestatus.com/feature/6251293127475200
      - 3y ago
janesconference 3y ago
You can do leader election[1] in that case [1] https://greenvitriol.com/posts/browser-leader https://greenvitriol.com/posts/browser-leader
tentacleuno 3y ago
That's just over HTTP/1. For HTTP/2 (which most people should be using anyway), the limit is 100.

by kreetx 3y ago

flaviut 3y ago

I've never worked with Web Workers, but the doc page mentions them at the very top. Isn't that the intended workaround? Have a background thread that receives the events & coordinates, rather than having each page deal with them?

silverwind 3y ago
Yes, that's `ShardedWorker`.
- nikeee 3y ago
  I wanted so use these in a project recently, only to find out that they aren't supported on Chrome for Android. This makes them non-usable for me, since there is no drop-in polyfill available yet.
  - silverwind 3y ago
    If you are doing websocket in there, you could fall back to main thread, but it comes at the cost of code duplication.

VWWHFSfQ 3y ago

Sophisticated services that offer SSE will have many different endpoint domains to get around browser limits on simultaneous connections to the same service. endpoint-00.example.com endpoint-01.example.com endpoint-02.example.com etc. It isn't specific to SSE. It's any HTTP request. SSE is just the most obvious because the connections stay open for long periods.

paulddraper 3y ago
And that's an easy workaround, with wildcard DNS entries and certs.
kreetx 3y ago
That's what I'm saying: it's not that good for non-sophisticated services, you need workarounds to make this "great technology" work. Might as well switch to websockets and not worry about this.
- miyuru 3y ago
  Another "workaround" is to enable HTTP/2, which should be already enabled if the system is managed by a competent admin who cares about his work.
  - kreetx 3y ago
    Right, but with websockets you wouldn't have to think about this at all. You'd also need to ensure http2 for local development, proxies in between, etc. You _can_ do all this, but you can also avoid putting any thought into this matter.

toomim 3y ago

This problem is fixed by using HTTP/2.

silverwind 3y ago
No, the browser's HTTP connection limits still apply on HTTP2, each `EventSource` per tab counts against this limit of I think 6 (?) connections. Websockets to my knowledge have no such limit because they are not HTTP requests.
- makkesk8 3y ago
  This is simply not true, it's negotiated between the client and server and defaults to 100 usually. 6 is the limit for http 1.1 not http/2. Source: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events https://developer.mozilla.org/en-US/docs/Web/API/Server-sent...
- nitwit005 3y ago
  I believe you have it essentially backward. Websockets consume a connection no matter what, as the protocol does not work with HTTP2 (there was an attempt, but I believe it wasn't adopted and abandoned). The SSE requests do work with HTTP2, as do some other old methods like long polling. All the tabs will generally share one connection to that domain.
  - DaiPlusPlus 3y ago
    > Websockets consume a connection no matter what, as the protocol does not work with HTTP2 (there was an attempt, but I believe it wasn't adopted and abandoned). Are you thinking of RFC 8441? https://www.rfc-editor.org/rfc/rfc8441 https://www.rfc-editor.org/rfc/rfc8441 If so, then it's already implemented by Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1434137 https://bugzilla.mozilla.org/show_bug.cgi?id=1434137 ...and by Chrome/Chromium since 91: https://chromestatus.com/feature/6251293127475200 https://chromestatus.com/feature/6251293127475200
    - 3y ago

janesconference 3y ago

You can do leader election[1] in that case [1] https://greenvitriol.com/posts/browser-leader https://greenvitriol.com/posts/browser-leader

tentacleuno 3y ago

That's just over HTTP/1. For HTTP/2 (which most people should be using anyway), the limit is 100.