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Re: Server-sent Events and HTTP connection limits

From: Ian Hickson <ian@hixie.ch>
Date: Sun, 26 Apr 2009 23:28:24 +0000 (UTC)
To: John Fallows <john.fallows@kaazing.com>
Cc: "public-html-comments@w3.org" <public-html-comments@w3.org>
Message-ID: <Pine.LNX.4.62.0904262315390.10370@hixie.dreamhostps.com>
On Thu, 19 Mar 2009, John Fallows wrote:
>
> The Server-sent Events specification currently states in section 8. 
> Notes:
> 
> "Implementations that support HTTP's per-server connection limitation 
> might run into trouble when opening multiple pages from a site if each 
> page has an EventSource to the same domain. Authors can avoid this using 
> the relatively complex mechanism of using unique domain names per 
> connection, or by allowing the user to enable or disable the EventSource 
> functionality on a per-page basis."
> 
> There are some problems with the proposed workarounds:
>
>   o Even using separate hostnames can cause a problem if the same site 
> is opened in multiple tabs.
>
>   o The user would be confused why they need to switch tabs, disable a 
> feature, and then switch back to enable a different feature (due to an 
> internal implementation strategy they should know nothing about)
> 
> If multiple connections to the same SSE stream URL were authorized by 
> the server to share the same data, then only one connection would be 
> needed per browser for the same scheme, host, port, path and query 
> combination.

Interesting point. In fact, since we now have shared workers, authors can 
do this themselves, by just putting the eventsource in the shared worker. 
I've added a note to that effect in the spec, and added EventSource to the 
list of APIs available to workers.

I've also mentioned explicitly what was previously allowed but not very 
obviously so, namely that browsers can share event source connections.

HTH,
-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Sunday, 26 April 2009 23:29:08 GMT

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