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Re: p1-message-07 S 7.1.4

From: Adrien de Croy <adrien@qbik.com>
Date: Mon, 20 Jul 2009 20:49:26 +1200
Message-ID: <4A642F96.4030702@qbik.com>
To: Henrik Nordstrom <henrik@henriknordstrom.net>
CC: Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>


Henrik Nordstrom wrote:
> mån 2009-07-20 klockan 18:08 +1200 skrev Adrien de Croy:
>
>   
>> * a busy - try again later status (like SMTP 421) (actually this would 
>> be exceedingly useful for rate limiting connections - a try again with a 
>> retry-after header - maybe new status 309?).
>>     
>
> 503 + Retry-After exists already for this purpose and closely related
> situations.
>   
I thought I tried this once before and found a lack of client support 
for it.  But that's still better than 0 current support for a new one 
though.

> 3xx is inappropriate as it's not a redirect to a new resource.
>
> 4xx is inappropriate as the request as such (when isolated) is fine.
>
> 2xx is inappropriate as it's not a successful response.
>
>   
>> * an advertisement for the number of connections a server will accept 
>> from a client
>>     
>
> Yes.
>
>   
>> * something else
>>     
>
> Not sure anything else is needed.
>
>   
>> However I think these could risk over-complicating the issue for dubious 
>> benefit.  Are we even clear on what it is desired to limit?
>>     
>
> For normal pageloads with pipelining enabled 2 is a very reasonable
> limit.
>
> Without pipelining at least 4, maybe more.
>
> For other applications other requrements may exists.
>
>   
>> I've seen this many many times.  Even accessing an idle test server 
>> (over GB LAN) via a proxy was hugely slowed down loading many images due 
>> to the 2 connection limit in IE7.  It makes sites slow, whether the 
>> sites are overloaded or idle. 
>>     
>
> Pipelining disabled?
>   

yes - via a proxy.  Due to complexity of heuristics for detecting if a 
server supports pipelining or not, and fallback processing, it's 
difficult to proxy pipelining.

We serialize all requests via WinGate, since otherwise all aspects of 
the request/response chain (including all plugin filters) need to 
support it.  We do this with TCP flow control (stop reading from the 
client socket while we process the request/response)

Regards

Adrien

> Regards
> Henrik
>
>
>   

-- 
Adrien de Croy - WinGate Proxy Server - http://www.wingate.com
Received on Monday, 20 July 2009 08:46:43 GMT

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