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Re: Retry-After header on 20X response -- HTTP/1.1 spec extension?

From: Adrien de Croy <adrien@qbik.com>
Date: Wed, 24 Dec 2008 00:52:38 +1300
Message-ID: <4950D106.3000708@qbik.com>
To: Bryce Nesbitt <bnesbitt@bepress.com>
CC: ietf-http-wg@w3.org

Hi Bryce

I couldn't find a browser that honoured Retry-After even on a 3xx 
response.  So I wouldn't hold out much hope about widespread support for 
honouring it on a 2xx.  It looks like it hasn't really been picked up by 
the browser vendors as far as I can tell.

I was testing it for rate-limiting connections, redirecting the client 
back to the URL they just requested if the rate was over threshold.

Interesting behaviour from different clients.

IE went into a retry loop, I clocked over 3500 req/s
Chrome and FF just showed an error page complaining about a retry loop.
Didn't test much after that due to unusable results of the main browsers.



Bryce Nesbitt wrote:
> Dear Working Group Folks,
> I am not a member of the working group.  But I have recently been 
> tempted to "stretch" the HTTP spec, and I'm writing to inquire if what 
> I'm doing is reasonable enough to eventually fold into the spec.
> Basically I'm sending a Retry-After header on a 20x HTTP response.
> I'm working with a "throttled" data service which rate limits 
> connections.   Clients are harvesting a huge volumes of data over 
> time.  Presently clients get some data with a 200 result, ask again 
> right away and get a 503 response, then wait out the proper 
> Retry-After time.
> If I can return Retry-After with the 20x result, it will cut the total 
> requests in half.  Clients can ask for data, and know immediately how 
> long to wait before they ask again.  Only a client that violates the 
> timeout would ever see a 503.
> The HTTP/1.1 spec is pretty clear (in section 14.37) that Retry-After 
> is for 503 and 3xx return codes only. Your thoughts?  Where would I go 
> to suggest an expansion of the Retry-After header, to be inclusive of 
> 20x results?  Is this a reasonable extension in your view?

Adrien de Croy - WinGate Proxy Server - http://www.wingate.com
Received on Tuesday, 23 December 2008 11:50:43 UTC

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