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

From: Bryce Nesbitt <bnesbitt@bepress.com>
Date: Fri, 21 Jan 2011 13:14:58 -0800
Message-ID: <AANLkTi=tAt3-eseWUSZP=3zDtvmZ8vU9nwFQY2U9b=J0@mail.gmail.com>
To: HTTP Working Group <ietf-http-wg@w3.org>
Cc: Mark Nottingham <mnot@mnot.net>, lisa.dusseault@gmail.com
My specific proposal is in italics below, compared to the existing HTTP 1.1
specification.  For those of you reading this in plain text, it is the
paragraph discussing a MAY rule for code 2xx:

14.37 Retry-After

The Retry-After response-header field can be used with a 503 (Service
Unavailable) response to indicate how long the service is expected to be
unavailable to the requesting client.
This field MAY also be used with any 3xx (Redirection) response to indicate
the minimum time the user-agent is asked wait before issuing the redirected
*This field MAY be included with any 2xx (OK) response to indicate rate
limiting: the minimum time the user-agent is asked wait before issuing a
subsequent request of the same resource.  Should the user-agent violate that
timeout, a 503 response MAY be issued.*

The value of this field can be either an HTTP-date or an integer number of
seconds (in decimal) after the time of the response.

       Retry-After  = "Retry-After" ":" ( HTTP-date | delta-seconds )

Two examples of its use are

       Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
       Retry-After: 120

In the latter example, the delay is 2 minutes.
Received on Friday, 21 January 2011 21:16:02 UTC

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