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Re: WGLC Issue for p4: Optionality of Conditional Request Support

From: Mark Nottingham <mnot@mnot.net>
Date: Mon, 19 Mar 2012 10:24:45 +1100
Cc: HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <C6DE67CE-DC49-47B0-AAE5-CA7A68EDBA4B@mnot.net>
To: Roy T. Fielding <fielding@gbiv.com>

On 17/03/2012, at 9:16 AM, Roy T. Fielding wrote:

> On Mar 16, 2012, at 1:53 AM, Mark Nottingham wrote:
>> Is p4 optional or not (for servers, clients, etc.)? I think it is, and so it should be explicitly marked as such.
> Nope, conditional requests have always been a SHOULD implement
> because of the benefits to the rest of Internet.

My .02 - The caching benefits are nice, but whether or not it's supported doesn't affect interop; it's a "moral" SHOULD. 

WRT pre-conditions on unsafe requests, most servers IME don't consistently honour If-Match or If-Unmodified-Since on POST, PUT, etc. requests (especially since POST is often handled by CGI). While we might say that it's REQUIRED or SHOULD or whatever, in real life it's treated as an optional add-on feature.

I think we should call it such; implying that it's required to be supported by servers leads clients to believe that they can count on it. We can encourage its implementation, highlight the dangers of not supporting it, etc., of course.

Mark Nottingham
Received on Sunday, 18 March 2012 23:25:15 UTC

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