Re: WGLC: p4 MUSTs

Roy T. Fielding <fielding@gbiv.com> Fri, 23 August 2013 13:24 UTC

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From: Roy T. Fielding <fielding@gbiv.com>
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Date: Fri, 23 Aug 2013 06:22:00 -0700
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To: Alex Rousskov <rousskov@measurement-factory.com>
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Subject: Re: WGLC: p4 MUSTs
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On Apr 30, 2013, at 5:33 PM, Alex Rousskov wrote:

>> The If-Match condition is met if and only if any of the entity-tags
>> listed in the If-Match field value match the entity-tag of the
>> selected representation using the weak comparison function (as per
>> Section 2.3.2), or if "*" is given and any current representation
>> exists for the target resource.
> 
> The "if and only if ... or if ..." construction looks funny. It is kind
> of correct because the first part applies to the non-* condition and the
> second part applies to the * condition, but still... Please consider
> dropping either "and only if" or the "if" in "or if".

Okay.

> Can a proxy with an empty cache determine whether "any current
> representation exists for the target resource" without forwarding the
> request to the origin server? In other words, does "exists" mean "exists
> in the proxy cache" or "exists on the origin server"? Perhaps you can
> add some test to clarify the scope of resource existence here from the
> caching proxy point of view.

Replaced with "has a representation" (and related changes).

> The same two concerns apply to the If-None-Match section.

Fixed.

> Here is a list of requirement-like statements that seem to be missing
> MUST/SHOULD/MAY keywords to make them formal requirements and indicate
> the level of those requirements:
> 
>> Preconditions are ignored if the server determines that an error or
>> redirect response applies before they are evaluated.

Fixed.

>> The conditional request header fields defined by this specification
>> are ignored for request methods that never involve the selection or
>> modification of a selected representation

Fixed.

>> The general rule of conditional precedence is that exact match
>> conditions are ...
> 
>> Specifically, the fields defined by this specification are evaluated
>> as follows:

Fixed.

http://trac.tools.ietf.org/wg/httpbis/trac/changeset/2361

....Roy