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Re: WGLC: p4 MUSTs

From: Roy T. Fielding <fielding@gbiv.com>
Date: Fri, 23 Aug 2013 06:22:00 -0700
Cc: IETF HTTP WG <ietf-http-wg@w3.org>
Message-Id: <680A2211-358C-4BAF-BA77-1D199D3F33F2@gbiv.com>
To: Alex Rousskov <rousskov@measurement-factory.com>
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".


> 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.


> 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.


>> 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


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



Received on Friday, 23 August 2013 13:22:22 UTC

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