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Re: PROPOSAL: Weak Validator definition [i101]

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 29 Jul 2008 20:04:00 +0200
Message-ID: <488F5B90.6050501@gmx.de>
To: Mark Nottingham <mnot@mnot.net>
CC: HTTP Working Group <ietf-http-wg@w3.org>

Mark Nottingham wrote:
> 
> I haven't seen any support for Lisa's straw-man proposals, and 
> discussion seems to confirm the below as the direction we want to take 
> this. Closing this one (although there may be other issues nearby...).

Mark and I discussed this yesterday, and Mark came up with a concrete 
proposal (see <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/101>):

> Suggestion:
> 
> P4, section 3:
> 
> A "weak entity tag," indicated by the "W/" prefix, MAY be shared by
> 
>     two entities of a resource only if the entities are equivalent and could be substituted for each other with no significant change in semantics.
> 
> to:
> 
> ... MAY be shared by two representations of a resource only if the origin server considers them to be semantically equivalent.
> 
> Section 5:
> 
>     However, there might be cases when a server prefers to change the validator only on semantically significant changes, and not when insignificant aspects of the entity change. A validator that does not always change when the resource changes is a "weak validator."
> 
>     Entity tags are normally "strong validators," but the protocol provides a mechanism to tag an entity tag as "weak." One can think of a strong validator as one that changes whenever the bits of an entity changes, while a weak value changes whenever the meaning of an entity changes. Alternatively, one can think of a strong validator as part of an identifier for a specific entity, while a weak validator is part of an identifier for a set of semantically equivalent entities.
> 
> Section 6:
> 
>     In order to be legal, a strong entity tag MUST change whenever the associated entity value changes in any way. A weak entity tag SHOULD change whenever the associated entity changes in a semantically significant way.
> 
> to:
> 
> ... A weak entity tag SHOULD change whenever the associated entity changes in a way that the server determines is semantically significant.

Feedback appreciated,

Julian
Received on Tuesday, 29 July 2008 18:04:47 GMT

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