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Re: Proposal for issue #101 (strong/weak validators).

From: Yves Lafon <ylafon@w3.org>
Date: Fri, 14 Nov 2008 18:45:50 -0500 (EST)
To: Werner Baumann <werner.baumann@onlinehome.de>
cc: ietf-http-wg@w3.org
Message-ID: <Pine.LNX.4.64.0811141828400.5395@ubzre.j3.bet>

On Fri, 14 Nov 2008, Werner Baumann wrote:

> This does not resolve the contradiction.
>
> "cases where the validator is use does not allow reliable identification of 
> changes". In current practise this means changes within the same second and 
> there is nothing that restricts the kind of changes that might occur.

Well, ETag is always either explicitely weak to denote "semantic 
equivalence". The text was added to explicit the definition of "weak"ness 
of other validators that have intrisic issue in outlining changes (like 
Last-Modified).

> "a weak entity tag value changes whenever the meaning of an entity changes. 
> .. a weak validator is part of an identifier for a set of semantically 
> equivalent entities" simply is not true for current practise.
>
> Why do you want to promise or suggest some kind of semantic equivalence when 
> arbitrary changes may happen without changing the weak etag?

What do you mean by that? If a weak Etag is reused after a major change 
occured, then it is an server choice, and it should accept the (possibly 
bad) consequences, even if that change arise in the same second 
(as it is irrelevant to the use of Etags as validators, just relevant when 
last-modified is used as a validator).
That is why the proposed text talks about "semantic equivalence" only in 
the context of Etags validators, and not validators in general (which I 
agree was ambivalent).
Cheers,

-- 
Baroula que barouleras, au tiéu toujou t'entourneras.

         ~~Yves
Received on Friday, 14 November 2008 23:46:00 GMT

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