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Re: i37 - Vary and non-existant headers

From: Jamie Lokier <jamie@shareable.org>
Date: Wed, 14 Nov 2007 19:10:51 +0000
To: Adrien de Croy <adrien@qbik.com>
Cc: Bjoern Hoehrmann <derhoermi@gmx.net>, "'HTTP Working Group'" <ietf-http-wg@w3.org>
Message-ID: <20071114191051.GB4691@mail.shareable.org>

Adrien de Croy wrote:
> IMO if the client doesn't advertise a capability for a request, it 
> should not be assumed to be available for that request, regardless of 
> any previous requests that may have advertised a capability. Therefore 
> to act as if an optional capability is available when not expliocitly 
> advertised is dangerous. 

Adding to this: whatever assumptions a server _might_ make (e.g. for
policy reasons, or knowing something about the clients another way),
in general caches should be conservative, and err on the side of
unnecessary cache misses, _never_ cache hits based on assumptions that
aren't the same as assumptions made by all compliant servers present,
past or future.  Whenever there's uncertainty, it's important to ask
the server if the request hits, and leave it to server policy to decide.

-- Jamie
Received on Wednesday, 14 November 2007 20:20:48 GMT

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