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Re: Require UAs and intermediary caches to assume Vary: User-Agent

From: Mark Nottingham <mnot@mnot.net>
Date: Wed, 17 Oct 2012 18:32:14 +1100
Cc: ietf-http-wg@w3.org
Message-Id: <3D77B8BC-B65D-4D88-8137-9E8B32A13844@mnot.net>
To: "Simon Pieters" <simonp@opera.com>
Um, no.

Not only will this retroactively make all intermediary caches non-conformant, it'll also make them completely useless, because of the large (and unnecessary) amount of variance in User-Agent headers.

I understand there are security issues here caused by CORS, but that doesn't give you the ability to force changes on the rest of the Web. 

Regards,


On 17/10/2012, at 6:19 PM, "Simon Pieters" <simonp@opera.com> wrote:

> See http://www.w3.org/mid/507D94AB.3000207@mit.edu
> 
> It would be useful if the spec required that UAs and intermediary caches act as if all responses had Vary: User-Agent specified, since many pages on the Web serve different content depending on the User-Agent header but do not bother specifying Vary: User-Agent.
> 
> I would like this to be filed as a new issue in the issue tracker.
> 
> cheers,
> -- 
> Simon Pieters
> Opera Software
> 

--
Mark Nottingham   http://www.mnot.net/
Received on Wednesday, 17 October 2012 07:32:47 GMT

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