Re: p6: Vary and effects on future requests

Mark Nottingham <mnot@mnot.net> Mon, 29 April 2013 12:39 UTC

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From: Mark Nottingham <mnot@mnot.net>
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Date: Mon, 29 Apr 2013 22:39:02 +1000
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Subject: Re: p6: Vary and effects on future requests
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On a related note, the text in p6 4.3 doesn't explicitly account for the case when there are stored responses both with and without Vary that might match.

I think this can be addressed by changing:

"If multiple selected responses are available..."

to

"If multiple selected responses (potentially including responses without a Vary header) are available..."


On 29/04/2013, at 3:13 PM, Mark Nottingham <mnot@mnot.net> wrote:

> p6 4.3 says:
> 
> """A Vary header field value of "*" always fails to match, and subsequent requests to that resource can only be properly interpreted by the origin server."""
> 
> Someone reading this could take away that *any* stored response with a Vary: * has an effect on ALL other stored responses that share that primary key (and a couple of the issues we discussed reflected this confusion, from memory).
> 
> As I recall, the goal for 4.3 Using Negotiated Responses was to assure that stored responses were independent and self-describing; i.e., that a cache didn't have to rationalise the value of the Vary header among multiple stored responses.
> 
> So, I'd suggest changing this to just:
> 
> "A Vary header field value of "*" always fails to match."
> 
> Make sense?
> 
> 
> --
> Mark Nottingham   http://www.mnot.net/
> 
> 
> 
> 

--
Mark Nottingham   http://www.mnot.net/