Re: X-Vary-Options patch

Mark,

Just create a wiki page in wiki.squid-cache.org and kick-start this.

Adrian

On Sun, Jun 08, 2008, Mark Nottingham wrote:
> +1 to what H says. I'm definitely interested in this area, but want to
> think through it a bit more.
>
> We can get a certain amount of functionality without any extension;
> e.g., canonicalising selecting headers to take care of whitespace and
> case issues, and perhaps even ordering (this doesn't work for generic
> headers, but where we know the semantics and ordering isn't
> significant, it isn't a problem).
>
> That doesn't take care of the qval problem, but it helps in the accept-
> encoding case, which is the most common (I don't often see qvals on a-
> e; anybody?). One of my concerns about X-Vary-Options (can we please
> drop the 'X-'?) is that there are non-obvious corner cases; it forces
> the origin server admin to think very carefully about all the
> different variants that they're going to issue, and the request
> headers that will match them. If we can get rid of the common cases by
> canonicalisation, they will have less opportunity to mess things up.
>
> Also, it's important to realise that at some point it's more
> worthwhile to take an approach like TCN and describe the available
> variants, rather than match against selecting headers.
>
> Cheers,
>
>
>
> On 07/06/2008, at 5:19 PM, Henrik Nordstrom wrote:
>
> >On l?r, 2008-06-07 at 10:43 +0800, Adrian Chadd wrote:
> >>I think some of their stuff was backed out of Squid-2.7 before
> >>release.
> >
> >The Vary invalidation patch was backed out from 2.7 as it's incomplete
> >and broke things.
> >
> >But this X-Vary-Options patch never got committed. Thread stops after
> >your request for him to file a bugzilla entry, and it got lost in the
> >noise until found again by Mark.
> >
> >I have concerns about the completeness about this patch, for example
> >if
> >it handles q values properly. It's not such abig deal on
> >Accept-Encoding, but can get quite messy if applying this to Accept or
> >Accept-Language.
> >
> >For Accept* heaers I think it needs to be extended with an option
> >instructing caches to parse the Accept* header to a limited degree,
> >which means the cache needs to know the list of available choices for
> >the header at the server and their order of priority.
> >
> >Also, for cookie it needs to be a little more elaborate as most often
> >one wants to match on cookie names, not their vaule.. and sometimes a
> >value of a specific cookie.
> >
> >Regards
> >Henrik
> >
>
> --
> Mark Nottingham mnot_at_yahoo-inc.com
>

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