Re: Fact-checking: do any in-service proxy caches ever ignore Expires?

> but ...
> >From Anthony Baxter <arb@connect.com.au>
> squid allows you to force certain pages to not be expired for certain
> amount of time. This is useful for, eg www.realaudio.com, who set all
> their pages to expire 'now' (well, they used to, anyway).
>
> "Kolics Bertold, University of Veszprem" <bertold@tohotom.vein.hu>
> It *is* possible in Squid-1.1.x.
> Excerpt from the Release-Notes:
> "Squid 1.1 switched from a Time-To-Live based expiration model
> to a Refresh-Rate model. Objects are no longer purged from the
> cache when they expire. Instead of assigning TTL's when the
> object enters the cache, we now check freshness requirements
> when objects are requested."
> Minimum age can be given for specific URL patterns. By default it is set
> to zero for all URL patterns, but for cache-unfriendly sites it is usually
> changed...
>
> So I am still a little confused about whether Squid simply lets stuff
> stay in the cache past the Expires time, or whether it always checks
> past-Expires responses with the origin server before providing them.
> Kolics Bertold's quote from the Squid 1.1 release notes implies (but
> does not specifically state) that Squid *always* checks freshness;
> Anthony Baxter's comments implies (but not specifically state) the
> opposite.
Squids refresh_pattern directive overrides expiration from the response,
that's squid never contact origin servers before the min-age parameter.
If someone specifies a non-zero min age, squid violates the spec.
I would be satisfied, if min-age and max-age specified in refresh_pattern
have effect only if Expires and cache-control max-age is absent in the
response - in sync with the spec.
However, an overriding version of refresh_pattern would be useful too,
because of human lousiness we still see too much pre-expired pages, or
pages lacking Last-modified and content-length. I really hate to see such pages,
but how current proxies handle Cache-Control: must-revalidate?
Squid honors Cache-Control: must-revalidate - the proper (http/1.1)
way to count hits and do dynamic html etc.
> Sorry about the confusing language the first time I sent this.
>
> -Jeff
>
Andrew. (Endre "Balint" Nagy) <bne@CareNet.hu> <bne@bne.ind.eunet.hu>
Received on Tue Jul 29 2003 - 13:15:40 MDT