RE: [squid-users] Can we use "no-cache" or "max-age=0" to refresh the cached objects

Hi Amos,

> Squid would request new data, I believe.
> Any time Squid receives new files from an authoritative source it
updates
> its cached copy with the new content (except possibly in cases of bug
#7).

I am scared by the "I believe" part :).

1. Can we relay on Squid to always update its cached content if the
response is newer (e.g. response has new Expires date and no other
validators)?
2. Squid does not change/optimize its behavior under high load in way
that could affect assumption (1)?
3. If (1) holds is this a (HTTP) standard behavior or Squid
implementation?

Thanks,
 Chris

> -----Original Message-----
> From: Amos Jeffries [mailto:squid3_at_treenet.co.nz]
> Sent: Thursday, October 02, 2008 4:05 AM
> To: Christian Tzolov
> Cc: squid-users_at_squid-cache.org
> Subject: Re: [squid-users] Can we use "no-cache" or "max-age=0" to
refresh
> the cached objects
>
> > Dear all,
> >
> > We have a Squid (2.6) server installed as a reverse proxy and
connected
> to
> > an original-server that uses the "Expire" header field to specify
when
> the
> > response should be considered stale.
> >
> > If the client requests includes a "no-cache" cache-control directive
can
> > we assume that Squid will be forced to *reload* the cached object
with a
> > fresh response returned by the original server (assuming that the
> response
> > has a new expiration date set)?
> >
> > The HTTP header specification
> > (http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.4)
says
> > that "the server MUST NOT use a cached copy when responding to such
a
> > request" but does not say what should happen with the current cached
> > object. Would it be replaced by new response?
> >
> > What would be the behavior of Squid in case of "max-age=0" request
> > directive (assuming again that the response has a newer expiration
date
> > set)?
>
> Squid would request new data, I believe.
> Any time Squid receives new files from an authoritative source it
updates
> its cached copy with the new content (except possibly in cases of bug
#7).
> A few other things come in to play such as whether its allowed to
store
> the content returned, Vary, ETag etc.
>
> Amos

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Received on Thu Oct 02 2008 - 09:02:20 MDT