Re: [squid-users] Caching Expired Objects

Adrian,
sorry but this is not a querry (?) issue. I think
Henrik explained why I am not caching. Just in case u
did not read his response I repeat for you info:
a) The object must have a cache validator
(Last-Modified or ETag). If there is no cache
validator then the response must be fresh for at least
minimum_expiry_time to get cached, this to avoid
wasting disk I/O ....

This is the exact problem I have that I am trying to
resolve, not querry string issues. If only I can
overide the lack of Last-Modified, Etag and not
meeting minimum_expiry_time conditions.

Thanks,
solomon.

--- Adrian Chadd <adrian@creative.net.au> wrote:

> On Tue, Sep 18, 2007, Solomon Asare wrote:
> > Hi Henrik,
> > thanks for your insightful response. However, the
> > object is a .flv file that hasn't changed in
> months.
> > The origin server certainly doesn't want the
> object
> > cached, but I want to. Any leads that can help me
> > achieve this?
>
> * set your refresh_pattern's right, you can override
> almost all the relevant
> headers in there;
> * if the URL has a ? in it then you need to look at
> the cache/no_cache directives
> * if in doubt, compile with the option to log
> request/reply headers (I forget
> what it is, ./configure --help will tell you) and
> take a look at exactly what
> headers they're sending back.
>
>
>
>
> Adrian
>
> > Regards,
> > solomon.
> >
> > --- Henrik Nordstrom <henrik@henriknordstrom.net>
> > wrote:
> >
> > > On m?n, 2007-09-17 at 11:55 -0700, Solomon Asare
> > > wrote:
> > > > Hi Amos,
> > > > I am not sure if refresh_pattern is the sole
> > > > determinant in caching an object, that is if
> it
> > > has
> > > > any influence at all.
> > >
> > > It has influence, both directly by assigning
> > > freshness information when
> > > there is none, and indirectly by overriding
> various
> > > HTTP controls..
> > >
> > > Requirementsto cache stale objects:
> > >
> > > a) The object must have a cache validator
> > > (Last-Modified or ETag). If
> > > there is no cache validator then the response
> must
> > > be fresh for at least
> > > minimum_expiry_time to get cached, this to avoid
> > > wasting disk I/O for
> > > caching content which can not be reused.
> > >
> > > b) There must not be other headers preventing it
> > > from getting cached.
> > > refresh_pattern can override most of these if
> > > needed.
> > >
> > > > I am not discussing getting a
> > > > HIT for a cached object, but rather caching an
> > > expired
> > > > object from an origin server. If this object
> is
> > > > expired, by say 60 seconds before being served
> > > from
> > > > the origin server, how do I cache it? Date
> and
> > > > Last-Modified dates are also not set.
> > >
> > > If there is no Last-Modified and no ETag then
> it's
> > > useless to cache an
> > > expired object, as it can not be reused on any
> > > future request and all
> > > you get is extra disk I/O for writing the object
> > > out.
> > >
> > > A cache validator (Last-Modified or ETag) is
> > > required to be able to
> > > verify with the origin server if an expired
> object
> > > is still valid or
> > > not. Without a cache validator there is nothing
> to
> > > relate to and there
> > > is no other choice than to fetch the complete
> object
> > > again when
> > > expired..
> > >
> > > Regards
> > > Henrik
> > >
>
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Received on Tue Sep 18 2007 - 03:55:11 MDT