[Zope] disable page cacheing

Adam Gotheridge adam@foxvalley.net
Thu, 2 Dec 1999 18:04:37 -0600


I still can't figure it out. The best I can come up with is
<!--#call "RESPONSE.setStatus('Cache-Control: no-cache')"-->

and that doesn't work

----- Original Message -----
From: Sam Gendler <sgendler@teknolojix.com>
To: Adam Gotheridge <adam@foxvalley.net>
Cc: zope <zope@zope.org>
Sent: Thursday, December 02, 1999 5:05 PM
Subject: Re: [Zope] disable page cacheing


> Adam Gotheridge wrote:
>
> > How do stop a page from being cached in either the browser or with Zope?
I
> > have added a meta tag like
> > <META http-equiv="EXPIRES" CONTENT="31 Dec 99">, but it doesn't do
anything
> > so I think the page is being cached from zope somehow.
> >
> > Thanks
> >
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>
> PLEASEdon't use META tags to provide HTTP functionality.  All web caches,
and
> most web servers ignore meta tags, since they deal exculsively with the
http
> protocol, and your meta tags are contained in the html.  Instead, set a
> Cache-Control: no-cache tag in the Response.  See the dtml guide for
syntax.
> For future reference, here are useful caching headers in http
>
> Cache-Control: no-cache makes an object uncachable
> Cache-Control: max-age=30 causes a client to cache the object for, at
most, 30
> seconds.
> Cache-Control: s-maxage: only applies to public cache, not private
(browser)
> caches.
> Cache-Control: private means a private cache (such as your browser cache)
can
> cache it, but public caches like the ones on your ISP's network, cannot
cache
> it.
> Cache-Control: no-store means don't store the object, same as
Cache-Control:
> no-cache
> Cache-Control: no-cache=Connection means don't store the connection header
> Cache-Control: must-revalidate means that all caches must validate their
stored
> object with the origin server, usually with an If-Modified-Since request
> Cache-Control: proxy-revalidate is the same as must-revalidate, but it
doesn't
> apply to private caches (browser caches)
> Cache-Control: public makes an object cacheable, regardless of other
headers
> that might imply that it is not cacheable.
>
> Any of these headers can be combined into a comma delimited list, such as
> Cache-Control: max-age=100, s-maxage=30, proxy-revalidate
>
> If you want to be backwards compatible with really old browsers, you
should
> throw a Pragma: no-cache header in there, as well.  Any new browsers will
give
> Cache-Control headers preference over Pragma headers, and old browsers
will not
> cache the object.
>
> The only other header that is object expiration secific is the Expires
header,
> which requires a date in a legal HTTP format.  This means rfc822 or
rfc1123, and
> rfc1123 is preferred.  It has the format 'Wed, 01 Dec 1999 13:42:23 GMT',
so
> Expires: Wed, 01 Dec 1999 13:42:23 GMT is the full form.  Alternatively,
> Expires: 0 can be used to specify an uncacheable object, according to the
spec,
> but I have no idea whether browsers support that in a Meta tag or not.
>
> --sam
>
>