You should be using RESPONSE.setHeader('Cache-Control', 'no-cache') --sam Adam Gotheridge wrote:
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
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