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From Brian Mearns <mearn...@gmail.com>
Subject Re: [users@httpd] How to avoid caching on apache (with tomcat in back-end)?
Date Mon, 23 Mar 2009 15:30:11 GMT
On Mon, Mar 23, 2009 at 10:12 AM, Darius Rus <dariusrus@gmail.com> wrote:
> Hi,
>
> I have an issue related to caching on apache server (my setup is
> Apache/2.2.11 (Win32) in front of tomcat/6.0.18 using mod_jk/1.2.27)
>
> I have a dynamic (JSP) page with a form that can be submitted that contains:
>
> response.setHeader("Cache-Control","no-cache"); //HTTP 1.1
> response.setHeader("Pragma","no-store, no-cache, must-revalidate"); //HTTP 1.0
> response.addHeader("Cache-Control", "post-check=0, pre-check=0");
> response.setDateHeader ("Expires", -1); //prevents caching at the proxy server
>
> I've added this to avoid caching, so that after the form is submitted
> and the user clicks on browser "back" button the form is not displayed
> from cache.
>
[clip]

If you're able to determine (or still strongly suspect) that the
browser is really behaving as you originally thought, check to see if
your browser is actually recognizing the page as expired, but is
checking back with a HEAD to see if it's actually been modified. If
any part of your server or server-side script is putting in a
Last-Modified or Etag headher, then the browser could be validating
against these and determining it does not actually need to update. If
this is happening, it should show up in your server's access logs as
an additional access.

Also, check your server's logs to find out what version of the HTTP
protocol your browser is requesting with; this will help you track
down where your problem is. It's most likely 1.1, but you never know,
and 1.0 client's are notoriously unfettered when it comes to caching.

Out of curiosity, where did the post-check and pre-check come from?
I'm not familiar with those (non-standard) cache-control directives.

-Brian

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