That's exactly what I did, in my case adding a timestamp up to the millisecond.

()-()
 \"/
  `                                                     

IE can be very stubborn. I've had issues with it caching cookies it shouldn't have, and to my dismay there wasn't much I could do to beat it into behaving. Adding a Cache-control header as dws proposed is avisable - in fact, I advise sending actual headers rather than the META tags you have.

On the other hand, in your case it sounds like it could well be an issue on the server side, as though your script is being kept alive after one invocation and won't accept data after one run; after some idle time it's killed, and then takes data once more when it's rerun.

The fact that behaviour differs depending on user agent is odd however - either way.

Makeshifts last the longest.

I once found a good example here in the PHP docs, that has seemed to work for all cases I've seen. It is most certainly overkill, but if no other solution presents itself...

This is the original code, which is easy to translate into perl, since it is just prints at the right moment (as in first). :) The function header in PHP is basically a print, that adds the correct \015\012 and must be emitted before the HTML itself, as expected.

header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); // Date in the past
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // alwa
+ys modified
header("Cache-Control: no-store, no-cache, must-revalidate"); // HTTP/
+1.1
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache"); // HTTP/1.0
[download]

That said it is pretty strange if it was the browser caching a POST, as I've never seen IE have that problem. But it is hard to think otherwise, since you say that Opera doesn't have that issue.

POST requests should never be cached, only for when the user uses the "back" function. Opera had some problems in versions 4 and 5 with this (it was reported a lot), and this is why I haven't bothered trying Opera 6. If it doesn't cache POST requests anymore, the problem has been fixed. This seems to be the case.

If the script gets executed, a cached version of the page is not being used. I don't know what $query->Dump should do, but you might want to check the raw contents waiting in STDIN (use a BEGIN block to make sure you are faster than CGI.pm or any module that slurps STDIN) to know for sure that it's not a bug in the module you're using.

Some modules don't work well with mod_perl. Do you work with mod_perl here? If so, you might want to check whether you're using a global instead of a lexical, or if a module does that.

Does this happen with MSIE on one computer, or on multiple computers? Have you tried several versions? I know of some who had to reinstall Windows because of strange MSIE behaviour. Does the problem occur with Mozilla too? Because of my disappointing experiences with Opera and caching, I wouldn't recommend using Opera for sane comparisons.

- Yes, I reinvent wheels.
- Spam: Visit eurotraQ.

print header({-pragma=>'no-cache'});
print $query->start_html(-title=>'My Florb'',
                         -author=>'web@domain.com',
                         -base=>'true',
                         -meta=>{'keywords'=> 'Palm PDA parser',
                                 'copyright'=> 'Copyright © 2002 
+Florb, Inc.',
                                 'Cache-Control'=>'no-cache',
                                 'robots'=> 'index,follow'},
                        );
[download]

"When you use the <HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE"> metatag in the header section at the beginning of an HTML Web page, the Web page may still be cached in the Temporary Internet Files folder."

As of version 1.56, all HTTP headers produced by CGI.pm contain the Pragma: no-cache instruction. However, as of version 1.57, this is turned OFF by default because it causes Netscape 2.0 and higher to produce an annoying warning message every time the ``back'' button is hit. Turn it on again with the method cache().

use CGI qw/:standard/;

$modtime = scalar(gmtime(time - (3600 * 8))) . " GMT";
$exptime = scalar(gmtime) . " GMT";

print header(-expires=>$exptime, 'last-modified'=>$modtime,
             'cache-control'=>"no-cache, must-revalidate",
             'pragma'=>"no-cache"),
start_html('Header Test'),
pre("\nModtime: $modtime\nExptime: $exptime\n"),
end_html;
[download]

200 OK
Cache-Control: no-cache, must-revalidate
Pragma: no-cache
Expires: Fri Jun  7 13:23:22 2002 GMT
Last-Modified: Fri Jun  7 05:23:22 2002 GMT
[download]

The Pragma: no-cache and Expires headers are the important ones for clients which do not understand the Cache-Control header.