Hi,
Both the introduction to session-handling and the session_start() page MUST
point out that when you start a session, PHP automatically sends headers
which inhibit caching. I only discovered this via "guvnor"'s post at
http://openwebmail.mirror.luxadmin.org/manual/en/function.header.php
The situation which forced me to investigate this was:
* one part of my site has a very large menu (it's an on-line course).
* I'm actually redesigning the site. In my new design, the menu is
generated
dynamically even though it only changes when I add new pages. I build an
array and write the nested ULs from the array. This save me from updating
next / previous links on each page, which would be very time-consuming -
instead I just call my menu object's "writePreviousNextLinks" method.
* I decided to put the menu in an Iframe to save users from downloading
the
menu every time they went to a new page.
* a simple test showed that the menu was being re-loaded every time I went
to a new page.
Setting the menu Iframe's headers via META tags worked in Internet Explorer
but not in Firefox.
So now I send the following headers before the menu:
* Cache-control: max-age=10800 // 3 hours.
* Expires {now + max-age}
* Pragma: // Empty pragma.
This solved the problem. Obviously if I don't want some pages to cache I
will have to over-ride the headers on these pages, but that's easy enough.
Best wishes,
Philip Chalmers
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