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proasp_codeclinic thread: IFRAME problem, javascript


Message #1 by "Steven Broos" <Steven.Broos@N...> on Thu, 8 Nov 2001 10:09:34 +0100
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
From: "Steven Broos" <Steven.Broos@N...>
Subject: [proasp_codeclinic] RE: IFRAME problem, javascript


: My serversettings should prevent caching, but apparently doesn't do the
: trick.
: Thx, this realy helped me out.
: Another problem solved :-)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

IIS settings do *not* prevent caching. There is a common misconception that
Expiring Page = No Caching. All the IIS settings do is set the expiry date.
The only cache-control header that is set is cache-control="private", ie
caching will be handled by the end user (stops proxies caching the data)

You can see this using telnet:

telnet> open www.yoursite.com 80
HEAD / HTTP/1.1
HOST: www.yoursite.com
{enter}
{enter}

Thus the client will still cache the page. Since the client may not have
their clock set correctly, the page may be reused.

To avoid this, either set the caching HTTP headers to not cache at all,
and/or set the expiry date in the past, or to an invalid format. A browser
will (should) treat this as immediate expiry (regardless of what their
current time is)

Cheers
Ken


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