Re: Transparent cache behaviour and complaining webdesigners

In a previous episode Hroi Sigurdsson said...
::
:: I've set up a transparent squid cache which seems to be working fine
:: most of the time. Though today several users complained about not being
:: able to see the changes they made to their websites.
:: They use IE for the most part and the all the sites in question are on
[..]
:: in IE on the other machines as well. So in this situation it seems that
:: a reload from within Netscape is required for squid to update the page.

classic problem with network transparent proxies (they aren't really
transparent)..

what's going on is that when you click reload and msie sends it's
request to a proxy it includes a directive that says "revalidate
end2end with origin server, an unchecked cached copy won't do".. but
when it addresses the request to the origin server itself (instead of
the proxy) it doesn't waste the bytes on that header, because of
course the origin server will use the authoritative copy... because
your proxy is essentially spoofing (hijacking) for the origin server
msie holds back the no-cache directive ( reasonably so imho, but
reasonable folks disagree on this) and the proxy reuses a cached copy
if there is no other reason not to...

netscape includes the no-cache directive on all reload requests
without regard to destination.

if you can use the wpad stuff to automatically configure MSIE (so it
autodiscovers the proxy) you'll be much happier with the results
overall.

-P
Received on Mon Nov 08 1999 - 15:59:18 MST