[Mediawiki-l] Browser caching problems (MediaWiki 1.3.9, IE 6)

[Jeremy Vignaux]

Thanks for all of your input. I resolve the image caching issue by
adjusting the Content Expiration settings on IIS. Beware of using the
"expire immediately" setting - as this will break all image downloads. I
set mine on 1 minute and that fixed the issue.




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Jeremy Vignaux wrote:
| We're having a lot of issues with pages (especially re-uploaded
images)
| not being displayed properly on end-user workstations because the
local
| browser is caching the pages even though they have been updated.
| Obviously manually clearing the cache (globally or with CTRL-F5) fixes
| the problem), but this simply doesn't scale well to end users.
|
| We're running MediaWiki on MS IIS 6.0 (Windows 2003) and all users are
| using IE 6 to view the site.

Images are not sent from the wiki, but come directly off the filesystem
through the web server, and we do not control the cache-related HTTP
headers that go with them.

Typically a changed image file (just like any other changed file with no
special cache headers) will require the user to manually reload to
actually get the browser go to the network to check for a short-term
change. If you do this sort of thing a lot, you might consider modifying
your web server's configuration to shorten the expiration time on images
on the uploads directory.

MediaWiki is developed and deployed primarily on Apache; most of us do
not have convenient access to IIS so if you are having problems with
caching of the actual wiki pages I'm afraid you'll have to debug it
yourself.

You should check that the correct cache headers are being sent. You can
use a network packet sniffer (such as ethereal) to grab HTTP traffic
between client and server, or if the problems are not IE-specific you
can use Mozilla Firefox with the 'Live HTTP Headers' extension
installed, which conveniently shows all the sent and received headers
for requested pages.

- -- brion vibber (brion @ pobox.com)