Handling browser caches

[Coilcore]

Good browser caches are our friend, it make users happy and it makes servers happy.

But sometime caches can be a nuisance. Right now this is the case for doing a Zimbra upgrade. Everything is in halfway states for most users, all kinds of strange behavior of mixed up 3.1 and 4.0 UI until their browsers cache is flushed. Not quite sure why but Zimbra seems a little more cache sticky than most webapps, I know theres even an extra parameter put in for version to try to work past this, but it doesn't seem to work most of the time.

Still it seems simple enough to just flush the cache. I mean in development I even have my cache turned off. But what does one do with a really large user base? Its really not practical to walk a thousand people through flushing the browser cache.

Is there anything that we can do programatically? Anyone have any advice on this?

[jonnyRo]

We experienced similar problems with our 35 user base at Raydiance. Can anyone confirm whether any cache expiry headers are being sent out with email.js? or any of the other files utilized by Zimbra?

Now I fully understand that it is desirable to keep this file cached for as long as possible to improve startup times for each client, but on the server side there is no really easy way to signal to clients that they should now refresh their cache. Or is there?

I've never quite understood how the Internet Explorer "Check for new versions of stored pages : Automatically" setting works, nor do I have a very good understanding of Mozilla Firefox's cache behaviour.

Thanks to the original poster for bringing this up, as I was curious if others had similar problems.

[bellzerr]

We ran into this. Also, Firefox had issues until we upgraded to the current version. We told all our users to shift-refresh their browser which worked for most. A few users needed to close and reopen their brower to clean up the Zimbra screens.

[jonnyRo]

It would be cool if there was a way to see what user agents were coming into zimbra by-user so we could determine which browsers to focus most of our efforts on.

I know that IE is big within my company, but I would like to know if older versions of firefox were being used in some cases as well, so we can go after that user's machine to upgrade it.

[bobby]

you could do a "join" of the /opt/zimbra/log/zimbra.log with the /opt/zimbra/tomcat/logs/access_log.<date>; the zimbra.log has the ip address and user, the access log has the ip address and user agent

[KevinH]

From 4.0.1 on this cache problem should be solved. We've added very strict no-cache/expires headers so upgrading from that release on should prevent you from needed to force a reload or clear the cache.

[KevinH]

Originally Posted by jonnyRo

It would be cool if there was a way to see what user agents were coming into zimbra by-user so we could determine which browsers to focus most of our efforts on.

I know that IE is big within my company, but I would like to know if older versions of firefox were being used in some cases as well, so we can go after that user's machine to upgrade it.

You can run a standard log processing software like awstats or webalizer across the tomcat access_log