Preventing caching

[JoeRT]

Has anyone heard of any new and creative ways to keep pages from being cached?  I'm familiar with the pragma no-cache  and expires 0 tags, but they don't always seem to work.  I have some dynamic content on a couple of my sites, and don't want info or pics from the morning showing up in the afternoon, making the pages look outdated.

Thanks!

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Joe Torsitano
www.weatherforyou.com
www.tiswest.com

[Justin]

I am behind a cache, and this particular cache is relentless... but it will not cache dynamic content that is obviously dynamic (eg, has a ? in the URL or is obviously a CGI). Using tricks like we did for www.aota.net actually cause the pages to be cached, but for our purposes it is fine, as it's not updated daily...

Also note that in my experience, sending *proper* no-cache headers works fine (read: not <meta> tags, actual HTTP headers - <meta> tags can easily be created or spoofed by anyone with a site on any server, so search engines/caches tend to ignore them). In PHP it's simple to add headers using the header() function.

Other than that, I don't really know of a way to prevent caching on static looking content... that's the point of static content (rather that's the point of a cache)...

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Justin Nelson
FutureQuest Support

[JoeRT]

Thanks, Justin.  My problem is the opening page (index.shtm) is the one that's dynamic on a couple of my sites... one has a map which is updated every hour or so, and the other has some general information which is updated hourly.  Oh well, guess I'll just leave the pragma and expires tags in there and let them work when they can.  

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Joe Torsitano
www.weatherforyou.com
www.tiswest.com

[PaulKroll]

Is it possible that the page cache isn't the problem? If the map is updated hourly, and I assume the map is a graphic of some kind, then the caching information that apache is sending when the .gif or .jpg (.png?) is requested, isn't the same data that the .shtml page is sending. Since graphics generally change far less often than pages, the default for the FutureQuest server for &quot;ExpiresByType image/gif&quot; (or ExpiresActive or ExpiresDefault) might be set very high.  You might wanna try adding ExpiresByType to .htaccess with a low (or at least, relatively low) value for gifs/jpgs in that directory. (Of course, this is just my understanding of how this works: I could be wrong.
[This message has been edited by PaulKroll (edited 01-22-00@2:20 pm)]

[JoeRT]

Thanks, Paul.  Now I need more help on how to use commands in the .htaccess files.    Anyone have any good references on .htaccess commands?

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Joe Torsitano
www.weatherforyou.com
www.tiswest.com

[Justin]

http://www.apache.org/docs/



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Justin Nelson
FutureQuest Support

[JoeRT]

Actually, Paul, you are right!  It works like a charm.  And thank you Justin for pointing me to the docs!

Just another reason why I'm SO glad I'm with FQ... community help and the tools to make it happen.  

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Joe Torsitano
www.weatherforyou.com
www.tiswest.com

[Mandi]

I am hoping this will help with my UBB users who find threads cached, and are unable to view their own replys until after they log off and log on (refresh isn't cutting it.)

I am a little confused by the code tag after the A:

ExpiresActive On
ExpiresByType text/html A____

Documentation on http://www.apache.org/docs/mod/mod_expires.html#AltSyn makes it sound as though ExpiresByType text/html &quot;access plus 1 month 15 days 2 hours&quot; is the proper context, rather than the A<code> featured on http://www.apache.org/docs/mod/mod_e...#expiresbytype

TIA . . . 

[JoeRT]

Since I just found out about this myself, I'm no expert yet.  But what I'm using is M#### where #### is the number of seconds until the content expires since it was modified.  At http://apache.org/docs/mod/mod_expires.html they talk about alternate syntax (which I'm going to experiment with later today just for the fun of it )... in other words, 'A' will work, but here's 'B' for those of you who like to use a little plainer english.  Like they say on their site... &quot;The ExpiresDefault and ExpiresByType directives can also be defined in a more readable syntax.&quot;  Since it says &quot;also&quot; I'm thinking either would work.  It appears either would function correctly.
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Joe Torsitano
www.weatherforyou.com
www.tiswest.com