Sounds like a badly broken application to me. If the data is truly cacheable, the application shouldn't be taking explicit steps to try to prevent just that. Depending on what the backend system is, you might be better off using some kind of a filter to just remove that killCache parameter in the body text before it gets to the client. Then, you don't have to worry about it at all.
Thanks, Rick Houser Auto-Owners Insurance Systems Support (517)703-2580 -----Original Message----- From: Anthony J. Biacco [mailto:abia...@formatdynamics.com] Sent: Thursday, March 19, 2009 3:36 PM To: modules-dev@httpd.apache.org Subject: rewrite before caching? I posted this on the users list, but didn't get any help, so I'm hoping the dev people here can either help or at least explain if what I'm seeing below is how it's meant to work.. I have a uri with cachebusting in it that looks like this: /path?killCache=x¶meter1=y%parameter2=z where x is a unix timestamp used to make sure the url isn't cached by the browser. Now though I want to use apache disk caching on this url. Obviously with the killCache parameters always changing though, this is futile. And I can't ignore the query string with CacheIgnoreQueryString because parameter1 and parameter2 are important to the output to the end-user, so the cache would be inconsistent if I had caching ignore the query string. So I decided to rewrite the url to remove the killCache parameter, and while this rule itself works fine (I'm rewriting to a path not a full url), it seems the cache check is done before the rewrite. My rule is: RewriteCond %{QUERY_STRING} ^killCache=(.+)\¶meter1=(.+)\¶meter2=(.+) RewriteRule ^/path /path?parameter1=%2¶meter2=%3 [L] And in the log I see: [Wed Mar 18 12:02:47 2009] [debug] mod_cache.c(131): Adding CACHE_SAVE filter for /path [Wed Mar 18 12:02:47 2009] [debug] mod_cache.c(138): Adding CACHE_REMOVE_URL filter for /path [Wed Mar 18 12:02:47 2009] [debug] mod_headers.c(740): headers: ap_headers_output_filter() mod_cache.c(639): cache: Caching url: /path?killCache=x¶meter1=y¶meter2=z [Wed Mar 18 12:02:47 2009] [debug] mod_cache.c(645): cache: Removing CACHE_REMOVE_URL filter. [Wed Mar 18 12:02:47 2009] [debug] mod_disk_cache.c(962): disk_cache: Stored headers for URL http://myhost/path?killCache=x¶meter1=y¶meter2=z [Wed Mar 18 12:02:47 2009] [debug] mod_disk_cache.c(1051): disk_cache: Body for URL http://myhost/path?killCache=x¶meter1=y¶meter2=z cached. And I get a different cache file stored for every value of the parameter killCache. Anybody know a way to get the rewriterule processed before the cache mechanism? I can rewrite to a full url and the new request will then pull from cache, but that induces an extra request and an extra log entry, which I'd like to avoid if at all possible. Thanx, -Tony --------------------------- Manager, IT Operations Format Dynamics, Inc. 303-573-1800x27 abia...@formatdynamics.com http://www.formatdynamics.com
