RE: [users@httpd] mod_cache

[Axel-Stéphane SMORGRAV <Axel-Stephane.SMORGRAV@xxxxxxxxxxxxxx>]

I use mod_cache very extensively with Apache 2.0.49 and 2.0.54.

 

With 2.0.49 we had no problems with neither disk cache or memory cache. In Apache 2.0.54 we had to drop using memory cache because of a bug that made the server coredump.

 

In my experience it works very well, but you need to be aware that there are some deviations from the HTTP 1.1 RFC, specifically in the way "Cache-Control: no-cache" is handled.

 

The cache will roughly speaking cache any content served with a cache validator (ETag, Expires, Last-Modified ...) unless there is a Cache-Control header present that disallows cacheing (Cache-COntrol: no-store). I also believes that Apache interprets pragmas in html documents. Some servers/applications use "Expires: 0" to prevent cacheing. AFAIK this is not standard compliant and does not prevent Apache 2.0 from cacheing the response, or serving the cached response. The correct header would be "Expires: Thu, 1 Jan 1970 00:00:00 GMT".

 

In short the mod_cache works very well as long as the applications serve content with the correct headers in order to prevent dynamic content from being cached. Correct headers to prevent caching would be "Expires: Thu, 1 Jan 1970 00:00:00 GMT" or "Cache-Control: no-store" or both. In 2.0.54, mod_mem_cache does not work (at least on Solaris).

 

-ascs

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From: Praveen Alavilli [mailto:Praveen1992@xxxxxxx]
Sent: Wednesday, October 19, 2005 12:57 PM
To: users@xxxxxxxxxxxxxxxx
Subject: [users@httpd] mod_cache

Hi Guys,
Just wanted to 
find out if anyone is using mod_cache and what their experiences are. The web 
site says it's still in experimental mode - though the page might be an outdated 
one.

thanks for any 
info
Praveen
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