[pmwiki-users] cache control

Petko Yotov 5ko at 5ko.fr
Tue Nov 24 18:05:03 CST 2009


On Tuesday 24 November 2009 18:43:16 Daniel Otis wrote:
> I added
> $HTMLHeaderFmt['cache'] = "<meta http-equiv='Cache-Control' content='cache'
> />"; to my config.php 

You shouldn't need to add this, with the next line, PmWiki will automatically 
tell the browsers which have seen the page, that it wasn't modified.

> and I have 
> $EnableIMSCaching = 1;
>
> But the headers have:
>
> GET / HTTP/1.1[CRLF]
> Host: www.moosoft.com[CRLF]
> Cache-Control: no[CRLF]
>
> Why is cache-control set to no?

It is Cache-Control: no-cache (just tested it on your server) and it is the 
correct thing to do, refer to
  http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9

Cache-Control: no-cache is about required validation, not about caching by the 
browser, but about caching by proxies -- the browser always asks the server 
if the page has changed, and if not, PmWiki sends a "304 Not modified" header 
and exits. It should work on your own site, check your apache logs and you'll 
have a number of 304 responses.

Note that a wiki page may include other pages, pagelists and conditional 
markup. Finding the actual Last Modified timestamp of all included pages is 
quite complex, so PmWiki just sends the timestamp of the latest edit of the 
latest edited page in the wiki - it's simpler, even if some browsers may 
download the same content twice.

Petko



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