On Wed, Apr 16, 2008 at 1:41 PM, howard chen <howachen@xxxxxxxxx> wrote: > Hi all, > > > On Wed, Apr 16, 2008 at 9:21 PM, Narendra Verma > <narendra.verma@xxxxxxxxxxxxx> wrote: > > Hi Howard, > > 1. Be sure to load following module > > > > LoadModule headers_module modules/mod_headers.so > > > > 2. Add following Header directive at the last of httpd.conf file. > > > > Header add Cache-Control max-age=3600 (in seconds) > > > > Here we can decide that what is the maximum age of cached response. > > If max-age passed then apache again sends request to backend(tomcat) for re-caching, if the body of response is not found modified then 304 status is found means existing cache would be used.If body changed then then it is re-cached. You can use any amount of time to decide re-caching. > > > > The problem is I don't know to cache for how long. Maybe 1 month, or > maybe one second, consider a blog post, it will be only updated when a > user leave a comment, but the exact time is unpredictable. > > Currently I am using PHP / Smarty cache, if a user leave a comment, I > will remove cache from the file system and the cache will be > re-generated next time if cache miss. > > The only draw back is since for a cached case, I am sending HTML via > PHP, so why I don't send the cache via Apache? The lighttpd Cache Meta > Language (http://en.wikipedia.org/wiki/Cache_Meta_Language) is what > exactly doing what I want, but I am just wondering if Apache users > have think of this before? ) > > On the other hand, mod_cache seems can't do what I want. Squid did > (wikipedia is using similar approach with "purge' multicast). Of coz > setting a squid is another overhead for my simple use. How, exactly, did you have squid configured? There are two ways to handle this problem in general: 1. You check for cache freshness on every request; or 2. You invalidate the cache when you know it becomes bad. For the first option, apache will send if-modified-since requests to the back-end on expired content (if the cache is in its own http layer). You can tune your php code to handle these quickly for the not-modified case, letting the cache send its copy. For the second option, there are two ways to invalidate a cache entry. First, you can send an HTTP request to the cache with Cache-control: max-age=0. Second, you can manipulate the cache directly on the filesystem. To see how this works, see the source code to htcacheclean. Joshua. --------------------------------------------------------------------- The official User-To-User support forum of the Apache HTTP Server Project. See <URL:http://httpd.apache.org/userslist.html> for more info. To unsubscribe, e-mail: users-unsubscribe@xxxxxxxxxxxxxxxx " from the digest: users-digest-unsubscribe@xxxxxxxxxxxxxxxx For additional commands, e-mail: users-help@xxxxxxxxxxxxxxxx
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