If you are using a Linux distribution that have SELinux enabled by default, there is one thing you'd have to do before you can begin. The SELinux context for the cache directory have to be changed from httpd_sys_content_t to httpd_sys_rw_content_t, otherwise the framework won't be able to cache files.
This is done by executing the following commands as root:
chcon -R -t httpd_sys_rw_content_t '$FIX_TARGET_PATH'The $FIX_TARGET_PATH have to be the absolute path to the cache directory.