mod_cache implements an RFC 2616 compliant HTTP content cache that can be used
to cache either local or proxied content. mod_cache requires the services of
one or more storage management modules.

Two storage management modules are included in the base Apache distribution:

* mod_disk_cache - implements a disk based storage manager for
use with mod_proxy.
* mod_mem_cache - implements an in-memory based storage manager.

mod_mem_cache can be configured to operate in two modes: caching open file
descriptors or caching objects in heap storage.

mod_mem_cache is most useful when used to cache locally generated content or to
cache backend server content for mod_proxy configured for ProxyPass (aka
reverse proxy)