CVMFS is a FUSE module which implements an HTTP read-only filesystem.
The idea is based on GROW-FS.  GROW-FS filesystem makes part 
of Parrot in the CC Tools developed at the University of Notre Dame.

CVMFS shows a remote HTTP directory as local file system.  The client
sees all available files.  On first access, a file is downloaded and
cached locally.  All downloaded pieces are verified with SHA-1.
 
To do so, a directory hive has to be transformed into a CVMFS
"repository", a form of content-addressable storage. 

This preparation of directories is transparent to web servers and
web proxies.  They just serve static content, i.e. arbitrary files.
Any HTTP server should do the job.

Developed for the delivery of experiment software stacks of the
LHC experiments at CERN.