WTF is FUSE?
Filesystems in Userspace
aka, really easy to write custom filesystem - bindings for nearly every language imaginable
implement a class consisting of up two dozen familiar POSIX methods such as mkdir, rename, symlink, open, read, write, etc. - basic filesystem in 50 lines of code or less
not unlike implementing a REST api - a hierarchy (file paths, URLs), using a simple set of verbs to manipulate the documents
like REST, you can do a lot with the basic concepts of directories and files - the unix philosophy, eg.: /dev/random, /dev/lp0, /dev/audio, /dev/rtc