Finesse is a hybrid implementation of FUSE (Filesystem in Userspace) that combines traditional upcall kernel support (via VFS) with a separate message passing/shared memory model.
The basic premise of Finesse is to permit extension of the underlying VFS interface without breaking backwards compatibility. This is achieved by adding an interposition layer between the application and the system call interface, as well as a layer between the FUSE library and the FUSE file system.
Behavior can be fallback (existing FUSE) behavior via the system call interface, optimized behavior via the Finesse message passing layer, or enhanced behavior via the Finesse message passing layer. Only the latter requires changing applications explicitly.
TBD: describe building and installing as well as a basic description of how Finesse functions.