The K Desktop Environment [KDE] provides a completely asynchronous virtual file system library called kio.
kio uses the same extended URI syntax that the GNU Midnight Commander uses; but unlike the Midnight Commander, all the file operations are performed through external helper processes ( kioslaves) in an asynchronous fashion. The helper process communicates with the master process using Unix domain sockets and custom protocols; the library performs encoding/decoding of such protocols automatically and notifies the programmer using the Qt [Qt] signal system.
Although this system is closer to the requirements that we have listed at the beginning of this paper, it is still suboptimal, for the following reasons: