9P, or the Plan 9 Filesystem Protocol, is a network protocol developed for the Plan 9 distributed operating system
as the means of connecting the components of a Plan 9 system (site).
The file is a central metaphor of Plan 9, and many things are represented as files, including windows, network connections, processes, and much more.
9P encourages caching and also serving of synthetic files (e.g. /proc to represent processes), unlike NFS.
9P was revised for the 4th edition of Plan 9 under the name 9P2000 that contained various fundamental improvements. The latest version of Inferno also uses 9P2000. The Inferno file protocol was originally called Styx, but technically it has always been a variant of 9P.
There is a server implementation of 9P for Unix called u9fs included in the Plan 9 distribution, and a kernel client driver for Linux as part of the v9fs project.
External links
- 9P Manual - Introduction to 9P
- v9fs - Implementation of 9P for Linux and Unix
- Inferno - The Inferno operating sytem that uses a variant of 9P called Styx (the latest version of Styx is compatible with 9P2000)
- The Organization of Networks in Plan 9
- IL - Transport protocol that was designed for 9P in local area networks. Note that 9P is mainly used over TCP currently.