Introduction to Plan B

This is the first native version of Plan B 3rd edition. Plan B is a derivative of Plan 9. Most of the system is taken verbatim from Plan 9. This includes most of the commands, system calls, and library functions. However, the the system is very different from a Plan 9 installation. It includes technology from both Plan 9 4th edition and Plan B 2nd edition.

In particular, resources are serviced by advertised volumes. A volume is a file system that has constraints and can be dynamically mounted. In Plan B, users say what kind of resources they want, and where in their namespace do they want them. The system does its best to provide the resources asked for, and adapts to resource availability as the environment changes.

Name spaces can now change underfeet, according to the application request to mount dynamic resources. The mount system call is new, there is a new volume driver, and there are new administration programs, new services (of a higher level of abstraction than their Plan 9 counterparts), and new file system conventions.

The system includes services for context handling, adaptation to environment changes, and assumes that there are multiple terminals per user.

Applications are now encouraged not to keep open file descriptors, and should use readf and writef instead.

Last, but not least, we have redesigned the system interfaces used to create graphic interfaces, execute programs, and several other important ones.

Laboratorio de Sistemas
GSyC, Rey Juan Carlos University of Madrid
Madrid, Spain
2004.