A Class Hierarchy for Building Stream-Oriented File Systems

This paper describes the object-oriented design and implementation of a family of stream-oriented le systems under UNIX and under an object-oriented operating system called Choices . A class hierarchy provides an object-oriented taxonomy of the algorithms and data structures used in the design of this family. The family includes the System V le system, the 4.2 BSD le system, and the MS-DOS le system. The class hierarchy has been developed by a series of experiments that are designed to lead to a framework for object-oriented le systems. The class hierarchy for stream-oriented le systems is the product of the second experiment in this series in which we revised a class hierarchy for UNIX-like le systems[MLRC88] to include the MS-DOS le system. We describe the hierarchy, how it evolved from the rst experiment to the second, and review the lessons that we have learned from the two experiments.