A File System for Information Management

Nebula is a le system that explicitly supports information management. It di ers from traditional systems in three important ways. First, Nebula implements les as sets of attributes. Each attribute describes some property of the le such as owner, protection, functions de ned, sections speci ed, project, or le type. The content of the le is represented by a special text attribute. Second, Nebula supports associative access of les within a scoped index. A scoped index restricts associative access to a subset of the les in one or more le systems. Finally, Nebula replaces traditional directories with database views. A directory implements a naming closure; i.e. the name of a le is assigned by the directories in which it resides. A view is a query that selects le objects from a scoped index. Thus, the name of a le is a property of the le, not the view. Like directories, views can be named and included in other views. When a le (or view) is created, it is placed in an index, not a directory. The le appears in the appropriate set of views when the le system is refreshed. In this way, views dynamically classify les. The unique properties of the Nebula le system enable users to locate, classify, and identify information quickly and easily as demonstrated by several Nebula-based applications.