GRAS, a graph-oriented database system for (software) engineering applications

Modern software systems for application areas like software engineering, CAD or office automation are usually highly interactive and deal with rather complex object structures. For the realization of these systems, a nonstandard database system is needed which is able to efficiently handle different types of coarse- and fine-grained objects (like documents and paragraphs), hierarchical and nonhierarchical relationships between objects (like composition-links and cross-references), and attributes of different size (like chapter numbers and bitmaps). Furthermore, this database system should support the computation of derived data, undo/redo of data modifications, error recovery from system crashes, and version control mechanisms. We describe the underlying data model and the functionality of GRAS (GRAph Storage), a database system which has been designed according to the above-mentioned requirements. The central design decisions concerning its realization are discussed.