GRAS, A GRAPH-ORIENTED (SOFTWARE) ENGINEERING DATABASE SYSTEM

Modern software systems for application areas such as software enginee ring, CAD, or office automation are usually highly interactive and dea l with rather complex object structures. For the realization of these systems a nonstandard database system is needed which is able to effic iently handle different types of coarse- and fine-grained objects (lik e documents and paragraphs), hierarchical and non-hierarchical relatio ns between objects (like composition-links and cross-references), and finally attributes of rather different size (like chapter numbers and bitmaps). Furthermore, this database system should support incremental computation of derived data, undo/redo of data modifications, error r ecovery from system crashes, and version control mechanisms. In this p aper, we describe the underlying data model and the functionality of G RAS, a database system which has been designed according to the requir ements mentioned above. Furthermore, we motivate our central design de cisions concerning its realization, and report on experiences and appl ications.