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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 non-hierarchical relations 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 recovery from system crashes, and version control mechanisms. In this paper, we describe the underlying data model and the functionality of GRAS, a database system which has been designed according to the requirements mentioned above. Furthermore, we motivate our central design decisions concerning its ...

Abstract: Specification and rapid prototyping of graph manipulation software by means of PROgrammed Graph REwriting Systems (PROGRES) is a paradigm, which attracts more and more interest in various fields of computer science. Nowadays produced specifications for process modeling tools, database query languages, etc. have a typical size of about 100 to 300 printed pages. They suffer severely from the lack of any module concept. This paper introduces a module concept for the graph rewriting (transformation) language PROGRES, which is closely related to the package concept of the standardized OO modeling language UML. It supports a variety of software

Current object-oriented modeling methods focus on the specification of the static structure of software objects and their interaction at runtime. A major deficiency of these methods is that they do not provide sufficient means to specify the behaviour of object structures. In this paper we propose a novel high-level, graphical method called Story Driven modeling (SDM). SDM employs so called story boards to analyse the dynamics of object structures as sequences of graphical snap shots for sample scenarios. A major benefit of this approach is that story boards allow to develop and illustrate design and ideas of a systems object structure and central mechanisms in a simple visual notation. On the other hand, story boards have well-defined syntax and semantics that gives way to semi-automatic derivation of subsequent specifications like e.g. the static class hierarchy and dynamic operations on object structures. For the latter, SDM employs a high-level, graphical formalism called story diagrams, which is based on the theory of programmed graph rewriting systems. In this paper we illustrate SDM with a sample case study which is the development of the bus route information system of Paderborn.

Client / Server distribution in (software) design environments can be achieved by distributing an underlying repository database management system. Several alternative approaches for such a distribution exist, which differ in the layer of the architecture at which client / server communication takes place. We discuss two approaches --- query-server and page-server --- we have studied in the context of the graph database management system GRAS which is used in the IPSEN project. We focus this discussion on the impact the two approaches have on DBMS architecture and functionality as well as on performance with respect to the communication overhead induced by them. The work which has been done to evaluate and implement these approaches in GRAS is presented and problems of both alternatives and the solution we have found are outlined. 1 Introduction Software systems for application areas like CAD or software engineering handle complex data structures to model the design objects they deal ...