15 Fakultätsübergreifend / Sonstige Einrichtung
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/16
Browse
85 results
Search Results
Item Open Access Practical methods and tools for specification(1987) Ludewig, JochenThis is a course on specification. Since it is based on experiences in the field of software engineering. It applies primarily to software specifications. Many observations and reports indicate, however, that, from specification aspects, there is not much difference between information processing systems in general and software in particular. Therefore, most of this course applies also to system specification. In the first chapter, some fundamentals are discussed. These include the life cycle model and the distribution of costs over the various activities, some definitions, and a rationale for semi-formal specification. The second chapter provides a general outline of a specification system, whose desirable properties are deduced from the qualities of good specifications. In the third chapter, we present some typical specification systems. The primary goal is to show some typical features of such systems rather than to describe them in detail. The fourth chapter addresses management aspects. In chapter 5, some general conclusions are drawn. The appendix (chapter 6) contains a bibliography on specification, and a list of suppliers.Item Open Access Philosophy of action and Its relationship to interactive visualisation and Molière’s theatre(2023) Feige, Daniel M.; Weiskopf, Daniel; Dickhaut, KirstenItem Open Access Ein Molekül-Atom-Datenmodell für Non-Standard-Anwendungen : Anwendungsanalyse, Datenmodellentwurf und Implementierungskonzepte(1988) Mitschang, BernhardZiel der vorliegenden Arbeit ist die Erarbeitung und Nutzbarmachung von Datenbankkonzepten für sog. Non-Standard-Anwendungen. Darunter versteht man im OB-Bereich Anwendungen aus den Gebieten CAD/CAM, VLSI-Entwurf, Software-Entwicklung, Büroautomatisierung, Expertensysteme etc. Die zentralen Fragestellungen, zu denen es Antworten zu finden gilt, sind: - Welche Anforderungen werden von den Non-Standard-Anwendungen an die Datenhaltung gestellt? - Wie sehen dazu passende Architekturen und Datenmodelle für NDBS (das sind DBS für Non-Standard-Anwendungen) aus? - Nach welchen Konzepten sind solche NDBS zu entwerten und zu implementieren? Dazu werden verschiedene OB-basierte Prototypen analysiert und vergleichend einander gegenübergestellt. Im einzelnen wurden basierend auf konventionellen Datenbanksystemen verschiedenen Typs (Netzwerk- und Relationenmodell) Anwendungssysteme aus unterschiedlichen ingenieurwissenschaftlichen Bereichen (3D-Modellierung, Verwaltung geographischer Daten und VLSI-Entwurfswerkzeug) sowie aus dem Expertensystembereich (Diagnosesystem) entwickelt; ihr Leistungsverhalten wurde unter einer praxisnahen Last aufgezeichnet und detailliert untersucht. Ausgehend von diesen Analyse- und Vergleichsergebnissen wird ein Anforderungskatalog erstellt, der konkrete Aussagen über die Datenstrukturen der Anwendungsobjekte und die zugehörigen Verarbeitungscharakteristika zusammenfaßt.Item Open Access A Bayesian network approach to assess and predict software quality using activity-based quality models(2009) Wagner, StefanAssessing and predicting the complex concept of software quality is still challenging in practice as well as research. Activity-based quality models break down this complex concept into more concrete definitions, more precisely facts about the system, process and environment and their impact on activities performed on and with the system. However, these models lack an operationalisation that allows to use them in assessment and prediction of quality. Bayesian Networks (BN) have been shown to be a viable means for assessment and prediction incorporating variables with uncertainty. This paper describes how activity-based quality models can be used to derive BN models for quality assessment and prediction. The proposed approach is demonstrated in a proof of concept using publicly available data.Item Open Access SQL/XNF - processing composite objects as abstractions over relational data(1993) Mitschang, Bernhard; Pirahesh, Hamid; Pistor, Peter; Lindsay, Bruce; Südkamp, NorbertAn extension to SQL, called the SQL extended normal form (XNF), is discussed. It enhances relational technology by a composite object facility, which comprises not only extraction of composite objects from existing databases but also efficient navigation and manipulation facilities provided by an appropriate application programming interface. The language itself allows sharing of the database among normal form SQL applications and composite object applications. It provides proper subsetting of the database and subsequent structuring, exploiting subobject sharing and recursion, all based on its powerful composite object constructor concept, which is closed under the language operations. XNF is integrated into the relational framework, thus benefiting from the available technology such as relational engine and query optimization.Item Open Access Extending the relational algebra to capture complex objects(1989) Mitschang, BernhardAn important direction in database research for non-standard applications (e.g. engineering or design applications) deals with adequate support for complex objects. Without doubt, the provision of network structures and shared subobjects as well as support for dynamic object definition and appropriate manipulation facilities is urgently needed for natural and accurate modeling as well as for efficient processing of the applications' objects. These concepts are the major concern of the molecule-atom data model (MAD model) and its molecule algebra which is introduced in this paper. They make the model stand out compared to the relational model and even to models limited to hierarchical and statically defined complex objects. By means of the molecule algebra a precise and complete specification of one conceivable kind of complex object processing and its inherent semantics is provided. Furthermore, this algebra is used as a sound basis to express the semantics of the high level query language MOL (molecule query language) that is able to deal with complex objects in a descriptive manner.Item Open Access Do code clones matter?(2009) Juergens, Elmar; Deißenböck, Florian; Hummel, Benjamin; Wagner, StefanCode cloning is not only assumed to inflate maintenance costs but also considered defect-prone as inconsistent changes to code duplicates can lead to unexpected behavior. Consequently, the identification of duplicated code, clone detection, has been a very active area of research in recent years. Up to now, however, no substantial investigation of the consequences of code cloning on program correctness has been carried out. To remedy this shortcoming, this paper presents the results of a large-scale case study that was undertaken to find out if inconsistent changes to cloned code can indicate faults. For the analyzed commercial and open source systems we not only found that inconsistent changes to clones are very frequent but also identified a significant number of faults induced by such changes. The clone detection tool used in the case study implements a novel algorithm for the detection of inconsistent clones. It is available as open source to enable other researchers to use it as basis for further investigations.Item Open Access Information structures and database support for solid modeling(1989) Härder, Theo; Hübel, Christoph; Mitschang, BernhardThe question we are going to investigate is how to map solid representations to DB structures and how to process this information efficiently. Starting from analytical representations based on analytical methods we discuss the use of constructive solid geometry and boundary representation models with various refinements. Furthermore, additional submodels (organizational, technological, physical) are considered in order to obtain an overall product model. This model representing all important aspects of a complex design object may serve to derive special object representations needed by existing engineering tools or by mathematical methods (e.g. finite elements). Today's DBMS are unable to meet the increasing requirements of engineering applications that would prefer to use a DBMS. To alter this situation, a new generation of DBMS architectures tailored to the demands of such enhanced applications have to be developed. As a consequence, the flexibility and expressiveness of data models as well as the handling of application objects must be greatly improved before interactive design work can be supported. We outline our data model concepts and architectural decisions to provide effective data management support. Our DBMS architecture consists of a neutral kernel part running on a server machine and an application layer tailored to solid modeling tasks which together with the application, i.e. the solid modeler is allocated to the workstation.Item Open Access Composite-object views in relational DBMS: an implementation perspective(1994) Pirahesh, Hamid; Mitschang, Bernhard; Südkamp, Norbert; Lindsay, BruceWe present a novel approach for supporting Composite Objects (CO) as an abstraction over the relational data. This approach brings the advanced CO model to existing relational databases and applications, without requiring an expensive migration to other DBMSs which support CO. The concept of views in relational DBMSs (RDBMS) gives the basis for providing the CO abstraction. This model is strictly an extension to the relational model, and it is fully upward compatible with it. We present an overview of the data model. We put emphasis in this paper on showing how we have made the extensions to the architecture and implementation of an RDBMS (Starburst) to support this model. We show that such a major extension to the data model is in fact quite attractive both in terms of implementation cost and query performance. We introduce a CO cache for navigation through components of a CO. With this technique, the performance of navigation through COs, which has been of a concern in RDBMSs in the past, is in fact quite satisfactory. We present our practical experience in using this facility. We show that our work on CO enables existing RDBMSs to incorporate efficient CO facilities at a low cost and at a high degree of application reusability and database sharability.Item Open Access Using PRIMA-DBMS as a testbed for parallel complex-object processing(1992) Hübel, Christoph; Mitschang, Bernhard; Gesmann, Michael; Grasnickel, Andreas; Käfer, Wolfgang; Schöning, Harald; Härder, TheoThe PRIMA-DBMS approach is explained by introducing PRIMA's architecture and query processing framework. The PRIMA-DBMS constitutes a testbed that is flexible enough to support evaluation and validation of quite a variation of different strategies for complex-object processing taking into account different parallelization levels and different hardware environments. Thus, PRIMA marks an important step towards our main research goal concerning measures for efficient complex-object processing: the measures that are in competition with each other are query optimization, query evaluation strategies, and massive storage, that all benefit from parallelism. The programming environment that supports the parallel DBMS processing is introduced with special emphasis on its ability for parametrization and configuration. A case study of the PRIMA testbed illustrates our first investigations and demonstrates a methodology for evaluation and tuning of PRIMA configurations.