Browsing by Author "Mitschang, Bernhard"

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Open Access
Abbildung von Frames auf neuere Datenmodelle
(1987) Härder, Theo; Mattos, Nelson Mendonca; Mitschang, Bernhard
Es wird die Abbildung von Frames mit ihren Modellierungskonzepten und charakteristischen Operationen auf objektorientierte Datenmodelle untersucht, um Wissensrepräsentation in sogenannten Non-Standard-Datenbanksystemen - beispielsweise für Expertensystem-Anwendungen - unterstützen zu können. Nach einem Vergleich der Eigenschaften von Relationenmodell, NF 2-Modell und MAD-Modell für diese Aufgabe wird eine Bewertung der verschiedenen Ansätze vorgenommen, um ihre Tauglichkeit für die Frame-Modellierung deutlicher herauszukristallisieren.
Open Access
Ein Ansatz zu graphischen Datenbanken und deren Verwendung in CAD-Systemen
(1986) Hübel, Christoph; Mitschang, Bernhard
Die zentrale Aufgabe eines CAD-Systems ist die adäquate Unterstützung des Konstruktionsvorganges. Dazu müssen die Entwurfsobjekte sowohl graphisch repräsentiert als auch in einer sog. rechnerinternen Darstellung verwaltet werden. Heutzutage stehen für diese Aufgaben GKS-orientierte Graphiksysteme sowie Datenbanksysteme mit hierarchischer, netzwerkartiger bzw. relationaler Schnittstelle zur Verfügung. Am Beispiel des KUNICAD-Systems (ein datenbankbasierter 3D-Bauteilmodellierer) werden die Schnittstellen zwischen Graphik-, Anwendungs- und Datenhaltungskomponente aufgezeigt und analysiert. Dabei wird die Wichtigkeit der Kopplung von Graphik- und Datenhaltungskomponente erkannt. Als unmittelbare Konsequenz daraus wird die Integration von Graphik- und DB-System zu einem Gesamtsystem, dem Graphischen Datenbanksystem, vorgeschlagen sowie dessen Architekturmerkmale und charakteristischen Eigenschaften vorgestellt.
Open Access
An approach to integrated office document processing & management
(1990) Mattos, Nelson Mendonca; Mitschang, Bernhard; Dengel, Andreas; Bleisinger, Rainer
We propose an approach towards an integrated document processing and management system that has the intention to capture essentially freely structured documents, like those typically used in the office domain. The document analysis system ANASTASIL is capable to reveal the structure as well as the contents of complex paper documents. Moreover, it facilitates the handling of the containing information. Analyzed documents are stored in the management system KRISYS that is connected to several different subsequent services. The described system can be considered as an ideal extension of the human clerk, making his tasks in information processing easier. The symbolic representation of the analysis results allow an easy transformation in a given international standard, e.g., ODA/ODIF or SGML, and to interchange it via global network.
Open Access
AssistML : an approach to manage, recommend and reuse ML solutions
(2023) Villanueva Zacarias, Alejandro Gabriel; Reimann, Peter; Weber, Christian; Mitschang, Bernhard
The adoption of machine learning (ML) in organizations is characterized by the use of multiple ML software components. When building ML systems out of these software components, citizen data scientists face practical requirements which go beyond the known challenges of ML, e. g., data engineering or parameter optimization. They are expected to quickly identify ML system options that strike a suitable trade-off across multiple performance criteria. These options also need to be understandable for non-technical users. Addressing these practical requirements represents a problem for citizen data scientists with limited ML experience. This calls for a concept to help them identify suitable ML software combinations. Related work, e. g., AutoML systems, are not responsive enough or cannot balance different performance criteria. This paper explains how AssistML, a novel concept to recommend ML solutions, i. e., software systems with ML models, can be used as an alternative for predictive use cases. Our concept collects and preprocesses metadata of existing ML solutions to quickly identify the ML solutions that can be reused in a new use case. We implement AssistML and evaluate it with two exemplary use cases. Results show that AssistML can recommend ML solutions in line with users’ performance preferences in seconds. Compared to AutoML, AssistML offers citizen data scientists simpler, intuitively explained ML solutions in considerably less time. Moreover, these solutions perform similarly or even better than AutoML models.
Open Access
Beanspruchungsgerechtes Konstruieren : Kopplung von CAD und FEM
(1994) Bies, Carlo; Mitschang, Bernhard; Mitschang, Peter
Die Kopplung der Bereiche CAD und FEM ist ein wesentlicher Schritt hin zu dem übergeordneten Ziel des fertigungsgerechten und beanspruchungsgerechten Konstruierens. Neue Bauteile werden mit CAD-Systemen entworfen und deren mechanische Eigenschaften anschließend mittels FEM-Systemen analysiert. Da diese Systeme auf ähnlichen Bauteilgeometrien aufbauen, ist es naheliegend, die im CAD-System vorliegende Geometriebeschreibung für die FEM-Analyse zu übernehmen. Ein direkter Austausch der Geometriedaten scheitert jedoch, da sich die jeweiligen Geometriemodelle stark unterscheiden. Aus diesem Grunde findet herkömmlicherweise kein rechnergestützter Datenaustausch statt. In dieser Arbeit berichten wir über die Konzepte, die Realisierung sowie über erste praktische Einsatzerfahrungen und Systembewertung zu einem Geometrie-Transformator (entwickelt für die Systeme EUCLID und ANSYS), der eine (weitestgehend) automatische Umsetzung der Geometriedarstellungen durchführt und somit einen durchgängigen rechnerunterstützten Prozeß für die Konversion vom CAD- zum FEM-Modell ermöglicht.
Open Access
Capturing design dynamics : the CONCORD approach
(1994) Ritter, Norbert; Mitschang, Bernhard; Härder, Theo; Gesmann, Michael; Schöning, Harald
'Computer-Supported Cooperative Work' is a young research area considering applications with strong demands on database technology. Especially design applications need support for cooperation and some means for controlling their inherent dynamics. However, today's CAD systems mostly consisting of a collection of diverse design tools typically do not support these requirements. Therefore, an encompassing processing model is needed that covers the overall design process in general as well as CAD-tool application in particular. As a consequence, this model has to be rich enough to reflect the major characteristics of design processes, e.g., goal-orientation, hierarchical refinement, stepwise improvement as well as team-orientation and cooperation. The CONCORD model that will be described in this paper, reflects the distinct properties of design process dynamics by distinguishing three levels of abstraction. The highest level supports application-specific cooperation control and design process administration, the second considers goal-oriented tool invocation and work-flow management while the third level provides tool processing of design data. To achieve level-spanning control, we rely on transactional facilities provided at the various system layers.
Open Access
Charakteristiken des Komplex-Objekt-Begriffs und Ansätze zu dessen Realisierung
(1985) Mitschang, Bernhard
Die Modellierung und Verwaltung von komplexen Objekten stellt eines der Hauptprobleme für den effektiven Einsatz von Datenbanksystemen in den sog. nichtkonventionellen Anwendungsgebieten dar. Unter dem Begriff "Komplexobjekt" wird dabei die Sicht der Anwendung auf den betreffenden Realitätsausschnitt verstanden (etwa Entwurfs- und Konstruktionsobjekte im CAD/CAM/CAE-Bereich, Objekte in der Computergrafik, Texte in der Büroautomatisierung etc.). Für eine adäquate Modellierung bzw. zur Konzeption von geeigneten Datenmodellen müssen die Anforderungen der Komplex-Objekt-Sicht erkannt und aufgegriffen werden. Hier werden nun zum einen die obigen Anforderungen in Form von inhärenten Charakteristiken dieser Komplex-Objekte ermittelt und anhand einleuchtender ·Beispiele klar herausgearbeitet. Zum anderen werden bestehende Lösungsansätze in dem vorgegebenen Rahmen erörtert sowie erste Hinweise zum Entwurf von auf den Komplex-Objekt-Begriff zugeschnittenen Datenmodellen angegeben.
Open Access
Composite-object views in relational DBMS: an implementation perspective
(1994) Pirahesh, Hamid; Mitschang, Bernhard; Südkamp, Norbert; Lindsay, Bruce
We 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.
Open Access
Composite-object views in relational DBMS: an implementation perspective : (extended abstract)
(1994) Pirahesh, Hamid; Mitschang, Bernhard; Südkamp, Norbert; Lindsay, Bruce
We 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 efficient navigation through components of a CO. 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.
Open Access
Coupling engineering workstations to a database server
(1987) Härder, Theo; Hübel, Christoph; Meyer-Wegener, Klaus; Mitschang, Bernhard
A DBMS kernel architecture is proposed for improved DB support of engineering applications running on a cluster 01 workstations. Using such an approach, part of the DBMS code - an application-specific layer - is allocated close to the corresponding application on a workstation while the kernel code is executed on a central server. Empirical performance results from DB-based engineering applications are reported to justify the chosen DBMS architecture. The paper focuses on design issues of the application layer including server coupling, processing model and application interface. Moreover, a transaction model for long-term database work in a coupled workstation-server environment is investigated in detail.
Open Access
Datenbankunterstützung für ein CAD-Arbeitsplatzsystem
(1984) Christmann, Hans-Peter; Meyer-Wegener, Klaus; Mitschang, Bernhard; Sikeler, Andrea
Die stetige Erweiterung und Integration von Anwendungen aus dem Bereich der graphischen Datenverarbeitung verursacht ein schnelles Wachstum von Umfang und Komplexität der zu verwaltenden Datenbestände und erfordert daher in steigendem Maße Datenbankunterstützung. Für die adäquate Unterstützung in einem CAD-Arbeitsplatzsystem ist die zugrunde gelegte Rechnerkonfiguration des Arbeitsplatzes, das zu verwendende Datenbanksystem und die Zusammenarbeit des Datenbanksystems mit dem eigentlichen CAD-System von großer Wichtigkeit. Hier werden nun zum einen Anforderungen an geeignete Datenbanksysteme vorgestellt und zum anderen, nach einer kurzen Diskussion über passende Rechnerkonfigurationen, einige Vorschläge für die Zusammenarbeit von Graphik- und Datenbanksoftware angegeben.
Open Access
DB-Schnittstellen für arbeitsplatzorientierte Ingenieuranwendungen
(1988) Hübel, Christoph; Mitschang, Bernhard
Die Schnittstellen gegenwärtig verfügbarer Datenbanksysteme erweisen sich als ungeeignet für den Bereich der lngenieuranwendungen. Dies gilt im besonderen, da bei Ingenieuranwendungen eine deutliche Arbeitsplatzorientierung vorherrscht und sie damit häufig auf einer speziellen Mehrrechnerarchitektur aufbauen. Ausgehend von einem Schichtenmodell für sog. Non-Standard-Datenbanksysteme (NDBS) schlagen wir daher eine spezielle Systemarchitektur mit einer entsprechend ausgelegten Datenmodell- und Anwendungsmodellschnittstelle für arbeitsplatzorientierte Ingenieuranwendungen vor.
Open Access
Enhancing knowledge processing in client/server environments
(1993) Thomas, Joachim; Mitschang, Bernhard; Mattos, Nelson Mendonca; Deßloch, Stefan
A great variety of techniques has been developed to optimize and enhance query processing for relational, client/server, distributed, parallel, and heterogeneous database systems (DBS). Based on that work and experience, we investigate how far those techniques are applicable to query processing in Knowledge Base Management Systems (KBMS). Our reference system is the KRISYS KBMS that consists of a knowledge-processing system at the client (clientbased processing) and a data-processing system at the server (database backend). We describe a unifying framework for query processing incorporating both processing systems (as realized in KRISYS). This allows to distribute and balance the amount of work done in the client and in the server. Based on an evaluation of that framework, several approaches to further enhance knowledge processing are reported.
Open Access
Exploiting domain knowledge to address class imbalance and a heterogeneous feature space in multi-class classification
(2023) Hirsch, Vitali; Reimann, Peter; Treder-Tschechlov, Dennis; Schwarz, Holger; Mitschang, Bernhard
Real-world data of multi-class classification tasks often show complex data characteristics that lead to a reduced classification performance. Major analytical challenges are a high degree of multi-class imbalance within data and a heterogeneous feature space, which increases the number and complexity of class patterns. Existing solutions to classification or data pre-processing only address one of these two challenges in isolation. We propose a novel classification approach that explicitly addresses both challenges of multi-class imbalance and heterogeneous feature space together. As main contribution, this approach exploits domain knowledge in terms of a taxonomy to systematically prepare the training data. Based on an experimental evaluation on both real-world data and several synthetically generated data sets, we show that our approach outperforms any other classification technique in terms of accuracy. Furthermore, it entails considerable practical benefits in real-world use cases, e.g., it reduces rework required in the area of product quality control.
Open Access
Extending the relational algebra to capture complex objects
(1989) Mitschang, Bernhard
An 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.
Open Access
Flexible Entwurfsdatenverwaltung für CAD-Frameworks : Konzept, Realisierung und Bewertung
(1993) Käfer, Wolfgang; Mitschang, Bernhard
Eine der Hauptzielrichtungen von CAD-Frameworks ist die Integration von einzelnen, eigenständigen CAD-Werkzeugen mittels einer zentralen Datenverwaltung. Wesentliche Aufgaben hierbei sind die Verwaltung aller entwurfsrelevanten Daten sowie die effiziente Bereitstellung werkzeugrelevanter Daten für den werkzeugspezifischen Entwurfsschritt. Hierzu sind die vom jeweiligen Werkzeug zu bearbeitenden Entwurfsdaten bzw. Entwurfsobjekte zu selektieren und in der jeweils benötigten Form bereitzustellen. Nach Beendigung des Entwufsschrittes sind die geänderten Daten in den aktuellen Datenbestand zu integrieren. Um diese schwierige Aufgabe meistern zu können, ist es nötig, die vorherrschenden Objekt- und Entwurfsstrukturen entsprechend zu berücksichtigen. Das hier vorgestellte Objekt-Versions-Modell OVM soll diesen hohen Anforderungen entsprechen. Mit OVM werden (versionierte) Objekte aus Elementarobjekten zusammengesetzt; zwischen diesen Objekten können Objekt-, Versions-, und Konfigurationsbeziehungen in flexibler Art und Weise aufgebaut werden. Die zugehörige Manipulationssprache OML erlaubt ein adäquates Arbeiten mit den so strukturierten Objekten. OVM bietet eine hohe Abstraktion von der zugrundeliegenden Datenrepräsentation, so daß eine OVM-Realisierung im Prinzip mit unterschiedlichen DBS durchgeführt werden kann. Unsere OVM-Realisierung mittels des PRIMA-Systems wird vorgestellt, die gewonnenen Erfahrungen berichtet und eine vergleichende Bewertung zu Realisierungsalternativen gegeben.
Open Access
Grand tour of concepts for object-orientation from a database point of view
(1993) Mattos, Nelson Mendonca; Meyer-Wegener, Klaus; Mitschang, Bernhard
Over the last few years, object-orientation has gained more and more importance within several disciplines of computer science (e.g. programming languages, knowledge engineering, and database systems). Numerous papers have defined one or another of its underlying concepts (sometimes in quite different ways), and some systems have been developed following those heterogeneous definitions. Nevertheless, papers investigating the dependencies and degrees of freedom of these concepts are rarely found. For this reason, the goal of this paper is not to add yet another definition of object-oriented concepts, but to identify existing relationships among these basic concepts that allow one to cover and classify various conceivable combinations of these conceptual building blocks. Dependencies, orthogonalities, and relations among concepts like object identity, encapsulation, classification, generalization, inheritance, etc. are revealed, showing numerous ways to compose different shades of object-orientation. This leads to alternatives encountered when constructing object-oriented systems, which are illustrated by classifying some well-known systems and prototypes from different areas. However, it is not our purpose to analyze the relative importance of these concepts. Instead, we investigate the concepts from a neutral point of view, presenting (but not evaluating) several degrees of object-orientation.
Open Access
Improving the processing of decision support queries : strategies for a DSS optimizer
(2001) Schwarz, Holger; Wagner, Ralf; Mitschang, Bernhard
Many decision support applications are built upon data mining and OLAP tools and allow users to answer information requests based on a data warehouse that is managed by a powerful DBMS. In this paper, we focus on tools that generate sequences of SQL statements in order to produce the requested information. Our thorough analysis revealed that many sequences of queries that are generated by commercial tools are not very efficient. An optimized system architecture is suggested for these applications. The main component is a DSS optimizer that accepts pre-viously generated sequences of queries and remodels them according to a set of optimization strategies, before they are executed by the underlying database system. The advantages of this extended architecture are discussed and a couple of appropriate optimization strategies are identified. Experimental results are given, showing that these strategies are appropriate to optimize query sequences of OLAP applications.
Open Access
Information structures and database support for solid modeling
(1989) Härder, Theo; Hübel, Christoph; Mitschang, Bernhard
The 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.
Open Access
An integrated document management system
(1990) Dengel, Andreas; Mattos, Nelson Mendonca; Mitschang, Bernhard
We propose an approach towards an integrated document processing and management system that has the intention to capture essentially freely structured documents, like those typically used in the office domain. The ANASTASIL component is capable to reveal the structure as well as the contents of complex office documents. Moreover, it facilitates the handling of the containing information. Analyzed documents are stored in a management system KRISYS that is connected to several different subsequent services. The described system is an ideal extension of the human clerk, making his tasks in information processing easier. The symbolic representation of the analysis results allow an easy transformation in a given international standard, e.g., ODA/ODIF or SGML, and to interchange it via global network.