Bernhard Thalheim

Conceptual modelling of web information systems

This paper presents the conceptual modelling parts of a methodology for the design of large-scale data-intensive web information systems (WISs) that is based on an abstract abstraction layer model (ALM). It concentrates on the two most important layers in this model: a business layer and a conceptual layer.The major activities on the business layer deal with user profiling and storyboarding, which addresses the design of an underlying application story. The core of such a story can be expressed by a directed multigraph, in which the vertices represent scenes and the edges actions by the users including navigation. This leads to story algebras which can then be used to personalise the WIS to the needs of a user with a particular profile.The major activities on the conceptual layer address the support of scenes by modelling media types, which combine links to databases via extended views with the generation of navigation structures, operations supporting the activities in the storyboard, hierarchical presentations, and adaptivity to users, end-devices and channels.

Fundamentals of Cardinality Constraints

The Entity-Relationship model is frequently used during conceptual database design phases. However, this model can be enriched and then used for the complete lifecycle of a database as an interface model. For this purpose, the concepts of the ER-model need to be theoretically wellfounded. The aim of this paper is to show how the theoretical basis of one of the most important class of integrity constraints can be constructed and then used for the exploitation in practical database tasks. The concept of cardinality constraints is defined, generalized and used for the simplification of the design, for the improvement of maintenance programs and for the detection of problematic design decisions.

Conceptual Modeling for E-Business and the Web

Towards Ontology-Based Harmonization of Web Content Standards.- The M*-COMPLEX Approach to Enterprise Modeling, Engineering, and Integration.- Conceptual Design of Electronic Product Catalogs Using Object-Oriented Hypermedia Modeling Techniques.- Generic Linear Business Process Modeling.- Business Modelling Is Not Process Modelling.- Modeling Electronic Workflow Markets.- Building Multi-device, Content-Centric Applications Using WebML and the W3I3 Tool Suite.- Abstraction and Reuse Mechanisms in Web Application Models.- From Web Sites to Web Applications: New Issues for Conceptual Modeling.- Using Webspaces to Model Document Collections on the Web.- Modeling Interactions and Navigation in Web Applications.- A General Methodological Framework for the Development of Web-Based Information Systems.- Managing RDF Metadata for Community Webs.- An Example-Based Environment for Wrapper Generation.- Flexible Category Structure for Supporting WWW Retrieval.

Foundations of entity-relationship modeling

Database design methodologies should facilitate database modeling, effectively support database processing, and transform a conceptual schema of the database to a high-performance database schema in the model of the corresponding DBMS. The Entity-Relationship Model is extended to theHigher-orderEntity-RelationshipModel (HERM) which can be used as a high-level, simple and comprehensive database design model for the complete database information on the structure, operations, static and dynamic semantics. The model has the expressive power of semantic models and possesses the simplicity of the entity-relationship model. The paper shows that the model has a well-founded semantics. Several semantical constraints are considered for this model.

Semantics in databases

The term “Semantics” is one of the overloaded in computer science and used in various meaning. This variety can also be observed in database literature. In computer linguistics or web research, semantics is a component of the language which associates words or components of a grammar with their meaning (linguistic content). In modeling and specification, semantics assigns set-theoretic denotations to formulas in order to characterize truth. At the same time, semantics is used as the basis for certain methods of proof (truth and proof semantics in semiotics). In programming language technology, semantics is often used in the sense of operational semantics, i.e. consists in an interpretation of commands of a programming language by machine operations. This widespread usage of the term “semantics” has led to very different goals, methods, and applications. Semantics includes at the same time the interpretation of utterances, temporal, contextual, subjective and other aspects. Semantics is either considered operationally on the basis of applications or implementations, or logically associating a database state or a collection of database states to a truth value or pragmatically by relating utterances to the understanding of the user. These three understandings may be mapped to each other.

SiteLang: Conceptual Modeling of Internet Sites

Internet information services are developed everywhere. Such services include content generation and functionality support which has to be modeled in a consistent way. Within our projects we developed a methodology resulting in a language SiteLang which allows specification of information services based on the concepts of the story and interaction spaces as well as media objects.The specification can be automatically mapped to implementations.

A Method for Verifiable and Validatable Business Process Modeling

We define an extensible semantical framework for business process modeling notations. Since our definition starts from scratch, it helps to faithfully link the understanding of business processes by analysts and operators, on the process design and management side, by IT technologists and programmers, on the implementation side, and by users, on the application side. We illustrate the framework by a high-level operational definition of the semantics of the BPMN standard of OMG. The definition combines the visual appeal of the graph-based BPMN with the expressive power and simplicity of rule-based modeling and can be applied as well to other business process modeling notations, e.g. UML 2.0 activity diagrams.

Design of data-intensive Web-based information services

One common usage of the WWW is to provide information services, e.g. for regional event calenders, university lecture management, travel information, etc. Their design requires a clear picture of the systems usage and the supported technical environment. The core of the problem is to provide flexible access units based on extended views on some underlying database. The extension consists of escort information, links, operational facilities and means for the generation of different presentations. We call such units media objects. In order to also allow a flexible presentation for them, we adapt the metaphor of a container. In this way it is possible to present the same information in various ways depending on the user profile and the possible technical restrictions of the display device.

OLAP databases and aggregation functions

Aggregation functions are a class of generic functions which must be usable in any database application. We characterize the case where the aggregation functions can be correctly applied on macrodata (data cube) which are computed on the microdata.

Modeling Interaction and Media Objects

Interaction of users with computational devices has to meet the u sers intention on one side and needs to be specified in a formal manner which can be uniquely interpreted by computers. Thus, we need a model of interaction which meets the intensional understanding of users and which has an extensional description that is directly implementable. In this paper we develop a model for interaction on the basis of the notion of interaction objects. We show further how this notion can be specialized to internet-based interaction. In the later case we use media objects for interaction.