Ingrid Wetzel

Integrity Enforcement in Object-Oriented Databases

In contrast to the relational model methods in OODBs must enforce structurally defined constraints such as inclusion and referential constraints. It has been shown that this is possible for basic generic update operations that are determined by the schema. However, such operations only exist for value-representable classes.

Identification, Genericity and Consistency in Object-Oriented Databases

It is claimed that object-oriented databases overcome many of the limitations of the relational data model especially by generalizing the notion of object identification. A clear distinction between objects and values turns out to be essential for the object-oriented approach whereas the relational model is based exclusively on values. Since, however, value uniqueness within scopes is a quite natural constraint for a wide class of applications, identification by value is also of interest for object-oriented datamodels.

On the inevitable intertwining of analysis and design: developing systems for complex cooperations

Developing interactive software systems requires the well known tasks of analysis, design and construction. In the context of work settings with complex cooperations these tasks and their relationsship undergo drastic changes. Analysis and design have to be accomplished at different levels of complexity, the heterogeneity of users envolved needs to be handled and the presentation of anticipated changes incorporating the organizational context goes beyond proven (object-oriented) techniques like prototyping. The article claims that complex cooperations require a close intertwining of analysis and design. It is accomplishable by application-driven documents usable in different stages of the development process. Based on a document-driven evolutionaly approach examples of such document types like Cooperation Pictures and Purpose Tables - are given. They are discussed based on expericences from projects in different application domains.

Serviceflow Management for Health Provider Networks

Exploding expenditure in health care has led to new reimbursement regulations forcing health care providers to conduct their organisations as business concerns. In order to be competitive providers have started to build networks that allow the delivery of interrelated health services in a well‐adjusted and uniform manner. However, besides strategic agreement, successful networking requires the support of information systems for efficient cooperation and process management in order to deliver efficient day to day service. With serviceflow management we provide a general concept that answers these needs. Based on modelling process patterns and the exchange of XML‐representations of process knowledge and data between service providers, serviceflow management supports organisations in jointly delivering services that cross provider boundaries. Furthermore, it enables flexible handling of processes, which is indispensable in health care. Based on a health care example, we explore the possibilities of serviceflow management and present a Web‐based prototype on the basis of our generic, four‐layered architecture.

On the Derivation of Executable Database Programs from Formal Specifications

Achieving wide acceptance of formal methods in software development requires a smooth integration with requirements analysis, design and implementation. Especially for database application systems there exist well-known approaches to conceptual modeling as well as a sophisticated implementation technology on the basis of database programming languagues. The work described in this paper is based on a scenario, where the B method is coupled with a conceptual modeling language TDL and a database programming language DBPL. Both these languages can be represented in B. We concentrate on the problem of characterizing those B specifications that are sufficiently refined in order to be transformed into equivalent DBPL programs. This gives rise to some kind of implementability proof obligation.

Specification and Refinement in an Integrated Database Application Environment

Traditionally, substantial portion of database application semantics are captured through static and dynamic integrity constraints. The work reported in this paper exploits this fact by interpreting such database constraints as invariants and preand postconditions in the style of ’Z’ [ScPi87,Spi88].

Information systems development with anticipation of change focussing on professional bureaucracies

The problems associated with the development of hospital information systems and their implementation in organizations have been the subject of much literary debate. The perspectives taken with regard to this phenomenon are often similar to the debate in IS design in general, in that the overseen social and organizational factors of IS implementation are mainly addressed. However, from our experiences in applied research projects, we claim that the specific organizational structure of hospitals as professional bureaucracies requires specialized development methods. This is the subject of the article. First we establish that hospitals represent a special organizational type. We then draw conclusions regarding the requirements for specialized IS development approaches. Third, we discuss limitations of existing approaches and introduce the Anchor method. Anchor supports the intertwining of anticipation of IS induced organizational change and IS development by the provision of participatory techniques, processes and tasks suitable for professional bureaucracies.The problems associated with the development of hospital information systems and their implementation in organizations have been the subject of much literary debate. The perspectives taken with regard to this phenomenon are often similar to the debate in IS design in general, in that the overseen social and organizational factors of IS implementation are mainly addressed. However, from our experiences in applied research projects, we claim that the specific organizational structure of hospitals as professional bureaucracies requires specialized development methods. This is the subject of the article. First we establish that hospitals represent a special organizational type. We then draw conclusions regarding the requirements for specialized IS development approaches. Third, we discuss limitations of existing approaches and introduce the Anchor method. Anchor supports the intertwining of anticipation of IS induced organizational change and IS development by the provision of participatory techniques, processes and tasks suitable for professional bureaucracies.

Specification and Refinement of Databases and Transactions

The development process of data-intensive information systems passes through several stages from requirements modeling through conceptual design down to implementation. In DAIDA we used the language TDL for design specification and DBPL, a procedural database programming language with persistent values and transactions, for implementation. In focusing on the transformation from TDL to DBPL we discuss the relationship between the specification and various refinement steps that lead to efficient database programs. As a framework for transformations we use Abrial’ s Abstract Machine formalism. TDL-designs can be mapped into Abstract Machines, which are then the subject of refinement. The complete reification of TDL designs is illustrated by an example.

XML-based Process Representation for e-Government Serviceflows

Addressing new public challenges such as the one-stop government and improved service quality, we introduce serviceflow management as a generic concept to coordinate cross-organizational e-government processes. Aiming at a serviceflow management infrastructure for networked service providers we present an XML-based process representation of serviceflows as well as a four layered IT architecture for realizing serviceflow related applications.