Joachim W. Schmidt

The software development environment as a knowledge base management system

This paper sketches a software development environment for data-intensive information systems. It is based on the premise that software can be viewed as a multilayered description, which includes a requirements specification, a design and an implementation, and that this description should be managed as a knowledge base. The proposed environment uses the requirements modelling language CML, the design language Taxis, and the implementation language DBPL. The paper outlines the features of these languages and illustrates the proposed multilayered structure of software with an example. It also discusses the features that will have to be supported by an environment suitable for constructing, maintaining, and testing software knowledge bases.

The TaxisDL Software Description Language

The purpose of the TaxisDL language is to express the conceptual design of an information system. The focus of the design process includes the data classes of the proposed system, the functions and transactions manipulating them, and the larger conceptual groupings of these actions into long-term activities, which we call scripts. The design of the language is based on ideas from semantic data models and formal specification languages.

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.

Introduction to Query Processing

Query processing in databases can be divided into two steps: selecting an ‘optimal’ evaluation strategy, and executing it. We first present elementary nested loop and relational algebra algorithms for query execution and point out some opportunities for improving their performance. A survey of optimization strategies, structured in query transformation techniques and access planning methods, follows. Finally, extensions for special-purpose query systems are briefly addressed.

Database Programming: Language Constructs and Execution Models

Relations are in the process of being accepted as a data structure adequate for a wide variety of applications. On the one hand this is due to the powerful and high level operators on relations, on the other it results from additional services such as recovery management, concurrency control and expression optimization provided by relational systems.

The DURESS project: Extending databases into an open systems architecture

The DURESS (Distributed University Research and Education and Support System) project is a joint effort of the Database and Information Systems Group at the Johann Wolfgang Goethe-University, Frankfurt, and the IBM European Networking Center, Heidelberg, West-Germany. In the DURESS project, the applicability of an integrated database and programming language is extended into an open distributed environment. The extended a chitecture allows for distributing database ‘modules‘ over separate nodes in a computer network and for accessing components of such modules in a distribution transparent way. In a corresponding prototype, it is demonstrated how the necessary database management and communication system extensions can be realized, exemplarily, based on a centralized DBMS and supported by standard ISO/OSI communication facilities.

Datenbankprogrammierung in Rechnernetzen

Programmiersprachen fur datenintensive Anwendungen stellen zusatzlich zu einem algorithmischen Kern noch Sprachkonstrukte zur Verfugung, die die Definition persistenter Daten (etwa mittels Relationen) und deren parallele Bearbeitung (etwa mittels Transaktionen) unterstutzen. Ausgehend von DBPL, einer Datenbankprogrammiersprache mit Modula-2 als Kern, werden in der vorliegenden Arbeit Moglichkeiten der Datenbankprogrammierung in Rechnernetzen erlautert. Probleme der Implementierung eines verteilten DBPL-Systems werden unter besonderer Berucksichtigung der Anforderungen an das Kommunikationssystem diskutiert.

Integrated fact and rule management based on relational technology

Database programming languages integrate concepts of databases and programming languages to provide both implementation tools for dataintensive applications and high-level user interfaces to databases. Frequently, database programs contain a large amount of application knowledge which is hidden in the procedural code and thus difficult to maintain with changing data and user views.

Monitoring Subjective Well-Being: Some New Empirical Evidence for Germany

What is subjective well-being influenced by? Since the Report by the Commission on the Measurement of Economic Performance and Social Progress by Stiglitz, Sen and Fitoussi a huge number of studies has raised this question – with partly different findings. In addition, international organizations are increasingly addressing subjective well-being issues. The post-2015 development agenda of the United Nations as well as the inclusive growth strategy of the OECD may be quoted as examples. Facing the current state of national and international discussion, this paper analyses appropriate indicators for the mostly named factors influencing subjective well-being. The goal of the empirical study for Germany is twofold: First of all, the indicators discussed prominently are analysed with regard to the relevance for explaining the degree of subjective well-being (micro level). Secondly, it is examined, whether the relevance of these indicators changes over time. The empirical results presented in this paper are mainly based on yearly longitudinal data of private households in Germany. Currently, the data set covers about 21,000 individuals living in more than 12,000 private households. The data set provides information on various indicators for subjective well-being mentioned by most of the recent studies, like for instance people’s life-circumstances and individual assessments. Concluding remarks concern on one hand the question if data from EU-SILC (because of its Europe-wide coverage) are useful in this context. On the other hand the combination of data at the micro level with indicators at the aggregate level is discussed as well.

Using Extensible Grammars for Data Modelling

We present a systematic approach to the rapid implementation of high-level data models and query languages in the polymorphic higher-order programming language TL. The static semantics of data model constructs are captured by a mapping to polymorphic types and associated data constructor and selector functions. The dynamic semantics of query languages are realised by a mapping to bulk data types and iteration abstractions. Contrary to conventional approaches, these two mappings are specified by user-defined grammar extensions of the target language TL based on user-defined library code and not by separate tools in the programming environment. We give examples of this syntax-directed approach to data modelling and discuss its ad450 tages and limitations.