We present a framework for the development of information systems based on the premise that the knowledge that influences the development process needs to somehow be captured, represented, and managed if the development process is to be rationalized. Experiences with a prototype environment developed in ESPRIT project DAIDA demonstrate the approach. The project has implemented an environment based on state-of-the-art languages for requirements modeling, design and implementation of information systems. In addition, the environment offers tools for aiding the mapping process from requirements to design and then to implementation, also for representing decisions reached during the development process. The development process itself is represented explicitly within the system, thus making the DAIDA development framework easier to comprehend, use, and modify.

Reports on extended database programming support which leads quite naturally from a centralized modular environment to distributed computing systems where modules can be spread over different nodes in a computer network. The proposed extended Modula-2 based database programming system implements a federative client/server architecture and integrates standardized communication services supporting the communication requirements of a heterogeneous network environment. The authors also report on the design and status of a prototype implementation that is currently being realized in a joint project of their corresponding institutions.>

In the database language PASCAL/R, the programming language PASCAL and concepts based on the relational data model are integrated. The paper investigates transformation strategies used in the PASCAL/R system to evaluate queries with existential and universal quantifiers. Intermediate data structures are described using a high-level language tool called a reference to a selected variable. The predicate calculus approach used in PASCAL/R offers new insight into recently proposed query optimization techniques and allows some of them to be extended.

For the extension of high-level languages by data types of mode relation, three language constructs are proposed and discussed:- a repetition statement controlled by relations- predicates as a generalisation of boolean expressions- a constructor for relations using predicates.The language constructs are developed step by step starting with a set of elementary operations on relations. They are designed to fit into PASCAL without introducing too many additional concepts.

For the extension of high level languages by data types of mode relation, three language constructs are proposed and discussed: a repetition statement controlled by relations, predicates as a generalization of Boolean expressions, and a constructor for relations using predicates. The language constructs are developed step by step starting with a set of elementary operations on relations. They are designed to fit into PASCAL without introducing too many additional concepts.