Rudolf Herzig

Sketching Concepts and Computational Model of TROLL light

The specification language TROLL light is intended to be used for conceptual modeling of information systems. It is designed to describe the Universe of Discourse (UoD) as a system of concurrently existing and interacting objects, i.e., an object community.

Integrating the ER Approach in an OO Environment

We translate Entity-Relationship (ER) schemas into the object-oriented specification language TROLL light. This language describes the Universe of Discourse (UoD) as a system of concurrently existing and interacting objects, i.e., an object community. Thereby two essential aspects, structure and behavior, are integrated in one formalism. By doing the translation from ER to TROLL light we preserve the visual advantages of the former and receive a formalism through the latter which can be mapped to an adequate object-oriented database system. Proceeding this way we hope our proposal for transforming ER schemas into TROLL light specifications provides a valuable link between structural and dynamic modeling.

An Algebraic Semantics for the Object Specification Language TROLL light

Within the KORSO project we have developed the object specification language TROLL light which allows to describe the part of the world to be modeled as a community of concurrently existing and communicating objects. Recently, we have worked out the basic notions of a pure algebraic semantics for our language. The main underlying idea is to present a transition system where the states represent the states of the specified information system, and state transitions are caused by the occurrence of finite sets of events. This semantics is formulated by representing states and state transitions as algebras. The various constructs of TROLL light are unified to general axioms restricting the possible interpretations for TROLL light object descriptions.

Towards Reliable Information Systems: The KorSo Approach

Within the compound project KorSo our team is concerned with the research on techniques and methods for the development of reliable information systems on the basis of formal specifications. Our work focuses on the specification language TROLL light which allows to describe the part of the world which is to be modeled as a community of concurrently existing and communicating objects by determining their structure as well as their behavior. Moreover we develop and implement a computer aided specification environment for TROLL light which permits a prototyping animation as well as the proof of properties of specifications.

Transforming Conceptual Data Models into an Object Model

In this paper a conceptually simple structural object model focusing on object types, attributes and ISA relationships is introduced. The model is derived mainly from an extended Entity-Relationship approach, but concepts from other semantic and object-oriented models have influenced its features. It is shown how high-level conceptual data models can be mapped to this model, and to what extent the object model subsumes classical modeling paradigms.

TROLL light - The Language and its Development Environment

In our sub-project we are concerned with techniques for the development of reliable information systems on the basis of their formal specification. Our work focuses on the specification language TROLL light which allows to describe the part of the world to be modeled as a community of concurrently existing and communicating objects. Our specification language comes along with an integrated, open development environment. The task of this environment is to give support for the creation of correct information systems. Two important ingredients of the environment to be described here in more detail are the animator and the proof support system.

A development environment for an object specification language

Techniques for the development of reliable information systems on the basis of their formal specification are the main concern in the project. Our work focuses on the specification language TROLL light which allows one to describe the part of the world to be modeled as a community of concurrently existing and communicating objects. Our specification language comes with an integrated, open development environment. The task of this environment is to give support for the creation of correct information systems. Two important ingredients of the environment are the animator and the proof support system. >

Korso Reference Languages - Concepts and Application Domains

This paper gives an overview of the three Korso reference languages Specturm, Trolllight, and Special, exposing their motivation and background, language concepts, and typical application domains. The presentation of the different languages is followed by a discussion to what extent these languages may complement each other in the software development process.

A SQL-like Query Calculus for Object-Oriented Database Systems

Currently much effort is being spent on providing object-oriented databases with ad hoc query facilities. In this paper we present a SQL-like query calculus whose major contribution lies in its inherent orthogonality and rigorous mathematical foundation. The calculus is essentially a calculus of complex values but it is defined independently of any concrete database model. The calculus can be used to formulate queries in value-based and object-based data models. Moreover it provides a general facility for the manipulation of complex values.

Safe Derivations in Object Hierarchies

We present a language for specifying structure and behavior of objects in information systems. This language is restricted to a set of core concepts for conceptual modeling. But it includes powerful concepts for specifying constraints and derived data. We present an algorithm for deciding on safe computation of derived information and demonstrate how this algorithm works with an example.