The influence of conceptual user models on the creation and interpretation of diagrams representing reactive systems

In system design, many diagrams of many different types are used. Diagrams communicate design aspects between members of the development team, and between these experts and the non-expert customers and future users. Mastering the creation of diagrams is often a challenging task, judging by particular errors persistently found in diagrams created by undergraduate computer science students. We assume a possible misalignment between human perception and cognition on the one hand and the diagrams’ structure and syntax on the other. This article presents the results of an investigation of such a misalignment. We focus on the deployment of so-called 'conceptual user models' (mental models, created by users in their mind) at the creation of diagrams. We propose a taxonomy for mental mappings, used for categorization of representations. We describe an experiment where naive and novice subjects created one or several diagrams of a familiar task. We use our taxonomy for analysing these diagrams, both for the represented task structure and the symbols used. The results indeed show a mismatch between mental models and currently used diagram techniques

A real-world Case Study in Information Technology for Undergraduate Students

Real-world case studies are important to complement the academic skills and knowledge acquired by computer science students. In this paper we relate our experiences with a course specifically designed to address this issue. The problem to be addressed is the replacement of a Hospital Information System (HIS) in a large regional hospital. The case mimics as close as possible the project as it really took place. The objectives of the course are threefold: to train management and communication skills, to integrate and apply knowledge gained at different previous courses, and to learn by experience the difference between a real-world problem and a textbook problem. Students’ evaluations show that the objectives of the course are met and that it is regarded as very useful. We found that the three objectives mutually reinforce each other, which is a decisive factor for the success of the course

An environment for object-oriented real-time system design

A concise object-oriented method for the development of real-time systems has been composed. Hardware components are modelled by (software) base objects; base objects are controlled by a hierarchy of coordinator objects, expressed in an organizational diagram. The behaviour of objects is specified by state transition diagrams. This approach considerably promotes requirements analysis and communication with the customer. A CASE tool has been constructed with diagram editors for graphical specifications of real-time systems. The tool can generate executable code for PLCs from these graphical specifications; reuse of previous results is supported by the repository function of the tool. Experiences attained in practice with method and tool show that time spent in system testing and installation is reduced considerabl