Chris Ho-Stuart

SOFL: a formal engineering methodology for industrial applications

Formal methods have yet to achieve wide industrial acceptance for several reasons. They are not well integrated into established industrial software processes, their application requires significant abstraction and mathematical skills, and existing tools do not satisfactorily support the entire formal software development process. We have proposed a language called SOFL (Structured-Object-based-formal Language) and a SOFL methodology for system development that attempts to address these problems using an integration of formal methods, structured methods and object oriented methodology. Construction of a system uses structured methods in requirements analysis and specifications, and an object based methodology during design and implementation stages, with formal methods applied throughout the development in a manner that best suits their capabilities. The paper describes the SOFL methodology, which introduces some substantial changes from current formal methods practice. A comprehensive, practical case study of an actual industrial Residential Suites Management System illustrates how SOFL is used.

Testing and Refinement for Nondeterministic and Probabilistic Processes

Transition systems are a basic semantic model for formal description, specification, and analysis of concurrent and distributed systems. In order to describe and analyze aspects of reliability, such as the likelihood of trace and failure, this model has been extended in various ways to handle probabilistic behavior. To use these models for specification and stepwise development of systems, it is important to develop appropriate refinement preorders. In the paper, we develop refinement preorders based on a framework of testing for a model that represents both nondeterministic and probabilistic choices as independent concepts [YL92]. Our main contribution is a notion of reward testing, and a denotational characterization of a testing preorder, which corresponds to a natural probabilistic extension of the trace model [Hoa85].

A formal operational semantics for SOFL

SOFL (Structured-Object-Based-Formal Language) is a formal language and method for practical systems development. As a language, it integrates data flow diagrams, VDM-SL, and Petri nets to provide a graphical and textual formal notation for specification construction. Previous publications introducing SOFL are based on its informal semantics. We provide a formal operational semantics which gives a firm foundation for consistent understanding and application of SOFL in practical systems development. Development of the semantics, and application of SOFL to practical systems, have led to some changes in the original definitions. This formal semantics will serve as a firm foundation for building an effective support environment for SOFL.

A sense of touch in online sculpting

This paper describes the work-in-progress of an online multimedia tool employing the sense of touch in exploring and learning sculpting techniques to be used over the Internet. Many game applications use haptic devices as a control mechanism, yet little has been documented on the use of this controlling procedure in an educational setting. The internet based instructional device presented here has a single modeling tool accessed by a customised interface designed with widely accessible software (Macromedia Director MX™). This will be extended to a small suite of modeling tools, in progress at this time. It makes use of a simple force-feedback joystick to control a spherical tool which makes changes to the surface of a 3D model represented onscreen. It is proposed that by using this device with Flash Web Server and the Internet, the system is able to support a collaborative environment encouraging interaction between student and tutor. It is hoped this system will become a research and development tool in online education.

Laboratory practice with software quality assurance

Students and indeed many practicing software professionals are often sceptical of the benefits of software quality assurance. Organizations which have experienced the benefits for themselves are in no doubt. In the Software Engineering major at the Queensland University of Technology, a Software Quality Assurance unit has been introduced. We have attempted to give students some practical experience by combining the practical work for this unit with project work from other units in the major. The quality assurance students interact with project students in reviews and walk throughs of baseline documents. Our experience with this experiment is described, and we draw some tentative conclusions.

Semi-automatic transformation from formal specifications to programs

As model-based formal methods (e.g. VDM, Z) are becoming popular for the development of safety-critical and complex systems in industry, automatic transformation from formal specifications to programs is an ideal and efficient approach to software production. However, it is impossible in general for this transformation to be fully automatic, because the language of first order logic used for specification is not decidable. This paper uses VDM (Vienna Development Method) as an example to investigate this difficulty, and proposes an approach to address the problem. Rules for automatically transforming abstract level VDM specifications are described and further transformation at a detailed level is discussed. Finally, further work towards the construction of a rule-based software system to support the transformation from VDM specifications to programs in general is addressed.