ABSTRACT

Various problems have been identified in popular object-oriented analysis methodologies because of the lack of a supporting theoretical foundation. For example: Object-oriented concepts are introduced by loosely and may be interpreted differently by individuals. Only syntax and static consistency checks are supported by CASE tools. Potential concurrency problems in target systems must be identified by human intuition from the graphical display. We propose an object-oriented model based on predicate-transition nets, with equivalent algebraic and graphical representations. We illustrate by means of a 3-dimensional graphical prototype how the static and dynamic properties of classes, attributes, methods and their relationships are modelled by predicates, transitions, arcs carrying algebraic terms, and net refinements. We also illustrate through the prototype how inheritance and overloading can be unified with message passing in the 3-dimensional model, but visualized as independent concepts by projecting vertically and horizontally on to 2-dimensional plains. Moreover, we can map the formal model to popular object-oriented analysis notations, so as to help to validate and verify formally the correctness of specifications in existing methodologies, including reachability, structural and behavioural consistencies, and inheritance and interaction couplings.

1. This research is supported in part by a grant of the Research Grants Council of Hong Kong. 2. Department of Computer Science, The University of Hong Kong, Pokfulam, Hong Kong. Email:

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