PhD thesis,
Conceptual Modeling of Objects: A Role Modeling Approach
University of Oslo, (1997)
Abstract
This is a deeply technical foundation for object oriented modeling. It makes a contribution to the problem of handling complexity due to the size of the modeling task. The subject is highly relevant. Modeling of large compex systems is central to development of computer systems and is not easy.
The role modeling techniques presented are novel contributions and very interesting. The treatment of overlapping states and analysis of legal statespaces is original, and the proposal for fair and unfair action is novel, amongst many other things. The author presents the ideas in a convincing manner and gives a number of good examples of the usefulness of role modeling. The chapter on composition of role models and virtual roles for manipulating conceptual models is also very convincing. (The original idea of role modeling is due to Trygve Reenskaug and Else Nordhagen, but the current dissertation extends the ideas and gives them a theoretical foundation that was missing from the earlier, largely intuitive work.)
The parts on modeling behavior presents a number of ideas for modeling the dynamic behavior of objects and extends work by David Harel and others. In addition to handle the 'state explosion' problem, problems regarding 'composition of separately developed descriptions' and 'separation of concerns' are handled. A number of interesting techniques for analyzing behavior descriptions are presented including deadlock and livelock.
