Objectives

This section deals with the transition from specification to design. It discusses the distinction between structural and behavioral aspects by comparing semantic modeling with an object-oriented approach. It introduces model-based specification techniques and discusses in an informal way a design methodology based on the notion of abstract systems and events. In this approach, a notion of events is employed as a means to characterize user actions, and as a structuring device that aids in maintaining global consistency.

Points to emphasize

Hints

You may comment on the efforts to integrate the object model of programming languages such as C++ and the object model of object data bases, as for example reported in  [Cattell94]. This research is currently only in its initial phase, but clearly indicates that many of the features employed in semantic modeling, such as n-m relations, will in the future be supported at a language level.

Questions

  1. Characterize the differences between semantic modeling and object-oriented modeling.
  2. How would you characterize the notion of abstract systems?
  3. Explain how events may be employed to maintain system integrity.

Comments

The notion of abstract systems is introduced by means of an example. The idea of using events as a means to maintain global consistency is clearly suggested in  [Henderson93] but not developed formally as an essential ingredient of the method. The use of events to interrelate distinct components of a system, however, seems to be very promising. See also sections events and duality.