1. Field of the Invention
This invention relates in general to object-oriented programming systems, and in particular, to a method for adding sequentiality to an arc language in an object modeling tool used in an object-oriented programming system.
2. Description of Related Art
Object modeling tools are available that provide an executable visual specification language for modeling the dynamic behavior of objects. An example is object modeling tools that are used to specify finite state machines (FSMs) of the Mealy machine variety, which are used extensively in telecommunication protocol design and object-oriented computer-assisted software engineering (CASE).
The reactive behavior of each object is specified by associating an extended finite-state machine with the object or by using object integration diagrams. The finite-state machines use an arc-language for behavioral specifications, while object interaction diagrams use constructs similar to the arc-language. Generally, each arc consists of an event-condition-actions triple: an "event" is a trigger in time, which may result in a state transition, concurrently initiating the actions, provided the corresponding condition holds.
However, existing arc-languages are weak on two counts: they cannot directly express sequencing of actions, and there is no way to refine conditions within the visual framework. The present invention solves these problems by introducing an additional connective for sequencing of actions and extending conditions to invoke events. Since it is preferable to remove some of the duality between methods and events, the present invention also incorporates return values from events.