Scenarios and use cases have been used interchangeably in several works meaning partial descriptions. In this paper, we suggest a requirement engineering process that composes (merge) use cases/scenarios and yields a formal specification of the system in form of a high-level Petri net. Use cases and scenarios are acquired in form of diagrams as defined by the Unified Modeling Language (UML). These diagrams are composed and transformed into Petri net specifications and merged to obtain a global Petri net specification capturing the behavior of the entire system. From the global specification, a system prototype can be generated and embedded in a user interface builder environment for further refinement. Based on end user feedback, the use cases and the input scenarios may be iteratively refined. The result of the overall process is a specification consisting of a global Petri net, together with the generated and refined prototype. This paper discusses some activities of this process. The need of a unified model of interaction (UMI) is also discussed at the end of this paper.

Use Case/Scenario engineering, Use Case/Scenario composition, Model transformation, UML, Unified Model of Interaction