Abstract

Use case models are used to capture functionality requirements of a system. Use cases can be described in term of the episodes, or subtasks, that are performed. An episode model captures the organization and relationships of the episodes in a use case. Refactoring is an approach to reorganize the internal structure of models in order to improve them or extend them in some way. Refactorings are behavior-preserving transformations of the models. This thesis looks at refactoring of use case models based on the information captured in episode models. We present a metamodel for the use case and the episode model in order to make precise the syntax of the models and explain the informal semantics of the models. We detail several refactoring rules for use case refactoring, including their verification of the behavior-preserving property. We also present a case study based on the Video Store System.