Specifying Use Case Sequencing Constraints Using Description Elements

The ability to express sequencing constraints is critical to use case based software development. These constraints are needed to effectively compose use case behavior and support verification and validation activities such as simulation and testing. In this paper, we consider the addition of use case description elements to explicitly express sequencing constraints between use cases. We introduce two complementary constructs. One allows to specify which use cases need to precede a use case and how these preceding use cases are synchronized. The second construct allows to specify which use cases are enabled from a use case and how these use cases execute concurrently. We relate the introduced elements to UML activity diagrams and implicit sequencing based on preconditions and postconditions.