The hybrid process that combines traditional requirements and use cases

For many years systems engineers have produced traditional system requirements specifications containing shall-statement requirements. The rapid adoption of use case modeling for capturing functional requirements in the software community has caused systems engineers to examine the utility of use case models for capturing system-level functional requirements. A transition from traditional shall-statement requirements to use case modeling has raised some issues and questions. This paper advocates a hybrid requirements process in which use case modeling and traditional shall-statement requirements are applied together to effectively express both functional and nonfunctional requirements for complex, hierarchical systems. This paper also presents a practical method for extracting requirements from the use case text to produce a robust requirements specification. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 303–319, 2004