|Authors||M. Zhang, T. Yue, S. Ali, B. Selic, O. Okariz, R. Norgren and K. Intxausti|
|Title||Specifying Uncertainty in Use Case Models in Industrial Settings|
|Publication Type||Technical reports|
|Year of Publication||2016|
|Publisher||Simula Research Laboratory|
|Keywords||Belief, Uncertainty, Use Case Modeling|
Latent uncertainty in the context of software-intensive systems (e.g., Cyber-Physical Systems (CPSs)) demands explicit attention right from the start of development. Use case modeling—a commonly used method for specifying requirements in practice, should also be extended for explicitly specifying uncertainty. To this end, we extend the Restricted Use Case Modeling (RUCM) methodology and its supporting tool to specify uncertainty as part of system requirements. Such uncertainties include those caused by insufficient domain expertise of stakeholders, disagreements among them, and known uncertainties pertaining to assumptions about the environment of the system. The extended RUCM, called U-RUCM, inherits the features of RUCM, such as automated analyses and generation of models, to mention but a few. Consequently, U-RUCM provides all the key benefits offered by RUCM (i.e., reducing ambiguities in requirements), but in addition, it allows specification of uncertainties with the possibilities of reasoning and refining existing ones and even uncovering unknown ones.
We evaluated U-RUCM in the context of the U-Test project (www.u-test.eu) with two industrial CPS case studies. Evaluation results showed that, with U-RUCM, we were able to get a significantly better and more precise characterization of the uncertainties involved compared to RUCM. This suggests that U-RUCM is an effective tool for dealing with uncertainty in requirements engineering. We present our experience, lessons learned, and future challenges based on the two industrial case studies.