Experience of pragmatically combining RE methods for performance requirements in industry

To meet end-user performance expectations, precise performance requirements are needed during development and testing, e.g., to conduct detailed performance and load tests. However, in practice, several factors complicate performance requirements elicitation: lacking skills in performance requirements engineering, outdated or unavailable functional specifications and architecture models, the specification of the system's context, lack of experience to collect good performance requirements in an industrial setting with very limited time, etc. From the small set of available non-functional requirements engineering methods, no method exists that alone leads to precise and complete performance requirements with feasible effort and which has been reported to work in an industrial setting. In this paper, we present our experiences in combining existing requirements engineering methods into a performance requirements method called PROPRE. It has been designed to require no up-to-date system documentation and to be applicable with limited time and effort. We have successfully applied PROPRE in an industrial case study from the process automation domain. Our lessons learned show that the stakeholders gathered good performance requirements which now improve performance testing.