Composing non-functional concerns with use cases for trade-off analysis

Functional and non-functional concerns are identified and refined during requirements analysis. These concerns are not always consistent; there may be conflicts between them, which must be discovered and resolved through trade-off analysis. Aspect-Oriented Requirements Engineering (AORE) can be used to first describe concerns independently of each other and then generate their composition. These are used to find conflicts and to conduct trade-off analysis. This paper uses the requirements conflict matrix (RCM) to represent the composition. It shows the positive or negative effect of non-functional concerns over use cases and other nonfunctional concerns. In order to support the RCM creation, Use Case Editor (UCEd), which is a tool that parses use case descriptions to provide simulation for conflict analysis, is extended to describe non-functional concerns and their relationships to other concerns. The extended tool uses the descriptions to generate representations for the composition in the form of RCM. The RCM is used as a reference for the "Conflicting Forces" method in order to gather questions for trade-off analysis with the stakeholders. A case study was performed to assess the effectiveness of the process and its tool support for trade-off analysis.