Tradeoff Analysis for Conflicting Software Non-Functional Requirements

The need for particular software non-functional requirements (NFRs) leads a project team to use specific design strategies to fulfill these NFRs. However, some of the strategies may cause deficiencies in other software NFRs. These strategies are called conflicting strategies. Making the tradeoff decision of these conflicting strategies for NFRs is crucial. Therefore, a conflicting NFRs tradeoff framework (CNTF) and the corresponding method are proposed. Firstly, the NFRs are obtained from stakeholders. Fuzzy set theory is used to express stakeholder assessments on the importance of each NFR. The assessment results are ranked using a fuzzy ranking method. Then, adapting from production theory in microeconomics, the degree of satisfaction by which NFRs are affected by conflicting strategies are plotted as tradeoff curves. Borrowing the concept from the linear programming in management science, a tradeoff method is presented to help software project teams make the best tradeoff decision for conflicting NFRs. Finally, feasibility and limitations of the CNTF are elaborated in a case study.