Relational-model based change management for non-functional requirements: Approach and experiment

In software industry, many organizations either focus their traceability efforts on Functional Requirements (FRs) or else fail entirely to implement an effective traceability process. Non-Functional Requirements (NFRs) such as security, safety, performance, and reliability are treated in a rather ad hoc fashion and are rarely traced. This is mainly because of the unique nature of NFRs. They are subjective, relative and they tend to become scattered among multiple modules when they are mapped from the requirements domain to the solution space. Furthermore, NFRs can often interact, in the sense that attempts to achieve one NFR can help or hinder the achievement of other NFRs at particular software functionality. Such an interaction creates an extensive network of interdependencies and tradeoffs among NFRs which is not easy to trace. In a previous work, we proposed a conceptualization of NFRs through the NFRs Ontology. In this paper, we extend the previous work by proposing a change management mechanism for tracing the impact of NFRs on the other constructs in the ontology such as FR or NFR operationalization and vice versa, and providing a traceability mechanism using Datalog expressions to implement queries on a relational model-based representation for the ontology. The proposed traceability queries are then evaluated through a multi-project variation quasi-experiment on regression testing conducted in the industry.