A Domain-Independent Ontology for Non-Functional Requirements

Despite considerable research on ontologies for representing requirements models (and metamodels), little progress has been made in using ontologies to represent non-functional requirements. Non-functional requirements define the overall qualities of the resulting system. Because they are restrictions on system services, non-functional requirements are often of critical importance, and functional requirements may need to be sacrificed to meet them. However, because of their diverse nature, non-functional requirements are often expressed in non-standard domain-specific ways. This paper describes a nonfunctional requirements ontology that can be used to structure and express constraints as part of quality of service specification. The approach is illustrated using a small case-study.