A Formalism for Extending the NFR Framework to Support the Composition of the Goal Trees

Non-functional requirements are considered as vital factors for producing software of better quality. As a widely adopted non-functional requirements analysis framework, the NFR Framework provides a graphical treatment for goal refinement and evaluation. This paper propose a logical representation for the NFR Framework. In addition, an NFR extension operator and an accompanying extension function for composing multiple viewpoints of NFR are proposed. Compared with the graphical NFR Framework, the logical approach further enhances the reasoning capabilities of the NFR framework. A real-world example has been used to illustrate the formal approach.