Process-Oriented Metrics for Software Architecture Adaptability

Adaptability is important to the survival and success of just about any software system, especially due to the rapid changes in technology, organizational structure, human perception and needs. Measurement of the degree to which a software system is adaptable to such changes is often times of a critical concern to software practitioners. This paper proposes a framework, POMSAA (ProcessOriented Metrics for Software Architecture Adaptability), which aims to provide numeric scores representing the adaptability of a software architecture as well as the intuitions behind these scores. In this framework, the intuitions behind the architectural adaptability scores are traced back to the "whys" of the architecture, namely, the requirements for which the architecture exists in the first place. POMSAA achieves the needed tracing by adopting the NFR Framework, which is a process-oriented qualitative framework for representing and reasoning about non-functional requirements (NFRs). In this paper we show how POMSAA can be used to calculate adaptability metrics for an architecture of a software system, how it helps detect weaknesses and strategic strengths in the architecture, how it helps to understand the reasons for the weaknesses/strengths and how to make improvements (that will help improve the metrics), and how to recalculate the metrics for the new architecture fast and intuitively. This paper also describes how POMSAA was used in supporting the development of an adaptable architecture for a real-system, a test and measuring instrument used for testing cell phones.