QUALITY ASSESSMENT OF SYSTEM ARCHITECTURES AND THEIR REQUIREMENTS (QUASAR)

Abstract

The quality of a software-intensive system is largely determined by the quality of its architecture and the quality of the architecturally significant requirements that drive its development. Unfortunately, although quality requirements typically have critical architectural ramifications, requirements engineers using such popular techniques as use case modelling tend to emphasize functional requirements over non-functional quality requirements, with the result that the quality requirements are often poorly specified or not specified at all. Similarly, system architects tend to emphasize a system's logical decomposition structure into major functions and subfunctions and the corresponding static physical decomposition structure into a hierarchy of subsystems. The system architects often do not adequately document how (or even if) these subsystems and subsubsystems collaborate to sufficiently support the achievement of their derived and allocated quality requirements. To address these two problem areas, the SEI QUality Assessment of software-intensive System Architectures and their Requirements (QUASAR) method was created to provide acquisition organizations with a proven and efficient means to determine if quality requirements have been properly engineered and if system architectures sufficiently meet these requirements.