Applying ISO/IEC 9126-1 Quality Model to Quality Requirements Engineering on Critical Software

In order to develop a software product for a critical system, specifying quality requirements is vitally important. Quality requirements should be defined based on various stakeholders’ needs. Software quality impacts the information system’s behavior, and the behavior impacts the behavior of the External-System that contains the information system. Safety is an issue of the External-System. A software product alone is harmless, because it can do nothing without computer hardware. However, any software quality characteristic, such as security and reliability, impacts the External-System’s safety. In this paper, conceptual models for quality requirements are presented. Then needs, requirements, and quality requirements are defined. Requirements for a Quality Requirements Engineering method are also stated. Then a method for Quality Requirements Engineering and associated specification is provided with a simple example.