ReQuEst: Requirements-driven quality estimator

Estimating quality of software systems has always been a good practice in software engineering. Presently, quality evaluation techniques are applied only as an afterthought to software design process. However, quality of a software system should be stated based on the end-user's requirement for quality. Based on this observation, this paper proposes an estimation model called ReQuEst (Requirements-driven Quality Estimator). ReQuEst is an attempt to quantitatively estimate the quality of a system being designed from its analysis model. The quality is estimated in terms of adaptability and extendibility which are also important parameters in system design. During requirements analysis, evolving requirements are also analyzed to capture a few quality indicators from them. These indicators are used to compute the requirements for the above parameters from the analysis model. Thus, the analyst can quantitatively specify the quality demands of the system to be designed along with the functional requirements. These quality specifications enable the system designer to precisely design systems meeting the values specified. Further, the model can be used to estimate the maintainability of the system in terms of the above parameters.