Goal-Based Modeling and Analysis of Non-Functional Requirements

Non-functional goals specify a quality attribute of the functional goals for the system-to-be (e.g., cost, performance, security, and safety). However, non-functional goals are often cross-cutting and do not naturally fit within the default decomposition expressed by a functional goal model. Further, any functional mitigations that ensure the satisfaction of a non-functional goal, or occur in the event a non-functional goal is violated, are conditionally applicable to the remainder of the system-to-be. Rather than modeling non-functional goals and their associated mitigations as a part of the system-to-be goal model, we introduce a method of modeling and analyzing non-functional goals and their associated mitigation as separate models. We illustrate our approach by applying our method to model non-functional goals related to an industry-based automotive braking system and analyzing for non-functional violations.