Tailoring and Evaluating Non-Functional Interests Towards Task-Oriented Functional Requirements

Without a specific functional context, non-functional requirements can only be approached as cross-cutting concerns and treated uniformly across all features of an enterprise system. This neglects, however, the heterogeneity of non-functional requirements that arises from the domains of stakeholders and the distinct functional scopes these systems, which mutually influence how these non-functional requirements have to be satisfied. Earlier studies showed that the different types and objectives of non-functional requirements result in either vague or unbalanced specification of non-functional requirements. We propose a task analytic method for eliciting and modeling user tasks and the stakeholders’ pursued interests towards the enterprise system. Stakeholder interests are structurally related to user tasks and each interest is specified individually as a quantitative constraint for a specific user task. These constraints can automatically be evaluated throughout the system’s lifecycle to assure that the respective stakeholder interest is fulfilled. Eventually, this allows to proactively counteract violations of constraints and thus stakeholder interests. We propose a structured method, intertwining task-oriented functional requirements with non-functional stakeholder interests to specify constraints on the level of user tasks. We also present results of an exploratory case study with domain experts, which reveals that our task modeling and interest-tailoring method facilitates shared understanding of stakeholder interests, clarity and quality of software constraints, prioritization of engineering efforts, and the impact of stakeholder interests on functional requirements.