Modeling and Analyzing Non-Functional Requirements in Service Oriented Architecture with the User Requirements Notation

Abstract

Non-functional properties (NFPs) represent an important facet of service descriptions, especially in a Service Oriented Architecture. Yet, they are seldom explicitly described, and their use in service selection and composition is still limited. This chapter presents the User Requirements Notation (URN) as a means to model and analyze functional and non-functional service requirements. Aspect-oriented extensions to URN (AoURN) enable the modeling and modularization of different concerns, including non-functional requirements, which can crosscut services or service components. The chapter also proposes a taxonomy of NFPs used to annotate services and service compositions modeled with AoURN. These annotations enable the specification of quantitative non-functional values for services, guide service selection, and support the computation of the NFP (e.g., the quality of service) of their composition. This approach is illustrated with a simple yet realistic composite service (BookItWell), with an emphasis on four types of NFPs, namely service cost, response time, reliability, and availability.