Scenario-Based Validation of Requirements for Context-Aware Adaptive Services

Context-awareness and adaptability are highly desirable features for services that are operating in dynamic environments. Recently, a number of approaches have been introduced to support the development of such services. But, validating the varying requirements of these services is still a major challenge. In this paper, we introduce a novel scenario-based approach to address this challenge. First, our approach captures a service´s requirements as two sets of scenarios: functional and adaptation. The functional scenarios represent the service´s core functionality, while the adaptation scenarios capture the service´s runtime adaptation in response to context changes. The service properties that need to hold at runtime are also represented graphically in a form similar to the scenarios. Second, a technique is introduced to enumerate and generate the specifications of a service´s variants from its scenarios. The generated variants are then validated against the service properties to ensure their validity. This technique also checks the consistency of the service´s adaptation requirements (scenarios). Case studies have shown that with our approach, a small number of service scenarios specified by the software engineer is able to cover a large number of service variants, which are generated and validated automatically.