Modeling Quality of Service Adaptability

Quality of service adaptability refers to the ability of services (or components) to adapt the quality exhibited during run-time, or to the faculty of architectural models to show that several alternatives concerning quality could be implemented. Enclosing quality properties with architectural models has been typically used to improve system understanding. Nevertheless, these properties can also be used to compose subsystems whose quality can be adapted or/and to predict the behavior of the run-time adaptability. Existing software modeling languages lack enough mechanisms to cope with adaptability, e.g. to describe software elements that may offer/require several quality levels. This paper presents concepts that such a language needs to include to model quality-adaptable systems, and how we use those concepts to compose and analyze software architectures.