On the Requirements for Quality Composability Modeling and Analysis

Real-time, embedded and safety-critical systems have to meet some quality criteria in order to provide certain reliance on its operation. The quality of a system depends on the complex composition of the quality of its subsystems. Quality composability depends on matchmaking the provided and required quality specifications. To allow for flexibility during the system design, we study composability as a configuration problem. We allow options of quality specifications to represent design choices, deployment choices, operation modes or component adaptability. This kind of assessments of system architectures is very important e.g., for COTS development. The contributions of this paper are: to study the modeling requirements to model composability analysis, to compare two modeling approaches, and to show how a model-driven environment can leverage composability assessments. The two modeling approaches, QoS-FT + OCL and MARTE + VSL, are used to attach quality specifications to system models. However, our ultimate goal is to evaluate these specifications, and we have implemented tool-support to evaluate composability using constraint satisfaction techniques.