Runtime software architecture based on reflective middleware

There exists a consensus that software architecture (SA) plays a central role in software development and also plays an important role in the lifecycle phases after software delivery. Particularly, SA can be used to reduce the great difficulty and cost of software maintenance and evolution. In this paper, runtime software architecture (RSA) based on reflective middleware is proposed to support architecture-based software maintenance and evolution. In this approach, the actual states and behaviors of the runtime system can be observed and manipulated in a consistent and understandable way through its architectural view. Being an accurate, up-to-date, semantic and operable view of SA, RSA looks components and connectors as "white-box" entities to accurately and thoroughly describe the runtime system, extends traditional architecture description languages to formally describe itself and naturally inherit plentiful semantics in traditional views of SA, and utilizes reflective middleware to observe and manipulate the runtime system. In order to demonstrate the feasibility of this approach, a reflective J2EE application server, called PKUAS, is implemented to observe and manipulate the components, connectors and constraints in the runtime system. Finally, the performance evaluation proves that making RSA explicit and operable at runtime has little effect on the runtime system.