Runtime Software Architecture Model Based on Design Hierarchy

On line system is hard to evolve dynamically because its runtime SA (Software Architecture) exists implicitly. A model of runtime SA based on design space is put forward, in the model runtime SA is expressed explicitly as first-class entity. The concept separation between abstract SA (ASA)on meta-layer and physical SA (PSA)on base-layer provides methods to take on SA views at diverse levels of abstraction and manage SA for users, thereby supports the reuse of software framework and component when system is running, and enhances system flexibility and expansibility. Then we have given an ADL (dynamic architecture description) of runtime software architecture model based on design space. Finally, we discuss dynamic structure reconfiguration issues.