GRACEFUL OBJECT-BASED PERFORMANCE EVOLUTION

Object-based design and development are thought to facilitate graceful evolution of functionality, and thus enhance the reusability of softw are components. They can also facilitate graceful performance evolutio n. The performance of a layered object-based component can be made tun able to meet changing needs by permitting clients to 'plug in' appropr iate implementations for its constituent components through generic pa rameters. If the components and their constituents are carefully desig ned, then performance tuning is possible without direct modification t o the internal details of the participating components, thus significa ntly lowering the cost for performance evolution. The contribution of this paper is to software practice. It explains how software engineers can build performance-tunable components using C++ templates. It incl udes empirical results confirming that tuning produces expected perfor mance improvements with minimal code change. The results are especiall y significant because they are scalable to arbitrarily large and heavi ly layered software components and subsystems.