Enhancing Dependability of Component-Based Systems

We present a method to add dependability features to component-based software systems. The method is applicable if the dependability features add new behavior to the system, but do not change its basic functionality. The idea is to start with a software architecture whose central component is an application component that implements the behavior of the system in the normal case. The application component is connected to other components, possibly through adapters. It is then possible to enhance the system by adding dependability features in such a way that the central application component remains untouched. Adding dependability features necessitates to evolve the overall system architecture by replacing or newly introducing hardware or software components. The adapters contained in the initial software architecture have to be modified, whereas the other software components need not to be changed. Thus, the dependability of a component-based system can be enhanced in an incremental way.