Software Component Specification Using Design by Contract

This paper describes methods for identifying appropriate software components for an application and for specifying the components' operations rigorously. It uses the theory and methods of the design by contract approach for specification of the functionality. The actual implementations of a component's operations are hidden from the clients and encapsulated within the component. A component communicates with another component only through one of the other component's supported interfaces. Hence, a component can be easily replaced by another that implements the same operations. By using design by contract, we build reliable reusable components.