Interface theories with component reuse

Interface theories have been proposed to support incremental design and independent implementability. Incremental design means that the compatibility checking of interfaces can proceed for partial system descriptions, without knowing the interfaces of all components. Independent implementability means that compatible interfaces can be refined separately, maintaining compatibility. We show that these interface theories provide no formal support for component reuse, meaning that the same component cannot be used to implement several different interfaces in a design. We add a new operation to interface theories in order to support such reuse. For example, different interfaces for the same component may refer to different aspects such as functionality, timing, and power consumption. We give both stateless and stateful examples for interface theories with component reuse. To illustrate component reuse in interface-based design, we show how the stateful theory provides a natural framework for specifying and refining PCI bus clients.