Towards a Failure Model of Software Components

We present a failure model for describing sequences of services that are provided and required, and services that may be blocked by software components. For any automata-based model introduced in our previous work, there is a corresponding failure model. We show that the failure model is expressive enough to describe non-blockable properties defined in the automata-based models. Plugging operation of failure models is given and proved to be consistent with plugging operation of automata-based models. A kind of components, called coordinators, are then introduced to coordinate behaviors of components, and coordination operation is presented too. An algorithm is developed to generate a coordinator which can filter out sequences of provided service invocations that may be blocked.