Design of Trusted Systems with Reusable Collaboration Models

We describe the application of our collaboration-oriented software engineering approach for the design of trust-aware systems. In this model-based technique, a specification does not describe a physical system component but the collaboration between various components which achieve system functions by cooperation. A system model is composed from these collaboration specifications and, by a set of transformations, executable code can be automatically generated. As a modeling language, we use UML 2.0 collaborations and activities, for which we defined a semantics based on temporal logic. Thus, formal refinement and property proofs can be provided by applying model checkers as well. We consider our approach as well-suited for the development of trust-based systems since the trust relations between different parties can be nicely modeled by the collaborations. This ability facilitates also a tight cooperation between trust management and software engineering experts which are both needed to create scalable trust-aware applications. The engineering approach is introduced by means of an electronic auction system executing different policies which are guided by the mutual trust of its principals. As a trust model we apply Jøsang’s Subjective Logic.