Timed Automata Semantics for Visual e-Contracts

C-O Diagrams have been introduced as a means to have a more visual representation of electronic contracts, where it is possible to represent the obligations, permissions and prohibitions of the different signatories, as well as what are the penalties in case of not fulfillment of their obligations and prohibitions. In such diagrams we are also able to represent absolute and relative timing constraints. In this paper we present a formal semantics for C-O Diagrams based on timed automata extended with an ordering of states and edges in order to represent different deontic modalities.Comment: In Proceedings FLACOS 2011, arXiv:1109.239

On the Specification of Full Contracts

Contracts specify properties of an interface to a software component. We consider the problem of defining a full contract that specifies not only the normal behaviour, but also special cases and tolerated exceptions. In this paper we focus on the behavioural properties of use cases taken from the Common Component Modelling Example (CoCoME), proposed as a benchmark to compare different component models. We first give the full specification of the use cases in the deontic-based specification language CL, and then we concentrate on three particular properties in order to compare deontic and operational specifications. We conjecture that operational specifications are well suited for normal cases, but are less easily extended for exceptional cases. This hypothesis is investigated by comparing specifications in CSP (operational) with specifications in CL. The outcome of the experiment supports the conjecture and demonstrates clear differences in the basic descriptive power of the formalisms