Interleaving semantics and verification of UML 2 dynamic interactions using process algebra

UML sequence diagrams provide a visual notation for modeling the behavior of object interactions in systems. They lack precise formal semantics due to the semi-formal nature of the UML language which hinders their automated analysis and verification. Process algebras have been widely used in the literature in order to deal with such problems. π-calculus is a well-known process algebra recognized for its rich theoretical foundation and high expressivity power. It is also characterized by its capabilities in specifying interleaving and weak sequencing which is considered by the OMG standard as the default semantics for interaction diagrams. Thus, this paper presents a novel approach to formalizing UML 2 sequence diagrams by translating them into π-calculus. The translation captures the semantics of their basic elements as well as their combined fragments. A compositional technique is adopted to gradually build the corresponding π-calculus specification which results in easy induction/recursion of elements and their meaning enabling reasoning about complex dynamic behaviors. The latter task could be done using different analysis tools such as the MWB tool used in this study. The mapping provides a formal semantics as well as formal analysis and verification for UML2 sequence diagrams according to the OMG standard. A case study is shown to illustrate the usefulness of the translation.