On a Process Algebraic Representation of Sequence Diagrams

Sequence diagrams depict the interaction between entities as a sequence of messages arranged in a temporal order. However, they lack a formal execution semantics: the Unified Modeling Language (UML) specification opts to use natural language to describe fundamental concepts such as interaction operators that alter the behaviour of a fragment. Communicating Sequential Processes (CSP) is a process-algebraic formalism that is suited to modelling patterns of behavioural interaction. Moreover, the associated refinement checker, Failures-Divergence Refinement (FDR), gives rise to a practical approach that enables us to reason about these interactions in a formal setting. In this paper, we show how CSP and FDR have been used to provide a process-algebraic representation of sequence diagrams that is amenable to refinement-checking.