The Systems Modeling Language (SysML), an extension of a subset of the Unified Modeling Language (UML), is a visual modelling language for systems engineering applications. At present, the semiformal SysML, which is widely utilised for the design of complex heterogeneous systems, lacks integration with other more formal approaches. In this paper, we describe how Communicating Sequential Processes (CSP) and its associated refinement checker, Failures Divergence Refinement (FDR), may be used to underpin an approach that facilitates the refinement checking of behavioural consistency of SysML diagrams; we also show how the proposed approach supports requirements traceability. We illustrate our contribution by means of a small case study.

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.

The Systems Modeling Language (SysML) is a semiformal, visual modelling language used in the specification and design of systems. In this paper, we describe how Communicating Sequential Processes (CSP) and its associated refinement checker, Failures Divergences Refinement (FDR), can be used in conjunction with SysML in a formal top-down approach to systems engineering. Typically, a system is composed from constituent systems or components using the concept of blocks. SysML allows two alternative interpretations with regards to the behaviour of the resulting composition. By making use of a process-algebraic formalism we are able to explore these interpretations more rigorously. A case study is used throughout to illuminate the concepts in an informal manner.

The Systems Modeling Language (SysML) is a semi-formal, visual modelling language used in the specification and design of systems. In this paper, we describe how Communicating Sequential Processes (CSP) and its associated refinement checker, Failures Divergences Refinement (FDR), gives rise to an approach that facilitates the refinement checking of the behavioural consistency of SysML diagrams. We formalise the conjoined behaviour of key behavioural constructs -state machines and activities -within the context of SysML. Furthermore, blocks, the fundamental modelling construct of the SysML language, can be combined in a compositional approach to system specification. The use of a process-algebraic formalism enables us to explore the behaviour of the resulting composition more rigorously. We demonstrate how CSP, in conjunction with SysML, can be used in a formal top-down approach to systems engineering. A small case study validates the contribution.

Abstract-The block concept is a fundamental modeling construct in the Systems Modeling Language (SysML), a visual modeling language for systems engineering applications. In a top-down systems engineering approach, an abstract block is decomposed into concrete communicating sub-blocks. However, the classifier behavior of the abstract block must be exhibited by the composition of the concrete sub-blocks. We show how the process algebra Communicating Sequential Processes (CSP) and its associated refinement checker, Failures Divergence Refinement (FDR), may be used to ensure that such decompositions are valid. We introduce a small case study in order to validate the approach.