Features of CML: A formal modelling language for Systems of Systems

TLDR

Systems of Systems can maintain local service continuity even when remote components fail, as illustrated by telephone exchanges that remain independent for local subscribers. The paper introduces CML, a formal language for modelling and analysing Systems of Systems. CML is demonstrated by refining a centralised telephone exchange into a network of distributed exchanges that partition subscribers to minimise cabling while preserving independent local service.

Abstract

We discuss the initial design for CML, the first formal language specifically designed for modelling and analysing Systems of Systems (SoSs). It is presented through the use of an example: an SoS of independent telephone exchanges. Its overall behaviour is first specified as a communicating process: a centralised telephone exchange. This description is then refined into a network of telephone exchanges, each handling a partition of the set of subscribers (telephone users). The refinement is motivated by a non-functional requirement to minimise the cabling required to connect geographically distributed subscribers, who are clustered. The exchanges remain as independent systems with respect to their local subscribers, whose service is unaffected by the loss of remote exchanges.