Architecturally describing the emergent behavior of software-intensive system-of-systems with SosADL

A System-of-Systems (SoS) is evolutionary developed from independent systems to achieve missions not possible to be accomplished by a single system alone. They are architecturally designed to exhibit emergent behavior, i.e. a new behavior that stem from the interactions among constituent systems, but cannot be deduced from the behaviors of the constituent systems themselves. This paper presents the concepts and constructs of a novel Architecture Description Language (ADL), named SosADL, for architecturally describing emergent behaviors of software-intensive SoSs. It refines the notion of emergent behavior and details how SosADL enables the architectural description of emergent behaviors. In particular, it demonstrates SosADL features for emergent behavior through an excerpt of a real application for architecting a Reconnaissance SoS, focusing on the flocking behavior of a fleet of Unmanned Aerial Vehicles (UAVs).