modeling. This paper considers the design of interoperable CPS as socio-technical development task, as CPS represent evolving interactive systems. Pathways from level I to 6 are provided suggesting structuring the development of a design language for modeling and architecting interoperable CPS as Systems-of-Systems. The pathways address various levels of complexity of architectural designs as well as language requirements for stakeholder-centered behavior advantage (cf. https://www.gartner.com/smarterwithgartner/top-10-technologies-driving-the-digitalworkplace). Individual activities will be bound to digital actions creating an “Internet of Behavior” in public communities and business settings (https://www.gartner.com/smarterwithgartner/gartner-topstrategic-predictions-for-2020-and-beyond/). Consequently, Cyber-Physical Systems (CPS) will be affected by continuous interactive change, requiring the (dynamic) adjustment of their components ensuring interoperability.
Interoperability Engineering is increasingly getting a design task requiring interactive access to design representation in a stakeholder-centered way. According to Gartner’s forecasts 2019, over the next several years, the workforce’s ability to exploit business-relevant technologies such as Internet-ofThings (IoT) systems, will decide whether many organizations can build up or keep competitive
2020 Copyright for this paper by its authors. the pathways differentiate architecture concerns from behavior representations, as the latter address tool requirements for modeling interoperable CPS.
CPS-architectures are traditionally run decentralized, being linked to communication and modular (e.g., agent-based) structures. Some parts need to co-operate through exchanging information and adapting to environmental changes, others deliver or process data on demand. Overall, CPS allow largescale interconnected processes as reconfigurable networks of locally autonomous actors, including IoTenabled sensory system [7]. Thereby, CPS link “cyber” (virtual, computational) and “physical” components. Their openness and socio-technical character stem from interconnecting physical, social, and virtual worlds.
CPS are heterogeneous systems, including distributed physical devices and computational components. As flexibility and re-configurability matter for operation due to changes in environment, the granularity of the system, the access to components, and the way information is exchanged are crucial design parameters. Any CPS architecture encompasses physical objects, sensors, actuators, computing devices, controllers and communication network(s) that are represented as digital twin in a model of the actual system. As such, it has to be capable to represent and support human-device interaction and device-to-device communication. According to Interaction Science, the ‘interaction is considered as the exchange of material or immaterial goods between acting parties (biological or technical entities) embodied in a certain context. Overtime, these interactions establish behavioral and cognitive schemas that transfer as patterns and expectations to further activities and in this way influence the acting stakeholders. Stakeholders are identified as the persons that are involved in systemand interaction-relevant processes, either operating, (re-)design, monitoring or controlling a system. As they interact in a certain environment, they create specific patterns in the system representing the environment.’ [1]
These system-wide patterns shape the behavior of each actor (humans, robots, applications, etc.,) resulting in a Complex Adaptive Systems and thus, creating challenges of interoperability in systems (cf. [8] for production). A System-of-System perspective on these kind of ecologies helps coping with complexity, taking into account emergent behavior and transformations (cf. [2]). Thereby, components (sub systems) are linked in a way their internal structure can handle their interaction to form a unified whole (cf. [5]), albeit their often physical and functional heterogeneity. As System-of-System they are organized hierarchically, with each component contributing to an overarching system function. Allowing for autonomous behavior of each component constitutes a federated system architecture. In this way, CPS can evolve from autonomous sub systems towards a network of interacting components (cf. [9]). In the course of interoperability engineering the protocol of interacting with the network actors is decisive for dynamic alignment to contribute to a common objective of a CPS. It needs to be considered part of the CPS architecture and as design enabler.
Engineering interoperable CPS supported by a design and architecture language requires not only a specific system perspective, as already indicated in the previous section, but development paths that take into account CPS architecting and design as an interactive process. Although being intertwined, they need to meet different requirements due to the interactive and socio-technical nature of evolvement processes.
Figure 1: Pathways
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