System-of-Systems Reliability - An Exploratory Study in a Brazilian Public Organization.

A System-of-systems (SoS) is defined as an arrangement of independent systems that work together to accomplish missions that could not be achieved by a single system in isolation. SoS can be observed in several domains, including mobility, healthcare, and safety. A significant concern of SoS engineers refers to the constituent systems’ independence since they may change the level of contribution or abandon the SoS, decreasing the overall reliability. In this paper, we performed a study of an SoS running in a Brazilian public organization focusing on identifying reliability issues. To do so, we first characterized the SoS by identifying the missions, constituent systems, relationships, and capabilities. We further conducted a focus group and a survey with the SoS engineering team to identify situations that decrease SoS reliability and how they can be treated. Both the focus group and the survey helped us to propose an initial mKAOS extension for the representation of reliability issues, such as failures and fault tolerance mechanisms in SoS. We believe that our extension can facilitate the communication of SoS reliability issues, considering the existing challenges.