Towards an understanding of reliability of software-intensive systems-of-systems

Context: Large-scale software-intensive Systems-of-Systems (SoS) have become present in several critical domains and have sometimes depended on diverse trending technologies, such as cloud computing and machine learning. At the same time, the SoS dynamic architecture makes it difficult to assure SoS reliability leading to diverse studies with specific solutions, while the need for a shared view of what precisely SoS reliability refers to still exists. Objective: The main contribution of this article is to go towards an understanding of SoS reliability. We present a conceptual model whose concepts as well as their definitions and relationships were defined by systematically examining the literature of the field. Methods: We surveyed 36 practitioners and researchers regarding ambiguity, explanatory power, parsimony, generality, and utility of our model. Next, we adjusted our model according to their contribution.Results: We reach a conceptual model containing 29 concepts and their relationships that help to comprehend SoS reliability. In addition, we provided a glossary with a definition of each concept of our conceptual model. We also proposed a SoS reliability definition grounded on the literature.Conclusions: By organizing the knowledge of SoS reliability, this conceptual model makes it possible to expand the body of knowledge in the area and opens several opportunities for further investigations; in particular, this model serves as a basis for novel solutions aiming to assure SoS reliability.