Flexible Composition of System of Systems on Cloud Federation

System of Systems (SoS), are designed primarily to fill the highly increasingly complex business needs. The inherent complexity of SoS raises issues at its development, its deployment and its customization. It has been reported that the service orientation principles are beneficial to SoS engineering but they are not sufficient to support it. Cloud federation and Software as a Service (SaaS), as service oriented paradigms, are promising solutions for managing the complexity of SoS as well as its costly and complex required infrastructure. However, additional issues should be seriously considered in the construction of a SoS to tackle the dynamic nature of a federated cloud environment. Building a SoS upon existing systems deployed in a federated cloud environment may influence the overall performance of the SoS, which can raise challenges in its composition process. In this paper, we focus on how building, in flexible way, a SoS from a set of existing systems deployed on heterogeneous cloud environments. Thus, we propose a flexible composition approach of federated cloud based SoS by considering both the functional and non-functional requirements to obtain the best composition in terms of overall quality of service (QoS). We implement an agent based SoS composition simulator providing composition scenarios and their related QoS, and evaluating the different special cloud criterion that can influence the quality of SoS composition. The obtained results show that the number of cloud providers and services involved in SoS federation has a great impact on the overall SoS performance.