Systems-of-systems are formed by the composition of independently created software components. These components are designed to satisfy their individual requirements, rather than the global requirements of the systems-of-systems. We refer to components that cannot be adapted to meet both individual and global requirements as "defiant" components. In this paper, we propose a "cautious" adaptation approach which supports changing the behaviour of such defiant components under exceptional conditions to satisfy global requirements, while continuing to guarantee the satisfaction of the components' individual requirements. The approach represents both normal and exceptional conditions as scenarios; models the behaviour of exceptional conditions as wrappers implemented using an aspect-oriented technique; and deals with both single and multiple instances of defiant components with different precedence order at runtime. We evaluated an implementation of the approach using drones and boats for an organ delivery application conceived by our industrial partners, in which we assess how the proposed approach helps achieve the systemof-systems' global requirements while accommodating increased complexity of hybrid aspects such as multiplicity, precedence ordering, openness, and heterogeneity.

Drone simulators can provide an abstraction of different applications of drones and facilitate reasoning about distinct situations, in order to evaluate the effectiveness of these applications. In this paper we describe Dragonfly, a simulator of the behaviours of individual and collection of drones in various environments, involving random contextual variables and different environmental settings. Dragonfly supports the use of several drones in applications and evaluates the satisfaction of requirements under normal and exceptional situations. It simulates adaptive behaviours of drones due to exceptional situations. The adaption of drones is based on the use of wrappers implemented using aspect-oriented programming.

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A defiant IoT component is a smart device of an IoT system-of-systems (SoS) that should adapt its local behaviour to accomplish the new global requirements of the SoS only in exceptional scenarios. There are several self-adaptive approaches for system-of-systems in the literature. However, to handle defiant components, there is currently only one solution, called cautious adaptation, which relies on the use of AOP-based wrappers. That approach may not be appropriate for IoT systems since the components expose their communication API. Therefore, this paper proposes a new cautious adaptation approach for IoT SoS that adds three external components, the Configurator, the Observer and the Effector, that realize the MAPE control loop to apply behaviour adaptation. The solution is evaluated through a proof of concept using two types of IoT device communication mechanisms that demonstrated that our proposal helps the SoS to achieve its global goals.