Interoperability is a major challenge for the IoT. The real potential of IoT lies in the “systems of IoT systems” rather than with disparate IoT silos [29,30]. An interoperable IoT system of systems provides a uniform way for sharing, finding, and accessing IoT sensing and tasking capabilities, the Internet, and different applications [31]. Interoperability requires layers of standards in order to address the heterogeneity issues amongst sensors, data, and networks [32]. Data and sensor interoperability refer to the ability to exchange and understand data formats, protocols, and sensor models. Network interoperability has no value if the bits and bytes are delivered but cannot be interpreted, i.e., if the data being exchanged over the network cannot be understood by machines a priori. Further, various levels of interoperability include synthetic, semantic, and cross-domain interoperability which mean the standardization of conceptual models, practices, and policies from disparate systems.