Semantic Enablers for Digital-Physical Object Dynamic Associations in a Federated Node Architecture for the Internet of Things

The Internet of Things (IoT) concept envisions a future where numerous physical world objects interacting with each other are engrained in the fabric of our environment. The IoT paradigm is inspired from the RFID and Wireless Sensor Networks (WSNs) research areas. However, the objects encompassing the IoT world will include not only RFID tags, readers and sensors, but all types of devices that can support interactions between the physical and virtual world. Such ‘connected and smart objects' are said to comprise the ‘things' in the IoT. The heterogeneity of the possible devices and the resulting data necessitates development of architectures and methods that facilitate a homogeneous representation of these objects and a uniform way of integrating their functionalities (services). The applicability of Semantic Web technologies to facilitate interoperability as well as enabling a standardised and machine-processible representation has already been identified in the literature. Existing research works in sensor networks have focused on sensor (and actuator) middleware frameworks that offer sensor measurement data services on the Web and/or at the application level. Standardisation activities such as the Semantic Sensor Network Incubator Group (SSN-XG) have resulted in the Semantic Sensor Network (SSN) ontology that provides a semantic framework to sensor descriptions and sensor site data. However, as identified by some, there is still a lack of standardised data models and ontologies that can be used in IoT applications. Moreover, the semantic sensor descriptions need to be linked to the measurements and domain knowledge and then to the observed IoT entity in the domain. To extend this to heterogeneous physical world objects, the various possible concepts in the IoT domain need to be identified and made available in a machine-processible way so as to enable automated reasoning of the data and possible interactions.