The Internet of Things (IoT) idea is having a significant impact on our daily lives these days. As the number of IoT devices is growing fast, many researchers have declared that the usage of IoT and the impact of IoT will make people always use IoT devices whatever they do or wherever they are. At the same time, IoT devices at home are receiving a lot of attention because they contribute to a comfortable home environment. Thus, IoT devices at home are increasing and diversifying. In addition, it is obvious that people will use various home services using various IoT devices. In this situation, it can be extremely difficult for both users and service providers to solve a problem if there is a fault in the smart home environment. To find the position of a fault easily, we define four social relationships between IoTs: IoT-IoT, IoT-Network, Foodservice and IoT-Physical space relationship.
The relationships can be used discover IoT devices, services and resources because it provides a distributed solution that is effective, efficient and reduces the burden on people. In addition, the idea of social relationships guarantees the network navigability of searching. To prevent needless burdens on users, we propose that the four relationships are generated automatically by an SDN-based home cloud. We simulated the automatic generation mechanism with 307 switches and 2007 device nodes. The results confirmed that the relationships are generated properly with high accuracy. The created relationships are stored as a RDF/XML format. The RDF/XML format could be used semantically for such tasks as answering a semantic query or smart home service recommendation. We anticipate that the proposed mechanism will bring huge benefits not only to users but also to home service providers in the purpose of smart home management.