WoTtrader: A trading service for the Web of Things

The increasing integration of Internet of Things (IoT) devices into various ecosystems necessitates an efficient trading service for discovering and managing these devices. The Web of Things (WoT) offers a model for representing and discovering IoT devices, facilitating their integration and search. However, the WoT discovery model lacks the capability for query delegation, the process of forwarding queries to other connected services in distributed discovery systems, particularly in multi-dependent ecosystems, such as smart cities. In response to this gap, this paper presents WoTtrader, a new trading service for the WoT that enhances the discovery model with expanded recommendation features. This service enables the discovery of devices in environments where it coexists with other WoT discovery services developed by third parties. Compared to existing WoT discovery systems, WoTtrader supports multi-level query delegation across syntactic, semantic, and natural language searches, enabling broader device coverage, higher accuracy, proactive device discovery, adaptation of IoT devices to the WoT framework, and the integration with third-party services. The proposed trading service has been deployed and evaluated against other WoT discovery implementations. The results indicate that WoTtrader provides moderate response times while maintaining the highest accuracy when searching for devices across different nodes. Finally, the paper discusses the findings, limitations, and future directions to improve WoTtrader and enhance its adaptability within diverse WoT environments. • A faceted trading service for the Web of Things that extends the World Wide Web recommendation. • Supports syntactic, semantic, and natural language searching. • Nodes can be connected between them or to third-party nodes to make up a federation. • Third-party semantic queries can make use of query delegation.