WOTS2E: A search engine for a Semantic Web of Things

A Semantic Web of Things (SWoT) brings together the Semantic Web and the Web of Things (WoT), associating semantically annotated information to web-enabled physical devices, services and their data, towards seamless data integration and better understanding of real-world information. A missing element in order to realize SWoT is a standardized, scalable and flexible way to globally discover in (near) real time web-connected embedded devices, as well as their semantic data. To address this gap, we propose WOT Semantic Search Engine (WOTS2E), which is a search engine for the SWoT, based on web crawling, being able to discover Linked Data endpoints and, through them, WoT-enabled devices and their services. In this paper, we describe the design, development and implementation of WOTS2E, as well as an evaluation procedure showing its operation and performance across the web.

I. Introduction

While the Internet of Things (IoT) [1] enables communication between heterogeneous devices at the network layer, the Web of Things (WoT) [2]–[4] envisions interoperability at the application layer, by reusing well-accepted and understood web standards. By using web technologies, protocols, description languages and formats such as REST, XML, JSON, MQTT, XMPP, Atom, WADL, OpenID and OAuth, the WoT has contributed in reducing the barriers for common understanding and smooth interplay among heterogeneous realworld devices, services and data. Although services offered by WoT devices can be described by using the REST architectural style [5], [6] (or WS-* services in some cases), microformats¹

Microformats. http:///microformats.org/

and description languages such as SensorML²

SensorML. http://www.opengeospatial.org/standards/sensorml

, WADL³

WADL. https://www.w3.org/Submission/wadl/

and WSDL⁴

WSDL. https://www.w3.org/TR/wsdl

, still the data provided by the WoT require some annotations to understand its semantics.