Tools, Languages, Methodologies for Representing Semantics on the Web of Things

With the proliferation of connected devices and the widespread adoption of the Web, ubiquitous computing success has recently been brought into the fashion of an emergent paradigm called the 'Web of Things', where Web-enabled objects are offered through interconnected smart spaces. While some predict a near future with billions of Web-enabled objects, the success of this vision now depends on the creation of efficient processes and the availability of tools enabling users or applications to find connected objects matching a set of requirements (and expectations). We present an on-going work that aims to develop a search process dedicated to the 'Web of Things' and that relies on three contributions. The creation and use of semantic profiles for connected objects, the establishment of similarities between semantic profiles of different connected objects to gather them into clusters and, the computation of a score associating a 'context of search' to an incoming request and enabling the selection of the most appropriate search algorithms, involving either probabilistic or precise reasoning.

The Web (and Internet) of Things has seen the rapid emergence of new protocols and standards, which provide for innovative models of interaction for applications. One such model fostered by the Web of Things (WoT) ecosystem is that of contactless interaction between devices. Near Field Communication (NFC) technology is one such enabler of contactless interactions. Contactless technology for the WoT requires all parties to agree one common definition and implementation and, in this paper, we propose a new lightweight architecture for the WoT, based on RESTful approaches. We show how the proposed architecture supports the concept of a mobile wallet, enabling users to make secure payments employing NFC technology with their mobile devices. In so doing, we argue that the vision of the WoT is brought a step closer to fruition.

The chaotic growth of the IoT determined a fragmented landscape with a huge number of devices, technologies, and platforms available on the market, and consequential issues of interoperability on many system deployments. The Web of Things (WoT) architecture recently proposed by the W3C consortium constitutes a novel solution to enable interoperability across IoT Platforms and application domains. At the same time, in order to see an effective improvement, a wide adoption of the W3C WoT solutions from the academic and industrial communities is required; this translates into the need of accurate and complete support tools to ease the deployment of W3C WoT applications, as well as reference guidelines about how to enable the WoT on top of existing IoT scenarios and how to deploy WoT scenarios from scratch. In this thesis, we bring three main contributions for filling such gap: (1) we introduce the WoT Store, a novel platform for managing and easing the deployment of Things and applications on the W3C WoT, and additional strategies for bringing old legacy IoT systems into the WoT. The WoT Store allows the dynamic discovery of the resources available in the environment, i.e. the Things, and to interact with each of them through a dashboard by visualizing their properties, executing commands, or observing the notifications produced. (2) We map three different IoT scenarios to WoT scenarios: a generic heterogeneous environmental monitoring scenario, a structural health monitoring scenario and an Industry4.0 scenario. (3) We make proposals to improve both the W3C standard and the node-wot software stack design: in the first case, new vocabularies are needed in order to handle particular protocols employed in industrial scenarios, while in the second case we present some contributions required for the dynamic instantiation and the migration of Web Things and WoT services in a cloud-to-edge continuum environment.

With the proliferation of connected devices and the widespread adoption of the Web, ubiquitous computing success has recently been brought into the fashion of an emergent paradigm called the 'Web of Things', where Web-enabled objects are offered through interconnected smart spaces. While some predict a near future with billions of Web-enabled objects, the success of this vision now depends on the creation of efficient processes and the availability of tools enabling users or applications to find connected objects matching a set of requirements (and expectations). We present an on-going work that aims to develop a search process dedicated to the 'Web of Things' and that relies on three contributions. Firstly, the creation and use of semantic profiles for connected objects. Secondly, the establishment of similarities between semantic profiles of different connected objects to gather them into clusters. Thirdly, the computation of a score associating a 'context of search' to an incoming request and enabling the selection of the most appropriate search algorithms, involving either probabilistic or precise reasoning.

Chapter 11 - Building Interoperable and Cross-Domain Semantic Web of Things Applications

Recently, Web of Things (WoT) expands its boundary to Cyber-physical Systems (CPS) that actuate or sense physical environments. However, there is no quantitative metric to measure the quality of physical effects generated by WoT services. Furthermore, there is no dynamic service selection algorithm that can be used to replace services with alternative ones to manage the quality of service provisioning. In this work, we study how to measure the effectiveness of delivering various types of WoT service effects to users, and develop a dynamic service handover algorithm using reinforcement learning to ensure the consistent provision of WoT services under dynamically changing conditions due to user mobility and changing availability of WoT media to deliver service effects. The preliminary results show that the simple distance-based metric is insufficient to select appropriate WoT services in terms of the effectiveness of delivering service effects to users, and the reinforcement-learning-based algorithm performs well with learning the optimal selection policy from simulated experiences in WoT environments.

WoT Store: Managing resources and applications on the web of things

The Web of Things (WoT) aspires to bring interoperability at the application layer, on top of the Internet of Things. Many state of the art platforms and frameworks claim to support the WoT, following its principles towards the seamless integration of heterogeneous physical devices and real-world services at the web. But do these platforms truly comply to the concepts of the WoT or only follow some of its characteristics? Do designers understand the WoT when claiming that their products follow the WoT specifications? This paper lists the main elements of the WoT, as defined by pioneering works in the field and examines 26 popular platforms and frameworks, aiming to shed light on how the WoT is understood and applied, both in academia and commerce.

A large amount of work is currently focusing on the development of standards for attaining interoperability in the Internet of Things (IoT). The numerous solutions and technologies reflect a fragmented landscape, in which the interoperability among heterogeneous and geographically distributed computer systems,́thingś and Information and Communication Technology (ICT) platforms remains unachieved. The Web of Things (WoT) initiative of the Web of Things Working Group aims at developing standards for the WoT to expose the potential of the IoT while addressing its current fragmentation, and encourage the growth of the market for the IoT devices and services. However, towards attaining seamless interoperability in the WoT, a challenging question is: Are standards sufficient to ensure interoperability in the WoT? Towards answering this research question, this article aims to identify existing WoT interoperability standardization initiatives and discuss the role and ability of standards to ensure interoperability in the WoT. Recommendations for moving forward towards attaining seamless interoperability in the WoT are advanced.

Several terms have been used to describe Internet of Things; Web of Things (WoT) is a term which can be used interchangeability and it is referred to as the capability of devices to interconnect to the World Wide Web and sharing the information and data to one another. WoT has been mentioned in the literature to improve interconnection between devices at all times. In WoT, two different modes of communication which are generally mentioned in previous studies include person-to-thing (or thing-to-person) and thing-to-thing. This paper presents an architecture for transiting from WoT to speech-enabled WoT known as Speech of Intelligent Things (SoIT). The system employs a combination of technologies such as system design, server-side scripting, speech-based system tools, and data management in developing the SoIT prototype system as a third mode of communication. This paper illustrates a scenario whereby remote monitoring and controlling of WoT devices within the university campus might be difficult to manage by only using the modes discussed in the literature. An evolution of WoT to SoIT was realized using speech technology to provide a prototype system. Technical implications involve using a telephone by connecting an object telephone number (OTN) and dial WoT objects and establish a control mechanism. The research limitation is mainly the cost of dialing an OTN number. The contribution of this paper is to favor and encourage the use of speech technology to enhance the convenience of communication between WoT devices within the school campus.

The IoT has primarily focused on establishing connectivity in a diversify of constrained networking environments, and the next logical aim is to build on top of network connectivity by focusing on the application layer. In the Web of Things (WoT), we are thinking about smart as first-class citizens of the Web. We position the Web of Things as a purification of the Internet of Things by integrating smart not only into the Internet, for instance, the network, but into the Web (the application layer). The Web of Things is a computing concept that describes a future where day-to-day objects are fully integrated with the Web. The WoT is very homogeneous to the IoT in some ways and in others it is drastically different. The stipulation for WoT is for the things to have embedded computer systems that enable communication with the Web. This type of smart devices would then be able to communicate with each other using current Web standards. For instance, renowned Web languages PHP, HTML, Python, and JavaScript can be used to easily build applications involving smart and users can leverage well-known Web mechanisms such as caching, browsing, searching, and bookmarking to communicate and share these devices. In this paper, aim to demonstrate a close-up view about Web of Things, including Web of architecture, Open platform in Web of Thing, Web-enabling devices, Web of Thing security, use cases of Web of Things. The WoT concept, smart things, and their services are fully integrated into the Web by reusing and conforming technologies and patterns commonly used for conventional Web content.

With the rapid advances in sensor data collection and communication, heterogeneous and real-time IOT data is increasing rapidly. To make full use of the information, lots of web technologies are introduced to integrate the IOT world and Web world into an unified Web of Things(WOT). While most of the existing efforts are mainly focused on the modeling, annotation, and representation of WOT data, there has been little work focusing on the background processing of large-scale streaming WOT data. In the paper, we present a general semantic processing framework and implement an elastic streaming engine for WOT applications. The proposed engine efficiently capture and model different scenarios for all kinds of WOT applications based on popular large-scale distributed computing platform SPARK. Based on the engine, a typical use case on home environment monitoring is given to illustrate the efficiency of our engine. The results show that our system can scale for large number of sensor streams with different types of WOT applications.

<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> Internet of Things (IoT) applications have been traditionally programmed using predefined device-level frameworks, tightly coupling software with the underlying hardware. The Web of Things (WoT) on the other hand abstracts interfacing with devices through the WoT Thing Description (TD) standard, allowing to program applications for Systems of Things, referred to as Mashups. In addition to the benefit of being programmed in high-level languages, WoT Mashups can be ported into serialization formats such as the WoT System Description (SD) for better insight and verification of the Mashup. Although WoT readily facilitates the development of WoT Mashups, it lacks a sound mechanism for remote deployment, management, and monitoring of such. In this paper, we propose a method and its corresponding open-source implementation, the WoT Runtime Framework, to close the development cycle of WoT Mashups. It allows users to deploy WoT Mashups either as code or in System Description format, manage their life cycle, verify the correct functionality and monitor both runtime and Mashup-specific information. The evaluation proves inter-runtime communication between multiple instances of the WoT Runtime is possible, and demonstrates this with examples from the industrial automation and smart agriculture domains.

The current state of the technologies related to the Web of Things (WoT) and the Internet of Things (IoT) fosters the creation of service directories gathering resource descriptions. These directories are aimed at enabling the service discovery and supporting providers and consumers with a shared element for their communication and interoperability between the involved agents. This interoperability can be ensured by using the abstract layer of the W3C WoT recommendations. However, many of the existing approaches do not include a service discovery mechanism and those that include a WoT directory lack certain functionalities required by distributed systems specific to the WoT such as a Service-Oriented Architecture (SOA). This paper proposes a federated service discovery approach to support the management of WoT applications which ensures that the integration of the whole system components can be addressed by following a SOA. It is aimed at providing query and storage functionality for WoT resources, but also is intended to be connected to other WoT directories by applying a customizable approach based on recommender systems. Thus, we guarantee a flexible mechanism to obtain sets of ranked WoT resources to be utilized in different kinds of applications and domains.

Chapter 2 - The Anatomy of An Intent Based Search and Crawler Engine for the Web of Things