This paper presents a decentralized Web-based architecture designed to support the development of distributed, dynamic, context-aware and interoperable services and applications. The architecture enables the detection and notification of changes over the Web of Data by means of a content-based publish-subscribe mechanism where the W3C SPARQL 1.1 Update and Query languages are fully supported and used respectively by publishers and subscribers. The architecture is built on top of the W3C SPARQL 1.1 Protocol and introduces the SPARQL 1.1 Secure Event protocol and the SPARQL 1.1 Subscribe Language as a means for conveying and expressing subscription requests and notifications. The reference implementation of the architecture offers to developers a design pattern for a modular, scalable and effective application development.

The Web of Things (WoT) has recently appeared as the latest evolution of the Internet of Things and, as the name suggests, requires that devices interoperate through the Internet using Web protocols and standards. Currently only a few theoretical approaches have been presented by researchers and industry, to fight the fragmentation of the IoT world through the adoption of semantics. This further evolution is known as Semantic Web of Things and relies on a WoT implementation crafted on the technologies proposed by the Semantic Web stack. This paper presents a working implementation of the Web of Things declined in its Semantic flavour through the adoption of a shared ontology for describing devices. In addition to that, the ontology includes patterns for dynamic interactions between devices, and therefore we define it as dynamic ontology. A practical example will give a proof of concept and overall evaluation, showing how the dynamic setup proposed can foster interoperability at information level allowing on one hand smart discovery, enabling on the other hand orchestration and automatic interaction through the semantic information available.

The smart grid is concerned with energy efficiency and with the environment, being a countermeasure against the territory devastations that may originate by the fossil fuel mining industry feeding the conventional power grids. This paper deals with the integration between the electromobility and the urban power distribution network in a smart grid framework, i.e., a multi-stakeholder and multi-Internet ecosystem (Internet of Information, Internet of Energy, and Internet of Things) with edge computing capabilities supported by cloud-level services and with clean mapping between the logical and physical entities involved and their stakeholders. In particular, this paper presents some of the results obtained by us in several European projects that refer to the development of a traffic and power network co-simulation tool for electro mobility planning, platforms for recharging services, and communication and service management architectures supporting interoperability and other qualities required for the implementation of the smart grid framework. For each contribution, this paper describes the inter-disciplinary characteristics of the proposed approaches.

The impact of IoT might significantly be increased by autonomous nodes with both sensing and actuating capabilities. This article describes the project of a wireless sensor and actuator network (WSAN) made up of autonomous nodes. Both the sensing and actuating nodes sense and communicate the temperature through the DASH7 coordinator. In addition the actuating node drives a motor to tune a valve controlling a radiator. Connectivity is provided by the above-mentioned low power protocol DASH7 running over a subGHz radio network. Nodes are powered by harvesters. The WSAN is intended to be a nearly unobtrusive component of a smart environment addressable by a gateway with edge-computing capabilities. Monitoring and actuating features are exposed by the network and are available to remote mobile clients. Thus an Internet of Things scenario is implemented with autonomous components, a gateway and a user friendly interface built on a simple Android application. The paper sketches the proposed architecture and is focused on the first node prototypes, their design challenges and preliminary measured performance. Requirements for self-sustainability and trade offs between service responsiveness and availability are discussed.

This article presents Tarsier, a tool for the interactive 3D visualization of RDF graphs. Tarsier is mainly intended to support teachers introducing students to Semantic Web data representation formalisms and developers in the debugging of applications based on Semantic Web knowledge bases. The tool proposes the metaphor of semantic planes as a way to visualize an RDF graph. A semantic plane contains all the RDF terms sharing a common concept; it can be created, and further split into several planes, through a set of UI controls or through SPARQL 1.1 queries, with the full support of OWL and RDFS. Thanks to the 3D visualization, links between semantic planes can be highlighted and the user can navigate within the 3D scene to find the better perspective to analyze data. Data can be gathered from generic SPARQL 1.1 protocol services. We believe that Tarsier will enhance the human friendliness of semantic technologies by: (1) helping newcomers assimilate new data representation formats; and (2) increasing the capabilities of inspection to detect relevant situations even in complex RDF graphs.

Interoperability among heterogeneous devices is one of the main topics investigated nowadays to realize the Ubiquitous Computing vision. Smart-M3 is a software architecture born to provide interoperability through the Semantic Web technologies and reactivity thanks to the publish-subscribe paradigm. In this paper we present a new implementation in Python of the central component of the Smart-M3 architecture: the Semantic Information Broker (SIB). The new component, named pySIB, has been specifically designed for embedded or resource constrained devices. pySIB represents a new open source lightweight and portable SIB implementation, but also introduces new features and interesting performances. JSON has been introduced as the default information encoding notation as it offers the flexibility of XML with minor bandwidth requirements. Memory allocation on disk and at runtime is in the order of Kilobytes i.e. minimal, if compared with the other reference implementations. Performance tests on existing (SP²B) and ad-hoc benchmarks point out possible improvements but also encouraging data such as the best insertion time among the existing SIB implementations.