WoX: Model-Driven Development of Web of Things Applications

Nodes of the Internet of Things (IoT) are heterogeneous: Bluetooth Low Energy (BLE), Radio Frequency Identification (RFID), Near Field Communication (NFC), Wireless Sensors Networks (WSN), Konnex (KNX), just to name the most popular. IoT clients are heterogeneous too: mobile apps, laptops, enterprise applications, business processes instances, not to mention that even IoT nodes can be clients for other nodes. In this many-to-many relationship scenario, developing a seamless IoT system is arduous even for a specialized developer. All the more so, enable non-technical people to autonomously define innovative IoT-based scenarios is far from being trivial. This calls for the definition of a common design model shared by all the IoT stakeholder: device manufacturers, developers, stakeholders, business entities, end users. The Web of Things (WoT) paradigm has brought the IoT a step closer to the people perception, because it allows treating a networked thing as a Web resource. Nevertheless, sharing a common application layer protocol on top of the physical "things" does not guarantee that IoT application will be fast-developed, robust and easily evolvable. REST APIs definition for the IoT objects is left to the individual developer. Technological needs may vary along the application lifecycle. Stakeholders are often interested in virtual or aggregated environment features, rather than the single networked thing. To overcome these open issues, we think that it is needed an additional abstraction level between the WoT and the application layer. This should be model-driven - in order this to be adequately agreed by all the IoT stakeholders - and topic-based - because of the event-driven nature of the IoT. In this work we propose Web of Topics (WoX), a Cloud platform for the Internet of (every)Thing (IoE). WoX APIs allows companies and organisations to realise robust and high-maintainable IoT-based services, while minimising deployment costs and the time-to-market. Its model-driven approach guarantees a great end-user experience and a seamless integration among the heterogeneous IoT entities. In this book chapter we present the WoX model and the concrete architecture supporting it. As a proof of concept, in this work we also show how we implemented an original IoT scenarios using the WoX concepts, APIs and architecture: the airport short-stay parking service.