At first glance, the World Wide Web Consortium (W3C) and the Internet of Things are two different worlds. The consortium is considered the authority on web standards and ensures that anyone can find information on the World Wide Web regardless of their device, plan their next trip, or make a bank. Both the relatively simple development of the web and the so-called mix of services (mix), in order to integrate and provide various and partially external services such as road maps, weather data or translation services, work mostly smoothly. .

Web frameworks such as WordPress allow various services to be easily integrated into a web page (Fig. 1).

Precisely it is precisely this orchestration of services that is less banal on the Internet of Things. IoT devices provide data and services such as temperature sensor values ​​for turning on or off a lamp. Communication works smoothly when companies use all the equipment from one manufacturer and rely exclusively on its application or ecosystem. Composing cross-producer service is much more difficult. Devices potentially use different communication protocols such as MQTT, Modbus or CoAP. There are different approaches to data models and semantics for serialization, such as JSON, XML, TLV (Type Length Value) or CBOR (Concrete Representation of Binary Object). After all, security requirements differ from one another. Challenges exist not only in the smart home environment, but also for companies in large IoT applications such as construction and industrial automation, smart cities, and the automotive sector.

Since different data points and protocols come together during service orchestration in the IoT, it is usually impossible to reuse applications in projects (Fig. 2).

At this point, the W3C would like to close a gap with Web of Things (WoT) standardization activity. It is not about creating another IoT standard in the form of an additional protocol or data model, but rather providing tools or so-called technological modules in order to create a uniform level of abstraction for the heterogeneous IoT landscape. It is deliberately kept simple and offers the following three key elements:

  • Characteristics usually determine the values ​​of the sensor, status or parameter,
  • Actions represent functions with input and output values, for example starting an engine, moving a robot arm, or taking a picture,
  • Events usually design alarm signals or data streams.

The so-called Description of Things (TD), which designs properties, actions, and events, plays a central role. Similar to index.html on a web page, it provides the access point of an IoT device or service. A TD provides information about the data and functions provided, the type of data serialization, and the security mechanisms used to control access. In addition, there are other metadata that can be read by machines or humans. A TD is written in JSON-LD (JavaScript Object Notation for Linked Data) format. The IoT device can provide it directly, or the information is in a repository such as a TD directory.

Web-of-Thing modules provide uniform access: The paradigm of interaction of properties, actions and events provides an abstraction between IoT systems and applications (Fig. 3).

WoT is a protocol-independent approach and provides a uniform mechanism for mapping specific protocols such as MQTT, HTTP, CoAP or Modbus to the abstract elements Properties, Actions and Events. There are WoT binding models for mapping and protocol specific metadata. For example, a specific protocol template provides a guide on how a client can enable any WoT interaction abstraction for the protocol through a network-side interface.

The optional WoT-Scripting-API component defines an ECMAScript-API, which is based strictly on TD specifications, and uses WoT interaction abstraction. Defines the interface between conducting behavior and a script-based WoT execution. Application is not limited to scripting environments: Java or C / C ++ programming language APIs can be derived from the WoT scripting API.

In addition, the Network of Things deals with topics such as detection and various aspects of security and privacy.