Introduction
This collection of chapters examines one of most important new waves in computing: the Internet of Things (IoT)! Capturing the essence of the IoT in one sentence is nearly impossible. It has become such a hot topic that there are no clear boundaries between what the IoT is and what it isn’t. Broadly speaking, the IoT vision is of a world where the internet is much more than the bunch of multimedia content it is today— where it extends into the physical, real-time world using a myriad of tiny computers. The simplest definition we can offer is the following: The Internet of Things is a system of physical objects that can be discovered, monitored, controlled, or interacted with by electronic devices that communicate over various networking interfaces and eventually can be connected to the wider internet.
The concept has been around since 1999, but the IoT has not yet truly material-ized. Yes, we have smart devices in our homes that can be controlled via mobile phones. We have smart thermostats that are aware of our location. We have smart scales that can help us manage our weight and fitness trackers that motivate us to move. Yet, all these devices largely exist in isolation. To put it bluntly, the Internet of Things of today is essentially a growing collection of isolated Intranets of Things that can’t be connected to each other. No need to worry too much—the internet itself went through a similar phase. It started as a network of computers that used multiple incompatible protocols to communicate with one another. It formed a network of connected computers, but without standard ways of building applications on top of this network the use of the internet was rather limited! Then came the web: a simple and universal application. The web allowed the internet to evolve from a network of computers exchanging bits of data to a world-wide service platform accessible through standard and universally understood protocols such as HTTP. Similarly, the Internet of Things desperately needs its own application layer to truly blossom. Just like the internet needed the web, the IoT needs a set of standards that applications can use to control, monitor, and aggregate the data of connected things; otherwise it is likely to remain an Intranet of isolated Things! We could reinvent the wheel once more, but because the web proved to be the most scalable, flexible, and versatile application layer out there, why shouldn’t we reuse it for the IoT? This is what we call the Web of Things!
The concept of the Web of Things (WoT) is fairly straightforward: it explores how we can re-use the goodness of the web to make these tiny computers talk together and push their data to places where it can be leveraged to build truly ground-breaking applications! To better grasp the different technologies that can be involved in making the IoT an integral part of the web, in our book Building the Web of Things, we create four layers for the WoT architecture: Access, Find, Share & Secure, and Compose (see figure 1). Each layer solves a set of problems using web technologies for the layer above it. For example, the Access layer is all about creating web APIs for Things, while the Find layer assumes these APIs exist and deals with making them discoverable and findable on the web.
Figure 1 The Web of Things architecture stack with its 4 layers.
This architecture probably makes Building the Web of Things the first comprehensive toolbox for building the WoT. However, each layer could entail an entire book of its own! That's what this collection of chapters is all about. We've borrowed chapters from other great Manning books that are spot-on when it comes to illustrating our WoT architecture and building the application layer of the IoT!
A chapter from Streaming Data: Designing the real-time pipeline by Andrew G. Psaltis builds on the Access layer by looking into data collection, patterns, and protecting from data loss.
Linked Data: Structured data on the Web by David Wood, Marsha Zaidman, Luke Ruth, and Michael Hausenblas takes you into the Find layer with an in-depth look at Resource Description Framework in Attributes.
In the Share layer, we delve into keeping code bug-free, dealing with attacks, and auditing code with a chapter from Express in Action: Node applications with Express and its companion tools by Evan M. Hahn.
The final layer, Compose, is illustrated with case study-like examples and in-depth visualizations from Real-World Machine Learning by Henrik Brink, Joseph W. Richards, and Mark Fetherolf, and from D3.js in Action by Elijah Meeks.