Things in the Internet of Things

Humans may soon not be the biggest contributors of online digital information any more. This trend is confirmed with a growing number of IoT devices (the predictions of over 50 billion connected devices by 2020 [1, 22]). Nevertheless,

this number of connected devices brings only a vision of changes to come without a more precise definition of “Things”. The heterogeneity of devices and technologies requires the agreement of a common definition. Different objects (e.g. books, houses, vehicles, etc.) are connected to the Internet using different communication protocols. The question is what are the Things in the Internet of Things? In order to give our definition of Things, let us briefly review the origin and technologies used to connect objects to the Internet. This analysis of design architectures of connecting technologies will allow identifying the properties that are common to physical objects and their virtual counterparts. Based on the common properties we will define the term Things within our framework.

The idea of embedding the computation power and micro computers into mundane objects roots back from the Ubiquitous Computing vision [73] also called Invisible Computing [18]. It introduced a vision of machines like light switches, thermostats, stereos, and ovens having embedded computers interconnected over a ubiquitous network. Following this vision, a research stream developed an entire domain of “Smart Technology”. With embedded computers, our surrounding objects and home appliances are becoming

“smarter” and interconnected. From this vision emerged more or less simple or complex devices and systems, from simple sensors to buildings and vehicles (e.g. Smart Sensors, Smart Cards, Smart Grid, Smart Homes, and Smart Cars).Consequently, these devices have embedded computing power and “self”

connectivity. Smart devices often embed wireless or wired connectivity hardware that enable their interconnection. Nowadays, it is common to find the Smart Sensors designed as groups of short distance interconnected devices with one base hub or router proxying them to the online services through the Internet.

Embedded computers are nowadays also accessible to IoT users and empower them to build smart devices in the “do it yourself” way. Open hardware platforms allow hobbyists to build their own or to hack existing home appliances with embedded Internet connectivity [74, 75]. Using these technologies devices can autonomously send digital information to the Internet, they can be controlled remotely, and they can also use online services and react autonomously.

The term “Internet of Things” has been coined with the emergence and especially with the decreasing cost of automatic identification technologies [2].

Simple identification tags attached to any objects are used to identify objects and automatically fetch the associated digital information from the Internet. The automatic identification process can be summarized as follow:

• An active or passive tag (e.g. RFID or NFC) is attached to an industrial product in the factory. Tags most often contain only a unique identifier for the product.

• Unique identifiers on the tags can afterwards be read anywhere but only in short range by tag reader devices.

• Tag readers send product unique identifiers to online repositories.

• Online repositories contain databases associating URIs to unique identifiers.

• When unique identifiers are provided, the repositories answer with the associated URIs.

• Tag readers receive the URIs and can use them to access online digital information about products.

Automatic identification technologies do not envision embedding computers in mundane objects. Instead, objects are most of the time “read only”, hence enabling them to have an online digital identity. Tagged object like books, clothes, and food cannot react autonomously to changes in the environment nor can they be controlled remotely through the Internet. Research on automatic identification technology is predominantly focused on building infrastructures for the management of product data available during the whole products lifecycle:

from raw materials to disposal [16].

Automatic identification technologies are crossing the boundaries of industrial sector and coming to our everyday lives [76]. In the IoT, object identification technologies will be embedded in objects without computation power that are in our homes (e.g. food, furniture) or public places (e.g. monuments). Currently,

“manual” identification technologies are already widespread (e.g. bar codes or QR codes) and automatic identification are intended to replace them (e.g. RFID or NFC).

From a high level, the common point between Smart Devices (Ubiquitous Computing) and any other identifiable objects is that both categories have their online digital counterparts. Therefore, we define Things as:

Thing in the IoT are Smart Devices or identifiable objects with online digital information about their identity and state. Their online digital information is

accessible through Internet protocols.

The previous analysis and the above definition enable to define categories of Things. Two simple categories of Things according to the autonomy of their interaction with online digital information are observed:

1. Things with read-write capabilities. This is a category of Smart Devices that can read and write online digital information using Internet protocols.

2. Things with read-only capabilities. This is a category of identifiable objects that require some proxy devices in order to access online digital information.

This categorization highlights the characteristics of Things, which are important for our framework by clarifying their role with respect to People and Places. In our framework, Place Masters create Places and register People. They are also the actors that arrange physical space and real world objects that are used.

Consequently, the IoT service platforms should mimic real world roles and empower Place Masters to register Things (Figure 17).

Figure 17: People, Places, and Things