ChapTeR 1 ■ The InTeRneT Of ThIngs and daTa
Chirp is simply the name of a small packet of data that contains only the minimal information needed
to convey the data to its destination. This fits the small overhead requirement for lighter protocols and also
permits for occasional loss of a packet. At the lowest point in the IOT solution, devices use protocols that
support chirps to be sent to nodes that can monitor the data and take appropriate action. For example, the
node may be built to take 30 samples generated in a minute and average them over time (say every five
minutes) to generate a smoother data sample. I’ve seen this technique employed for solutions that used less
accurate sensors where spikes (high or low) beyond a threshold were not used, thus allowing for a smoother
reading from the sensor at a slower rate. It is less data but potentially more accurate.
Thus, the IOT solution would be built with several layers. At the lowest layers, IOT devices are
networked to nodes that collect or process the data, which are then connected to devices that provide or
enable certain services. For example, an IOT camera could be connected to an intermediate node that takes
commands from a node at a higher layer. Similarly, a sensor network could be employed and monitored
using several data aggregation and data-processing nodes that send the data to a database, which is then
accessed by nodes in the higher layers. Figure 1-9 shows an example of this concept.
Figure 1-9. Concept of layered IOT solution
Notice at the top I’ve marked the layers behind the IOT service as private. This is to indicate that these
layers and the devices within them are not directly accessible from the Internet. That doesn’t cease to
make them IOT devices; on the contrary, it helps define an architecture for layering the solution to permit
optimization by using only the necessary protocols (and hardware needed for each layer). For instance, the
sophistication of the devices, security practices, and programming increases from left to right in the drawing.
For example, on the left side of Figure 1-9 is a set of sensors or lightweight IOT devices connected using
a ZigBee network. This could take the form of small devices employing XBee modules for sending data to the
next layer, which contains the data aggregation and database nodes. At this layer, you could employ a private
IPv4 Ethernet network. Why IPv4? Because most small devices like Arduino and Raspberry Pi support it