ChApTEr 3 ■ how IoT DATA Is sTorED
In addition to how to interpret the data, you should consider how the data flows through your network.
I like to make a drawing that shows where each type of data originates and how it moves through the
network. Figure 3-2 shows an example of a data flow chart. You can use any form you want—from a simple
list written in a log book to a graphical picture written in a structured design language like the Unified
Modeling Language (UML).^12
Figure 3-2. Data flow chart
This example is for a pond-monitoring system. I show the data collected in its original form and how
the data should be interpreted. This helps me design a database to store the data and decide where to place
any code or features that may be helpful interpreting the data.
For example, the water-level detection uses an audible tone generated on the Arduino that hosts the
sensor. This allows me to hear a warning when the water level drops (the sensor is triggered). Since I walk
by the pond every day on my way to and from work, it is a great example of using multiple cues for the user
interface. In this case, the user interface is a web page and the signal generator is on the Arduino.
(^12) http://uml.org