Take the example of a lighting system. The mental model of a lamp is simple:
it has power, a switch, a fitting and a bulb (see figure 9.6). If the lamp doesn’t
work it’s probably because the power has failed or the bulb has blown.
Figure 9.6: A conventional lamp has a simple conceptual model
A connected lighting system has bulbs, switches, fittings and power too
(typically either the bulbs or switches will be connected). It also has an
internet service, probably hosted remotely. It has a smartphone app and
perhaps a web app too. It probably also has a gateway device. It has more parts
(see figure 9.7) and more different kinds of part. It can also do more. It may
run automated rules to turn lights on and off at certain times, or when certain
trigger events happen (such as the security alarm being activated). The
in telligence that controls the system may live in several places: in the bulb or
switch itself, in the gateway, in the internet service, or even in the smartphone
app.