Figure 9.12: Netflix is a multi-channel service
However, many IoT services run on a mix of devices with different
capabilities. Service functionality and user interactions will be distributed
across different devices. Some functionality may be exclusive to a specific
device. For example, in the Withings ecosystem, only the scale can measure
body mass and only the blood pressure monitor can measure blood pressure.
Some devices may be custom designed for the service. We’ve seen many
examples of these already throughout the book, from connected door locks to
smart watches and thermostats.
For reasons of cost, or practicality, these may have limited inputs and outputs
that are quite different from a conventional ‘computer’ UI. A door lock may
have a keypad and handle and perhaps an LED to show whether it is connected
or not. It probably doesn’t have a screen. In these systems, we have to figure
out which device handles which functionality. Each device (and the internet
service itself) may have a different role in terms of providing user interactions,
connectivity, information gathering, processing or display. In the terminology
of Wäljas et al. this is a cross-media system (figure 9.13 is an example).
Figure 9.13: Withings is a cross-media ecosystem
For example, a heating service as shown in figure 9.14 below may comprise: