Fig 4.16: FedEx Senseaware sensor and web app
It goes almost without saying that your system needs to be reliable enough to
fulfill its promise. Glitches and outages are inevitable in most systems and
early adopters will forgive these more readily. But if there are contexts of use
in which you cannot afford failure, the product must be 100% reliable. For
example, emergency alarms for elderly or vulnerable people must always
work. You’ll need a backup power supply and connectivity (see figure 4.17),
and regular checks to ensure these work.