Internet of Things – Architecture © - 80 -
Flexibility.Cost reduction: In order to control the cost of a system, it is designed for a
maximum amount of users and/or use cases. ―A way for the designer to deal
with the requirements of multiple groups of users is to abstract from the
differences in [the] requirements and [to] parameterise the design‖[Pras
1995]. Upon commissioning or start-up of the system, these parameters will be
initialised by the Management FG.
Attending unexpected events: The IoT system is based on an incomplete
model of reality - as literally all system are. For example, even for the same
type of user, unforeseen activity patterns in the physical world and thus
unforeseen usage may arise may arise. For instance, errors are introduced into
the system through explicit, erroneous management directives (Harrisburg,
Chernobyl). Another example is that Devices can suddenly just die. The latter is
most likely to become prevalent in the IoT, since the cost margins for IoT
equipment and thus their reliability can be much lower than that for traditional
telecommunications equipment (back-bone routers, etc.). The management FG
can provide strategies and actions for the mitigation of impacts from unforeseen
situations. Such impacts can be link failure, queue overload, etc. In order to
better adapt to new situations, it is of course paramount that the Management
FG has a good overview of the system state. To that end the management
system provides supports collection.
Fault handling: This goal addresses the unpredictability of the future behaviour
of the system itself. This is of special interest in complex IoT systems and also
in IoT systems in which, for instance, the devices in an IoT system do not
provide a model for their behaviour. The measures implied by this goal are:
Prediction of potential failures; Detection of existing failures; Reduction of the effects of failures; Repair.The first three measures can be achieved by comparing the current behaviour
of system components with previous and/or expected behaviour.
Flexibility: The design of a system is based on use-case requirements.
However, these use-case requirements are not static. Instead of designing a
new system every time the requirements change, some flexibility should be built
into the system. Due to this flexibility, the Management FG of the IoT system
will be able to react to changes in the user requirements. This can take place
during boot up, commissioning or also at run time.