Build variation points into the software, Use standard extension
points: By using standardised protocols and gateways, even legacy
devices could be linked to IoT-A systems.Design Choices for Interoperability and Evolution cannot be named on this
(application and domain independent) level. The IoT Reference Model and
Reference Architecture are built with interoperability and evolution as the main
drivers. To allow a system to evolve and to react to new technology and new
requirements the following general remarks should be kept in mind:
The IoT-A Reference Architecture is built out of modular blocks to allow
changes and additions. When deriving the IoT-A work to a concrete
architecture, this modularity and also the loose coupling between those
blocks should be kept. This concept is also used in the ̳Dispatcher‘
component [Hyttinen 2013] for the standardized processing of
incoming requests without exposing the internal methods and functions; Not all of the systems functionality can be defined in advance. Therefore,
some additional spaces and extensions points, e.g. for upcoming
functionality, should be reserved. This can for example be done in
interface definitions or data models, like the reserved bits in the TCP
header definition. This allows the designers and architects to update the
system and to adapt it to new requirements.The tactics not considered as relevant are listed in Table 19 ..
Tactic Reason
Contain change Not possible for public IoT-systems, new devices will participate in
the systems.
Achieve reliable change Same as above
Preserve development
environments
Due to the multiplicity of developers and technology providers, a
common development environment will not exist.
Table 19 : Tactics identified as not relevant for evolution and interoperability in IoT
Systems.5.2.10.3 Design Choices addressing performance and scalability
Performance and scalability are closely related. In the Internet of Things, with its
anticipated billion or trillion nodes both performance and scalability will play a
crucial role. In Section 4.3.1, the Performance and Scalability Perspective
together with a set of tactics are presented. In the following we applied the
tactics from the Performance and Scalability Perspective to our Design Choices.
We furthermore evaluated their expected impact on the Functional, Information,
and Deployment and Operation Views.
Desired Quality The ability of the system to predictably execute within
its mandated performance profile and to handle
increased processing volumes in the future if required