Internet of Things Architecture

4.3 Perspectives

Architectural decisions often address concerns that are common to more than
one view, or even all of them. These concerns are often related to non-
functional or quality properties. We are following the approach of [Rozanski
2005], which suggests special perspectives to address these aspects of a
concrete architecture. They emphasize the importance of stakeholder
requirements just like we do within our project. Therefore we are adopting their
definition of perspective for usage within IoT-A:

An architectural perspective is a collection of activities, tactics, and guidelines
that are used to ensure that a system exhibits a particular set of related quality
properties that require consideration across a number of the system‘s
architectural views. [Rozanski 2005]

where a quality property is defined as:

A quality property is an externally visible, non-functional property of a system
such as performance, security, or scalability [Rozanski 2005]

The stakeholder requirements clearly show a need of addressing non-functional
requirements. Based on them, we identified the perspectives, which are most
important for IoT-systems:

 Evolution and Interoperability;

 Availability and Resilience;

 Trust, Security and Privacy and

 Performance and Scalability.

As these requirements are requiring some kind of quality for a real system, the
perspectives aim more at the concrete system architecture, than at a Reference
Architecture.

We got 18 requirements concerning the Evolution and Interoperability
perspective, 15 concerning Availability and Resilience, more than 20 related to
Trust, Security and Privacy, and 17 more related to Performance and
Scalability. As can be seen from the definition above there is a close
relationship between Perspectives, Views and Guidance.

We will generally follow the structure as suggested by Rozanski/Woods, to
describe the perspectives, but adjusted according to our needs. Each
perspective contains the following information:

Desired Quality The desired quality that the perspective is addressing

IoT-A Requirements The IoT-A requirements this perspective addresses