[Miller 2003], Pattern-Based Design [Gamma 1994], and the Spiral Model
[Boehm 1988].
The only limitation we see is the choice of our views. Some architectural
methodologies prescribe different sets of views. Some of them, for instance the
―4+1‖ approach, lack some of the views we prescribe (mainly information and
context view) [Kruchten 1994]. In this case one could choose to embed the
―4+1‖ framework into the process described in this section. Other
methodologies though comprise views that are not part of the IoT ARM set. In
this case the option is to integrate the IoT ARM views (and how they are
derived) into this other methodology.
5.2.4 IoT architecture generation and related activities
Since neither the IoT Context View nor the Physical-Entity View are addressed
in the IoT Reference Architecture (see Chapter 4 ), and since they are integral
parts in the architecting process (Figure 66 ), we need to have a closer look at
both of them, and we need to understand how they inform the architecting
process.
5.2.4.1 Physical-Entity View
Before we describe the Physical-Entity View we need to discuss what it is not:
the ―traditional‖ physical view in system architecting. The latter architecture view
is a well-established view in software-system architectures (see, for instance,
[Kruchten 1994]). ―It is concerned with the topology of software components
on the physical layer, as well as the physical connections between these
components. This view is also known as the deployment view‖ [Wikipedia
2013a]. As can be inferred from Figure 65 , we are using the term deployment
view instead of physical view in order to avoid confusion with the Physical-Entity
View
The Physical-Entity View does of course refer to the Physical Entity in the IoT
Domain Model (see Section 3.3.2 and Section 5.4.1). The Physical Entity is
―any physical object that is relevant from a user or application perspective‖
(Appendix B). For a concrete use case and application scenario this is of course
a well-defined set of physical objects. For instance, in the recurring example
(see Section 2.3), the Physical Entities are the orchids that are transported in a
truck and these orchids are subject to environmental monitoring.
It is obvious that for many reasons why the architecture of an IoT system also
needs to include a Physical-Entity View:
First, the dimensions, the distribution, and the properties of the Physical Entities
have various implications. Examples for these implications are:
Devices: what sensors/actuators are needed and where are they
situated; what is their relationship to the Physical Entity (directly
mounted; touching; remote but in sight, etc.), etc. Notice that the device
choice is influenced the Physical Entity. In the recurring example, it is too