System Description: Background

The concept of a system has been around for a long time. There have been many approaches to understand and describe systems. Today, there are many approaches and some fragmentation in approaches.

Though I have been architecting systems for many years, in 2011, I thought I would take a more formal approach and was pointed to the international standard ISO 42010. I started using this standard and started to see the value of views of a system. After a number of years using this standard, I then came across the 'Framework for Architecture Frameworks (FAF)' which has into the COMPASS Architectural Framework Framework (CAFF). This provides the process to design an architecture description framework and is a good example of using the architecture description standard.

The CAFF includes one important view called the Ontology Definition View. This requires that any architecture description framework be based upon a set of concepts that form the ontology of the system-of-interest for the architecture description framework. This is a very powerful concept especially when seen to constrain any concepts included in the architecture description framework to be included in the ontology.

After using the CAFF on a number of systems, I realized that the concept of a system could be used as the system-of-interest. This provided the basis for the conceptual models for the system and system-of-interest used in this system description.

I then realized that the views that were emerging in this 'system architecture description framework' provided a possible way to integrate the number of different approaches to system and system thinking. The key elements that emerge in the views are:

• Structural View: the parts and their relationships

• Behavioral View: The system dynamics

• System Properties View: The emergent properties created through the interaction of the parts.

In this exercise, I also realized that there were different words used to describe the same views in the living systems area vs the system engineering area. For example:

• The phrase 'pattern of organization' is similar to 'structure'

• The phrase 'structural changes is similar to 'behavior

The system description concepts have also been used to describe living systems. After using the system description for a number of living systems, the concept of cognition and shared knowledge of both a thing and a system became very visible. The system concepts section in this system description highlight bring attention to the role a person plays in understanding the concept of a thing and the thing as a system. As a result, there can be many approaches to describe a thing as a system. All of these are from different stakeholder perspectives.

After going through this process, I also realized that the basic structure of UML can be used to describe or model any system. As a result many of the methods and tools that are used in systems engineering and systems thinking can be mapped onto these views. For example, systems dynamics and causal loop diagrams (CLD) can be used to support the dynamic perspective.

This system description structure is based upon the 'System Description Architecture Description Framework. Each section of a system description is a view based upon this architecture description framework. In this way a system description is a system architecture description.