View: Ontology Definition

Answers the question: What domain concepts must the AF support?

This view identifies the concepts that are to be used within the System Description Architecture Description Framework These concepts are the underlying conceptual models for the System-of-Interest situated in its environment.

System Element Definition Assumptions

There are a number of terms that are used across the various definitions for system. The following model describes the current mapping of terminology onto a simpler model consisting of: Suprasystem, system and subsystem allong with System-of-Interest. This consolidation of definitions allows simplification of the system model and the set of systems used to describe the various categories using Category Theory.

The following model contains the current terminology used in the model and the various mappings to the simpler structure.

System Element Definition: System Element now using Subsystem

Note: System Element has been replaced by "Subsystem" and is no longer used in the System Model. Environment (Context) has been replaced by "Suprasystem" and is no longer used in the system model. Environment (Context) continues to be the name of the viewpoint as the environment can include 1 or more Suprasystems.

This set of concepts is also called a 'concept model' or 'meta model'. This approach to the ontology focuses on whole systems. The following types of classes and models are defined in this section:

  • Abstract (or Conceptual) Class
    • System (as an abstract class)
  • Concrete (or Physical) Class
    • System-of-Interest as a Concrete Class

Abstract System Conceptual Model used as the basis for the System Architecture Description Framework

Note: The "CT Element" Stereotype is a Category Theory Element based upon a model of a Category. These are part of a different Ontology and model and identify specific sets of information. These CT Elements are included in the viewpoint definition models.

This diagram provides more details on the system property section of the system conceptual model.

System Properties for System Conceptual Model

System-of-Interest Conceptual Model

The following highlights the relationship of the abstract system and the system of interest.

System-of-Interest Conceptual Model with relationship to System Description, Thing and Stakeholder with Notes

The System Conceptual Model includes the 'System' element as a UML Abstract Class where the class does not have any implementation or instances (See UML Definitions). The 'System-of-Interest' element, on the other hand, is a UML Concrete Class that can have implementation and instances and can be seen through the interests and concerns of the stakeholders of the system. The stakeholders capture their shared understanding of the system-of-interest using a System Description.

The System as an abstract class provides the root definitions for all subsequent System-of-Interest. The terminology and elements of a system are inherited by any system-of-interest.

The UML Generalization association is used to show the inheritance of these definitions in the system-of-interest or any further derived system definitions.

The system-of-Interest

"Thing" represents an "abstract class" representing a place holder for the specific thing that the stakeholders focus their attention and intention through the lens of a system. In this case, the system description provides a description of the "Thing as a System".

The 'System Class' element provides a way to associate a system to a system classification scheme. As an example, Peter Checkland has identified a system classification system that uses the following system classes:

  • Natural Systems
  • Designed Physical Systems
  • Designed Abstract Systems
  • Human Activity Systems
  • Transcendental Systems

The system classes provide a way to classify types of systems that can become a system-of-interest. Link to System Classifications

System Classification based upon Peter Checkland's Model

System-of-Interest situated in its environment

Concepts and Terminology

The concepts and terminology for the System situated in its environment describe an abstract system that can be used to describe any system-of-interest. These concepts and terminology are used in the design of the System Description Architecture Description Framework that can be used to create a System Description of a system-of-interest.