Views and Viewpoints

• View: A representation of a whole system from the perspective of a related set of concerns. Views are modular allowing a view to utilize multiple notations and a model may be shared between multiple views.
• Viewpoints: Each view corresponds to only one viewpoint. Viewpoints define resources and rules for constructing views.

View is

• What you see
• System/model specific

Viewpoint is

• Where you look from
• System/model generic. Therefore it is proposed that there is a library of viewpoints

The model of a system is often rich in information and addresses concerns from a wide range of stakeholders. To reduce perceived complexity, separate the concerns into different views. Views and Viewpoints provide a 'window' into the model that allows the viewer to obtain the information that they need.

Each view addresses one or more concerns of the stakeholders. If a view does not answer some stakeholder concerns then do not create view.

Each architectural viewpoint is determined by:

1. Create a Viewpoint
   1. Viewpoint name
   2. Stakeholders addressed by the viewpoint
   3. Architectural concerns “framed” by the viewpoint
   4. Method used to construct, illustrate and analyze resulting view
   5. Source (if any) of the viewpoint
   6. (optional) Consistency or completeness checks associated with underlying method to be applied
   7. (optional) Evaluation or analysis techniques to be applied
   8. (optional) Heuristics, patters or guidelines which aid the synthesis of an associated view
2. Create a View
3. Apply a Conform edge from View to Viewpoint (edge is now replaced with a solid line with an empty arrow, similar to the Generalization edge)
4. Apply a Expose edge from View to element that the View exposes (e.g. “Requirements” package)

• Architectural Description (AD): Collection of products to document an architecture. AD addresses all identified stakeholders' concerns. Includes at least,
  • Identification of stakeholders and concerns
  • Selection and declaration of the viewpoints used
  • Views, each conforming to a viewpoint
  • Any known inconsistencies
  • Architectural rationale
• Stakeholder: Individual, team or organization with interests in, or concerns relative to, a system
• Concerns: Those stakeholders' interests which pertain to the development, operation, or other key characteristics of the system