Artifact: Viewpoints List
A list of all the relevant viewpoints reflecting the concerns of the main stakeholders.
Domains: Systems Requirements
Purpose
To capture all the viewpoints reflecting the concerns of the system's stakeholders and drive the architectural views that need to be developed.
Relationships
Description
Main Description

A viewpoint (on a system) is "a form of abstraction achieved using a selected set of architectural concepts and structuring rules, in order to focus on particular concerns within a system" [ISO/IEC 10746-2: Information Technology - Open Distributed Processing - Reference Model: Foundations]. The table lists some of the viewpoints chosen to capture the various concerns. These viewpoints are aligned with those found in ISO/IEC 10746-1: Information technology - Open Distributed Processing - Reference Model: Overview.

Viewpoint Concern Impact
Worker Concerned with the roles and responsibilities of the organization and system workers (and the policies affecting these). Worker activities, human/system interaction. Human performance specification and human factors.
Information The kinds of information handled by the system and constraints on the use and interpretation of that information. Information integrity, capacity limitations.
Information accessibility, timeliness.
Logical The decomposition of the system into a set of subsystems that interact at interfaces, collaborating to provide the system services. System exhibits desired behavior.
System is extendible, adaptable, maintainable.
Assets are reusable.
Distribution/Physical The infrastructure required to support system functionality and distribution. Adequacy of physical characteristics of system to host functionality and meet non-functional requirements.
Process Concurrency, scalability, performance, throughput, reliability. Adequacy of system responsiveness, throughput, fault-tolerance.

Common System Viewpoints.

These viewpoints are some of the most common for software-intensive systems. Many system architectures also require additional, domain-specific viewpoints. Examples include safety, security, and mechanical viewpoints. Viewpoints represent different areas of concern that must be addressed in the system architecture and design. If there are system stakeholders or experts whose concerns are important to the overall architecture, there is likely to be a need for a set of viewpoint work products to capture their design decisions. 

It is important to build a system architecture team with staff who are competent to look after the various viewpoints. The team might consist of business analysts and users who take primary responsibility for the worker viewpoint, software architects who attend to the logical viewpoint, and engineers who concern themselves with the physical viewpoint, as well as experts on domain-specific viewpoints.

Tailoring
Impact of not havingWithout this artifact, the needs of some stakeholders might be overlooked or not properly expressed in the overall system architecture.
Representation OptionsThe viewpoints with their associated stakeholders' concerns could be captured in a document or a spreadsheet, or in some cases in a modeling tool.