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Software Architecture Guide

Additional Architecture Viewpoints (Security, Information, Operational, Development, Process, Evolution)

Explanation

Section titled “Explanation”

Basic structural views do not answer every question. Some stakeholders ask how data is handled, how developers work, or how the system runs in production. Extra viewpoints give those questions a home.

The facts here come from the Rozanski & Woods set of viewpoints and from arc42, a documentation template. They describe these topics:

  • Information viewpoint. It describes how the architecture stores, manipulates, manages and distributes information.
  • Development viewpoint. It describes the architecture that supports the software development process.
  • Operational viewpoint. It describes how the system is operated, administered and supported once it runs in production.
  • Deployment viewpoint. It describes the environment the system is deployed into: hardware, network and runtime dependencies.
  • Security. Here it is a perspective, not a viewpoint. A perspective is a cross-cutting quality concern. Security is about reliably controlling, monitoring and auditing who can do what to which resources.
  • Evolution. This is also a perspective. It is about staying flexible as change arrives over the life of a system.

arc42 covers the deployment topic in its deployment view. This view documents the technical infrastructure that runs the system. arc42 says to document it especially when the software runs as a distributed system. Infrastructure can influence the system and its cross-cutting concepts, so the view is needed. See the articles on Deployment View and Crosscutting Concept.

To choose which extra views a project needs, start from the questions its stakeholders ask. Add a view only where a real concern has no home yet.

Example

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A team builds a booking service that runs on several servers. Operations staff ask who will run and support it in production, so the team adds an operational view. The security officer asks who may change a booking, so the team describes security as a perspective. The team skips other extra views because no stakeholder raised a matching concern.

Trade-offs

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Every extra view is more documentation to write and keep current. Adding views no stakeholder needs wastes effort. Leaving out a needed view hides decisions, for example about infrastructure in a distributed system.

Checks

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  • If the software runs as a distributed system, the document includes a deployment view of the technical infrastructure.
  • Security is described as a cross-cutting concern: who can do what to which resources, and how this is controlled, monitored and audited.
  • Operation, administration and support in production are described.
  • How information is stored, managed and distributed is described.
Section titled “Related”

Sources

Section titled “Sources”