# Architecture View Model **In short:** An architecture view model is a ready-made set of viewpoints that fit together to describe a system. Reusing one, such as 4+1, avoids inventing views and avoids one overloaded model. ## Explanation A complex system cannot be captured in one model. Rozanski and Woods warn against a single, overloaded, all-encompassing model. They split the architecture description into separate but related views. Each view describes one aspect of the architecture. A **viewpoint** is a collection of patterns, templates and conventions for building one type of view. (See *Architecture Viewpoint* and *Architecture View*.) A **view model** is a set of viewpoints chosen to work together, so architects can reuse it instead of inventing their own. The IEEE standard does not prescribe a fixed set of views. Rozanski and Woods therefore offer a catalog of core viewpoints. (See *ISO/IEC/IEEE 42010 Architecture Description Standard*.) **Kruchten's 4+1 model** was introduced in a 1995 IEEE Software article, "Architectural Blueprints". It describes software-intensive systems through multiple concurrent views: - The **logical view** covers the functionality offered to end users. - The **development view**, also called the implementation view, shows the system from a programmer's perspective. - The **physical view**, also called the deployment view, shows the system from a system engineer's perspective. - The **+1** is a small set of scenarios (use cases). They illustrate the architecture and form a fifth view. (See *4+1 View Model* for the full model.) **RM-ODP** defines five complementary viewpoints. The enterprise viewpoint covers purpose, scope and policies. The information viewpoint covers what the information means and how it is processed. The technology viewpoint covers the technology choices made for the system. The **Zachman Framework** is a matrix. Its columns are communication interrogatives and its rows are reification transformations. (See *Zachman Framework*.) Other approaches are related but differ in kind. **C4** is a diagramming approach with hierarchical diagrams: context, containers, components and code. It does not depend on a notation, and it is not a formal view model. **arc42** has a building block view that shows the static decomposition. It is mandatory in every architecture documentation. Runtime views and crosscutting concepts complement it. ## Example A team building an online shop adopts a 4+1-style set of views. One view lists the features customers use. Another shows how developers organize the code. A third shows the servers the shop runs on. A few scenarios, such as "customer places an order", tie the views together. When a reviewer asks "where do we describe hosting?", the answer is already in the set. ## Trade-offs A view model gives you proven viewpoints, so you do not start from a blank page. A single overloaded model is the risk it helps you avoid. Several views also mean more documents to keep consistent. Models differ in kind: C4 is a diagramming approach, not a formal view model, and arc42 pairs a mandatory building block view with other views. The facts here do not say which model is best, so pick one that fits your system and stakeholders. ## Checks - The documentation states which set of viewpoints (view model) it uses, rather than an ad hoc collection of diagrams. - Each view covers one aspect of the architecture and is not an overloaded all-in-one model. - If 4+1 is used, a small set of scenarios is included to illustrate the architecture. - The building block view is present, since arc42 requires it in every architecture documentation. ## Related - [4+1 View Model](https://arc.fuet.ch/concepts/documentation/4-1-view-model.md) - [Architecture Viewpoint](https://arc.fuet.ch/concepts/documentation/architecture-viewpoint.md) - [Architecture View](https://arc.fuet.ch/concepts/documentation/architecture-view.md) - [Zachman Framework](https://arc.fuet.ch/concepts/enterprise-architecture/zachman-framework.md) - [ISO/IEC/IEEE 42010 Architecture Description Standard](https://arc.fuet.ch/concepts/documentation/iso-iec-ieee-42010-architecture-description-standard.md) - [C4 Model](https://arc.fuet.ch/concepts/documentation/c4-model.md) - [arc42 Architecture Documentation Template](https://arc.fuet.ch/concepts/documentation/arc42-documentation-template.md) - [Common Features of Architecture Frameworks](https://arc.fuet.ch/concepts/enterprise-architecture/common-features-of-architecture-frameworks.md) ## Sources - [4+1 architectural view model - Wikipedia](https://en.wikipedia.org/wiki/4%2B1_architectural_view_model) — en.wikipedia.org, accessed 2026-11-09 - [Software Systems Architecture](https://www.viewpoints-and-perspectives.info/home/viewpoints/) — viewpoints-and-perspectives.info, accessed 2026-11-09 - [RM-ODP - Wikipedia](https://en.wikipedia.org/wiki/RM-ODP) — en.wikipedia.org, accessed 2026-11-09 - [About the Zachman Framework - Zachman International - FEAC Institute](https://zachman-feac.com/zachman/about-the-zachman-framework) — zachman-feac.com, accessed 2026-11-09 - [Home | C4 model](https://c4model.com/) — c4model.com, accessed 2026-11-09 - [5 - Building block view | arc42 Documentation](https://docs.arc42.org/section-5/) — docs.arc42.org, accessed 2026-11-09