# Component View Antipattern: Lifting Code to Model Level

**In short:** Lifting code to model level means copying code packages, such as Facade, Service or Dto, into the architecture view. The diagram then mirrors the source code instead of abstracting it into meaningful building blocks.

## Explanation

A building block view shows the parts of a system and how they relate. arc42 says this view should make the source code understandable through abstraction. It should not reproduce the code.

The antipattern appears when a team copies code structure into the model. Packages named Facade, Service, Dto or Converter become boxes in the diagram. The diagram is then a second copy of the code. It adds no new insight.

arc42 describes the view as levels of black boxes (outside only) and white boxes (inside shown). Level 3 zooms only into selected level 2 blocks. It is not a place to list every code package.

C4 (see the article C4 Model) points the same way. A component sits one abstraction level above code. It groups related functionality behind an interface. It is not a single package or class. In object-oriented languages, one or more classes implement a component.

**Better alternatives**

- Form building blocks by cohesion. Group code that belongs together by responsibility.
- Create component diagrams only when they add value. Automate their creation for long-lived documentation, so the model does not drift from the code.
- Skip code-level diagrams in long-lived documentation. IDEs can generate them on demand. Keep this detail for the most important or complex components.

## Example

A team documents an order system. Its level 3 diagram shows boxes named OrderFacade, OrderService, OrderDto and OrderConverter, repeated for customers and payments. Every box matches a code package.

A better view shows three blocks: Ordering, Customer Management and Payment. Each groups code by responsibility. A developer who needs package detail generates it from the code with an IDE.

## Trade-offs

Code-level detail has a use. It is warranted only for the most important or complex components. Generating diagrams with tools costs setup effort. In return, they stay current with the code. Hand-drawn abstract views need judgment about what to select and what to hide.



## Checks

- Building blocks in the view are grouped by responsibility, not named after code packages such as Facade, Service or Dto.
- Level 3 zooms only into selected level 2 blocks, not into every block.
- Code-level detail appears only for the most important or complex components.
- Code-level diagrams are generated by tooling rather than drawn by hand.

## Related

- [Component View](https://arc.fuet.ch/concepts/documentation/component-view.md)
- [Component View Refinement Levels](https://arc.fuet.ch/concepts/documentation/component-view-refinement-levels.md)
- [C4 Component Diagram](https://arc.fuet.ch/concepts/documentation/c4-level-3-component-diagram.md)
- [C4 Level 4: Code Diagram](https://arc.fuet.ch/concepts/documentation/c4-level-4-code-diagram.md)
- [Unclear Level of Abstraction Antipattern](https://arc.fuet.ch/concepts/documentation/unclear-level-of-abstraction-antipattern.md)
- [Coupling and Cohesion](https://arc.fuet.ch/concepts/principles/coupling-and-cohesion.md)
- [Runtime View Antipattern: Code-Level Activity Diagram](https://arc.fuet.ch/concepts/documentation/runtime-view-antipattern-code-level-activity-diagram.md)
- [C4 Model](https://arc.fuet.ch/concepts/documentation/c4-model.md)

## Sources

- [5 - Building block view | arc42 Documentation](https://docs.arc42.org/section-5/) — docs.arc42.org, accessed 2026-11-09
- [Component | C4 model](https://c4model.com/abstractions/component) — c4model.com, accessed 2026-11-09
- [Component diagram | C4 model](https://c4model.com/diagrams/component) — c4model.com, accessed 2026-11-09
- [Code diagram | C4 model](https://c4model.com/diagrams/code) — c4model.com, accessed 2026-11-09