The C4 Model

Chapter 5. Component Diagram

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This chapter looks at the C4 component diagram, which provides a way to zoom in to show the components that reside inside a single container.

Key Aspects of the Component Diagram

To understand why and how to use component diagrams, it’s helpful to have a grasp of their intent, scope, content, use cases, and audience.

Intent

A component diagram helps you answer the following questions, particularly for the containers that are applications rather than data stores:

• How has the container been decomposed into a collection of components?

• What are the responsibilities of those components?

• How do the components collaborate and communicate with one another?

• What are the primary technology choices (e.g., frameworks and libraries) used to implement the components?

• As a software engineer, where do I need to write code to add a feature?

If you’re drawing a component diagram during an up-front design exercise, you might not have some of the technical details, such as the frameworks and libraries you are using to implement a ...