How does the dependency direction differ from the data flow direction?

The direction of dependencies and the direction of data flow are different concepts, although they can intersect.

Direction of dependencies describes which modules or components depend on which. If component A depends on component B, it means A uses B, and changes in B can affect A. This relationship indicates the structure and architecture of the system.

Direction of data flow is the path along which data is transmitted or moved within the system or application. For example, in a unidirectional data flow (like in React), data flows from top to bottom from parent components to children.

Example:

• In MVC architecture, the model does not depend on the view, but the view depends on the model — this is the direction of dependencies.
• When updating the state in the UI, data may flow from the model to the view — this is the direction of data flow.

Thus, the direction of dependencies is about architectural relationships and dependencies between components, while the direction of data flow concerns the dynamic movement of data within the application.