The Robustness Analysis involves analyzing the narrative text of use cases, identifying a first-guess set of objects that participate in those use cases and classifying the objects based on the roles they play.

• Boundary or Interface objects are what actors use in communicating with the system.
• Entity objects are mostly objects from the domain model.
• Control objects (known as controllers because they often are not real objects) serve as the "glue" between boundary objects and entity objects.

The Robustness Analysis acts as a preliminary design within the project lifecycle, providing the missing link between an analysis and a detailed design.

Four basic rules apply:

1. Actors can only talk to the boundary objects.
2. The boundary objects can only talk to the controllers and actors.
3. The entity objects can only talk to the controllers.
4. The controllers can talk to the boundary objects and entity objects, and to other controllers, but not to the actors.

Both the boundary objects and entity objects are nouns; the controllers are verbs. Nouns cannot talk to other nouns, but verbs can talk to either nouns or verbs.

Example of the Robustness diagram Logging In

Related pages

• UML diagrams
• Extension diagram