Realization Relationships

A realization is a relationship that exists between two model elements when one of them must realize, or implement, the behavior specified by the other. In the realization relationship, the model element that specifies the behavior is considered the supplier, and the model element that implements the behavior is considered the consumer.

For example, you could model a realization that connects an interface that specifies the behaviors of a credit card scanner to the subsystem that implements the behaviors. You could also model a realization that connects a use case that specifies behaviors for a system to the collaboration instance that shows how the behaviors are implemented.

A realization appears in one of two styles, depending on the shape of the supplier model element. If the supplier is an interface that appears as a small circle, the realization connector appears as a solid line. Otherwise, the realization appears as a dashed line with an unfilled arrowhead. The realization points from the consumer shape (realizing the behavior) to the supplier shape (specifying the behavior). The correct line style is automatically created.

Frequently modeled realizations include those between interfaces and classifiers (for example, classes, components, subsystems) and those between use cases and collaborations. When a component or subsystem realizes an interface, the operations are usually available only through the interface.

You can add realization relationships to your model to indicate the following:

• A class, component or subsystem provides an implementation for the operations that are specified in an interface.

• A collaboration instance contains the objects and messages needed to implement the behaviors specified by a use case.

The realization relationships in a model usually appear in class and component diagrams.

Realization relationships usually do not have names. If you name a realization, the name is displayed next to the realization connector on the diagram.

• Working with Class Diagrams
• Working with Component Diagrams
• Working with Use-Case Diagrams
• Adding Realization Relationships
• Classes
• Collaboration Instances
• Collaborations
• Dependency Relationships
• Interfaces
• Use Cases

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