In UML, a relationship is a connection between model elements. A UML relationship is a type of model element that adds semantics to a model by defining the structure and behavior between the model elements.
| Category | Function |
|---|---|
| Activity edges | Represent the flow between activities |
| Associations | Indicate that instances of one model element are connected to instances of another model element |
| Dependencies | Indicate that a change to one model element can affect another model element |
| Generalizations | Indicate that one model element is a specialization of another model element |
| Realizations | Indicate that one model element provides a specification that another model element implements |
| Transitions | Represent changes in state |
The following topics describe the relationships that you can use in use case diagrams: