Dependency

A dependency is a relationship between two model elements in which a change to one model element will affect the other model element. Use a dependency relationship to connect model elements with the same level of meaning. Typically, on class diagrams, a dependency relationship indicates that the operations of the client invoke operations of the supplier.

You can connect model elements with dependencies on any diagram except state machine diagrams and object diagrams. For example, you can connect a use case to another use case, a package to another package, and a class to a package. Dependencies are also used on component diagrams to connect model elements.

Extend Stereotype

An extend relationship is a stereotyped relationship that specifies how the functionality of one use case can be inserted into the functionality of another use case. You can place extend stereotypes on all relationships. However, most extend stereotypes are placed on dependencies or associations. Extend relationships are important because they show optional functionality or system behavior.

Include Stereotype

An include relationship is a stereotyped relationship that connects a base use case to an inclusion use case. An include relationship specifies how behavior in the inclusion use case is used by the base use case. Include relationships are important because they represent that the inclusion use case functionality is used by the base use case.

Refine Stereotype

A refine relationship is a stereotyped relationship that connects two or more model elements at different semantic levels or development stages. It represents a fuller specification of something that has already been specified at a certain level of detail. For example, a design class is a refinement of an analysis class. In a refine relationship, the source model element is general and more broadly defined whereas the target model element is more specific and refined.