Realization relationships in UML modeling

In UML modeling, a realization relationship is a relationship between two model elements, in which one model element (the client) realizes the behavior that the other model element (the supplier) specifies. Several clients can realize the behavior of a single supplier. You can use realization relationships in class diagrams and component diagrams.

Typically, realization relationships do not have names. If you name a realization, the name is displayed beside to the realization connector in the diagram.

As the following figure illustrates, a realization is displayed in the diagram editor as a dashed line with an unfilled arrowhead that points from the client (realizes the behavior) to the supplier (specifies the behavior).

A component named Component2 realizes the behavior of Class3.

You can model the following situations using realization relationships:

A component is realized by a set of classifiers that provide its implementation.
A collaboration instance contains the objects and messages that are needed to implement the behaviors that a use case specifies.