The Interaction group is used to model dynamic interactions between elements at run-time. The Actor element models a user of the system, while the other elements model things within the system, including standard elements (rectangular element), user interface component (circle with left positioned vertical bar), controller (circle with arrow head in top-most position) and entity (circle with bar at bottom). The meaning of these symbols is discussed further in the topic on Sequence diagrams. The Message relationship is used to model the flow of information and processing between elements.

The following model elements are supported: Actor (sequence element), Lifeline (sequence element), Boundary (sequence element), Control (sequence element), Entity (sequence element) and Message.

Note: Messages can be simple or recursive calls.

To add an element to the current diagram, click on the required icon, and drag it into position on the diagram. Set an element name and other properties as prompted.

To add a relationship, click on the required icon, then click on the start element in the diagram and drag to the end element.