The Communication 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).
Communication diagrams are used to model work flow and sequential passing of messages between elements in real time. They are often placed beneath Use Case elements to further expand on Use Case behavior over time.
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.