Concept

A Communication diagram is the cross between a symbol and a sequence diagram. It describes a specific scenario. Numbered arrows show the movement of messages during the course of a scenario.
Communication diagrams show the same information as sequence diagrams, but focus on object roles instead of the times that messages are sent.
UML Communication diagrams, like UML sequence diagrams, are used to explore the dynamic nature of your software.
Communications diagrams are often used to:

• provide an overview of a collection of collaborating objects
• allocate functionality to classes
• model the logic of implementation
• examine the roles that objects take within a system
  

In a sequence diagram, object roles are the verticals and messages the connecting links. In a Communication diagram, the object-role rectangles are labeled with either a class or object name.

The elements of the Communication diagram are available in the tool bar:

                       New Actor can be created by selecting the icon in the toolbar.

                       New Object can be created by selecting the icon in the toolbar.

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