Communication diagram

In the Unified Modeling Language (UML) 2.0, a communication diagram is a simplified version of the UML 1.x collaboration diagram.

UML has four types of Interaction Diagrams

- Sequence Diagram

- Communication Diagram

- Interaction Overview Diagram

- Timing Diagram

A Communication diagram models the interactions between objects or parts in terms of sequenced messages. Communication diagrams represent a combination of information taken from Class, Sequence, and Use Case Diagrams describing both the static structure and dynamic behavior of a system.

However, communication diagrams use the free-form arrangement of objects and links as used in Object diagrams. In order to maintain the ordering of messages in such a free-form diagram, messages are labeled with a chronological number and placed near the link the message is sent over. Reading a communication diagram involves starting at message 1.0, and following the messages from object to object.

Its the choice of developer/architect to use either sequence diagram or communication diagram. Both serves the same purpose but with variation in ease of use

Both the kind of diagrams use similar notations.