You can componentize interactions on a Sequence diagram using the InteractionUse and PartDecomposition symbols. An Interaction Use is a fragment that enables you to use (or call) another interaction. This notation is used to simplify large and complex Sequence diagrams.
The InteractionUse is a rectangle with a ref for ‘reference’ in the upper-left corner.
An InteractionUse works in the following way:
•The referenced interaction has formal gates.
•The InteractionUse provides a set of actual gates that must match the formal gates.
•When encountering an InteractionUse, the contents of the referenced interaction are copied to where the interaction needs to be used, formal parameters are substituted with arguments, and the formal gates are replaced with the actual ones.
Note PartDecomposition is a specialization of an InteractionUse.
