Interaction occurrences

In Unified Modeling Language (UML) sequence diagrams, an interaction occurrence is an interaction that is referenced in another interaction frame. You can use interaction occurrences to take common content from one interaction and reuse it in another sequence diagram.

An interaction is a root element of a sequence diagram. It is a unit of behavior that focuses on the observable exchange of information between connectable elements, or properties, of the enclosing classifier. You can add interactions to collaborations to contain the diagram elements that participate in one of the collaboration's interactions.

In sequence diagrams, you can create a new interaction occurrence or select an existing interaction as an interaction occurrence. The advantage of using interaction occurrences in a sequence diagram is that your diagrams can be smaller and less complex.

As the following figure illustrates, an interaction occurrence is displayed as a frame that crosses one or more lifelines.

An interaction frame shows two interaction occurrences crossing two lifelines.

The keyword ref in the corner of the interaction occurrence indicates that the interaction is referenced from within another interaction.

Parent topic: Sequence diagrams and diagram elements

Related concepts
Sequence diagrams
Interaction frames
Lifelines
Messages
Execution occurrences
Combined fragments
Interaction operators
Interaction operands
Guard conditions
Stop nodes

Related tasks
Referencing interactions from within other interactions
Creating interaction occurrences

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