In UML models, an interaction is a behavior that represents communication between one or more participants. A sequence diagram is a UML interaction diagram that models interactions in a chronological order and passes messages between participants, such as objects and roles. You can add and modify lifelines, messages, execution occurrences, combined fragments, interaction occurrences, and stop nodes in sequence diagrams.
Creating lifelines in sequence diagrams
In sequence diagrams, you can create lifelines to represent participants and to show the chronological order of their interactions.Creating messages in sequence diagrams
In sequence diagrams, you can create messages to represent the communication that occurs between participants in lifelines. You can add, delete, reposition, and assign new operations to messages in an interaction frame.Showing the flow of control in interactions by using execution occurrences
In sequence diagrams, execution occurrences represent the behavior of a participant on a lifeline that is bound by a start event and a finish event. You can add, resize, move, and delete execution occurrences in an interaction.Creating combined fragments in sequence diagrams
In sequence diagrams, you create a combined fragment to represent a construct, such as optional, alternative, parallel, and loop. You group the messages and interaction fragments involved in the interaction in a combined fragment to compact and simplify complex interactions. Interaction fragments refer to the event occurrences, execution occurrences, interaction occurrences, and combined fragments in sequence diagrams.Referencing interactions from within other interactions
In sequence diagrams, you can reference an interaction from within the body of another interaction. This reference is called an interaction occurrence. You can then reuse the definitions in an interaction to abstract and simplify your model. You can add and modify interaction occurrences in sequence diagrams.Terminating participants in interactions by using stop nodes
In sequence diagrams, you can add a stop node to a lifeline to represent the termination of a participant in an interaction. You can only delete a stop node that you created manually.
Related concepts
Sequence diagrams
Interaction frames