Systems Engineering with SysML/UML

4.10. Interaction Diagrams

In UML, this category includes four specific diagrams: the sequence diagram, the communication diagram, the timing diagram, and the interaction overview diagram. Of these diagrams SysML uses only the sequence diagram (Figure 4.58).

Figure 4-58. Example for the “unlock car” sequence diagram.

While activity diagrams allow us to describe flows more or less independently of the executing system elements, interaction diagrams show us who calls which system behavior. In interaction, it is normally used to describe a concrete flow (scenario).