Representing Subsystems on a Sequence Diagram ◆| interfaces Represent any model element that realizes the interface No message should be drawn from the interface ◆ Subsystem Component Represents a specific subsystem Messages can be drawn from the subsystem Obiect A Interface Object B ObjectA Subsystem Object B Component 1: Message 1 Message 1 2:Me、sa,e2 2: Message 2 Invalid message Valid message E写喜8 Representing Subsystems on a Sequence Diagram  Interfaces  Represent any model element that realizes the interface  No message should be drawn from the interface  Subsystem Component  Represents a specific subsystem  Messages can be drawn from the subsystem Object A Interface Object B 1: Message 1 2: Message 2 Object A Subsystem Component Object B 1: Message 1 2: Message 2 X Invalid message Valid message