## 25.6.4 UML Sequence and State Diagrams (cont.)

### Leave a Message sequence diagram

1. Caller keys in extension (shown as single call to `dial`)
2. `Connection` calls system's `find_mailbox`
3. The `Mailbox` object on the right is returned
4. Connection invokes `get_greeting`
   (greeting is passive; doesn't appear on diagram)
5. Connection plays appropriate greeting
6. Telephone reads msg from user, passes it to connection
7. Telephone reads hangup, passes it to connection
8. Connection constructs `Message`, adds it to mailbox

prev |top |next