1. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 1 synchronous indicates nested flow of control used to ensure that state cannot be compromised by external factors e.g. not interrupted by the operating system invoking object halts execution while it waits for a return completion invoked object finishes asynchronous signal from one object to another invoking object does not halt execution while it waits a return callback notification of completion from invoked object types of message flows

2. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 2 iteration and conditions

3. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 3 branching and asynchronous messages and deletion of objects print shop

4. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 4 use case “place a telephone call” (R, S) this diagram could be extended to show the two parties disconnecting

5. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 5 Fig. 12.24 UML and the Unified Process: Practical Object-Oriented Analysis and Design. Arlow & Neustadt. Addison-Wesley. 2002

6. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 6 showing active

7. University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 sequence diagrams 7 multi- threading