OOAD - Object Oriented Analysis and Design
Sequence Diagram
Sequence diagram
Sequence diagram is a UML diagram which shows the dynamic behavior of the system. It shows the sequence of interaction between objects, life of the objects. The order in which messages are exchanged between the objects are clearly seen in the sequence diagram. Sequence diagrams are used to understand users’ requirement from the new system. It is used to:
- To show the details of a case case.
- To know the methods of the objects
- To model the logic of procedure, function
Symbols used in Sequence diagram
| Symbol | Name> | Description |
|---|---|---|
| Rectangle | Object Symbol | Represents a class or object |
| Vertical rectangle | Activation box | Represents the time taken by object to complete a task |
| Sticky Symbol | Actor symbol | Show entity with the system |
| small vertical rectangle with dashed vertical line beneath the rectangle | Lifeline symbol | Represents the passage of time |
| Frame | Used for loop or alternative condition | Used to model loop construct or conditional statement |
| Arrow | Synchronous message symbol | Used to show a message send from a sender |
| Arrow with dashed line | Return message symbol | shows the reply messages |
Sequence Diagram for Searching book in Search Engine
Sequence Diagram for Issuing book from library
