Page 100 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN

Object Oriented Analysis and Design

Notes An activity represents an operation on some class in the system that results in a change in
the state of the system.

7.5 Keywords

Action flow: Action flow arrows illustrate the relationships among action states.
Active object: An object running under its own thread.
Activity diagram: Activity diagram is a variation or special case of a state machine, in which the
states are activities representing the performance of operations and the transitions are triggered
by the completion of the operations.
Attribute: A significant piece of data owned by a Class, often containing values describing each
instance of the class. Besides the attribute name and a slot for the attribute value, an attribute
may have specified Visibility, Type, Multiplicity, Default value, and Property-string.
Scenario: A scenario is an instance of a use case, and represents a single path through the use
case.
Sequence diagram: Sequence diagram is the way to explain the behaviour of a system with a
view to make interaction between the system and its surrounded environment.
Use case diagram: A use case diagram displays the relationship among actors and use cases.
Use case model: A use case model is a model of how different types of users interact with the
system to solve a problem.

7.6 Review Questions

1. What are interaction diagrams? Analyze the purpose of interaction diagrams.
2. What is use case model? Discuss.
3. Elucidate the use case concept and use case diagrams with example.

4. Give explanation on the concept of use case package.
5. “Use cases are related to actors.” Comment.
6. Discuss the constraints included in use case.

7. Illustrate the concept of sequence diagram with example.
8. Discuss the concept of loops within a sequence diagram. Illustrate with diagram.
9. What is an activity diagram? Discuss the basic activity diagram symbols and notations.
10. Make distinction between sequence diagram and activity diagram.

Answers: Self Assessment

1. use-case 2. Scenario

3. Associations 4. Use Cases
5. <<extend>> 6. Sequence
7. Class roles 8. Activation
9. Messages 10. Lifelines

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