Chaptor 5 Review Questions : OOSD
These are the answers for Review Questions on Chapter 5 Object oriented analysis & Design with the unified Process by Satzinger, J,
Jackson, R.B. & Burd, S.D
1. What is an event?
- An event is an occurrence at a specific time and place that can be described and is worth remembering by the system.
2. What are three types of models?
- Mathematical models
- Descriptive models
- Graphical models.
3. What are the two key concepts used to begin defining system requirements?
- Events the system needs to respond to and things that the system needs to store information about.
5. What are the three types of events?
- External events
- Temporal events
- State events.
6. What are some examples of system controls?
- Validating user input
- Requiring user IDs and passwords for logging on to the system
- Backing up data regularly
- Encrypting data that is transmitted, and so on.
7. What does the perfect technology assumption state?
- The perfect technology assumption states that events should be included during analysis only if the system would be required to respond under perfect conditions—that is, with equipment never breaking down, capacity for processing and storage being unlimited, and people operating the system being completely honest and never making mistakes. Basically, the perfect technology assumption prevents analysts from worrying about systems controls until later during the design phase.
8. In the event table,
- what is a trigger?
- A trigger is a data input for an external event and a definition of a point of time for a temporal event.
- A source?
- A source is what external agent or actor supplies the data input for an external event.
- An activity or use case?
- The activity/use case is what the system does when the event occurs (the process).
- A response?
- A response is a data output from the system.
- A destination?
- The destination is the external agent or actor that receives the data output
9. What is a “thing” called in models used in the traditional approach?
- A data entity.
10. What is a “thing” called in the object-oriented approach?
- An object.
11. What is a relationship?
- A naturally occurring association among specific things, such as an order is placed by a customer, and an employee works in a department.
12. What is cardinality of a relationship (also called multiplicity)?
- The number of associations that occur between specific things, such as a customer places many orders, and an employee works in one department.
13. What is encapsulated along with the values of attributes in an object?
- Methods of the class (what each object knows how to do) are combined with the attributes of objects of the class.
14. What is a generalization/specialization hierarchy?
- A hierarchy that structures or ranks classes from the more general superclasses to the more specialized subclasses. In OO, the attributes and methods (plus relationships) of the superclass are inherited by a subclass.
15. From what type of class do subclasses inherit?
- Superclass.
16. What are two types of whole-part hierarchies?
- Aggregation
- Composition.
17. What three pieces of information about a class are put in the three parts of the class symbol?
- Name at the top
- Attributes in the middle
- Methods at the bottom.
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