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Chapter 6
171 Final ch 6
31
Computer Science
Undergraduate 4
12/06/2013

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Term
Object-oriented (O-O) analysis
Definition
describes an IS by identifying things called objects.
An object represent a real person, place,
event, or transaction.
Term
Instance
Definition
Is a specific member of a class.

(Honda Accord is an instance of the car class)
Term
Class
Definition
is a group of similar objects.

(Honda Accord and Toyota Camry's belong in the class called cars)
Term
Attributes
Definition
Characteristics that describe the object
- For ex. for a car, attributes would be the make, color, and model
Term
Methods
Definition
Task or functions that the objects perform when it receives a message or command
- defines specific tasks that an object can perform
- resembles verbs that describe WHAT and HOW an object does something
Term
Messages
Definition
 A command that tells an object to perform a certain method
 You can view an object as a black box, message can trigger a
change in the object without specifying how the changes must be carried out.

(In a school information system, an INSTRUCTOR object sends an ENTER
GRADE message to an instance of the STUDENT RECORD class)
Term
Polymorphism
Definition
The same message to two different
objects can produce different results. The concept that a message gives different meanings to different objects
- Ex. message GOOD NIGHT signals PARENT object to read bedtime story, GOD to sleep and CHILD to get ready for bed
Term
Encapsulation
Definition
All data and methods are self-contained.
- concept of black box
- allows objects to be used as modular components anywhere in the system, because objects send and receive messages but do not alter the internal methods of other objects

(ie. a black box. A black box does not want or need outside interference. By
limiting access to internal processes, an object prevents its internal code from being altered by another object or process.)
Term
Superclass
Definition
a general category.

(Novel class belongs in the superclass called books, because all novels are books)
Term
Relationships
Definition
◦ Enable objects to communicate and interact as they perform business functions and transactions required
by the system. Relationships describe what objects need to know about each other, how objects respond to changes in other objects, and the effects of
membership in classes, superclasses, and subclasses.
Term
What is the strongest relationship called?
Definition
Inheritance; enables an object, called a child, to derive one or more of its attributes from another object, called a parent.
Term
Object Relationship Diagram:
Definition
shows the objects and how they interact to perform business functions and transactions
Term
Class Diagrams
Definition
shows the object classes and relationships involved in a use case. Like a DFD, a class diagram is a logical model, which evolves into a physical model and finally becomes a functioning information system.
Term
Cardinality
Definition
class diagrams also include cardinality, which describes how instances of one class relates to another class.
Term
State
Definition
adjective that describes current status of an object.
Ex. can be future student, current student or past student
Term
State Transition Diagram
Definition
shows how an object changes from one state to another, depending
on events that affect the object. All possible states must be documented in the state transition diagram.
- Ex. bank account can be opened as NEW then changed to ACTIVE or EXISTING, then be CLOSED or FROZEN
- states appear as rounded rectangles with state names inside
- filled circle represents start of workflow
- encircled filled circle represents end state
Term
Activity Diagrams
Definition
resembles a horizontal flowchart that shows the actions and events
as they occur. Activity diagrams show the order in which the actions take place and identify the outcomes.
Term
Use Case Modeling
Definition
◦ UML symbol for a use case is an oval with a label that describes the action or event
◦ The actor is shown as a stick figure, with a label that identifies the actor’s role
Term
Unified modeling language (UML)
Definition
widely used method of visualizing and documenting an information system
Term
Object model
Definition
- end product of object oriented analysis
- represents the information system in terms of objects and object oriented concepts
Term
object
Definition
represent a real person, place,
event, or transaction.
Term
subclasses
Definition
objects within a class
- Ex. instructor, manager, staff objects represent sub-classes within the EMPLOYEE class
Term
black box
Definition
- object can be a black box because a message to the object triggers changes within the object without specifying how the changes must be carried out
- Ex. when you select the economy gas pump option, you do not need to think about how the pump determines correct price and right fuel as long as it does so properly
- does not want or need outside interference
- example of encapsulation
Term
use case
Definition
represents steps in a specific business function or process
- Ex. MAKE APPOINTMENT
- UML symbol for use case is a oval with a label
- can interact with other use cases
Term
actor
Definition
- initiates use case by requesting the system to perform a function or process
- external entity
- Ex. PATIENT
Term
use case description
Definition
- for each use case, you develop a use case description in the form of a table
- documents the name of the use case, the actor, a description of the use case, a step by step list of the tasks and actions required for successful completion, a description of alternative course of action, preconditions, post-conditions, and assumptions
Term
system boundary
Definition
shows that is included int he system (inside the rectangle) and what is not included in the system (outside the rectangle)
- represented by a rectangle
Term
sequence diagram
Definition
dynamic model of a use case, showing the interaction among classes during a specified time period
- graphically documents the use case by showing the classes, messages, and timing of messages
- includes symbols that represent classes, lifelines, messages, and focuses
Term
lifeline
Definition
represents the time during which the object above it is able to interact with the other objects in the use case
- identified by dashed line and ends with an X
Term
focus
Definition
identified by a narrow vertical shape that covers the lifeline
- indicates when an object sends or receives a message
Term
business process modeling (BPM)
Definition
- represent people, events, and interaction in a system
- can use anything during systems development process (was discussed as a requirements modeling tool)
- works well with object modeling because both methods focus on the actors and the way they behave
- Pool - outside rectangle
-swim lanes - show specific actions and events and can interact when certain events occur
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