Object-Oriented Application Development Using VB.NET 1 Chapter 5 Object-Oriented Analysis and...
-
Upload
manuel-fithian -
Category
Documents
-
view
226 -
download
3
Transcript of Object-Oriented Application Development Using VB.NET 1 Chapter 5 Object-Oriented Analysis and...
Object-Oriented Application Development Using VB .NET
1
Chapter 5
Object-Oriented Analysis and Design
Object-Oriented Application Development Using VB .NET
2
Objectives
In this chapter, you will:
• Explore OOA and OOD
• Understand the Unified Modeling Language (UML)
• Use three-tier design in OO development
• Learn about the Bradshaw Marina case study
Object-Oriented Application Development Using VB .NET
3
Exploring OOA and OOD
• System analysis: – Study
– Understand
– Define
the system requirements
• System design: show how various system components will be implemented using specific technology
Object-Oriented Application Development Using VB .NET
4
Exploring OOA and OOD
• System requirements– Define what the system needs to accomplish for
users in business terms
– Usually described using • Diagrams• Models
Object-Oriented Application Development Using VB .NET
5
Exploring OOA and OOD
• A model depicts some aspect of the required system– Logical models: created during system analysis
– Physical models: created during system design
• Model-driven development: creating logical and physical models during analysis and design
Object-Oriented Application Development Using VB .NET
6
Exploring OOA and OOD
• OO development models– Define classes of objects
– Depict object interactions
– Are based on UML
– Include• Use case diagrams• Class diagrams• Sequence diagrams
Object-Oriented Application Development Using VB .NET
7
Exploring OOA and OOD
• OO development works well with an iterative approach to development
• Iterative development– Analysis, design, and programming are performed
in parallel, with the process repeated several times until the project is done
– Contrasts with the waterfall method• An earlier approach• All of analysis was completed before design could
start, and all of design was completed before programming could start
Object-Oriented Application Development Using VB .NET
8
Exploring OOA and OOD
Object-Oriented Application Development Using VB .NET
9
Exploring OOA and OOD
• OO development also uses incremental development– Some of the system is completed and put into
operation before the entire system is finished
Object-Oriented Application Development Using VB .NET
10
Exploring OOA and OOD
• Spiral model– An increasingly popular approach to development
– Emphasizes the iterative nature of development
– Project appears as a spiral starting in the middle and working its way out
– Development team completes analysis, design, prototyping, and evaluation tasks for each iteration, starting in the middle of spiral
Object-Oriented Application Development Using VB .NET
11
Exploring OOA and OOD
Object-Oriented Application Development Using VB .NET
12
Understanding the Unified Modeling Language
• Object-oriented development requires a collection of models that depict system requirements and designs
• UML defines a standard set of constructs and diagrams to model OO systems
Object-Oriented Application Development Using VB .NET
13
Creating and Interpreting the Use Case Diagram
• First step in system modeling: define the main system functions
• A use case diagram shows two key concepts: – Use case: a system function
– Actor: person or entity using the system
Object-Oriented Application Development Using VB .NET
14
Creating and Interpreting the Use Case Diagram
Object-Oriented Application Development Using VB .NET
15
Creating and Interpreting the Use Case Diagram
• One approach to identifying use cases is to identify events the system must respond to
• Three types of events can affect a system: – External events: occur outside the system and
require the system to respond
– Temporal events: occur at a specific point in time, such as at the end of each day or at the end of the month
– State event: occur when the properties of an object change. Require system processing
Object-Oriented Application Development Using VB .NET
16
Creating and Interpreting the Use Case Diagram
• Each use case can be documented as a series of steps users follow when they interact with the system
• Scenarios: variations in the main steps• As the development team identifies use cases, it
creates use case diagrams
Object-Oriented Application Development Using VB .NET
17
Creating and Interpreting the Use Case Diagram
• An activity diagram– An additional diagram defined by UML that can be
used to document use cases
– Sometimes created for each scenario for a use case
Object-Oriented Application Development Using VB .NET
18
Creating and Interpreting the Class Diagram
• Class diagram– Shows the classes involved in the system
– Is a rectangle with three sections• Top section contains name of the class• Middle section contains attributes of the class• Bottom section contains methods of the class
Object-Oriented Application Development Using VB .NET
19
Creating and Interpreting the Class Diagram
Object-Oriented Application Development Using VB .NET
20
Creating and Interpreting the Class Diagram
• Class Diagram– Association relationship between two classes is
shown with a line connecting the two classes• Number of associations between classes is written
on each end of the line• UML refers to the number of associations as
multiplicity
Object-Oriented Application Development Using VB .NET
21
Creating and Interpreting the Class Diagram
• Class Diagram– Shows generalization/specialization hierarchies
(inheritance)
– Abstract classes shown in italics• Objects cannot be created for an abstract class• Only serves to allow subclasses to inherit from it
Object-Oriented Application Development Using VB .NET
22
Creating and Interpreting a Sequence Diagram
Object-Oriented Application Development Using VB .NET
23
Creating and Interpreting a Sequence Diagram
• Sequence diagram– Shows interactions between objects in a system,
usually for one use case or scenario
– Often called a dynamic model
• Class diagram– Does not highlight object interactions
– Often called a static model
Object-Oriented Application Development Using VB .NET
24
Creating and Interpreting a Sequence Diagram
• In a sequence diagram– Actor can be shown as a stick figure or a rectangle
– Objects are shown as rectangles
– Lifelines• Represent a sequence of time• Shown as either a dashed line or a narrow box
– Horizontal arrows represent messages sent or received in sequence
– Data returned in response to a message is shown as a dashed line
Object-Oriented Application Development Using VB .NET
25
Creating and Interpreting a Sequence Diagram
Object-Oriented Application Development Using VB .NET
26
Creating and Interpreting a Sequence Diagram
• In a sequence diagram– Object names are always underlined and begin
with a lowercase letter
– Class names are always capitalized
– Objects can be named by • Using generic object names to clarify the class• Including the name of the class after the name of the
object, separated by a colon
– Message names are written above the message line
Object-Oriented Application Development Using VB .NET
27
Using Three-Tier Design in OO Development
• Three-tier design requires that OO system developers separate three categories of classes when designing and building a system
• Three tiers– Graphical user interface (GUI) classes
– Problem domain classes
– Data access classes
Object-Oriented Application Development Using VB .NET
28
Using Three-Tier Design in OO Development
• Separating GUI classes, problem domain classes, and data access classes leads to loosely coupled system components
• With loosely coupled components– A component can be modified with minimal effects
on other components• Makes it easier to maintain and enhance the system
– Components are easier to reuse
Object-Oriented Application Development Using VB .NET
29
Using Three-Tier Design in OO Development
• Three-tier design– Provides a framework for defining OOA and OOD
• OOA involves identifying and modeling the problem domain classes
• In OOD, decisions about the user interface and about database management are made
– Works well with• Iterative development • Incremental development
• The book follows the three-tier design approach
Object-Oriented Application Development Using VB .NET
30
Introducing the Bradshaw Marina Case Study
• Bradshaw Marina case study demonstrates OO development principles and practices
• When a business determines it needs a computer system, it works with a team of developers to design and develop the system
Object-Oriented Application Development Using VB .NET
31
Introducing the Bradshaw Marina Case Study
• Tasks of development team– Analyze business and identify system functions
– Begin object-oriented analysis to identify the required use cases and scenarios, creating use case diagrams
– Identify required problem domain classes and create class diagram
– Develop sequence diagrams to model object interactions
Object-Oriented Application Development Using VB .NET
32
Exploring the Background of Bradshaw Marina
• Bradshaw Marina– A privately owned corporation that rents boat slips
and provides boat services on Clinton Lake
– Wants an automated system to track customers, slips they lease, and boats in the slips
Object-Oriented Application Development Using VB .NET
33
Exploring the Background of Bradshaw Marina
• System– Initially: system will maintain basic information for
customers, slips, and boats, and perform day-to-day business tasks
– Later: Bradshaw wants to enhance the system• Add boat service records• Add billing features
Object-Oriented Application Development Using VB .NET
34
Identifying Bradshaw Use Cases and Scenarios
• First step in OOA process: identify use cases that fall within system scope
• Since main events of interest involve customers, boats, and slips, use cases also focus on customers, boats, and slips
• Bradshaw Marina use case diagram indicates the use cases
• Several scenarios could be associated with each use case
Object-Oriented Application Development Using VB .NET
35
Identifying Bradshaw Use Cases and Scenarios
Object-Oriented Application Development Using VB .NET
36
Identifying Bradshaw Problem Domain Classes
• To explore problem domain classes, the development team would– Meet with Bradshaw Marina to ask about things
that are involved in the work of the marina• For example – customers, boats, leases, slips, and
docks
– Begin an initial class diagram that includes these potential classes
Object-Oriented Application Development Using VB .NET
37
Identifying Bradshaw Problem Domain Classes
• Development team would further develop the class diagram by– Showing generalization/specialization hierarchies
– Adding specific information about each class
– Identifying and modeling the association relationship among classes
Object-Oriented Application Development Using VB .NET
38
Creating a Bradshaw Sequence Diagram
• Methods can be added to the class diagram by exploring scenarios and documenting them with sequence diagrams
• A sequence diagram should be created for each scenario of each use case
• As you move from OOA to OOD, you will expand the diagram to show– GUI objects the actor interacts with
– Data access classes that handle interaction with database
Object-Oriented Application Development Using VB .NET
39
Summary
• System analysis: study, understand, and define requirements for the system
• System requirements define what a system needs to accomplish for users in business terms
• Model-driven development: creating logical and physical models during analysis and design
• Iterative development: analysis, design, and programming are performed in parallel, with the process repeated several times until the project is done
Object-Oriented Application Development Using VB .NET
40
Summary
• Incremental development: part of the system is put to use before the rest is finished
• Use case diagram shows system functions, called use cases
• Class diagram shows classes of objects that interact in the system
• Sequence diagram shows messages that the actor sends to objects and that objects send to each other
• Three-tier design divides classes into GUI classes, problem domain classes, and data access classes