Chapters 10, 11

SSD (Revision)SDDCDExam

Object-Oriented Design

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Problem Statement: A customer wants to search for books written

by a specific author from a library. The customer wants to specify an author, and

gets the search results

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Approach: Chapter 11: “Advanced design is based on

the concepts of use case realization by using Sequence diagrams and Design patterns

Once you become proficient with these two subjects, you are an OO designer

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Use case: Components:

Actor Use case (What the system must do)

First: The EVENT table

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Event Type Trigger Source Use Case Response Destination

             

             

             

             

             

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Background: Object-oriented analysis models were

discussed in Chapters 2 - 5 Chapter 10, the fundamental principles:

A complete coverage of design principles and skills to at least do basic object-oriented design

Chapter 11 presents more advanced concepts particularly for detailed design with use case realizations: enhanced detailed design skills, and concepts related to design patterns, which are critically important for programming.

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Foundation: Object-oriented design is a process by which

a set of detailed object-oriented design models are built and then used by the programmers to write and test the new system.

One of the strengths of the object-oriented approach is that the design models are often just extensions of the requirements models.

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Question: The previous slide shows the artefacts. Don’t

confuse with waterfall approach: What is our SDLC? What is agile development? Iterative development?

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Notation SSD:

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Message Notation

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Use Case Controller An artifact invented by the designer to

handle a system function Serves as a collection point for incoming

messages Intermediary between the outside world and

the internal system

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Designing with Sequence Diagrams An SSD captures the interactions between the

system and the external world represented by actors The system is treated like a black box

A detailed sequence diagram (SD) uses all of the same elements as an SSD The :System object is replaced by all of the internal

objects and messages within the system

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Guidelines for Preliminary Sequence Diagram Development Determine all of the internal messages that

result from each input message Define origin and destination objects

Identify the complete set of classes that will be affected by each message

Flesh out the components for each message Iteration, true/false conditions, return

values, and passed parameters

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Developing a Multilayer Design View layer

Design the user interface for each use case Develop dialog designs for forms Add the window classes to the sequence diagram

Data access layer Initialize domain objects with data from the

database Query the database and send a reference object Return information in the reference object

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Search for Author: The Customer specifies an author on the

“Search Page” and then presses the Search button

The system validates the Customer’s search criteria

The system searches the Catalogue for books associated with the specified author

When the search is complete, the system displays the search results.

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O-O program The previous slide shows how an object-

oriented program works. Hidden, it also illustrates the three-layer

architecture: Abstract Three Layer Architecture

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Objective of O-O design: The objective of object-oriented design is to

identify and specify all the objects that must work together to carry out each use case. As shown in Figure 10-1, these objects include user-interface objects, problem domain objects, and data access objects.

Can you identify these objects?

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The OO diagrams: O-O analysis:

Use case, Use case description, Activity diagram, Domain Model Diagrams, System Sequence Diagram, State Machine Diagram

O-O design: Component diagrams, deployment diagrams,

design class diagrams, interaction diagrams, state machine diagrams, and package diagrams.

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Revision: An object class (or a class) is… Set of people Places Things Or transactions that share common attributes and perform

common functions to help an organization reaches its goals.

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Examples: People: employees, vendors, customers Places: warehouses, office, branches,

shipping docks Things: products, office equipment, supplies Transaction: purchases, sales, returns,

payments

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Example: Draw money from ATM Processes:

Insert credit card Enter PIN Enter Amount

What happens behind UI? Verification from bank system ……

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Classes? Customer ATM: ATM System Bank System

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Interaction: What message/communication takes place

between customer and ATM? Introducing Design Class Diagram: Customer wants to enter PIN If verified, Customer wants to draw money

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Three layer Architecture: user-interface objects, problem domain objects, and data access objects.

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Two Things (p284-287): Identifying design classes: use interactions to

add operations to classes. Identifying stereotypes (<<…>>)in UML

models: Entity class Boundary class Control class Data access class

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Steps to follow: Develop use case, use case description,

activity diagram: Domain class diagram, SSD Draw the SD Sort-out the interactions or messages Add the operations/behaviour Can you identify the ‘three layer diagram’?

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Exam: Q1: p264, problems 1, 2, 3:system vision

document Q2: project management: NPV, Payback

period, graph, ROI: pr 4, 5, 6, 7 Q3:Network diagram Q4:UI design. Going to include blocks AppInv Q5: SD Q6: DCD