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Chapter 7: The Object-Oriented Approach

to Requirements

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The Unified Modeling Language and the Object Management Group

Object-oriented modeling notation is Unified Modeling Language (UML)

UML was presented to Object Management Group (OMG) as standard modeling technique

Purpose of Object Management Group

Promote theory and practice of object technology for development of distributed systems

Provide common architectural framework for OO

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Object-Oriented Requirements

Systems development process starts with identification of events and things

Events are business processes that new system must address

Things are problem domain objects involved in business process

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Object-Oriented Approach Models

Class diagram – definition of system components

Use case diagrams and use case descriptions – show user roles and how they use the system

Systems sequence diagrams (SSDs) – define inputs and outputs and sequence of interactions between user and system for a use case

Statechart diagrams – describe states of each object

Activity diagrams – describe user activities

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Requirements Diagrams: Traditional and OO Models

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The System Activities – A Use Case / Scenario View

Use case analysis used to identify and define all business processes that system must support

Use Case - single function performed by system for those who use that function

Actors

Role played by user

Outside automation boundary and organization

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Simple Use Case with an Actor

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Use Case Diagram with System Boundary

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Use Case of Customer Support System

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All Use Cases Including Customer

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Example of Order-Entry Subsystem with <<Includes>> Use Cases (Figure 7-6)

<<includes>>Common

Subroutines

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Developing a Use Case Diagram

Starting points for use case development

Use event table

Identify all actors of the system

Identify functions actors perform with system

Develop flow of activities to identify various scenarios

Common internal use cases can be identified and separated into different use cases

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Brief Description of Create New Order Use Case

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Intermediate Description of the Telephone Order Scenario for Create New Order

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Intermediate Description of the Web Order Scenario for Create New Order

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Fully Developed Description of Telephone Order Scenario for Create New Order

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Fully Developed Description of Web Order Scenario for Create New Order

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Activity Diagram: Telephone Order Scenario

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Activity Diagram: Web Order Scenario

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Problem Domain Modeling – The Domain Model Class Diagram

Class diagram is focal point of object-oriented development

Provides definition of system components

Contains important class structural information for implementation with object-oriented programming

Provides conceptual data model to describe classes for database definition

Consists of problem domain classes and implementation classes

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RMO Domain Model Class Diagram

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Relationships Between OO Requirements Models

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Use Case Diagram for Inventory System

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Relationships Between OO Requirements Models (Figure 7-28)