UML for the IT business analyst : a practical guide to object-oriented requirements gathering

385 Pages·2005·5.83 MB·English

by  Howard Podeswa

UML™ for the IT
Business Analyst:
A Practical Guide to
Object-Oriented
Requirements Gathering
Howard Podeswa
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Contents
chapter 1 Who Are IT Business Analysts?.................................................1
Chapter Objectives.....................................................................................1
The IT and Non-IT BA.................................................................................1
Perspective on the IT BA Role....................................................................1
Why Modeling Is a Good Thing.................................................................2
The Dynamic (Behavioral) Model..............................................................3
The Static (Structural) Model.....................................................................3
For Those Trained in Structured Analysis..................................................4
Chapter Summary.......................................................................................5
chapter 2 The BA’s Perspective on Object Orientation............................7
Chapter Objectives.....................................................................................7
What Is OO?................................................................................................8
The UML Standard......................................................................................8
Cognitive Psychology and OO?..................................................................8
Objects........................................................................................................9
The BA Perspective............................................................................9
Attributes and Operations.........................................................................9
The BA Perspective............................................................................9
Operations and Methods.........................................................................10
The BA Perspective..........................................................................10
Encapsulation...........................................................................................10
The BA Perspective..........................................................................10
OO Concept: Classes.................................................................................11
The BA Perspective..........................................................................12
OO Concept: Relationships......................................................................12
OO Concept: Generalization....................................................................12
The BA Perspective..........................................................................14
OO Concept: Association.........................................................................14
The BA Perspective..........................................................................14
OO Concept: Aggregation.......................................................................15
The BA Perspective..........................................................................15
OO Concept: Composition.......................................................................15
The BA Perspective..........................................................................16
OO Concept: Polymorphism.....................................................................16
The BA Perspective..........................................................................17
Use Cases and Scenarios...........................................................................18
The BA Perspective..........................................................................18
Business and System Use Cases................................................................19
The BA Perspective..........................................................................19
Chapter Summary.....................................................................................20
chapter 3 An Overview of Business Object-Oriented
Modeling (B.O.O.M.)................................................................21
Chapter Objectives...................................................................................21
B.O.O.M. and SDLCs.................................................................................21
The B.O.O.M. Steps...................................................................................22
1: Initiation......................................................................................22
2: Analysis........................................................................................23
Sequencing the Steps...............................................................................24
What Do You Define First—Attributes or Operations?.........................25
Chapter Summary.....................................................................................25
chapter 4 Analyzing End-to-End Business Processes.............................27
Chapter Objectives...................................................................................27
B.O.O.M. Steps..........................................................................................27
1. Initiation......................................................................................27
Interviews During the Initiation, Analysis, and Test Phases..................28
Step 1: Initiation.......................................................................................29
What Happens During Initiation?..................................................29
How Long Does the Initiation Phase Take?...................................29
Deliverables of the Initiation Step: BRD (Initiation Version)........29
Business Requirements Document Template..........................................30
Timetable..................................................................................................39
Step 1a: Model Business Use Cases..........................................................49
How Do You Document Business Use Cases?................................49
Step 1a i: Identify Business Use Cases (Business Use-Case Diagram).....49
Other Model Elements....................................................................50
Putting Theory into Practice....................................................................51
Note to Rational Rose Users....................................................................51
Case Study D1: Business Use-Case Diagrams...........................................53
Problem Statement.........................................................................53
Suggestions......................................................................................53
Step 1a ii: Scope Business Use Cases (Activity Diagram)........................68
Activity Diagrams for Describing Business Use Cases....................68
Case Study D2: Business Use-Case Activity Diagram with Partitions.....77
Problem Statement.........................................................................79
Suggestions......................................................................................79
Business Use Case: Manage Case (Dispute)....................................79
Business Use Case: Administer Payments.......................................80
Case Study D2: Resulting Documentation.....................................81
Next Steps........................................................................................81
Chapter Summary.....................................................................................84
chapter 5 Scoping the IT Project with System Use Cases......................85
Chapter Objectives...................................................................................85
Step 1b: Model System Use Cases............................................................85
Step 1b i: Identify Actors (Role Map).............................................86
Case Study E1: Role Map..........................................................................91
Problem Statement.........................................................................91
Case Study E1: Resulting Documentation......................................92
Step 1b ii: Identify System Use-Case Packages (System Use-Case
Diagram)...................................................................................................92
Managing a Large Number of Use Cases.......................................92
What Criteria Are Used to Group System Use Cases into
Packages?.........................................................................................93
Naming Use-Case Packages............................................................93
Diagramming System Use-Case Packages......................................94
What If a Use-Case Package Is Connected to All of the
Specialized Actors of a Generalized Actor?...................................95
Case Study E2: System Use-Case Packages..............................................96
Problem Statement.........................................................................96
Suggestions......................................................................................96
Case Study E2: Resulting Documentation......................................96
Step 1b iii: Identify System Use Cases (System Use-Case Diagram).......98
System Use Cases.............................................................................98
Features of System Use Cases.........................................................99
What Is the Purpose of Segmenting the User Requirements
into System Use Cases?...................................................................99
Modeling System Use Cases..........................................................100
Is There a Rule of Thumb for How Many System Use Cases
a Project Would Have?..................................................................102
Case Study E3: System Use-Case Diagrams...........................................103
A) Manage Case............................................................................103
B) Administer Payments................................................................104
C) Other Business Use Cases..........................................................108
Case Study E3: Resulting Documentation....................................108
Step 1c: Begin Static Model (Class Diagrams for Key Business
Classes)....................................................................................................111
Step 1d: Set Baseline for Analysis (BRD/Initiation)...............................112
Chapter Summary...................................................................................112
chapter 6 Storyboarding the User’s Experience...................................113
Chapter Objectives.................................................................................113
Step 2: Analysis.......................................................................................113
Step 2a i: Describe System Use Cases...........................................114
The Use-Case Description Template......................................................115
The Fundamental Approach Behind the Template.....................115
Documenting the Basic Flow.................................................................118
Use-Case Writing Guidelines..................................................................118
Basic Flow Example: CPP System Review Case Report.........................120
Documenting Alternate Flows...............................................................120
Typical Alternate Flows.................................................................121
Alternate Flow Documentation...................................................121
Example of Use Case with Alternate Flows: CPP
System/Review Case Report..........................................................122
Documenting an Alternate of an Alternate................................123
Documenting Exception Flows..............................................................124
Guidelines for Conducting System Use-Case Interviews......................124
Activity Diagrams for System Use Cases................................................125
Related Artifacts.....................................................................................125
Decision Tables.......................................................................................126
The Underlying Concept...............................................................126
When Are Decision Tables Useful?...............................................126
Example of a Use Case with a Decision Table.............................127
A Step-by-Step Procedure for Using a Decision Table
During an Interview to Analyze System Behavior......................128
Case Study F1: Decision Table................................................................129
Suggestion.....................................................................................129
Case Study F1: Resulting Documentation....................................129
Decision Trees.........................................................................................130
How to Draw a Decision Tree.......................................................130
Case Study F2: Decision Tree..................................................................131
Case Study F2: Resulting Documentation....................................131
Condition/Response Table......................................................................132
Business Rules.........................................................................................133
Advanced Use-Case Features.................................................................133
Case Study F3: Advanced Use-Case Features........................................144
Problem Statement.......................................................................144
Case Study F3: Resulting Documentation....................................144
Chapter Summary...................................................................................145
chapter 7 Life Cycle Requirements for Key Business Objects..............147
Chapter Objectives.................................................................................147
What Is a State Machine Diagram?.......................................................148
Step 2a ii: 1. Identify States of Critical Objects....................................149
Types of States...............................................................................150
Case Study G1: States.............................................................................152
Case Study G1: Resulting Diagram...............................................152
Step 2a ii: 2. Identify State Transitions..................................................152
Depicting State Transitions in UML..............................................154
Mapping State Machine Diagrams to System Use Cases............156
Case Study G2: Transitions.....................................................................157
Case Study G2: Resulting Documentation...................................158
Step 2a ii: 3. Identify State Activities....................................................160
Case Study G3: State Activities..............................................................161
Case Study G3: Resulting Diagram...............................................162
Step 2a ii: 4. Identify Composite States................................................162
Case Study G4: Composite States..........................................................164
Suggestion.....................................................................................164
Case Study G4: Resulting Documentation...................................164
Step 2a ii: 5. Identify Concurrent States...............................................166
Concurrent State Example............................................................166
Chapter Summary...................................................................................167
chapter 8 Gathering Across-the-Board Rules with Class Diagrams....169
Chapter Objectives.................................................................................169
Step 2b: Static Analysis..........................................................................170
FAQs about Static Analysis............................................................171
Step 2b i: Identify Entity Classes............................................................172
FAQs about Entity Classes.............................................................172
Indicating a Class in UML..............................................................173
Naming Conventions.....................................................................174
Grouping Classes into Packages...................................................174
The Package Diagram...................................................................175
Interview Questions for Finding Classes......................................175
Challenge Questions.....................................................................176
Supporting Class Documentation.................................................177
Case Study H1: Entity Classes.................................................................178
Your Next Step...............................................................................179
Suggestions....................................................................................179
Case Study H1: Resulting Documentation...................................179
Notes on the Model......................................................................179
Step 2b ii: Model Generalizations.........................................................181
Subtyping.......................................................................................181
Generalization...............................................................................182
Case Study H2: Generalizations.............................................................186
Suggestions....................................................................................186
Case Study H2: Resulting Documentation...................................186
Notes on the Model......................................................................187
Step 2b iii: Model Transient Roles.........................................................188
Example of Transient Role............................................................189
How Does a Transient Role Differ from a Specialization?..........189
Some Terminology.........................................................................189
Why Indicate Transient Roles?......................................................189
Rules about Transient Roles..........................................................189
Indicating Transient roles..............................................................190
Sources of Information for Finding Transient Roles...................190
Interview Questions for Determining Transient Roles................190
What If a Group of Specialized Classes Can All Play the
Same Role?.....................................................................................191
Case Study H3: Transient Roles..............................................................191
Case Study H3: Resulting Documentation...................................192
Step 2b iv: Model Whole/Part Relationships........................................193
The “Whole” Truth........................................................................193
Examples of Whole/Part Relationships........................................194
Why Indicate Whole/Part Relationships?.....................................194
How Far Should You Decompose a Whole into Its Parts?..........194
Sources of Information for Finding Aggregation and
Composition...................................................................................195
Rules Regarding Aggregation and Composition........................195
Indicating Aggregation and Composition in UML......................195
The Composite Structure Diagram........................................................195
Interview Questions for Determining Aggregation and
Composition...................................................................................197
Challenge Question.......................................................................197
Case Study H4: Whole/Part Relationships.............................................199
Case Study H4: Resulting Documentation...................................199
Notes on the Model......................................................................199
Step 2b v: Analyze Associations............................................................200
Examples of Association...............................................................200
Why Indicate Association?............................................................201
Why Isn’t It the Developers’ Job to Find Associations?..............201
Discovering Associations...............................................................201
Rules Regarding Associations.......................................................201
The Association Must Reflect the Business Reality.....................202
Redundant Association Rule of Thumb.......................................204
Exception to the Rule of Thumb..................................................205
Case Study H5: Associations...................................................................208
Your Next Step...............................................................................208
Case Study H5: Resulting Documentation...................................208
Step 2b vi: Analyze Multiplicity.............................................................210
Example of Multiplicity.................................................................210
Why Indicate Multiplicity?............................................................210
Indicating Multiplicity in UML......................................................210
Rules Regarding Multiplicity........................................................210
Sources of Information for Finding Multiplicity..........................212
The Four Interview Questions for Determining Multiplicity......212
Case Study H6: Multiplicity....................................................................213
Your Next Step...............................................................................214
Case Study H6: Resulting Documentation...................................214
Chapter Summary...................................................................................217
chapter 9 Optimizing Consistency and Reuse in Requirements
Documentation......................................................................219
Chapter Objectives.................................................................................219
Where Do You Go from Here?..............................................................220
Does the Business Analyst Need to Put Every Attribute
and Operation on the Static Model?...........................................220
Step 2b vii: Link System Use Cases to the Static Model.......................221
Case Study I1: Link System Use Cases to the Static Model...................222
Suggestions....................................................................................222
Case Study I1: Results.............................................................................224
Step 2b viii: Add Attributes...................................................................225
Analyzing Attributes.....................................................................225
Example..........................................................................................227
Why Indicate Attributes?..............................................................227
Don’t Verification Rules about Attributes Belong with
the System Use-Case Documentation?.........................................227
Sources of Information for Finding Attributes............................227
Rules for Assigning Attributes......................................................228
Derived Attributes.........................................................................228
Indicating Attributes in the UML.................................................229
Meta-Attributes......................................................................................231
Case Study I2: Add Attributes................................................................232
People/Organizations....................................................................232
Events/Transactions.......................................................................233
Products and Services....................................................................233
Your Next Step...............................................................................233
Suggestions....................................................................................233
Case Study I2: Resulting Documentation.....................................234
Association Classes........................................................................234