Discovering Requirements: How to Specify Products and Services

Discovering Requirements......Page 4
Contents......Page 10
Acknowledgements......Page 18
Foreword......Page 20
Part I: Discovering Requirement Elements......Page 22
1 Introduction......Page 24
1.2 Why You Should Read This Book......Page 25
1.3 Simple but Not Easy......Page 27
1.4 Discovered, Not Found......Page 28
1.4.1 Many Different Situations......Page 30
1.5 A Softer Process, at First......Page 33
1.6.1 A Network of Requirement Elements......Page 37
1.7 A Minimum of Process: The Discovery Cycle......Page 39
1.8 The Structure of this Book......Page 41
1.8.1 Part I: Discovering Requirement Elements......Page 42
1.9.1 Books on ‘Softer’ Approaches......Page 43
1.9.2 Books on the Philosophical Background......Page 44
1.9.3 Books on ‘Harder’ Approaches......Page 45
2 Stakeholders......Page 48
2.2 Discovering Stakeholders......Page 49
2.2.2 Stakeholders in the Containing System and Wider Environment......Page 51
2.3.2 With a Template such as the Onion Model......Page 58
2.3.4 By Analysing Context......Page 61
2.4.1 Engaging with Stakeholders......Page 62
2.4.3 Analysing Influences......Page 63
2.4.4 Prioritising Stakeholders......Page 64
2.5 Validating Your List of Stakeholders......Page 66
2.7 Next Steps: Requirements from Stakeholders......Page 67
2.9 Further Reading......Page 70
3 Goals......Page 72
3.2 Discovering Goals......Page 73
3.2.1 Worked Example: Goals for a Spacecraft......Page 75
3.2.2 Worked Example: Goals for a Restaurant......Page 78
3.2.3 Worked Example: Tram Goals and Trade-offs......Page 80
3.2.4 Finding Solutions to Goal Conflicts......Page 83
3.2.5 Contexts for Discovering Goals......Page 84
3.2.6 The Negative Side......Page 86
3.3.1 Drawing Goal Diagrams......Page 89
3.3.2 Other Ways of Documenting Goals......Page 90
3.4 Validating Goals......Page 92
3.7 Exercises......Page 94
3.8.3 The i* Goal Modelling Notation......Page 95
4 Context, Interfaces, Scope......Page 96
4.2 Introduction......Page 97
4.3 A ‘Soft Systems’ Approach for Ill-Defined Boundaries......Page 98
4.3.1 You are Part of the Soft System you are Observing......Page 99
4.3.2 From Stakeholders to Boundaries......Page 100
4.3.3 Identifying Interfaces......Page 104
4.3.4 Documenting Interfaces......Page 105
4.3.5 Validating your Choice of Boundary......Page 107
4.4.2 Scope as a List of Events......Page 108
4.4.3 Expressing Event-handling Functions......Page 110
4.4.4 Strengths and Weaknesses of Context Diagrams......Page 113
4.4.5 Validating Interfaces and Events......Page 114
4.7 Exercise......Page 116
4.8.3 Writing Requirements......Page 117
5 Scenarios......Page 118
5.2 Discovering Scenarios......Page 119
5.2.1 Interviews, storytelling......Page 120
5.2.2 Scenario Workshops......Page 122
5.2.3 Discovering Negative Scenarios......Page 128
5.3 Documenting Scenarios......Page 135
5.3.1 Index Cards, User Stories......Page 136
5.3.2 Storyboards......Page 137
5.3.3 Operational Scenarios......Page 139
5.3.4 Use Cases......Page 140
5.5.1 Scenario Walkthroughs......Page 145
5.5.2 Animation, Simulation, Prototyping......Page 147
5.7 Next Steps......Page 148
5.9.2 Alternative Scenario Approaches......Page 149
5.9.4 The Principle of Commensurate Care......Page 150
6 Qualities and Constraints......Page 152
6.2.2 Qualities that Govern Choices......Page 153
6.3 Discovering Qualities and Constraints......Page 154
6.3.1 Using Goals to Discover Qualities and Constraints......Page 155
6.3.3 Using a Checklist to Discover Qualities and Constraints......Page 157
6.4 Documenting Qualities and Constraints......Page 162
6.4.1 Constraints......Page 163
6.4.2 Development (Process) Qualities......Page 167
6.4.3 Usage (Product) Qualities......Page 168
6.5 Validating Qualities and Constraints......Page 178
6.5.1 Things To Check Qualities and Constraints Against......Page 179
6.8 Exercises......Page 180
6.9 Further Reading......Page 181
7 Rationale and Assumptions......Page 182
7.2 The Value of Rationale......Page 183
7.3 Discovering Rationale and Assumptions......Page 184
7.3.1 Asking Why......Page 185
7.3.2 Looking for the word ‘will’ in vision statements, plans, etc......Page 186
7.3.3 Rationalising a Set of Requirements......Page 187
7.3.4 Inverting Risks......Page 189
7.4 Documenting Rationale......Page 190
7.4.1 Justification Text Field......Page 192
7.4.2 Lists of Assumptions, Risks, Issues and Decisions......Page 193
7.4.3 Traceability to Goals, Assumptions, etc......Page 194
7.4.4 Rationale Models......Page 199
7.4.5 The Goal Structuring Notation (GSN)......Page 203
7.5 Validating Rationale and Assumptions......Page 204
7.5.2 Analysis of Traceability......Page 205
7.5.3 Things To Check Rationale and Assumptions Against......Page 207
7.9.1 Discovering Assumptions......Page 208
7.9.6 Satisfaction Arguments......Page 209
8 Definitions......Page 210
8.2 Discovering Definitions......Page 211
8.2.1 Synonyms......Page 212
8.2.2 Homonyms......Page 214
8.3 Constructing the Project Dictionary......Page 215
8.3.2 Definitions and Designations......Page 216
8.3.3 Roles (Operational Stakeholders)......Page 220
8.3.4 Data Definitions......Page 222
8.3.5 Constraints as Data......Page 223
8.4 Validating the Project Dictionary......Page 225
8.4.1 Validating Data Models......Page 226
8.8.1 Definitions and Designations......Page 227
8.8.2 Data Modelling......Page 228
9 Measurements......Page 230
9.1 Summary......Page 231
9.2 Discovering and Documenting Acceptance Criteria......Page 232
9.2.1 Acceptance Criteria for Behavioural Requirements......Page 233
9.2.2 Acceptance Criteria for Qualities......Page 237
9.2.3 Acceptance Criteria for Constraints......Page 239
9.2.4 Verification Method......Page 240
9.3.1 Testing from Day One......Page 243
9.4 Measuring Quality of Service (QoS)......Page 244
9.4.1 Example Service: Office Carpeting......Page 245
9.4.2 Two Opposite Approaches......Page 246
9.4.3 A Spectrum of Service Approaches......Page 247
9.4.4 Worked Example: QoS Measures for Food Preparation Services......Page 249
9.5.1 Qualities of a Good QoS Measure......Page 251
9.5.2 Will your QoS Measures Work?......Page 252
9.5.4 Validating QoS with Negative Scenarios......Page 253
9.9 Further Reading......Page 254
10 Priorities......Page 256
10.2 Two Kinds of Priority......Page 257
10.3.1 Discovering Input Priority......Page 258
10.3.2 Documenting Input Priority......Page 262
10.3.3 Validating Input Priority......Page 263
10.4.1 Discovering Output Priority......Page 264
10.4.2 Documenting Output Priority......Page 272
10.4.3 Validating Output Priority......Page 274
10.5 Things To Check Priority Against......Page 275
10.9.1 Triage......Page 276
10.9.5 Life Cycles......Page 277
Part II: Discovery Contexts......Page 278
11 Requirements from Individuals......Page 280
11.2 Introduction......Page 281
11.3.1 Planning an Interview Campaign......Page 282
11.3.2 Planning Each Interview......Page 288
11.3.3 Documenting Interviews......Page 289
11.3.4 Validating Interview Findings......Page 294
11.4.1 Making Observations......Page 295
11.4.2 Being ‘Talked Through’ Operations......Page 297
11.4.3 Documenting Observations......Page 298
11.6 Exercises......Page 301
11.7.2 Using Video......Page 302
11.7.7 Philosophy......Page 303
12 Requirements from Groups......Page 304
12.2.1 Unique Capabilities......Page 305
12.2.3 Mediating Group Work (on one site or many)......Page 306
12.3.1 Define Workshop Mission......Page 307
12.3.2 Workshop Planning......Page 308
12.3.3 Workshop Rehearsal......Page 310
12.3.4 Workshop Setup......Page 311
12.3.5 Workshop Recording......Page 320
12.3.6 Validating Workshop Findings......Page 323
12.4.1 Project Wall......Page 326
12.4.2 Project Website......Page 327
12.4.3 Project Wiki......Page 328
12.4.4 Modelling Tool......Page 329
12.4.5 Requirements Management Tool......Page 330
12.4.6 Groupware and Working at a Distance......Page 331
12.4.7 The Role of Group Media......Page 333
12.7 Exercise......Page 335
12.8.2 Working in Groups......Page 336
13 Requirements from Things......Page 338
13.2 Requirements Prototyping......Page 339
13.2.2 Techniques......Page 340
13.3.1 From an Existing Product......Page 351
13.4.1 Type 1: Naïve Reuse......Page 358
13.4.4 Tool Support for Reuse......Page 359
13.8.1 Prototyping......Page 361
14 Trade-offs......Page 364
14.2.1 The Requirements-First Life-Cycle Myth......Page 365
14.2.2 An Optioneering Life Cycle......Page 366
14.2.3 The Optioneering Process......Page 371
14.2.4 Selecting the Winning Option......Page 373
14.2.5 Optioneering with PCA: A Worked Example......Page 381
14.5 Next Steps......Page 388
14.6 Exercises......Page 389
14.7.1 Trade-offs......Page 390
14.7.6 Quality Function Deployment (QFD)......Page 391
14.7.7 Questions, Options, Criteria (QOC)......Page 392
15 Putting it all Together......Page 394
15.2.1 Everything Depends on the Requirements......Page 395
15.2.2 Principles for the Requirements Chef......Page 396
15.3 The Right Process for your Project......Page 397
15.3.1 Case Study: A Retail IT Project......Page 398
15.3.2 Case Study: Transport Planning......Page 400
15.3.3 Requirements-Driven Project Management......Page 402
15.4.2 Levels......Page 406
15.4.4 Organising Product Functions......Page 407
15.4.5 Traditional ‘Shalls’......Page 408
15.4.6 Relating Requirements of Different Types......Page 409
15.4.8 The Benefit of Requirements (Traceability) Tools......Page 411
15.4.9 An Alternative View: Competing Approaches......Page 412
15.6.1 Choosing and Tailoring Development Life Cycles......Page 415
15.6.2 Managing Projects From Requirements......Page 416
15.6.4 A Look Ahead......Page 417
Appendix A: Exercise Answers and Hints......Page 418
Appendix B: Getting the Level Right......Page 426
Appendix C: Tools for Requirements Discovery......Page 432
Appendix D: Template......Page 444
Bibliography......Page 450
Glossary......Page 454
Index......Page 466