Table of Contents
Foreword Pascal Grojean xi
Preface xv
Chapter 1 Why Simplicity? 1
1.1 Solving conflicting requirements 1
1.2 Three periods in IS management 5
1.2.1 Management driven by technology 5
1.2.2 Management through cost reduction 6
1.2.3 Management through value creation 8
1.3 And now simplicity! 10
1.3.1 Technology, cost reduction, value creation So what's next? 10
1.4 Plan of the book 13
Chapter 2 Complexity, Simplicity, and Abstraction 17
2.1 What does information theory tell us? 17
2.1.1 Shannon's entropy 20
2.1.2 Kolmogorov complexity 22
2.1.2.1 Complexity of objects versus complexity of binary strings 24
2.1.2.2 Relation to Shannon's entropy 25
2.1.2.3 Can we compute K-complexity? 26
2.1.3 Bennett's logical depth 27
2.1.4 Abstraction in light of scale and depth 29
2.1.5 Harvesting information theory 31
2.2 What does the design tell us? 33
2.2.1 Simplicity by reduction 36
2.2.2 Simplicity by hiding complexity 38
2.2.2.1 Customers 40
2.2.2.2 Business analysts 40
2.2.2.3 IT personnel 41
2.2.3 Simplicity through organization 42
2.2.4 Simplicity through learning 45
2.2.4.1 Learning obviates the need to hide complexity 45
2.2.4.2 Learning allows complexity transformation 48
2.2.5 Simplicity implies time saving 49
2.2.5.1 Lack of time 49
2.2.5.2 How simplicity saves time 50
2.2.6 Simplicity needs trust 51
2.2.7 What does software architecture tell us? 53
2.2.7.1 The complexity of code and of IS architecture 54
2.2.8 Abstraction in software engineering 60
2.2.8.1 Abstraction is everywhere in software 60
2.2.8.2 Depth and scale revisited 60
Chapter 3 Value or Values? 77
3.1 Who is concerned? 79
3.1.1 Internal stakeholders 79
3.1.2 External stakeholders 80
3.2 Concepts of value for an IS 80
3.2.1 Bookvalue 81
3.2.2 Net worth 82
3.2.3 Use value 83
3.2.3.1 Functional criterion 84
3.2.3.2 Non-functional criteria 84
3.2.4 Strategic value 86
3.2.5 Sustainability value 87
3.3 Are these values sufficient and independent? 90
3.3.1 IT chaos 92
3.3.2 Tech academy 92
3.3.3 Alignment trap 92
3.3.4 Users are unimportant 93
3.3.5 Business-user tyranny 93
3.3.6 Wrong direction 94
3.3.7 Architecture is a waste of money 94
3.3.8 IS heaven 95
Chapter 4 Promoting Value Through Simplicity 97
4.1 Growing technical heterogeneity 100
4.1.1 Openness 104
4.1.1.1 Why complexity increases 105
4.1.1.2 Implementing simplicity 105
4.1.2 Rapid obsolescence of IT 106
4.1.2.1 Why complexity increases 110
4.1.2.2 Implementing simplicity 113
4.1.3 Absence of technological vision and leadership 118
4.1.3.1 Why complexity increases 118
4.1.3.2 Implementing simplicity 120
4.2 Changing requirements 121
4.2.1 Why complexity increases 123
4.2.2 Implementing simplicity 125
4.2.2.1 Technical answers 125
4.2.2.2 Organizational answers 129
4.3 Human factors 131
4.3.1 Multidisciplinarity 132
4.3.1.1 Why complexity increases 132
4.3.1.2 Implementing simplicity 135
4.3.2 Disempowerment of IT Skills 136
4.3.2.1 Why complexity increases 136
4.3.2.2 Implementing simplicity 140
4.3.3 Local interest is not global interest 143
4.3.3.1 Why complexity increases 143
4.3.3.2 Implementing simplicity 145
Chapter 5 Simplicity Best Practices 149
5.1 Putting simplicity principles into practice 149
5.2 Defining a generic IS 149
5.3 A simplicity framework 152
5.3.1 Simplicity in hardware 153
5.3.1.1 Growing technical heterogeneity 153
5.3.1.2 Changing requirements 155
5.3.1.3 Human factors 155
5.3.2 Simplicity in software - data access 156
5.3.2.1 Growing technical heterogeneity 156
5.3.2.2 Changing requirements 158
5.3.2.3 Human factors 159
5.3.3 Simplicity in software - services 160
5.3.3.1 Growing technical heterogeneity 161
5.3.3.2Changing requirements 162
5.3.3.3 Human factors 163
5.3.4 Simplicity in software-user interface 165
5.3.4.1 Growing technical heterogeneity 165
5.3.4.2 Changing requirements 166
5.3.4.3 Human factors 167
5.3.5 Simplicity in Functional Architecture 169
5.3.5.1 Growing technical heterogeneity 169
5.3.5.2 Changing requirements 169
5.3.5.3 Human factors 170
Conclusion 173
Appendices 177
Appendix 1 Digging into Information Theory 179
A1.1 Shannon entropy 179
A1.2 Shannon entropy in short 182
A1.3 Kolmogorov complexity 183
A1.4 Choosing a scale of description 186
A1.5 Relation to Shannon entropy 187
A1.6 Computing the Kolmogorov complexity 187
A1.7 Kolmogorov complexity in short 189
A1.8 Bennett's logical depth 189
A1.9 Bennett's logical depth in short 192
Appendix 2 Two Measures of Code Complexity 195
A2.1 Cyclomatic complexity 195
A2.2 An example of a scale-invariant complexity measure 198
A2.3 Conclusion 204
Appendix 3 Why Has SOA Failed So Often? 207
A.3.1 The need for flexibility 207
A.3.2 First issue: no suitable enterprise architecture 208
A.3.3 Second issue: no data integration 209
A.3.4 Identifying the operating model 210
A.3.4.1 Data integration 211
A.3.4.2 Process standardization 212
A.3.5 Which models are compatible with SOA? 213
A.3.5.1 Diversification model 214
A.3.5.2 Replication model 215
A.3.5.3 Coordination model 215
A.3.5.4 Unification model 216
A.3.6 Conclusion on SOA 217
Bibliography 219
Index 221
