Architecture Principles (eBook)

Danny Greefhorst is a principal consultant and owner of ArchiXL, and works for clients in the financial and public sector. Danny acts as an IT architect and IT consultant, and is TOGAF 9 certified. He has extensive experience with the definition and implementation of enterprise architectures, application architectures and technical architectures. In addition, he coaches organizations in setting up and executing their architecture function, and is active as an instructor for several classes on architecture. Before starting ArchiXL he worked as a principal consultant at Yellowtail, as a senior IT architect at IBM Business Consulting Services and as a researcher at the Software Engineering Research Centre. Danny is active in the architecture community and regularly publishes on IT and architecture related topics. He is the chairman of the governing board of Via Nova Architectura, a portal and electronic magazine on enterprise architecture. He is also a member of the governing board of the architecture department of the Dutch Computer Science Association (Ngi).Erik (H.A.) Proper is a senior research manager at the Public Research Centre -- Henri Tudor in Luxembourg, where he leads Services-oriented Enterprise Engineering programme. He also holds a chair in Information Systems at the Radboud University Nijmegen in the Netherlands. Erik has a mixed industrial and academic background. In the past, Erik worked for companies such as Asymetrix, InfoModeller, Origin, ID Research, Ordina and Capgemini, while interleaving this with his work at research institutions such as the Radboud University of Nijmegen, Queensland University of Technology, the Distributed Systems Technology Centre, and the University of Queensland. His general research drive is the modeling of systems. He applies this drive mainly in the fields of service science, enterprise modeling, enterprise engineering and enterprise architecting. He was co-initiator of the ArchiMate project, and currently also serves on the board of the ArchiMate forum of The Open Group. Erik is also one of the editors in chief of Springer's series on enterprise engineering.

Foreword 5
Preface 7
Acknowledgements 8
Contents 9
Chapter 1: Introduction 14
1.1 Challenges to Enterprises 14
1.2 Enterprise Architecture and Architecture Principles 16
1.3 Motivations and Target Audience 17
1.4 Outline of the Book 18
Chapter 2: The Role of Enterprise Architecture 20
2.1 Introduction 20
2.2 Enterprise Transformations and Enterprise Engineering 22
2.3 Streams of Activities in Enterprise Engineering 24
2.4 Architecture-Based Governance of Enterprise Transformations 27
2.4.1 The Need for Architecture 27
2.4.2 Architecture as a Bridge from Strategy to Design 29
2.4.3 Steering with Architecture 31
2.4.4 The Three Roles of Enterprise Architecture 32
2.5 Defining Enterprise Architecture 33
2.5.1 The Purpose of an Enterprise Architecture 34
2.5.2 The Meaning of an Enterprise Architecture 35
2.5.3 The Elements of an Enterprise Architecture 35
2.5.4 Definition of Enterprise Architecture 37
2.6 Other Forms of Architecture 37
2.7 Standards for Enterprise Architecture 39
2.8 The Role of Architecture Principles 41
2.9 Key Messages 42
Chapter 3: A Conceptual Framework for Principles 43
3.1 Introduction 43
3.2 Background of Architecture Principles 44
3.3 Key Classes of Principles 46
3.3.1 Scientific Principles 46
3.3.2 Design Principles as Normative Principles 47
3.3.3 From Credos to Norms 50
3.3.4 Conceptual Framework 52
3.4 Architecture Principles as Pillars from Strategy to Design 56
3.4.1 Architecture Principles 56
3.4.2 Business and IT Principles 56
3.4.3 Bridging from Strategy to Design 58
3.4.4 Extended Conceptual Framework 60
3.5 Motivating Architecture Principles 61
3.5.1 Sources for Finding Motivation 62
3.5.2 Drivers as Motivation for Architecture Principles 64
3.5.3 Extended Conceptual Framework 66
3.6 Formal Specification of Normative Principles 68
3.7 Key Messages 70
Chapter 4: Architecture Principle Specifications 71
4.1 Introduction 71
4.2 Dimensions in Architecture Principles 74
4.2.1 Type of Information Dimension 75
4.2.2 Scope Dimension 75
4.2.3 Genericity Dimension 76
4.2.4 Level of Detail Dimension(s) 77
4.2.5 Stakeholder Dimension 78
4.2.6 Transformation Dimension 78
4.2.7 Quality Attribute Dimension 79
4.2.8 Meta-level Dimension 81
4.2.9 Representation Dimension 81
4.3 Attributes 82
4.3.1 Basic Structure 83
4.3.2 Advised Attributes 85
4.3.3 Attributes for Classification 87
4.3.4 Potential Attributes 87
4.3.5 Generic Meta-data Attributes 88
4.3.6 Relationships 89
4.4 Architecture Principle Sets 91
4.5 Quality Criteria 93
4.6 Key Messages 95
Chapter 5: A Practical Approach 96
5.1 Introduction 96
5.2 Generic Process 99
5.2.1 Determine Drivers 99
5.2.1.1 Example: Determining Drivers for EnsureIt 101
5.2.2 Determine Principles 102
5.2.2.1 Generate Candidate Principles 102
5.2.2.2 Select Relevant Principles 104
5.2.2.3 Formulate Principle Statements 107
5.2.2.4 Example: Determining Architecture Principles for EnsureIt 107
5.2.3 Specify Principles 109
5.2.3.1 Example: Specifying Architecture Principles for EnsureIt 110
5.2.4 Classify Principles 111
5.2.4.1 Example: Classifying Architecture Principles for EnsureIt 111
5.2.5 Validate and Accept Principles 111
5.2.5.1 Example: Validating Principles for EnsureIt 112
5.2.6 Apply Principles 112
5.2.6.1 Transformation 113
5.2.6.2 Example: Transforming an Architecture Principle for EnsureIt 114
5.2.6.3 Architectural Knowledge Management 115
5.2.7 Manage Compliance 116
5.2.7.1 Example: Reviewing Principles for EnsureIt 118
5.2.8 Handle Changes 119
5.2.8.1 Example: Handling Changes for EnsureIt 120
5.3 Key Messages 120
Chapter 6: Case Studies 121
6.1 Introduction 121
6.2 ICTU 122
6.2.1 Introduction 122
6.2.2 Architecture Principles 123
6.2.3 Approach 125
6.3 CVZ 125
6.3.1 Introduction 125
6.3.2 Architecture Principles 127
6.3.3 Approach 128
6.4 Enexis 130
6.4.1 Introduction 130
6.4.2 Architecture Principles 131
6.4.3 Approach 131
6.5 TKP Pensioen 134
6.5.1 Introduction 134
6.5.2 Architecture Principles 135
6.5.3 Approach 137
6.6 Schiphol 137
6.6.1 Introduction 138
6.6.2 Architecture Principles 139
6.6.2.1 Principle: Reuse Before Buy Before Build 139
6.6.2.2 Principle: Adhere to the Corporate Data Model 140
6.6.3 Approach 140
6.7 Key Messages 142
Chapter 7: Architecture Principles in Context 143
7.1 Introduction 143
7.2 Types of Architectures 144
7.2.1 Enterprise Architecture Development 144
7.2.2 Reference Architecture Development 145
7.2.3 Solution Architecture Development 146
7.3 Architecture Maturity 147
7.3.1 Department of Commerce Maturity Model 147
7.3.2 Architecture Maturity and Architecture Principles 149
7.4 Culture 152
7.5 Key Messages 155
Chapter 8: Summary, Conclusions and Future Work 156
8.1 Summary and Conclusions 156
8.2 Future Work 158
Appendix A Principles Catalogue 161
Abstract 161
A.1 Business Units Are Autonomous 161
A.2 Customers Have a Single Point of Contact 162
A.3 Stock Is Kept to a Minimum 162
A.4 Processes Are Straight Through 163
A.5 Processes Are Standardized 163
A.6 Management Layers Are Minimized 164
A.7 Tasks Are Designed Around Outcome 164
A.8 Routine Tasks Are Automated 164
A.9 Primary Business Processes Are not Disturbed by Implementation of Changes 165
A.10 Components Are Centralized 165
A.11 Front-Office Processes Are Separated from Back-Office Processes 166
A.12 Channel-Specific Is Separated from Channel-Independent 166
A.13 The Status of Customer Requests Is Readily Available Inside and Outside the Organization 167
A.14 Data Are Provided by the Source 167
A.15 Data Are Maintained in The Source Application 167
A.16 Data Are Captured Once 168
A.17 Data Are Consistent Through All Channels 168
A.18 Content and Presentation Are Separated 169
A.19 Data Are Stored and Exchanged Electronically 169
A.20 Data That Are Exchanged Adhere to a Canonical Data Model 170
A.21 Data Are Exchanged in Real-Time 170
A.22 Bulk Data Exchanges Rely on ETL Tools 171
A.23 Documents Are Stored in the Document Management System 171
A.24 Reporting and Analytical Applications Do Not Use the Operational Environment 172
A.25 Applications Have a Common Look-and-Feel 172
A.26 Applications Do Not Cross Business Function Boundaries 172
A.27 Applications Respect Logical Units of Work 173
A.28 Applications Are Modular 173
A.29 Application Functionality is Available Through an Enterprise Portal 174
A.30 Applications Rely on One Technology Stack 174
A.31 Application Interfaces Are Explicitly Defined 175
A.32 Proven Solutions Are Preferred 175
A.33 IT Systems Are Scaleable 176
A.34 Only in Response to Business Needs Are Changes to IT Systems Made 176
A.35 Components Have a Clear Owner 177
A.36 IT Systems Are Standardized and Reused Throughout the Organization 177
A.37 IT Systems Adhere to Open Standards 178
A.38 IT Systems Are Preferably Open Source 178
A.39 IT Systems Are Available at Any Time on Any Location 179
A.40 IT Systems Are Sustainable 179
A.41 Processes Are Supported by a Business Process Management System 179
A.42 Presentation Logic, Process Logic and Business Logic Are Separated 180
A.43 IT Systems Communicate Through Services 180
A.44 Reuse Is Preferable to Buy, Which is Preferable to Make 181
A.45 IT Systems Support 24*7 Availability 181
A.46 IT Systems Are Selected Based on a Best-of-Suite Approach 182
A.47 Sensitive Data Are Exchanged Securely 182
A.48 IT Systems May Under no Circumstances Revert to Insecure Mode 183
A.49 Management of IT Systems is Automated as Much as Possible 183
A.50 End-to-End Security Must Be Provided Using Multiple Defensive Strategies 184
A.51 Access Rights Must Be Granted at the Lowest Level Necessary for Performing the Required Operation 184
A.52 Authorizations Are Role-Based 185
A.53 The Identity Management Environment Is Leading for All Authentications and Authorizations 185
A.54 Security Is Defined Declaratively 185
A.55 Access to IT Systems Is Authenticated and Authorized 186
A.56 Integration with External IT Systems Is Localized in Dedicated IT Components 186
A.57 Application Development Is Standardized 187
A.58 All Messages Are Exchanged Through the Enterprise Service Bus 187
A.59 Rules That Are Complex or Apt to Change Are Managed in a Business Rules Engine 188
Appendix B Architecture Principles in TOGAF 189
Abstract 189
B.1 Architecture Principles in TOGAF 189
B.2 Architecture Principles in TOGAF ADM 190
B.3 Mapping the Generic Process to TOGAF's ADM 192
Glossary 194
References 196
About the Authors 204
Danny Greefhorst 204
Erik (H.A.) Proper 204