Published by Pearson (December 23, 2016) © 2017
Thomas Erl
The Top-Selling, De Facto Guide to SOA--Now Updated with New Content and Coverage of Microservices!
For more than a decade, Thomas Erl’s best-selling Service-Oriented Architecture: Concepts, Technology, and Design has been the definitive end-to-end tutorial on SOA, service-orientation, and service technologies. Now, Erl has thoroughly updated the industry’s de facto guide to SOA to reflect new practices, technologies, and strategies that have emerged through hard-won experience and creative innovation.
This Second Edition officially introduces microservices and micro task abstraction as part of service-oriented architecture and its associated service layers. Updated case study examples and illustrations further explain and position the microservice model alongside and in relation to more traditional types of services.
Coverage includes:
• Easy-to-understand, plain English explanations of SOA and service-orientation fundamentals (as compiled from series titles)
• Microservices, micro task abstraction, and containerization
• Service delivery lifecycle and associated phases
• Analysis and conceptualization of services and microservices
• Service API design with REST services, web services, and microservices
• Modern service API and contract versioning techniques for web services and REST services
• Up-to-date appendices with service-orientation principles, REST constraints, and SOA patterns (including three new patterns)
Service-Oriented Architecture: Analysis and Design for Services and Microservices, Second Edition, will be indispensable to application architects, enterprise architects, software developers, and any IT professionals interested in learning about or responsible for designing or implementing modern-day, service-oriented solutions.
Chapter 1: Introduction
Chapter 2: Case Study Backgrounds
Part I: Fundamentals
Chapter 3: Understanding Service-Orientation
Chapter 4: Understanding SOA
Chapter 5: Understanding Layers with Services and Microservices
Part II: Service-Oriented Analysis and Design
Chapter 6: Analysis and Modeling with Web Services and Microservices
Chapter 7: Analysis and Modeling with REST Services and Microservices
Chapter 8: Service API and Contract Design with Web Services
Chapter 9: Service API and Contract Design with REST Services and Microservices
Chapter 10: Service API and Contract Versioning with Web Services and REST Services
Part III: Appendices
Appendix A: Service-Orientation Principles Reference
Appendix B: REST Constraints Reference
Appendix C: SOA Design Patterns Reference
Appendix D: The Annotated SOA Manifesto
For more than a decade, Thomas Erl’s best-selling Service-Oriented Architecture: Concepts, Technology, and Design has been the definitive end-to-end tutorial on SOA, service-orientation, and service technologies. Now, Erl has thoroughly updated the industry’s de facto guide to SOA to reflect new practices, technologies, and strategies that have emerged through hard-won experience and creative innovation.
This Second Edition officially introduces microservices and micro task abstraction as part of service-oriented architecture and its associated service layers. Updated case study examples and illustrations further explain and position the microservice model alongside and in relation to more traditional types of services.
Coverage includes:
• Easy-to-understand, plain English explanations of SOA and service-orientation fundamentals (as compiled from series titles)
• Microservices, micro task abstraction, and containerization
• Service delivery lifecycle and associated phases
• Analysis and conceptualization of services and microservices
• Service API design with REST services, web services, and microservices
• Modern service API and contract versioning techniques for web services and REST services
• Up-to-date appendices with service-orientation principles, REST constraints, and SOA patterns (including three new patterns)
Service-Oriented Architecture: Analysis and Design for Services and Microservices, Second Edition, will be indispensable to application architects, enterprise architects, software developers, and any IT professionals interested in learning about or responsible for designing or implementing modern-day, service-oriented solutions.
Chapter 1: Introduction
Chapter 2: Case Study Backgrounds
Part I: Fundamentals
Chapter 3: Understanding Service-Orientation
Chapter 4: Understanding SOA
Chapter 5: Understanding Layers with Services and Microservices
Part II: Service-Oriented Analysis and Design
Chapter 6: Analysis and Modeling with Web Services and Microservices
Chapter 7: Analysis and Modeling with REST Services and Microservices
Chapter 8: Service API and Contract Design with Web Services
Chapter 9: Service API and Contract Design with REST Services and Microservices
Chapter 10: Service API and Contract Versioning with Web Services and REST Services
Part III: Appendices
Appendix A: Service-Orientation Principles Reference
Appendix B: REST Constraints Reference
Appendix C: SOA Design Patterns Reference
Appendix D: The Annotated SOA Manifesto
Chapter 1: Introduction 1
1.1 How Patterns Are Used in this Book 3
1.2 Series Books That Cover Topics from the First Edition 4
1.3 How this Book Is Organized 6
Part I: Fundamentals 6
Chapter 3: Understanding Service-Orientation 6
Chapter 4: Understanding SOA 6
Chapter 5: Understanding Layers with Services and Microservices 6
Part II: Service-Oriented Analysis and Design 7
Chapter 6: Analysis and Modeling with Web Services and Microservices 7
Chapter 7: Analysis and Modeling with REST Services and Microservices 7
Chapter 8: Service API and Contract Design with Web Services 7
Chapter 9: Service API and Contract Design with REST Services and Microservices 7
Chapter 10: Service API and Contract Versioning with Web Services and REST Services 7
Part III: Appendices 7
Appendix A: Service-Orientation Principles Reference 7
Appendix B: REST Constraints Reference 7
Appendix C: SOA Design Patterns Reference 8
Appendix D: The Annotated SOA Manifesto 8
1.4 Page References and Capitalization for Principles, Constraints, and Patterns 8
Additional Information 9
Symbol Legend 9
Updates, Errata, and Resources (www.servicetechbooks.com) 9
Service-Orientation (www.serviceorientation.com) 10
What Is REST? (www.whatisrest.com) 10
Referenced Specifications (www.servicetechspecs.com) 10
SOASchool.com SOA Certified Professional (SOACP) 10
CloudSchool.com Cloud Certified Professional (CCP) 10
BigDataScienceSchool.com Big Data Science Certified Professional (BDSCP) 11
Notification Service 11
Chapter 2: Case Study Backgrounds 13
2.1 How Case Studies Are Used 14
2.2 Case Study Background #1: Transit Line Systems, Inc. 14
2.3 Case Study Background #2: Midwest University Association 15
PART I: FUNDAMENTALS
Chapter 3: Understanding Service-Orientation 19
3.1 Introduction to Service-Orientation 20
Services in Business Automation 21
Services Are Collections of Capabilities 22
Service-Orientation as a Design Paradigm 24
Service-Orientation Design Principles 26
3.2 Problems Solved by Service-Orientation 29
Silo-based Application Architecture 29
It Can Be Highly Wasteful 31
It’s Not as Efficient as It Appears 32
It Bloats an Enterprise 32
It Can Result in Complex Infrastructures and Convoluted Enterprise Architectures 33
Integration Becomes a Constant Challenge 34
The Need for Service-Orientation 34
Increased Amounts of Reusable Solution Logic 35
Reduced Amounts of Application-Specific Logic 36
Reduced Volume of Logic Overall 36
Inherent Interoperability 37
3.3 Effects of Service-Orientation on the Enterprise 38
Service-Orientation and the Concept of “Application” 38
Service-Orientation and the Concept of “Integration” 40
The Service Composition 42
3.4 Goals and Benefits of Service-Oriented Computing 43
Increased Intrinsic Interoperability 44
Increased Federation 46
Increased Vendor Diversification Options 47
Increased Business and Technology Domain Alignment 48
Increased ROI 48
Increased Organizational Agility 50
Reduced IT Burden 52
3.5 Four Pillars of Service-Orientation 54
Teamwork 54
Education 55
Discipline 55
Balanced Scope 55
Chapter 4: Understanding SOA 59
Introduction to SOA 60
4.1 The Four Characteristics of SOA 61
Business-Driven 61
Vendor-Neutral 63
Enterprise-Centric 66
Composition-Centric 68
Design Priorities 69
4.2 The Four Common Types of SOA 70
Service Architecture 71
Service Composition Architecture 77
Service Inventory Architecture 83
Service-Oriented Enterprise Architecture 85
4.3 The End Result of Service-Orientation and SOA 86
4.4 SOA Project and Lifecycle Stages 91
Methodology and Project Delivery Strategies 91
SOA Project Stages 94
SOA Adoption Planning 95
Service Inventory Analysis 96
Service-Oriented Analysis (Service Modeling) 97
Step 1: Define Business Automation Requirements 99
Step 2: Identify Existing Automation Systems 99
Step 3: Model Candidate Services 100
Service-Oriented Design (Service Contract) 101
Service Logic Design 103
Service Development 103
Service Testing 103
Service Deployment and Maintenance 105
Service Usage and Monitoring 105
Service Discovery 106
Service Versioning and Retirement 106
Project Stages and Organizational Roles 107
Chapter 5: Understanding Layers with Services and Microservices 111
5.1 Introduction to Service Layers 113
Service Models and Service Layers 113
Service and Service Capability Candidates 115
5.2 Breaking Down the Business Problem 115
Functional Decomposition 115
Service Encapsulation 116
Agnostic Context 117
Agnostic Capability 119
Utility Abstraction 120
Entity Abstraction 121
Non-Agnostic Context 122
Micro Task Abstraction and Microservices 123
Process Abstraction and Task Services 123
5.3 Building Up the Service-Oriented Solution 124
Service-Orientation and Service Composition 124
Capability Composition and Capability Recomposition 127
Capability Composition 129
Capability Composition and Microservices 130
Capability Recomposition 132
Logic Centralization and Service Normalization 134
PART II: SERVICE-ORIENTED ANALYSIS AND DESIGN
Chapter 6: Analysis and Modeling with Web Services and Microservices 139
6.1 Web Service Modeling Process 140
Case Study Example 141
Step 1: Decompose the Business Process (into Granular Actions) 142
Case Study Example 142
Step 2: Filter Out Unsuitable Actions 144
Case Study Example 145
Step 3: Define Entity Service Candidates 146
Case Study Example 146
Step 4: Identify Process-Specific Logic 149
Case Study Example 149
Step 5: Apply Service-Orientation 150
Step 6: Identify Service Composition Candidates 151
Case Study Example 151
Step 7: Analyze Processing Requirements 152
Case Study Example 152
Step 8: Define Utility Service Candidates 153
Case Study Example 154
Step 9: Define Microservice Candidates 154
Case Study Example 155
Step 10: Apply Service-Orientation 155
Step 11: Revise Service Composition Candidates 156
Case Study Example 156
Step 12: Revise Capability Candidate Grouping 157
Chapter 7: Analysis and Modeling with REST Services and Microservices 159
7.1 REST Service Modeling Process 160
Case Study Example 162
Step 1: Decompose Business Process (into Granular Actions) 164
Case Study Example 164
Step 2: Filter Out Unsuitable Actions 165
Case Study Example 165
Step 3: Define Entity Service Candidates 166
Case Study Example 167
Step 4: Identify Process-Specific Logic 169
Case Study Example 169
Step 5: Identify Resources 170
Case Study Example 171
Step 6: Associate Service Capabilities with Resources and Methods 172
Case Study Example 173
Step 7: Apply Service-Orientation 174
Case Study Example 174
Step 8: Identify Service Composition Candidates 175
Case Study Example 175
Step 9: Analyze Processing Requirements 176
Case Study Example 177
Step 10: Define Utility Service Candidates (and Associate Resources and Methods) 178
Case Study Example 179
Step 11: Define Microservice Candidates (and Associate Resources and Methods) 180
Case Study Example 181
Step 12: Apply Service-Orientation 181
Step 13: Revise Candidate Service Compositions 181
Case Study Example 182
Step 14: Revise Resource Definitions and Capability Candidate Grouping 182
7.2 Additional Considerations 183
Uniform Contract Modeling and REST Service Inventory Modeling 183
REST Constraints and Uniform Contract Modeling 186
REST Service Capability Granularity 188
Resources vs. Entities 189
Chapter 8: Service API and Contract Design with Web Services 191
8.1 Service Model Design Considerations 193
Entity Service Design 193
Utility Service Design 194
Microservice Design 196
Task Service Design 196
Case Study Example 198
8.2 Web Service Design Guidelines 208
Apply Naming Standards 208
Apply a Suitable Level of Contract API Granularity 210
Case Study Example 212
Design Web Service Operations to Be Inherently Extensible 212
Case Study Example 213
Consider Using Modular WSDL Documents 214
Case Study Example 214
Use Namespaces Carefully 215
Case Study Example 215
Use the SOAP Document and Literal Attribute Values 216
Case Study Example 217
Chapter 9: Service API and Contract Design with REST Services and Microservices 219
9.1 Service Model Design Considerations 221
Entity Service Design 221
Utility Service Design 222
Microservice Design 223
Task Service Design 225
Case Study Example 226
9.2 REST Service Design Guidelines 231
Uniform Contract Design Considerations 231
Designing and Standardizing Methods 231
Designing and Standardizing HTTP Headers 233
Designing and Standardizing HTTP Response Codes 235
Customizing Response Codes 240
Designing Media Types 242
Designing Schemas for Media Types 244
Complex Method Design 246
Stateless Complex Methods 249
Fetch Method 249
Store Method 250
Delta Method 252
Async Method 254
Stateful Complex Methods 256
Trans Method 256
PubSub Method 257
Case Study Example 259
Chapter 10: Service API and Contract Versioning with Web Services and REST Services 263
10.1 Versioning Basics 265
Versioning Web Services 265
Versioning REST Services 266
Fine and Coarse-Grained Constraints 266
10.2 Versioning and Compatibility 267
Backwards Compatibility 267
Backwards Compatibility in Web Services 267
Backwards Compatibility in REST Services 268
Forwards Compatibility 271
Compatible Changes 273
Incompatible Changes 275
10.3 REST Service Compatibility Considerations 276
10.4 Version Identifiers 279
10.5 Versioning Strategies 282
The Strict Strategy (New Change, New Contract) 282
Pros and Cons 283
The Flexible Strategy (Backwards Compatibility) 283
Pros and Cons 284
The Loose Strategy (Backwards and Forwards Compatibility) 284
Pros and Cons 284
Strategy Summary 285
10.6 REST Service Versioning Considerations 286
PART III: APPENDICES
Appendix A: Service-Orientation Principles Reference 289
Appendix B: REST Constraints Reference 305
Appendix C: SOA Design Patterns Reference 317
What’s a Design Pattern? 318
What’s a Design Pattern Language? 320
Pattern Profiles 321
Appendix D: The Annotated SOA Manifesto 367
The SOA Manifesto 368
The SOA Manifesto Explored 369
Preamble 370
Priorities 371
Guiding Principles 375
About the Author 383
Index 384
1.1 How Patterns Are Used in this Book 3
1.2 Series Books That Cover Topics from the First Edition 4
1.3 How this Book Is Organized 6
Part I: Fundamentals 6
Chapter 3: Understanding Service-Orientation 6
Chapter 4: Understanding SOA 6
Chapter 5: Understanding Layers with Services and Microservices 6
Part II: Service-Oriented Analysis and Design 7
Chapter 6: Analysis and Modeling with Web Services and Microservices 7
Chapter 7: Analysis and Modeling with REST Services and Microservices 7
Chapter 8: Service API and Contract Design with Web Services 7
Chapter 9: Service API and Contract Design with REST Services and Microservices 7
Chapter 10: Service API and Contract Versioning with Web Services and REST Services 7
Part III: Appendices 7
Appendix A: Service-Orientation Principles Reference 7
Appendix B: REST Constraints Reference 7
Appendix C: SOA Design Patterns Reference 8
Appendix D: The Annotated SOA Manifesto 8
1.4 Page References and Capitalization for Principles, Constraints, and Patterns 8
Additional Information 9
Symbol Legend 9
Updates, Errata, and Resources (www.servicetechbooks.com) 9
Service-Orientation (www.serviceorientation.com) 10
What Is REST? (www.whatisrest.com) 10
Referenced Specifications (www.servicetechspecs.com) 10
SOASchool.com SOA Certified Professional (SOACP) 10
CloudSchool.com Cloud Certified Professional (CCP) 10
BigDataScienceSchool.com Big Data Science Certified Professional (BDSCP) 11
Notification Service 11
Chapter 2: Case Study Backgrounds 13
2.1 How Case Studies Are Used 14
2.2 Case Study Background #1: Transit Line Systems, Inc. 14
2.3 Case Study Background #2: Midwest University Association 15
PART I: FUNDAMENTALS
Chapter 3: Understanding Service-Orientation 19
3.1 Introduction to Service-Orientation 20
Services in Business Automation 21
Services Are Collections of Capabilities 22
Service-Orientation as a Design Paradigm 24
Service-Orientation Design Principles 26
3.2 Problems Solved by Service-Orientation 29
Silo-based Application Architecture 29
It Can Be Highly Wasteful 31
It’s Not as Efficient as It Appears 32
It Bloats an Enterprise 32
It Can Result in Complex Infrastructures and Convoluted Enterprise Architectures 33
Integration Becomes a Constant Challenge 34
The Need for Service-Orientation 34
Increased Amounts of Reusable Solution Logic 35
Reduced Amounts of Application-Specific Logic 36
Reduced Volume of Logic Overall 36
Inherent Interoperability 37
3.3 Effects of Service-Orientation on the Enterprise 38
Service-Orientation and the Concept of “Application” 38
Service-Orientation and the Concept of “Integration” 40
The Service Composition 42
3.4 Goals and Benefits of Service-Oriented Computing 43
Increased Intrinsic Interoperability 44
Increased Federation 46
Increased Vendor Diversification Options 47
Increased Business and Technology Domain Alignment 48
Increased ROI 48
Increased Organizational Agility 50
Reduced IT Burden 52
3.5 Four Pillars of Service-Orientation 54
Teamwork 54
Education 55
Discipline 55
Balanced Scope 55
Chapter 4: Understanding SOA 59
Introduction to SOA 60
4.1 The Four Characteristics of SOA 61
Business-Driven 61
Vendor-Neutral 63
Enterprise-Centric 66
Composition-Centric 68
Design Priorities 69
4.2 The Four Common Types of SOA 70
Service Architecture 71
Service Composition Architecture 77
Service Inventory Architecture 83
Service-Oriented Enterprise Architecture 85
4.3 The End Result of Service-Orientation and SOA 86
4.4 SOA Project and Lifecycle Stages 91
Methodology and Project Delivery Strategies 91
SOA Project Stages 94
SOA Adoption Planning 95
Service Inventory Analysis 96
Service-Oriented Analysis (Service Modeling) 97
Step 1: Define Business Automation Requirements 99
Step 2: Identify Existing Automation Systems 99
Step 3: Model Candidate Services 100
Service-Oriented Design (Service Contract) 101
Service Logic Design 103
Service Development 103
Service Testing 103
Service Deployment and Maintenance 105
Service Usage and Monitoring 105
Service Discovery 106
Service Versioning and Retirement 106
Project Stages and Organizational Roles 107
Chapter 5: Understanding Layers with Services and Microservices 111
5.1 Introduction to Service Layers 113
Service Models and Service Layers 113
Service and Service Capability Candidates 115
5.2 Breaking Down the Business Problem 115
Functional Decomposition 115
Service Encapsulation 116
Agnostic Context 117
Agnostic Capability 119
Utility Abstraction 120
Entity Abstraction 121
Non-Agnostic Context 122
Micro Task Abstraction and Microservices 123
Process Abstraction and Task Services 123
5.3 Building Up the Service-Oriented Solution 124
Service-Orientation and Service Composition 124
Capability Composition and Capability Recomposition 127
Capability Composition 129
Capability Composition and Microservices 130
Capability Recomposition 132
Logic Centralization and Service Normalization 134
PART II: SERVICE-ORIENTED ANALYSIS AND DESIGN
Chapter 6: Analysis and Modeling with Web Services and Microservices 139
6.1 Web Service Modeling Process 140
Case Study Example 141
Step 1: Decompose the Business Process (into Granular Actions) 142
Case Study Example 142
Step 2: Filter Out Unsuitable Actions 144
Case Study Example 145
Step 3: Define Entity Service Candidates 146
Case Study Example 146
Step 4: Identify Process-Specific Logic 149
Case Study Example 149
Step 5: Apply Service-Orientation 150
Step 6: Identify Service Composition Candidates 151
Case Study Example 151
Step 7: Analyze Processing Requirements 152
Case Study Example 152
Step 8: Define Utility Service Candidates 153
Case Study Example 154
Step 9: Define Microservice Candidates 154
Case Study Example 155
Step 10: Apply Service-Orientation 155
Step 11: Revise Service Composition Candidates 156
Case Study Example 156
Step 12: Revise Capability Candidate Grouping 157
Chapter 7: Analysis and Modeling with REST Services and Microservices 159
7.1 REST Service Modeling Process 160
Case Study Example 162
Step 1: Decompose Business Process (into Granular Actions) 164
Case Study Example 164
Step 2: Filter Out Unsuitable Actions 165
Case Study Example 165
Step 3: Define Entity Service Candidates 166
Case Study Example 167
Step 4: Identify Process-Specific Logic 169
Case Study Example 169
Step 5: Identify Resources 170
Case Study Example 171
Step 6: Associate Service Capabilities with Resources and Methods 172
Case Study Example 173
Step 7: Apply Service-Orientation 174
Case Study Example 174
Step 8: Identify Service Composition Candidates 175
Case Study Example 175
Step 9: Analyze Processing Requirements 176
Case Study Example 177
Step 10: Define Utility Service Candidates (and Associate Resources and Methods) 178
Case Study Example 179
Step 11: Define Microservice Candidates (and Associate Resources and Methods) 180
Case Study Example 181
Step 12: Apply Service-Orientation 181
Step 13: Revise Candidate Service Compositions 181
Case Study Example 182
Step 14: Revise Resource Definitions and Capability Candidate Grouping 182
7.2 Additional Considerations 183
Uniform Contract Modeling and REST Service Inventory Modeling 183
REST Constraints and Uniform Contract Modeling 186
REST Service Capability Granularity 188
Resources vs. Entities 189
Chapter 8: Service API and Contract Design with Web Services 191
8.1 Service Model Design Considerations 193
Entity Service Design 193
Utility Service Design 194
Microservice Design 196
Task Service Design 196
Case Study Example 198
8.2 Web Service Design Guidelines 208
Apply Naming Standards 208
Apply a Suitable Level of Contract API Granularity 210
Case Study Example 212
Design Web Service Operations to Be Inherently Extensible 212
Case Study Example 213
Consider Using Modular WSDL Documents 214
Case Study Example 214
Use Namespaces Carefully 215
Case Study Example 215
Use the SOAP Document and Literal Attribute Values 216
Case Study Example 217
Chapter 9: Service API and Contract Design with REST Services and Microservices 219
9.1 Service Model Design Considerations 221
Entity Service Design 221
Utility Service Design 222
Microservice Design 223
Task Service Design 225
Case Study Example 226
9.2 REST Service Design Guidelines 231
Uniform Contract Design Considerations 231
Designing and Standardizing Methods 231
Designing and Standardizing HTTP Headers 233
Designing and Standardizing HTTP Response Codes 235
Customizing Response Codes 240
Designing Media Types 242
Designing Schemas for Media Types 244
Complex Method Design 246
Stateless Complex Methods 249
Fetch Method 249
Store Method 250
Delta Method 252
Async Method 254
Stateful Complex Methods 256
Trans Method 256
PubSub Method 257
Case Study Example 259
Chapter 10: Service API and Contract Versioning with Web Services and REST Services 263
10.1 Versioning Basics 265
Versioning Web Services 265
Versioning REST Services 266
Fine and Coarse-Grained Constraints 266
10.2 Versioning and Compatibility 267
Backwards Compatibility 267
Backwards Compatibility in Web Services 267
Backwards Compatibility in REST Services 268
Forwards Compatibility 271
Compatible Changes 273
Incompatible Changes 275
10.3 REST Service Compatibility Considerations 276
10.4 Version Identifiers 279
10.5 Versioning Strategies 282
The Strict Strategy (New Change, New Contract) 282
Pros and Cons 283
The Flexible Strategy (Backwards Compatibility) 283
Pros and Cons 284
The Loose Strategy (Backwards and Forwards Compatibility) 284
Pros and Cons 284
Strategy Summary 285
10.6 REST Service Versioning Considerations 286
PART III: APPENDICES
Appendix A: Service-Orientation Principles Reference 289
Appendix B: REST Constraints Reference 305
Appendix C: SOA Design Patterns Reference 317
What’s a Design Pattern? 318
What’s a Design Pattern Language? 320
Pattern Profiles 321
Appendix D: The Annotated SOA Manifesto 367
The SOA Manifesto 368
The SOA Manifesto Explored 369
Preamble 370
Priorities 371
Guiding Principles 375
About the Author 383
Index 384