SOA with REST Principles, Patterns & Constraints for Building Enterprise Solutions with REST
, by Erl, Thomas; Carlyle, Benjamin; Pautasso, Cesare; Balasubramanian, Raj
- ISBN: 9780137012510 | 0137012519
- Cover: Hardcover
- Copyright: 8/10/2012
The Definitive Guide to Building Web-Centric SOA with REST The World Wide Web is based on the most successful technology architecture in the history of IT. It has changed how we view, access, and exchange information and, with the advent of REST, it has also provided us with compelling ways to build and improve automation solutions. REST provides a great deal of guidance to ensure that an architecture and its automation logic are technically sound, but the responsibility of ensuring that what you build actually provides value to the business is yours. Service-orientation has established a proven method for realizing a specific target state that has proven strategic value to many organizations. Achieving this target state requires that we apply service-orientation to a suitable distributed computing medium. SOA with RESTis the first comprehensive tutorial and reference for designing and building RESTful services as part of service-oriented solutions and in conjunction with service-oriented architecture (SOA). This book demonstrates that REST is not only a suitable medium for building truly service-oriented solutions, but also that the service-oriented architectural model is a suitable, and often necessary, foundation for REST technology architectures to realize their full business potential. The authors provide thorough mapping of REST constraints and architectural goals with service-orientation principles and SOA characteristics. Utilizing real-world examples, they show how to leverage REST's simplicity, flexibility, and low overhead without compromising the power or manageability of service-oriented solutions and architectures. This bookwill be valuable to IT architects, developers, and any practitioner seeking to use SOA and REST together. Topic areas covered include: 14 new REST-inspired design patterns defining common goals of REST and SOA designing REST service contracts with service-orientation designing REST architectures with SOA programming REST services with SOA (for Java and .NET) building REST service compositions, mashups and solutions versioning REST services distinguishing REST and SOA service concepts and terminology fundamental REST concepts fundamental SOA and service-orientation REST constraints, REST architectural goals and properties REST service contracts, messaging and resources
Thomas Erl is a best-selling IT author and the world’s top-selling SOA author. His books encompass topics ranging from cloud computing, semantic Web technology, and SOA. He is the series editor of the Prentice Hall Service Technology Series from Thomas Erl, as well as the editor of the Service Technology Magazine. With more than 160,000 copies in print world-wide, his published books have become international bestsellers and have been formally endorsed by senior members of major IT organizations, such as IBM, Microsoft, Oracle, Intel, Accenture, IEEE, MITRE, SAP, CISCO, and HP. As the founder of Arcitura Education Inc., Thomas has overseen the development of curricula for the internationally recognized SOASchool.com SOA Certified Professional (SOACP) and CloudSchool.com Cloud Certified Professional (CCP) accreditation programs, which have established a series of formal, vendor-neutral industry certifications. Thomas has toured over 20 countries as a speaker and instructor for public and private events and regularly participates in SOA, Cloud + Service Technology Symposium, and Gartner conferences. More than 100 articles and interviews by Thomas have been published in numerous publications, including The Wall Street Journal and CIO Magazine.
Benjamin Carlyle is a founding developer of the Invensys Rail “SystematICS” services framework, and has worked for many years as a software developer, software architect, and systems engineer on railway projects worldwide. He has focused on integrating REST and services technologies since around 2004. His work is referenced in several books on Restful Web services and on microformats, he has presented at the International SOA Symposium, and has served on the technical committee for international workshops on RESTful Design. He is credited with helping inspire the RESTlet framework for Java, and coined the term “REST Triangle” to describe the structure of a REST uniform contract. He has a deep understanding of both the theory and practice of REST and related styles as well as broader software and systems architecture topics.
Cesare Pautasso is an assistant professor at the Faculty of Informatics at the University of Lugano, Switzerland. Previously he was a researcher at the IBM Zurich Research Lab and a senior researcher at ETH Zurich, where he also completed his graduate studies with a Ph.D. in 2004. His teaching, research, and consulting activities both in academia and in industry cover advanced topics related to Software Architecture, Service Oriented Computing, and emerging RESTful Web services technologies. His research group focuses on building experimental systems to explore the intersection between the REST architectural style and model-driven software composition techniques, business process management, and liquid, self-organizing service-oriented architectures. He is an active member of IEEE and ACM, where he has participated in more than 100 international conference/workshop program committees. He has started the series of International Workshops on RESTful Design (WS-REST) at the WWW conference and was the general chair of the 9th IEEE European Conference on Web Services (ECOWS 2011). He regularly referees for Swiss, EU, and international funding agencies.
Raj Balasubramanian is a senior technologist from the Business Process Optimization (BPO) team within IBM Software Group focused on delivering SOA/BPM/Cloud solution across industries. Depending on the needs of the customer he has played the role of an enterprise architect, system architect, or solution architect to deliver on the engagement at hand. Prior to the focus on BPO, he was a lead portal architect delivering portal solutions to medium and large enterprise as part of the Lotus brand. He has published numerous articles on IBM DeveloperWorks and speaks at industry conferences on a variety of topics. His interests are in distributed systems, applying Web constructs to solution design, and using formal models and analytics to reason about large systems. Raj is also pursuing a Ph.D. in ECE at University of Texas at Austin where he is applying machine learning and data mining techniques to networked data from social Web to human travel. His official profile is on http://raj.balasubramanians.com, which links to his various personas.
Foreword by Stefan Tilkov xxix
Acknowledgments xxxiii
Chapter 1: Introduction 1
1.1 About this Book 2
Who this Book is For 2
What this Book Does Not Cover 3
1.2 Recommended Reading 3
1.3 How this Book is Organized 4
1.4 Conventions 8
Use of the Color Red 8
Design Constraints, Principles, and Patterns: Page References and Capitalization 8
Design Goals: Capitalization 9
Symbol Legend 9
1.5 Additional Information 10
Updates, Errata, and Resources (www.servicetechbooks.com) 10
Master Glossary (www.soaglossary.com) 10
Service-Orientation (www.serviceorientation.com) 10
What Is REST? (www.whatisrest.com) 10
Referenced Specifications (www.servicetechspecs.com) 10
The Service Technology Magazine (www.servicetechmag.com) 10
SOASchool.com SOA Certified Professional (SOACP) 11
CloudSchool.com Cloud Certified (CCP) Professional 11
Notification Service 11
Chapter 2: Case Study Background 13
2.1 How Case Studies Are Used 14
2.2 Case Study Background #1: Midwest University Association (MUA) 14
History 14
IT Environment 14
Business Goals and Obstacles 16
1. Build Reusable Business Services 18
2. Consolidate Systems and Information 18
3. Improve Channel Experience 18
4. Build Services Infrastructure 18
2.3 Case Study Background #2: KioskEtc Co. 18
History 19
IT Environment 19
Business Goals and Obstacles 19
Part I: Fundamentals
Chapter 3: Introduction to Services 23
3.1 Service Terminology 24
Service 24
Service Contract 24
Service Capability 26
Service Consumer 26
Service Agent 27
Service Composition 27
3.2 Service Terminology Context 29
Services and REST 29
Services and SOA 29
REST Services and SOA 29
Chapter 4: SOA Terminology and Concepts 31
4.1 Basic Terminology and Concepts 32
Service-Oriented Computing 33
Service-Orientation 34
Service-Oriented Architecture (SOA) 37
SOA Manifesto 38
Services 39
Cloud Computing 40
IT Resources 41
Service Models 41
Agnostic Logic and Non-Agnostic Logic 42
Service Inventory 42
Service Portfolio 43
Service Candidate 44
Service Contract 44
Service-Related Granularity 45
Service Profiles 46
SOA Design Patterns 46
4.2 Further Reading 49
4.3 Case Study Example 50
Chapter 5: REST Constraints and Goals 51
5.1 REST Constraints 52
Client-Server 53
Stateless 54
Cache 55
Interface/Uniform Contract 55
Layered System 56
Code-On-Demand 57
5.2 Goals of the REST Architectural Style 58
Performance 58
Scalability 59
Simplicity 60
Modifiability 61
Visibility 61
Portability 62
Reliability 62
Case Study Example 63
Part II: RESTful Service-Orientation
Chapter 6: Service Contracts with REST 67
6.1 Uniform Contract Elements 68
Resource Identifier Syntax (and Resources) 69
URIs (and URLs and URNs) 69
Resource Identifiers and REST Services 71
Methods 71
Media Types 73
6.2 REST Service Capabilities and REST Service Contracts 75
6.3 REST Service Contracts vs. Non-REST Service Contracts 77
Non-REST Service with Custom Service Contract 77
REST Service with Uniform Contract 79
HTTP Messaging vs. SOAP Messaging 81
REST Service Contracts with WSDL? 82
6.4 The Role of Hypermedia 83
URI Templates and Resource Queries 86
6.5 REST Service Contracts and Late Binding 87
Case Study Example 90
Chapter 7: Service-Orientation with REST 93
7.1 “SOA vs. REST” or “SOA + REST”? 95
7.2 Design Goals 97
Increased Intrinsic Interoperability 97
Increased Federation 98
Increased Vendor Diversity Options 99
Increased Business and Technology Alignment 100
Increased ROI 100
Increased Organizational Agility 102
Reduced IT Burden 102
Common Goals 103
7.3 Design Principles and Constraints 104
Standardized Service Contract 104
Service Loose Coupling 105
Service Abstraction 107
Service Reusability 109
Service Autonomy 110
Service Statelessness 111
Service Discoverability 113
Service Composability 114
Common Conflicts 114
Stateful Interactions 115
Service-Specific Contract Details 115
Case Study Example 116
Part III: Service-Oriented Analysis and Design with REST
Chapter 8: Mainstream SOA Methodology and REST 127
8.1 Service Inventory Analysis 131
8.2 Service-Oriented Analysis (Service Modeling) 133
8.3 Service-Oriented Design (Service Contract) 135
8.4 Service Logic Design 137
8.5 Service Discovery 137
8.6 Service Versioning and Retirement 138
Chapter 9: Analysis and Service Modeling with REST 139
9.1 Uniform Contract Modeling and REST Service Inventory Modeling 141
REST Constraints and Uniform Contract Modeling 144
REST Service Centralization and Normalization 146
9.2 REST Service Modeling 147
REST Service Capability Granularity 148
Resources vs. Entities 149
REST Service Modeling Process 150
Case Study Example 152
Step 1: Decompose Business Process (into Granular Actions) 152
Case Study Example 152
Step 2: Filter Out Unsuitable Actions 154
Case Study Example 154
Step 3: Identify Agnostic Service Candidates 155
Case Study Example 157
Event Service Candidate (Entity) 157
Award Service Candidate (Entity) 158
Student Service Candidate (Entity) 158
Notification Service Candidate (Utility) 159
Document Service Candidate (Utility) 159
Step 4: Identify Process-Specific Logic 160
Case Study Example 160
Confer Student Award Service Candidate (Task) 161
Step 5: Identify Resources 161
Case Study Example 162
Step 6: Associate Service Capabilities with Resources and Methods 163
Case Study Example 164
Confer Student Award Service Candidate (Task) 164
Event Service Candidate (Entity) 164
Award Service Candidate (Entity) 165
Student Service Candidate (Entity) 165
Notification Service Candidate (Utility) 166
Document Service Candidate (Utility) 166
Step 7: Apply Service-Orientation 167
Case Study Example 167
Step 8: Identify Candidate Service Compositions 167
Case Study Example 168
Step 9: Analyze Processing Requirements 169
Step 10: Define Utility Service Candidates 170
Step 11: Associate Utility-Centric Service Capabilities with Resources and Methods 171
Step 12: Apply Service-Orientation 171
Step 13: Revise Candidate Service Compositions 171
Step 14: Revise Resource Definitions 171
Step 15: Revise Capability Candidate Grouping 172
Additional Considerations 172
Chapter 10: Service-Oriented Design with REST 173
10.1 Uniform Contract Design Considerations 175
Designing and Standardizing Methods 175
Designing and Standardizing HTTP Headers 177
Designing and Standardizing HTTP Response Codes 179
Customizing Response Codes 184
Designing Media Types 186
Designing Schemas for Media Types 188
Service-Specific XML Schemas 189
10.2 REST Service Contract Design 191
Designing Services Based on Service Models 191
Task Services 191
Entity Services 192
Utility Services 193
Designing and Standardizing Resource Identifiers 194
Service Names in Resource Identifiers 195
Other URI Components 196
Resource Identifier Overlap 197
Resource Identifier Design Guidelines 199
Designing with and Standardizing REST Constraints 201
Stateless 201
Cache 202
Uniform Contract 203
Layered System 204
Case Study Example 205
Confer Student Award Service Contract (Task) 205
Event Service Contract (Entity) 207
Award Service Contract (Entity) 207
Student Transcript Service Contract (Entity) 208
Notification and Document Service Contracts (Utility) 209
10.3 Complex Method Design 211
Stateless Complex Methods 214
Fetch Method 214
Store Method 215
Delta Method 217
Async Method 219
Stateful Complex Methods 221
Trans Method 221
PubSub Method 222
Case Study Example 224
OptLock Complex Method 224
PesLock Complex Method 226
Part IV: Service Composition with REST
Chapter 11: Fundamental Service Composition with REST 231
11.1 Service Composition Terminology 233
Compositions and Composition Instances 233
Composition Members and Controllers 234
Service Compositions Are Actually Service Capability Compositions 235
Designated Controllers 236
Collective Composability 236
Service Activities 238
Composition Initiators 239
Point-to-Point Data Exchanges and Compositions 240
11.2 Service Composition Design Influences 241
Service-Orientation Principles and Composition Design 241
Standardized Service Contract and the Uniform Contract 242
Service Loose Coupling and the Uniform Contract 243
Service Abstraction and Composition Information Hiding 244
Service Reusability for Repeatable Composition 245
Service Autonomy and Composition Autonomy Loss 245
Service Statelessness and Stateless 246
Service Composability and Service-Orientation 246
REST Constraints and Composition Design 247
Stateless and Stateful Compositions 247
Cache and Layered System 248
Code-on-Demand and Composition Logic Deferral 248
Uniform Contract and Composition Coupling 248
11.3 Composition Hierarchies and Layers 249
Task Services Composing Entity Services 250
Entity Services Composing Entity Services 251
11.4 REST Service Composition Design Considerations 253
Synchronous and Asynchronous Service Compositions 253
Idempotent Service Activities 254
Lingering Composition State 255
Binding Between Composition Participants 255
11.5 A Step-by-Step Service Activity 258
1. Request to Purchase a Ticket 258
2. Verify the Requested Flight Details 258
3. Confirm a Seat on the Flight 259
4. Generate an Invoice 259
5. Create the Ticket 260
Summary 260
Chapter 12: Advanced Service Composition with REST 261
12.1 Service Compositions and Stateless 263
Composition Design with Service Statelessness 264
Composition Design with Stateless 265
12.2 Cross-Service Transactions with REST 266
REST-Friendly Atomic Service Transactions 267
Phase 1: Initialize 267
Phase 2: Reserve 268
Phase 3A: Confirm 269
Phase 3B: Cancel 269
Phase 3C: Timeout 270
Compliance with Stateless 271
Additional Considerations 272
REST-Friendly Compensating Service Transactions 272
Phase 1: Begin 273
Phase 2: Do 273
Phase 3A: Complete 274
Phase 3B: Undo 274
Phase 3C: Timeout 275
Compliance with Stateless 276
Additional Considerations 276
Non-REST-Friendly Atomic Service Transactions 276
Phase 1: Initialize 277
Phase 2: Do 277
Phase 3: Prepare 278
Phase 4A: Commit 279
Phase 4B: Rollback 279
Phase 4C: Timeout 280
Compliance with Stateless 280
Additional Considerations 281
12.3 Event-Driven Interactions with REST 282
Event-Driven Messaging 282
Compliance with Stateless 283
Message Polling 285
Compliance with Stateless 287
12.4 Service Composition with Dynamic Binding and Logic Deferral 288
Denormalized Capabilities Across Normalized Services 289
Composition Deepening 292
Dynamically Binding with Common Properties 294
Runtime Logic Deferral 297
12.5 Service Composition Across Service Inventories 299
Inventory Endpoint with REST 299
Dynamic Binding Between Service Inventories with Baseline Standardization 302
Chapter 13: Service Composition with REST Case Study 305
13.1 Revisiting the Confer Student Award Process 306
13.2 Application Submission and Task Service Invocation 310
13.3 Confer Student Award Service Composition Instance (Pre-Review Service Activity View) 312
Step 1: Composition Initiator to Confer Student Award Task Service (A) 312
Step 2: Confer Student Award Task Service to Event Entity Service (B) 312
Step 3: Event Entity Service to Confer Student Award Task Service (B) 313
Step 4: Confer Student Award Task Service to Award Entity Service (E) 314
Step 5: Award Entity Service to Confer Student Award Task Service (E) 314
Step 6: Confer Student Award Task Service to Award Entity Service (E) 314
Step 7: Award Entity Service to Confer Student Award Task Service (E) 315
Step 8: Confer Student Award Task Service to Student Entity Service (F) 315
Step 9: Student Entity Service to Confer Student Award Task Service (F) 315
Step 10: Confer Student Award Task Service to Student Transcript Entity Service (F) 316
Step 11: Student Transcript Entity Service to Confer Student Award Task Service (F) 316
Step 12: Confer Student Award Task Service to Composition Initiator 316
13.4 Review of Pending Applications and Task Service Invocation 317
Confer Student Award Service Composition Instance (Post-Review Service Activity View) 318
Step 1: Composition Initiator to Confer Student Award Task Service (L) 320
Step 2: Confer Student Award Task Service to Notification Utility Service (N) 320
Step 3: Notification Utility Service to Student Entity Service (N) 320
Step 4: Student Entity Service to Notification Utility Service (N) 320
Step 5: Notification Utility Service to Confer Student Award Task Service (N) 321
Intermediate Step: Confer Student Award Task Service to Transaction Coordinator (P, Q) 321
Intermediate Step: Transaction Coordinator to Confer Student Award Task Service (P, Q) 321
Step 6: Confer Student Award Task Service to Conferral Entity Service (P) 322
Intermediate Step: Conferral Entity Service to Transaction Coordinator (P) 322
Intermediate Step: Transaction Coordinator to Conferral Entity Service 322
Step 7: Conferral Entity Service to Confer Student Award Task Service (Q) 322
Step 8: Confer Student Award Task Service to Student Manuscript Entity Service (Q) 323
Intermediate Step: Student Transcript Entity Service to Transaction Controller (Q) 323
Intermediate Step: Transaction Controller to Student Transcript Entity Service (Q) 323
Step 9: Student Transcript Entity Service to Confer Student Award Task Service (Q) 324
Intermediate Step: Confer Student Award Task Service to Transaction Coordinator (P, Q) 324
Intermediate Step: Transaction Coordinator to Confer Student Award Task Service (P, Q) 324
Step 10: Confer Student Award Task Service to Composition Initiator 324
Part V: Supplemental
Chapter 14: Design Patterns for SOA with REST 327
14.1 REST-Inspired SOA Design Patterns 329
Content Negotiation 331
Related Patterns 332
Related Service-Oriented Computing Goals 332
Endpoint Redirection 332
Related Patterns 333
Related Service-Oriented Computing Goals 333
Entity Linking 333
Related Patterns 335
Related Service-Oriented Computing Goals 335
Idempotent Capability 335
Related Patterns 335
Related Service-Oriented Computing Goals 335
Lightweight Endpoint 336
Related Patterns 337
Related Service-Oriented Computing Goals 337
Reusable Contract 338
Related Patterns 338
Related Service-Oriented Computing Goals 339
Uniform Contract 339
14.2 Other Relevant SOA Design Patterns 340
Contract Centralization 340
Contract Denormalization 340
Domain Inventory 340
Schema Centralization 341
State Messaging 341
Validation Abstraction 342
Chapter 15: Service Versioning with REST 343
15.1 Versioning Basics 346
REST Service Contract Compatibility 346
Compatible and Incompatible Changes 348
Uniform Contract Method Compatibility 349
Uniform Contract Media Type Compatibility 350
Media Types and Forwards-compatibility 354
15.2 Version Identifiers 355
Using Version Identifiers 356
Version Identifiers and the Uniform Contract 358
Chapter 16: Uniform Contract Profiles 361
16.1 Uniform Contract Profile Template 362
Uniform-Level Structure 363
Method Profile Structure 364
Media Type Profile Structure 365
16.2 REST Service Profile Considerations 367
16.3 Case Study Example 369
Uniform-Level Structure: MUAUC 370
Method Profile Structure: Fetch 371
Response Code Handling for GET Methods in Fetch Method 373
Method Profile Structure: Store 374
Response Code Handling for PUT and DELETE Methods in Store Method 376
Method Profile Structure: GET 377
Method Profile Structure: PUT 378
Media Type Profile Structure: Invoice (application/vnd.edu.mua.invoice+xml) 379
Part VI: Appendices
Appendix A: Case Study Conclusion 383
Appendix B: Industry Standards Supporting the Web 387
The Internet Engineering Taskforce (IETF) 388
The World Wide Web Consortium 389
Other Web Standards 390
Appendix C: REST Constraints Reference 391
Appendix D: Service-Orientation Principles Reference 409
Appendix E: SOA Design Patterns Reference 425
Appendix F: State Concepts and Types 521
State Management Explained 522
State Management in Abstract 522
Origins of State Management 523
Deferral vs. Delegation 527
Types of State 527
Active and Passive 527
Stateless and Stateful 528
Session and Context Data 528
Measuring Service Statelessness 530
Appendix G: The Annotated SOA Manifesto 533
Appendix H: Additional Resources 547
www.whatisrest.com 548
Bibliography and References 548
Resources 551
www.servicetechbooks.com 551
www.soaschool.com, www.cloudschool.com 551
www.servicetechmag.com 552
www.soaglossary.com 552
www.servicetechspecs.com 552
www.soapatterns.org, www.cloudpatterns.org 552
www.serviceorientation.com, www.soaprinciples.com, www.whatissoa.com 552
www.servicetechsymposium.com 552
About the Authors 553
About the Pattern Co-Contributors 555
About the Foreword Contributor 557
Index 559
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