Synopses & Reviews
“For software developers of all experience levels looking to improve their results, and design and implement domain-driven enterprise applications consistently with the best current state of professional practice,
Implementing Domain-Driven Design will impart a treasure trove of knowledge hard won within the DDD and enterprise application architecture communities over the last couple decades.”
–Randy Stafford, Architect At-Large, Oracle Coherence Product Development
“This book is a must-read for anybody looking to put DDD into practice.”
–Udi Dahan, Founder of NServiceBus
Implementing Domain-Driven Design presents a top-down approach to understanding domain-driven design (DDD) in a way that fluently connects strategic patterns to fundamental tactical programming tools. Vaughn Vernon couples guided approaches to implementation with modern architectures, highlighting the importance and value of focusing on the business domain while balancing technical considerations.
Building on Eric Evans’ seminal book, Domain-Driven Design, the author presents practical DDD techniques through examples from familiar domains. Each principle is backed up by realistic Java examples–all applicable to C# developers–and all content is tied together by a single case study: the delivery of a large-scale Scrum-based SaaS system for a multitenant environment.
The author takes you far beyond “DDD-lite” approaches that embrace DDD solely as a technical toolset, and shows you how to fully leverage DDD’s “strategic design patterns” using Bounded Context, Context Maps, and the Ubiquitous Language. Using these techniques and examples, you can reduce time to market and improve quality, as you build software that is more flexible, more scalable, and more tightly aligned to business goals.
Coverage includes
- Getting started the right way with DDD, so you can rapidly gain value from it
- Using DDD within diverse architectures, including Hexagonal, SOA, REST, CQRS, Event-Driven, and Fabric/Grid-Based
- Appropriately designing and applying Entities–and learning when to use Value Objects instead
- Mastering DDD’s powerful new Domain Events technique
- Designing Repositories for ORM, NoSQL, and other databases
Review
“With
Implementing Domain-Driven Design , Vaughn has made an important contribution not only to the literature of the Domain-Driven Design community, but also to the literature of the broader enterprise application architecture field. In key chapters on Architecture and Repositories, for example, Vaughn shows how DDD fits with the expanding array of architecture styles and persistence technologies for enterprise applications—including SOA and REST, NoSQL and data grids—that has emerged in the decade since Eric Evans’ seminal book was first published. And, fittingly, Vaughn illuminates the blocking and tackling of DDD—the implementation of entities, value objects, aggregates, services, events, factories, and repositories—with plentiful examples and valuable insights drawn from decades of practical experience. In a word, I would describe this book as thorough. For software developers of all experience levels looking to improve their results, and design and implement domain-driven enterprise applications consistently with the best current state of professional practice, Implementing Domain-Driven Design will impart a treasure trove of knowledge hard won within the DDD and enterprise application architecture communities over the last couple decades.”
—Randy Stafford, Architect At-Large, Oracle Coherence Product Development
“Domain-Driven Design is a powerful set of thinking tools that can have a profound impact on how effective a team can be at building software-intensive systems. The thing is that many developers got lost at times when applying these thinking tools and really needed more concrete guidance. In this book, Vaughn provides the missing links between theory and practice. In addition to shedding light on many of the misunderstood elements of DDD, Vaughn also connects new concepts like Command/Query Responsibility Segregation and Event Sourcing that many advanced DDD practitioners have used with great success. This book is a must-read for anybody looking to put DDD into practice.”
—Udi Dahan, Founder of NServiceBus
“For years, developers struggling to practice Domain-Driven Design have been wishing for more practical help in actually implementing DDD. Vaughn did an excellent job in closing the gap between theory and practice with a complete implementation reference. He paints a vivid picture of what it is like to do DDD in a contemporary project, and provides plenty of practical advice on how to approach and solve typical challenges occurring in a project life cycle.”
— Alberto Brandolini, DDD Instructor, Certified by Eric Evans and Domain Language, Inc.
“Implementing Domain-Driven Design does a remarkable thing: it takes a sophisticated and substantial topic area in DDD and presents it clearly, with nuance, fun and finesse. This book is written in an engaging and friendly style, like a trusted advisor giving you expert counsel on how to accomplish what is most important. By the time you finish the book you will be able to begin applying all the important concepts of DDD, and then some. As I read, I found myself highlighting many sections . . . I will be referring back to it, and recommending it, often.”
— Paul Rayner, Principal Consultant & Owner, Virtual Genius, LLC., DDD Instructor, Certified by Eric Evans and Domain Language, Inc., DDD Denver Founder and Co-leader
“One important part of the DDD classes I teach is discussing how to put all the ideas and pieces together into a full blown working implementation. With this book, the DDD community now has a comprehensive reference that addresses this in detail. Implementing Domain-Driven Design deals with all aspects of building a system using DDD, from getting the small details right to keeping track of the big picture. This is a great reference and an excellent companion to Eric Evans seminal DDD book.”
— Patrik Fredriksson, DDD Instructor, Certified by Eric Evans and Domain Language, Inc.
“If you care about software craftsmanship—and you should—then Domain-Driven Design is a crucial skill set to master and Implementing Domain-Driven Design is the fast path to success. IDDD offers a highly readable yet rigorous discussion of DDD’s strategic and tactical patterns that enables developers to move immediately from understanding to action. Tomorrow’s business software will benefit from the clear guidance provided by this book.”
—Dave Muirhead, Principal Consultant, Blue River Systems Group
“There’s theory and practice around DDD that every developer needs to know, and this is the missing piece of the puzzle that puts it all together. Highly recommended!”
—Rickard Öberg, Java Champion and Developer at Neo Technology
“In IDDD, Vaughn takes a top-down approach to DDD, bringing strategic patterns such as bounded context and context maps to the fore, with the building block patterns of entities, values and services tackled later. His book uses a case study throughout, and to get the most out of it you’ll need to spend time grokking that case study. But if you do you’ll be able to see the value of applying DDD to a complex domain; the frequent sidenotes, diagrams, tables, and code all help illustrate the main points. So if you want to build a solid DDD system employing the architectural styles most commonly in use today, Vaughn’s book comes recommended.”
—Dan Haywood, author of Domain-Driven Design with Naked Objects
“This book employs a top-down approach to understanding DDD in a way that fluently connects strategic patterns to lower level tactical constraints. Theory is coupled with guided approaches to implementation within modern architectural styles. Throughout the book, Vaughn highlights the importance and value of focusing on the business domain all while balancing technical considerations. As a result, the role of DDD, as well as what it does and perhaps more importantly doesn’t imply, become ostensibly clear. Many a time, my team and I would be at odds with the friction encountered in applying DDD. With Implementing Domain-Driven Design as our luminous guide we were able to overcome those challenges and translate our efforts into immediate business value.”
—Lev Gorodinski, Principal Architect, DrillSpot.com
Synopsis
Succeed with Domain-Driven Design (DDD), today's best-practice framework and common language for making design decisions that accelerate projects, keeping them on track while smoothly incorporating inevitable change. Vaughn Vernon's Implementing Domain-Driven Design builds on Eric Evans' seminal Domain-Driven Design, helping practitioners flatten the DDD learning curve, identify their best opportunities to apply DDD, and overcome common implementation pitfalls. Vernon presents concrete and realistic DDD techniques through examples from familiar domains, such as a Scrum-based project management application that integrates with a collaboration suite and security provider. Each principle is backed up by realistic Java examples, and all content is tied together by a single case study of a company charged with delivering a set of advanced software systems with DDD. Using this book's techniques, organizations can reduce time-to-market and build better software that is more flexible, more scalable, and better aligned to business goals. For software practitioners who are new to DDD, for those who've used DDD but not yet succeeded; and for DDD users who have experienced success and want to become even more effective. Readers will likely include software architects, systems anaysts, application developers, and project managers.
Synopsis
“For software developers of all experience levels looking to improve their results, and design and implement domain-driven enterprise applications consistently with the best current state of professional practice,
Implementing Domain-Driven Design will impart a treasure trove of knowledge hard won within the DDD and enterprise application architecture communities over the last couple decades.”
–Randy Stafford, Architect At-Large, Oracle Coherence Product Development
“This book is a must-read for anybody looking to put DDD into practice.”
–Udi Dahan, Founder of NServiceBus
Implementing Domain-Driven Design presents a top-down approach to understanding domain-driven design (DDD) in a way that fluently connects strategic patterns to fundamental tactical programming tools. Vaughn Vernon couples guided approaches to implementation with modern architectures, highlighting the importance and value of focusing on the business domain while balancing technical considerations.
Building on Eric Evans’ seminal book, Domain-Driven Design, the author presents practical DDD techniques through examples from familiar domains. Each principle is backed up by realistic Java examples–all applicable to C# developers–and all content is tied together by a single case study: the delivery of a large-scale Scrum-based SaaS system for a multitenant environment.
The author takes you far beyond “DDD-lite” approaches that embrace DDD solely as a technical toolset, and shows you how to fully leverage DDD’s “strategic design patterns” using Bounded Context, Context Maps, and the Ubiquitous Language. Using these techniques and examples, you can reduce time to market and improve quality, as you build software that is more flexible, more scalable, and more tightly aligned to business goals.
Coverage includes
- Getting started the right way with DDD, so you can rapidly gain value from it
- Using DDD within diverse architectures, including Hexagonal, SOA, REST, CQRS, Event-Driven, and Fabric/Grid-Based
- Appropriately designing and applying Entities–and learning when to use Value Objects instead
- Mastering DDD’s powerful new Domain Events technique
- Designing Repositories for ORM, NoSQL, and other databases
About the Author
Vaughn Vernon is a veteran software craftsman with more than twenty-five years of experience in software design, development, and architecture. He is a thought leader in simplifying software design and implementation using innovative methods. He has been programming with object-oriented languages since the 1980s, and applying the tenets of Domain-Driven Design since his Smalltalk domain modeling days in the early 1990s. He consults and speaks internationally, and has taught his Implementing Domain-Driven Design classes on multiple continents.
Table of Contents
Foreword xvii
Preface xix
Acknowledgments xxix
About the Author xxxiii
Guide to This Book xxxv
Chapter 1: Getting Started with DDD 1
Can I DDD? 2
Why You Should Do DDD 6
How to Do DDD 20
The Business Value of Using DDD 25
The Challenges of Applying DDD 29
Fiction, with Bucketfuls of Reality 38
Wrap-Up 41
Chapter 2: Domains, Subdomains, and Bounded Contexts 43
Big Picture 43
Why Strategic Design Is So Incredibly Essential 53
Real-World Domains and Subdomains 56
Making Sense of Bounded Contexts 62
Sample Contexts 72
Wrap-Up 84
Chapter 3: Context Maps 87
Why Context Maps Are So Essential 87
Wrap-Up 111
Chapter 4: Architecture 113
Interviewing the Successful CIO 114
Layers 119
Hexagonal or Ports and Adapters 125
Service-Oriented 130
Representational State Transfer–REST 133
Command-Query Responsibility Segregation, or CQRS 138
Event-Driven Architecture 147
Data Fabric and Grid-Based Distributed Computing 163
Wrap-Up 168
Chapter 5: Entities 171
Why We Use Entities 171
Unique Identity 173
Discovering Entities and Their Intrinsic Characteristics 191
Wrap-Up 217
Chapter 6: Value Objects 219
Value Characteristics 221
Integrate with Minimalism 232
Standard Types Expressed as Values 234
Testing Value Objects 239
Implementation 243
Persisting Value Objects 248
Wrap-Up 263
Chapter 7: Services 265
What a Domain Service Is (but First, What It Is Not) 267
Make Sure You Need a Service 268
Modeling a Service in the Domain 272
Testing Services 281
Wrap-Up 284
Chapter 8: Domain Events 285
The When and Why of Domain Events 285
Modeling Events 288
Publishing Events from the Domain Model 296
Spreading the News to Remote Bounded Contexts 303
Event Store 307
Architectural Styles for Forwarding Stored Events 312
Implementation 318
Wrap-Up 331
Chapter 9: Modules 333
Designing with Modules 333
Basic Module Naming Conventions 336
Module Naming Conventions for the Model 337
Modules of the Agile Project Management Context 340
Modules in Other Layers 343
Module before Bounded Context 344
Wrap-Up 345
Chapter 10: Aggregates 347
Using Aggregates in the Scrum Core Domain 348
Rule: Model True Invariants in Consistency Boundaries 353
Rule: Design Small Aggregates 355
Rule: Reference Other Aggregates by Identity 359
Rule: Use Eventual Consistency Outside the Boundary 364
Reasons to Break the Rules 367
Gaining Insight through Discovery 370
Implementation 380
Wrap-Up 388
Chapter 11: Factories 389
Factories in the Domain Model 389
Factory Method on Aggregate Root 391
Factory on Service 397
Wrap-Up 400
Chapter 12: Repositories 401
Collection-Oriented Repositories 402
Persistence-Oriented Repositories 418
Additional Behavior 430
Managing Transactions 432
Type Hierarchies 437
Repository versus Data Access Object 440
Testing Repositories 441
Wrap-Up 448
Chapter 13: Integrating Bounded Contexts 449
Integration Basics 450
Integration Using RESTful Resources 458
Integration Using Messaging 469
Wrap-Up 508
Chapter 14: Application 509
User Interface 512
Application Services 521
Composing Multiple Bounded Contexts 531
Infrastructure 532
Enterprise Component Containers 534
Wrap-Up 537
Appendix A: Aggregates and Event Sourcing: A+ES 539
Inside an Application Service 541
Command Handlers 549
Lambda Syntax 553
Concurrency Control 554
Structural Freedom with A+ES 558
Performance 558
Implementing an Event Store 561
Relational Persistence 565
BLOB Persistence 568
Focused Aggregates 569
Read Model Projections 570
Use with Aggregate Design 573
Events Enrichment 573
Supporting Tools and Patterns 576
Contract Generation 580
Unit Testing and Specifications 582
Event Sourcing in Functional Languages 583
Bibliography 585
Index 589