Vlad Khononov is a software engineer with extensive industry experience, working for companies large and small in roles ranging from webmaster to chief architect. His core areas of expertise are distributed systems and software design. Vlad consults with companies to make sense of their business domains, untangle monoliths, and tackle complex architectural challenges.Vlad maintains an active media career as a public speaker and author. Prior to Balancing Coupling in Software Design, he authored the best-selling O'Reilly book Learning Domain-Driven Design. He is a sought-after keynote speaker, presenting on topics such as domain-driven design, microservices, and software architecture in general.

"Your software can get easier to change over time, but it’s hard work to make that happen. With the concepts and skills you'll gain from this book, though, you will be well on your way."--Kent Beck, creator of Extreme Programming and Test-Driven Development"Get ready to unravel the multi-dimensional nature of coupling and the forces at work behind the scenes. The reference for those looking for a means to both assess and understand the real impact of design decisions."--Chris Bradford, Director of Digital Services, Cambridge Consultants"Coupling is a tale as old as software. It's a difficult concept to grasp and explain, but Vlad effortlessly lays out the many facets of coupling in this book, presenting a tangible model to measure and balance coupling in modern distributed systems. This is a must-read for every software professional!"--Laila Bougria, solutions architect & engineer"This book is essential for every software architect and developer, offering an unparalleled, thorough, and directly applicable exploration of the concept of coupling. Vlad's work is a crucial resource that will be heavily quoted and referenced in future discussions and publications."--Michael Plöd, fellow @ INNOQ"Every software engineer is sensitive to coupling, the measure of interconnection between parts. Still, many times the understanding of such a fundamental property remains unarticulated. In this book, Vlad introduces a much-needed intellectual tool to reason about coupling in a systematic way, offering a novel perspective on this essential topic."--Ilio Catallo, senior software engineer"Coupling is among the most slippery topics in software development. However, with this book, Vlad simplifies for us how coupling, from a great villain, can become a design tool when well understood. This is an indispensable guide for anyone dealing with software design--especially complex ones."--William Santos, software architect"Balancing Coupling in Software Design by Vlad Khononov is an essential read for architects aiming for quality, evolvable systems. Khononov expertly classifies dependencies and reveals how varying designs impact effort based on component distance and change frequency, introducing a unified metric for coupling. With insightful case studies, he guides readers toward achieving optimal modularity and long-term system adaptability by illustrating and rectifying imbalances."--Asher Sterkin, independent software technology expert"Khononov's groundbreaking work unifies paramount forces of software design into a coherent model for evaluating coupling of software systems. His insights provide an invaluable framework for architects to design modular, evolving systems that span legacy and modern architectures."--Felipe Henrique Gross Windmoller, staff software engineer, Banco do Brasil"This book systematizes over five decades of software design knowledge, offering a comprehensive guide on coupling, its dimensions, and how to manage it effectively. If software design is a constant battle with complexity, then this book is about mastering the art of winning."--Ivan Zakervsky, IT architect

• Series Editor Foreword xvForeword by Rebecca Wirfs-Brock xixForeword by Kent Beck xxiPreface xxiiiAcknowledgments xxixAbout the Author xxxiIntroduction 1Part I: Coupling 3Chapter 1: Coupling and System Design 5What Is Coupling? 5Magnitude of Coupling 6Flow of Knowledge 10Systems 10Key Takeaways 16Quiz 17Chapter 2: Coupling and Complexity: Cynefin 19What Is Complexity? 19Cynefin 20Comparing Cynefin Domains 26Cynefin in Software Design 27Cynefin Applications 31Cynefin and Complexity 32Key Takeaways 32Quiz 33Chapter 3: Coupling and Complexity: Interactions 35Nature of Complexity 35Complexity and System Design 36Hierarchical Complexity 39Degrees of Freedom 43Complexity and Constraints 46Coupling and Complex Interactions 47Example: Connecting Coupling and Complexity 48Key Takeaways 54Quiz 54Chapter 4: Coupling and Modularity 57Modularity 57Modules 59Modularity in Software Systems 62Modularity, Complexity, and Coupling 68Coupling in Modularity 73Key Takeaways 74Quiz 74Part II: Dimensions 77Chapter 5: Structured Design's Module Coupling 79Structured Design 80Module Coupling 80Comparison of Module Coupling Levels 94Key Takeaways 95Quiz 96Chapter 6: Connascence 97What Is Connascence? 97Static Connascence 98Dynamic Connascence 104Evaluating Connascence 110Key Takeaways 113Quiz 114Chapter 7: Integration Strength 117Strength of Coupling 118Integration Strength 121Intrusive Coupling 122Functional Coupling 125Model Coupling 128Contract Coupling 134Integration Strength Discussion 143Integration Strength and Asynchronous Execution 146Key Takeaways 147Quiz 148Chapter 8: Distance 151Distance and Encapsulation Boundaries 151Additional Factors Affecting Distance 157Distance Versus Proximity 160Distance Versus Integration Strength 161Key Takeaways 161Quiz 162Chapter 9: Volatility 165Changes and Coupling 165Why Software Changes 166Evaluating Rates of Changes 169Volatility and Integration Strength 175Inferred Volatility 177Key Takeaways 178Quiz 179Part III: Balance 181Chapter 10: Balancing Coupling 183Combining the Dimensions of Coupling 184Combining Strength, Distance, and Volatility 189Balancing Coupling on a Numeric Scale 192Key Takeaways 198Quiz 199Chapter 11: Rebalancing Coupling 201Resilient Design 201Software Change Vectors 202Rebalancing Coupling 205Key Takeaways 213Quiz 213Chapter 12: Fractal Geometry of Software Design 215Growth 215Innovation 223Fractal Geometry 228Fractal Modularity 230Key Takeaways 230Quiz 231Chapter 13: Balanced Coupling in Practice 233Microservices 233Architectural Patterns 239Business Objects 245Methods 251Key Takeaways 256Quiz 256Chapter 14: Conclusion 257Epilogue 261Appendix A: The Ballad of Coupling 263Appendix B: Glossary of Coupling 265Appendix C: Answers to Quiz Questions 271Bibliography 275Index 279

Vlad Khononov is a software engineer with extensive industry experience, working for companies large and small in roles ranging from webmaster to chief architect. His core areas of expertise are distributed systems and software design. Vlad consults with companies to make sense of their business domains, untangle monoliths, and tackle complex architectural challenges.Vlad maintains an active media career as a public speaker and author. Prior to Balancing Coupling in Software Design, he authored the best-selling O'Reilly book Learning Domain-Driven Design. He is a sought-after keynote speaker, presenting on topics such as domain-driven design, microservices, and software architecture in general.

"Your software can get easier to change over time, but it’s hard work to make that happen. With the concepts and skills you'll gain from this book, though, you will be well on your way."--Kent Beck, creator of Extreme Programming and Test-Driven Development"Get ready to unravel the multi-dimensional nature of coupling and the forces at work behind the scenes. The reference for those looking for a means to both assess and understand the real impact of design decisions."--Chris Bradford, Director of Digital Services, Cambridge Consultants"Coupling is a tale as old as software. It's a difficult concept to grasp and explain, but Vlad effortlessly lays out the many facets of coupling in this book, presenting a tangible model to measure and balance coupling in modern distributed systems. This is a must-read for every software professional!"--Laila Bougria, solutions architect & engineer"This book is essential for every software architect and developer, offering an unparalleled, thorough, and directly applicable exploration of the concept of coupling. Vlad's work is a crucial resource that will be heavily quoted and referenced in future discussions and publications."--Michael Plöd, fellow @ INNOQ"Every software engineer is sensitive to coupling, the measure of interconnection between parts. Still, many times the understanding of such a fundamental property remains unarticulated. In this book, Vlad introduces a much-needed intellectual tool to reason about coupling in a systematic way, offering a novel perspective on this essential topic."--Ilio Catallo, senior software engineer"Coupling is among the most slippery topics in software development. However, with this book, Vlad simplifies for us how coupling, from a great villain, can become a design tool when well understood. This is an indispensable guide for anyone dealing with software design--especially complex ones."--William Santos, software architect"Balancing Coupling in Software Design by Vlad Khononov is an essential read for architects aiming for quality, evolvable systems. Khononov expertly classifies dependencies and reveals how varying designs impact effort based on component distance and change frequency, introducing a unified metric for coupling. With insightful case studies, he guides readers toward achieving optimal modularity and long-term system adaptability by illustrating and rectifying imbalances."--Asher Sterkin, independent software technology expert"Khononov's groundbreaking work unifies paramount forces of software design into a coherent model for evaluating coupling of software systems. His insights provide an invaluable framework for architects to design modular, evolving systems that span legacy and modern architectures."--Felipe Henrique Gross Windmoller, staff software engineer, Banco do Brasil"This book systematizes over five decades of software design knowledge, offering a comprehensive guide on coupling, its dimensions, and how to manage it effectively. If software design is a constant battle with complexity, then this book is about mastering the art of winning."--Ivan Zakervsky, IT architect

• Series Editor Foreword xvForeword by Rebecca Wirfs-Brock xixForeword by Kent Beck xxiPreface xxiiiAcknowledgments xxixAbout the Author xxxiIntroduction 1Part I: Coupling 3Chapter 1: Coupling and System Design 5What Is Coupling? 5Magnitude of Coupling 6Flow of Knowledge 10Systems 10Key Takeaways 16Quiz 17Chapter 2: Coupling and Complexity: Cynefin 19What Is Complexity? 19Cynefin 20Comparing Cynefin Domains 26Cynefin in Software Design 27Cynefin Applications 31Cynefin and Complexity 32Key Takeaways 32Quiz 33Chapter 3: Coupling and Complexity: Interactions 35Nature of Complexity 35Complexity and System Design 36Hierarchical Complexity 39Degrees of Freedom 43Complexity and Constraints 46Coupling and Complex Interactions 47Example: Connecting Coupling and Complexity 48Key Takeaways 54Quiz 54Chapter 4: Coupling and Modularity 57Modularity 57Modules 59Modularity in Software Systems 62Modularity, Complexity, and Coupling 68Coupling in Modularity 73Key Takeaways 74Quiz 74Part II: Dimensions 77Chapter 5: Structured Design's Module Coupling 79Structured Design 80Module Coupling 80Comparison of Module Coupling Levels 94Key Takeaways 95Quiz 96Chapter 6: Connascence 97What Is Connascence? 97Static Connascence 98Dynamic Connascence 104Evaluating Connascence 110Key Takeaways 113Quiz 114Chapter 7: Integration Strength 117Strength of Coupling 118Integration Strength 121Intrusive Coupling 122Functional Coupling 125Model Coupling 128Contract Coupling 134Integration Strength Discussion 143Integration Strength and Asynchronous Execution 146Key Takeaways 147Quiz 148Chapter 8: Distance 151Distance and Encapsulation Boundaries 151Additional Factors Affecting Distance 157Distance Versus Proximity 160Distance Versus Integration Strength 161Key Takeaways 161Quiz 162Chapter 9: Volatility 165Changes and Coupling 165Why Software Changes 166Evaluating Rates of Changes 169Volatility and Integration Strength 175Inferred Volatility 177Key Takeaways 178Quiz 179Part III: Balance 181Chapter 10: Balancing Coupling 183Combining the Dimensions of Coupling 184Combining Strength, Distance, and Volatility 189Balancing Coupling on a Numeric Scale 192Key Takeaways 198Quiz 199Chapter 11: Rebalancing Coupling 201Resilient Design 201Software Change Vectors 202Rebalancing Coupling 205Key Takeaways 213Quiz 213Chapter 12: Fractal Geometry of Software Design 215Growth 215Innovation 223Fractal Geometry 228Fractal Modularity 230Key Takeaways 230Quiz 231Chapter 13: Balanced Coupling in Practice 233Microservices 233Architectural Patterns 239Business Objects 245Methods 251Key Takeaways 256Quiz 256Chapter 14: Conclusion 257Epilogue 261Appendix A: The Ballad of Coupling 263Appendix B: Glossary of Coupling 265Appendix C: Answers to Quiz Questions 271Bibliography 275Index 279