Java Application Architecture: From Monolith to Microservices

The book "Java Application Architecture" is a practical guide to designing, building, and maintaining scalable, reliable, and flexible systems in Java. The author, experienced architect Alexey Sokolov, shares proven approaches and real-world cases that will help you transition from writing "working" code to creating professional architecture.

What is this book about?

The book covers the full lifecycle of Java application architecture: from requirements analysis and pattern selection to refactoring and migrating to microservices. You will learn how to avoid common mistakes, how to properly structure code, and how to make architecture resilient to change.

Who is this book for?

• Java developers (middle and senior) who want to deepen their knowledge of architecture.
• Tech leads and team leads responsible for code quality and architectural decisions.
• Software architects looking to systematize their experience and learn modern approaches.
• Developers transitioning from other languages to Java who want to understand the specifics of the ecosystem.

What will you learn from the book?

• Architecture fundamentals: SOLID, GRASP, and Domain-Driven Design (DDD) principles in the context of Java.
• Design patterns: how to correctly apply GoF patterns, as well as modern patterns (Builder, Strategy, Observer, etc.) in real projects.
• Layered architecture: building clean layers (Controller, Service, Repository), working with dependencies, and dependency injection (DI).
• Working with databases: designing the ORM layer (JPA/Hibernate), transactions, migrations, and query optimization.
• Microservice architecture: when and how to transition from a monolith, organizing inter-service communication (REST, gRPC, messaging).
• Architecture testing: unit, integration, component tests, contract testing, and dependency emulation.
• Refactoring and evolution: how to safely change architecture, extract modules, and introduce new patterns without system downtime.
• Tools and practices: Maven/Gradle, Spring Boot, Docker, Kubernetes, CI/CD, monitoring, and logging.

Why should you read this book?

The book is written in a lively style, with minimal abstract reasoning. Each chapter contains code examples, diagrams, and practical exercises. You will not just learn theory — you will learn how to make architectural decisions, justify them to your team, and implement them in Java. This is a desk reference for those who want to build systems that are easy to maintain, extend, and scale.

Whether you are working on a corporate monolith or a microservices startup, this book will be your reliable guide in the world of Java architecture.