Java Application Architecture: From Monolith to Microservices

The book "Java Application Architecture: From Monolith to Microservices" is a practical guide for developers who want to learn how to design, build, and maintain complex enterprise systems in Java. The author, Alexey Sokolov, shares years of experience in creating high-load and fault-tolerant applications, starting from classic monolithic architectures and ending with modern microservice approaches.

The book is not overloaded with theory — each section is backed by real code examples, diagrams, and practical advice. You will learn how to avoid common design mistakes, how to choose the right architecture for specific business tasks, and how to evolve a system without stopping its operation.

Who is this book for?

• Java developers at Middle and Senior levels who want to deepen their knowledge of architecture.
• Team Leads and Architects looking for a structured approach to system design.
• Developers transitioning from other languages to Java who want to understand its ecosystem.
• IT students and graduates preparing for interviews for Java architect positions.

What will you learn from the book?

• Basic architectural styles: monolith, client-server, layered architecture, microservices.
• How to design application layers (Controller, Service, Repository) using Spring Boot.
• Design patterns for Java: Factory, Builder, Strategy, Observer, Dependency Injection, and others.
• SOLID principles and their practical application.
• Working with databases: choosing between SQL and NoSQL, schema design, ORM (Hibernate).
• Asynchronous programming: CompletableFuture, Reactive Streams, Spring WebFlux.
• Microservice architecture: Spring Cloud, Service Discovery, API Gateway, inter-service communication (REST, gRPC, Kafka).
• Ensuring security: Spring Security, JWT, OAuth2, protection against common vulnerabilities.
• Architecture testing: unit, integration, contract testing (Pact).
• Monitoring, logging, and tracing: Prometheus, Grafana, ELK, Jaeger.
• CI/CD, containerization with Docker, and orchestration with Kubernetes.
• Performance: caching, connection pools, JVM optimization, profiling.

The book is written in a lively, understandable language. Each chapter ends with a practical assignment and review questions, allowing you to immediately reinforce the material. Special attention is paid to modern trends: cloud deployments, Event-Driven architecture, and Domain-Driven Design.

If you want to become a sought-after Java application architect, learn to make informed technical decisions, and build systems that are easy to scale and maintain — this book will be your reliable guide.