Kotlin Application Architecture: From Monolith to Microservices

The book "Kotlin Application Architecture: From Monolith to Microservices" is a comprehensive guide to designing modern, scalable, and easily maintainable software systems in Kotlin. The author, Andrey Volkov, a senior developer with 10 years of experience, shares proven patterns and approaches that will help you stop writing "spaghetti code" and start building professional solutions.

What is this book about?

The book covers the full application design cycle — from choosing an architectural style to deploying to production. You will learn:

• How to apply Clean Architecture and Hexagonal Architecture in Kotlin projects
• Implementation specifics of MVVM and MVI for Android and server applications
• Principles of building microservice architecture using Ktor and Spring Boot
• Effective state management with coroutines, Flow, and StateFlow
• Dependency injection (DI) with Koin and Dagger Hilt
• Testing architectural layers: unit, integration, and E2E tests
• Patterns CQRS, Event Sourcing, and Saga for distributed systems

Who is this book for?

• Beginner Kotlin developers who want to master best design practices
• Android developers striving to improve the architecture of their applications
• Backend developers transitioning to Kotlin and wanting to build reliable server systems
• Tech leads and architects looking for ready-made templates for scaling projects

What will you learn after reading?

• How to properly split an application into layers and modules so that code is easy to modify and test
• How to choose an architecture for a specific task: monolith, modular monolith, or microservices
• How to integrate coroutines and reactive streams into architecture without losing performance
• How to organize inter-service communication via REST, gRPC, and message brokers
• How to automate build, testing, and deployment using Gradle, Docker, and CI/CD

Each chapter contains practical code examples, diagrams, and exercises for independent work. By the end of the book, you will be able to confidently design systems of any scale — from a simple Android application to a distributed server solution handling millions of requests.

"Kotlin Application Architecture" is not just theory, but a tool you will immediately apply in your projects. Whether you are working on a mobile application or a corporate backend, this book will be your reliable guide in the world of professional Kotlin development.