GraphQL on Java: A Complete Guide to Building Modern APIs

The book "GraphQL on Java" is a practical guide for developers who want to master a modern approach to building flexible and efficient APIs. Unlike traditional REST, GraphQL allows clients to request only the data they need, which significantly speeds up development and optimizes application performance.

The book starts with the basics: you will learn what GraphQL is, how it works, and how it differs from REST. Then the author sequentially guides the reader through all stages of creating a full-fledged API in Java. Special attention is paid to practical aspects — from schema design to deployment in production.

What you will learn from the book:

• GraphQL Basics: query language syntax, data types, mutations, and subscriptions
• Environment Setup: integrating GraphQL with Java projects, including Spring Boot and Micronaut
• Schema Design: creating efficient schemas using types, interfaces, and union types
• Resolvers: writing DataFetchers, handling relationships between objects, and working with databases
• Validation and Error Handling: configuring query validation, custom exceptions, and error formatting
• Subscriptions: implementing real-time functionality using WebSocket and Reactive Streams
• Security: authentication, authorization, and protection against typical GraphQL vulnerabilities
• Performance Optimization: batch data loading (DataLoader), caching, and monitoring
• Testing: writing unit tests and integration tests for the GraphQL layer
• Deployment and Monitoring: deploying in Docker, configuring metrics, and logging

Who this book is for:

• Java developers who want to learn GraphQL for building modern APIs
• Backend developers using Spring Boot who want to expand their toolkit
• Architects looking for alternatives to REST for complex systems
• Students and beginner developers with basic Java knowledge

The book contains many code examples ready for use in real projects. You will learn not only to write code but also to design architecture that will scale and be easily maintainable. The author shares best practices and typical mistakes that beginners make when transitioning from REST to GraphQL.

After reading this book, you will be able to independently create high-performance GraphQL APIs in Java, integrate them with existing systems, and effectively solve tasks of any complexity.