Posts Tagged ‘DevoxxGR2026’
[DevoxxGR2026] Bootiful Spring Boot 4: Exploring the Latest Advancements with Java 25
Lecturer
Josh Long is a Spring Developer Advocate at VMware, widely recognized as one of the most prominent voices in the Spring ecosystem. Known affectionately as “Mr. Spring,” he is the author of numerous books and a prolific speaker who travels the globe sharing insights on modern Java development. Long co-hosts the “Coffee with a Java Champion” YouTube channel and continues to champion practical, production-ready Spring applications.
Abstract
In this engaging session at Devoxx Greece 2026, Josh Long showcases the transformative capabilities of Spring Boot 4 alongside Java 25. Through live coding of a dog adoption service, he demonstrates powerful new features including virtual threads, API versioning, modular architecture with Spring Modulith, resilient patterns, and seamless integration with AI capabilities. The presentation highlights how the Spring ecosystem empowers developers to build scalable, observable, secure, and intelligent applications with remarkable efficiency.
Java 25 and the Evolution of Spring Boot 4
Spring Boot 4 represents a significant generational leap, aligned with Spring Framework 7. Long emphasizes the decomposition of auto-configuration, resulting in leaner classpaths and faster startup times. Java 25 introduces compelling enhancements, most notably the ability to run simple applications with a single void main() method, effectively delivering the first truly elegant Java scripting experience.
These advancements set the stage for building modern, efficient services that leverage the full power of the JVM while maintaining developer productivity.
Building a Modular Dog Adoption Service
Long begins with a practical example: a service to help adopt dogs. Using Spring Initializr, he configures a project with PostgreSQL, Spring Data JDBC, web support, security, observability through OpenTelemetry and Actuator, and development tools.
The application employs a clean, feature-oriented package structure rather than traditional layered architecture. Records simplify domain modeling, while Spring Data repositories provide type-safe data access with compile-time query generation via AOT processing—beneficial for both JVM and native image deployments.
API Versioning and Resilience Features
To handle evolving requirements, Long demonstrates Spring’s new API versioning capabilities. Multiple endpoint versions coexist, with sensible defaults and header-based selection, ensuring backward compatibility.
Resilience4j integration showcases retryable methods and circuit breakers. Long simulates downstream failures to illustrate automatic recovery, highlighting how declarative resilience patterns simplify robust service design.
Modular Architecture with Spring Modulith
A standout demonstration involves refactoring into feature modules—dogs, cats, and veterinary services—using Spring Modulith. This enforces architectural boundaries at compile time while supporting event-driven communication between modules through ApplicationModuleListener and the outbox pattern for reliable, eventually consistent inter-module interactions.
The framework automatically generates documentation, C4 architecture diagrams, and verifies module dependencies, bridging the gap between intended design and runtime reality.
Security and Production Readiness
Security configuration leverages Spring Security 7’s additive customizers, preserving sensible defaults while enabling features like one-time token login and password migration. Passkeys (WebAuthn) integration provides passwordless authentication using biometrics, representing a significant usability and security improvement.
Observability is built-in through Actuator and OpenTelemetry, with production considerations like resource limits addressed from the start.
Integrating AI Capabilities
Long concludes by incorporating Spring AI 2.0, demonstrating how to augment the application with intelligent assistants. Using skills and tool calling, the service can answer domain-specific questions about dogs and cats, showcasing the natural convergence of Spring Boot with modern AI workflows.
The Bright Future of Java and Spring Development
Throughout the session, Long reinforces that the combination of Java’s efficiency, Spring’s comprehensive ecosystem, and new generative AI tools positions developers exceptionally well. Despite industry hype cycles, the fundamentals of solid engineering—modularity, resilience, observability, and security—remain paramount.
Spring Boot 4 and Java 25 deliver the tools necessary to build systems that are faster, more scalable, more maintainable, and more intelligent than ever before.