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Insights from Spring I/O Barcelona 2024

Spring IO

The Spring I/O Barcelona 2024 is the premier event for developers, engineers and tech enthusiasts who are and technology enthusiasts passionate about Java and its ecosystem. Set against the backdrop of one of Europe’s most vibrant cities, this annual conference brings together industry leaders, expert speakers and a community of innovators to share insights, explore cutting-edge technologies and discuss the future of Java development.

With a rich agenda of hands-on workshops, keynote sessions and networking opportunities, the Spring I/O Conference provides a unique platform for learning and collaboration, making it a must-attend event for anyone looking to stay at the forefront of Java programming and technology trends.

Although Spring was born about twenty years ago and Spring Boot almost ten years ago, it has been confirmed as one of the most widely used frameworks in the Java world. Our Bitrockers attended several talks and workshops: here’s a summary of some of the ones we found most interesting.

Spring Framework 6.2: Core Container Revisited

Juergen Hoeller’s presentation focused on Spring Framework 6.2 and the enhancements that have been introduced to various aspects of the core container to improve performance, simplify configuration, and provide new functionality. Special attention was given to:

  • Bean Management and Dependency Injection Enhancements
  • Advanced Locking Mechanism
  • Lifecycle Management and Asynchronous Processing
  • Dependency management and reproducibility
  • Application Context Bootstrap
  • CRaC and Snapshot Support

Spring Framework 6.2 introduces several significant enhancements that improve the performance, flexibility and reliability of bean management, dependency injection and lifecycle management. By refining existing mechanisms and introducing new features such as background initialization, reentrant locking, and pulse restarting, Spring 6.2 addresses long-standing issues and meets the needs of modern applications. These enhancements ensure that Spring continues to provide a robust and efficient framework for building complex, concurrent, high-performance applications. With Spring 6.2, the framework is not only more powerful, but also more user-friendly, enabling developers to build better applications with greater ease and confidence.

The Modern Monolith, with Spring Modulith

In the ever-evolving landscape of software architecture, the debate between monolithic and microservices architectures is an ongoing one.

However, Cora Iberkleid‘s presentation at Spring I/O 2024, titled “The Modern Monolith, with Spring Modulith”, offers a fresh perspective on this debate. Using the capabilities of Spring Modulith, Iberkleid will demonstrate how developers can build modular monolithic applications that combine the best of both worlds: the maintainability and simplicity of monoliths with the flexibility of microservices.

Spring Modulith aims to bridge the gap between monolithic and microservices architectures by providing a modular approach to monolithic application design. According to Iberkleid, Spring Modulith enables developers to create well-structured, maintainable and modular applications without the overhead and complexity of managing microservices.

Spring Modulith builds on the core principles of Domain-Driven Design (DDD) and emphasises the importance of clear boundaries between modules. Each module encapsulates a specific business capability, making the overall system more organized and easier to manage. This modular approach allows teams to work independently on different parts of the application, facilitating parallel development and reducing the risk of conflict. The Key Features of Spring Modulith are:

  • Module Independence
  • Clear Boundaries
  • Domain-Driven Design (DDD)
  • Module Communication 
  • Testing and Deployment 
  • Advantages of the Modern Monolith

Iberkleid highlights several advantages of using Spring Modulith to build modular monolithic applications (simplicity, maintainability, performance and resource efficiency).

Iberkleid also provides practical insights into the implementation of Spring modules in real projects. It shows how to structure an application into different modules, each representing a specific business capability. By following DDD principles, developers can create entities, aggregates and repositories that align with the business domain. Last but not least, Iberkleid presents a case study of a modular e-commerce application to illustrate the benefits of Spring Modulith.

Cora Iberkleid’s presentation at Spring I/O 2024 makes a compelling case for rethinking traditional monolithic architecture in favour of a modular approach with Spring Modulith. By combining the simplicity and performance of monoliths with the modularity and maintainability of microservices, Spring Modulith offers a balanced solution for modern application development.

The key takeaway from the presentation is that modular monolithic applications can offer the best of both worlds. With clear boundaries, independent modules and event-driven communication, developers can build applications that are easy to maintain, scale and evolve over time. Spring Modulith empowers teams to focus on delivering business value without getting bogged down in the complexities of managing microservices.

At a time when software requirements are constantly evolving, the ability to adapt quickly is critical. Spring Modulith provides the tools and framework needed to build flexible and resilient applications that meet the demands of today’s dynamic business environment.

This Ain’t Your Parents’ Java

Venkat Subramaniam, Java rock star, gave one of the most interesting talks at the event. In this presentation, Venkat clearly and simply illustrated some of the most significant innovations introduced in Java in recent years. Java, like any respectable language, has evolved over time, incorporating successful features from other languages inspired by Java based on the JVM. Among them we can mention:

  • Functional Style Programming
  • Text Blocks
  • Pattern Matching with Instanceof
  • Records
  • Keyword Sealed

These are just some of the features that keep Java as a language current and evolving. Venkat Subramaniam’s presentation was, as always, clear, engaging and rich in practical examples. His passionate style made the presentation very enjoyable. Java’s ability to adapt and integrate with modern programming paradigms ensures its relevance in the ever-changing landscape of software development, providing developers with powerful tools to write efficient, maintainable and high quality code.

Spring AI: Effortlessly Integrate AI into Your Spring Boot Apps

Spring AI bridges the gap between the powerful world of Artificial Intelligence (AI) and the familiar convenience of Spring Boot development. It allows developers to easily integrate various AI capabilities into their applications without having to deal with complex, vendor-specific details.

With Spring AI, you can leverage AI capabilities such as chatbots, text summarisation and text-to-image generation, all within the well-established Spring ecosystem. The platform provides a single API that works across all major AI vendors, allowing you to focus on the core functionality of your application and leave the intricacies of different AI platforms behind. Spring AI empowers developers to seamlessly integrate powerful AI features into their Java applications.


Spring I/O 2024 was a truly wonderful experience, marked by its many strengths such as insightful sessions, innovative presentations and valuable networking opportunities. These aspects not only enriched our understanding of the Spring ecosystem, but also inspired us to apply these new insights in our projects.

Authors: Danilo Ventura – Senior Software Engineer; Federico Vidali – Java Software Engineer; Federico Gradizzi – Java Software Developer; Tommaso Giovannelli – Software Engineer @ Bitrock

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