In October 2025, I visited Devoxx Belgium and again it was an awesome event! I learned a lot and received quite some information which I do not want to withhold from you. In this blog, you can find my takeaways of Devoxx Belgium 2025!
1. Introduction
Devoxx Belgium is the largest Java conference in Europe. This year, it was already the 22nd edition. As always, Devoxx is being held in the fantastic theatres of Kinepolis Antwerp. Each year, there is a rush on the tickets. Tickets are released in several batches, so if you could not have a ticket during the first batch, you will get another chance.
The first two days of Devoxx are Deep Dive days where you can enjoy more in-depth talks (about 2-3 hours) and hands-on workshops. Days three up and including five are the Conference Days where talks are being held in a time frame of about 30-50 minutes. You receive a lot of information!
This edition was a special one for me, because I got the opportunity to speak at Devoxx myself, which has been an awesome experience! I gave a Deep Dive session on Monday, but more on that later on.
Enough for the introduction, the next paragraphs contain my takeaways from Devoxx. This only scratches the surface of a topic, but it should be enough in order to make you curious to dive a bit deeper into the topic yourself.
Do check out the Devoxx Youtube channel. All the sessions are recorded and can be viewed there. If you intend to view them all: there are 250 of them…
2. Artificial Intelligence
Let’s start with AI first. More and more AI-related talks are given, which makes Devoxx Belgium also the largest AI conference in the world. But, there are sufficient other topics to choose from, but I cannot neglect the importance of AI during this conference.
2.1 AI Agents
Agents are on the rise and the major libraries for using AI with Java have support for it, or are working on this topic. In general, they all support three flows (explanation is mainly taken from the LangChain4j documentation):
- Sequential workflow: A sequential workflow is the simplest possible pattern where multiple agents are invoked one after the other, with each agent’s output being passed as input to the next agent. This pattern is useful when you have a series of tasks that need to be performed in a specific order.
- Loop workflow: In this case, you want to improve the output of an LLM in a loop until a certain condition has been met. The agent is invoked multiple times. An end condition can of course also be a maximum number of times in order to prevent the agent to get stuck in the loop.
- Parallel workflow: With the parallel workflow, you can start multiple agents in parallel and combine their output once they are done with their task.
Next to these flows, it is also possible to create Agent to Agent workflows. A2A is an open standard that enables AI agents to communicate and collaborate across different platforms and frameworks, regardless of their underlying technologies. With this approach, you can combine several agents altogether.
It is good to know about these capabilities and which support is available in the libraries: LangChain4j, Spring AI, Agent Development Kit.
And do check out the Embabel Framework created by Rod Johnson. This makes use of Goal-Oriented-Action-Planning (GOAP).
From LLM orchestration to autonomous agents: Agentic AI patterns with LangChain4j
Discover the Agent Development Kit for Java for building AI agents
Gen AI Grows Up: Enterprise JVM Agents With Embabel
2.2 Model Context Protocol
If you want to add agents to your AI workflow, you should know about Model Context Protocol (MCP). MCP is a standardized way of interacting with agents. Creating an MCP server is quite easy to do with the above mentioned libraries. If you want to test your agents, then you can do so by using the MCP Inspector. Something which is not yet addressed sufficiently in the MCP specification, is how to secure MCP servers. There is some temporary solution currently, but this probably will change in the near future.
Beyond local tools: Deep dive into the Model Context Protocol (MCP)
2.3 AI Coding Assistants
Of course, I have to mention my own Deep Dive. If you want to know more about how to improve the model responses during coding, or if you want to know which tasks can be executed (or not) by AI, etc. Do definitely watch the first part of my Deep Dive. If you are interested in adding MCP servers to your coding workflow in order that a model can make use of your terminal, retrieve up-to-date documentation for your libraries or write End-to-End tests for you, do watch the second part (starting at 1:17).
Unlocking AI Coding Assistants: Real-World Use Cases
3. Software Architecture
I have read about Architecture Decision Records (ADR) before and they were mentioned in some talks. But I never had a decent explanation like in the talk I visited. So if you want to get started with ADR, you should definitely take a look at the talk.
Creating effective and objective architectural decision records (ADRs)
And to continue the architecture paragraph, also watch Making significant Software Architecture decisions. If someone wants to make an architecture decision, you should make use of the 5 why’s. So, if someone is telling you to use technology A, you ask ‘but why?’, the person will explain, and then you ask ‘but why?’, etc. If you still got a decent answer after the fifth why, you are good to go. This and other tips are given in this talk.
4. Security
4.1 Spring Security
I always try to visit a talk about Spring Security, just to freshen up my knowledge and to learn new things, of course. This year I went to a Spring Security Authorization Deep Dive. You learn about Request, Method and Object authorization, and how to design your security authorization.
Authorization in Spring Security: permissions, roles and beyond
4.2 Vulnerabilities
Ah, vulnerabilities… often a nightmare to developers. Because we need to update our dependencies often. This talk explains CVE’s, SBOMs, how to expose your SBOM by means of Spring Boot Actuator, how to use Dependency Track to manage your SBOMs, etc. And also that you should use distroless base images for your own container images in order to reduce the number of dependencies in your container.
From Vulnerability to Victory: Mastering the CVE Lifecycle for Java Developers
5. Other
5.1 Java 25
Between all the AI content, we would almost forget that Java 25 has been released on the 16th of September. In order to get a complete overview, you should take a look at Java 21 to 25 – Better Language, Better APIs, Better Runtime. I was unfortunately not able to attend this Deep Dive because it was scheduled together with my Deep Dive. But that is the beauty of Devoxx Belgium: all talks are recorded and available the next day. This is definitely one of the first talks I will look at.
If you are interested in what is coming forward, you should take a look at Weather the Storm: How Value Classes Will Enhance Java Performance. Value classes are immutable and also available for Records. You will get the same performance as with primitive types, meaning that creating value classes comes at almost no performance cost.
5.2 Spring Boot 4
Another major release coming up, is Spring Boot 4 and Spring Framework 7, which is scheduled for November 2025. Discover the new HTTP client, the use of JSpecify annotations, Jackson 3, API versioning, and so on.
5.3 IntelliJ IDEA
If you are a Java developer, you probably are using IntelliJ IDEA. IntelliJ covers quite some features and also a lot of them you do not know about. Learn more about it and watch Be more productive with IntelliJ IDEA. You will definitely learn something new.
If you are using Spring Boot, you should install the Spring Debugger plugin. At least the ability to see which properties files are loaded, which beans are loaded is already so valuable that it will help you during debugging.
Spring Debugger: Behind The Scenes of Spring Boot
6. Conclusion
Devoxx 2025 was great and I am glad I was able to attend the event. As you can read in this blog, I learned a lot and I need to take a closer look at many topics. At least I do not need to search for inspiration for future blogs!
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