iiinova — where your digital self keeps evolving

Step by step, we are making #Spring documentation as suitable for #Kotlin developers as it is for #Java ones. Today, we are adding a Kotlin snippet to the official Spring quickstart page. spring.io/quickstart#k...

Kotlin snippet of a Spring Boot application

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Sébastien Deleuze @seb.deleuze.fr · 14/04/2026

At @springio.net keynote, Rossen shares how Spring embraces Virtual Threads, Structured Concurency, and what is coming in Spring Framework 7.1+ to support streaming on Spring MVC stack (RestClient server-sent events for example), as well as related performance improvements. #java #springio26

Rossen on stage with « a Loom-friendly stack » slide

Data points about Spring MVC performance improvements

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Sébastien Deleuze @seb.deleuze.fr · 13/04/2026

Is it possible to use Claude Code or Cursor to add automatically JSpecify annotations to make your Spring Boot 4 application null-safe? I will answer to this question tomorrow (Tuesday) 14:00 in the track 2 at @springio.net! #springio26 2026.springio.net/sessions/nul...

Sample Java code annotated with JSpecify nullability annotations

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Sébastien Deleuze @seb.deleuze.fr · 11/04/2026

We have opened a US-based position to work on the Spring AI project, and we are looking for somebody with expertise in Java, Spring and AI engineering! If you are interested and want to join the Spring OSS team, apply via the link shared below. broadcom.wd1.myworkdayjobs.com/en-US/Extern...

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Sébastien Deleuze @seb.deleuze.fr · 06/04/2026

Putting the final touches on my upcoming @springio.net and @kotlinconf.com talk "Idiomatic Kotlin applications with Spring Boot 4" where I will share all my guidelines for build, logging, observability, persistence, etc. Should be useful both for human developers and agentic engineering workflows.

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Sébastien Deleuze @seb.deleuze.fr · 19/03/2026

Live from @wasm.io, @lukewagner.name shares a Wasm Component Model 1.0 roadmap update. Highlights are: - Lazy and GC-friendly ABI - Native browser support - Ease implementation by toolchains and runtimes - Growing the ecosystem - Close the gap in terms of features #wasm #webassembly

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Sébastien Deleuze @seb.deleuze.fr · 14/03/2026

Breaking news : the Kotlin/Wasm team has just shared the very first incarnation of their server-side wasi-http support based on the Wasm Component Model. github.com/Kotlin/sampl... #wasm #webassembly #wasi #kotlin

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Sébastien Deleuze @seb.deleuze.fr · 16/02/2026

Reading « Quand la machine apprend » by @yann-lecun.bsky.social, pretty good book so far to learn more about machine learning and the history of AI. In addition to French, it exists in Chinese, Japanese, and Russian but surprinsingly not (yet ?) in English.

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Sébastien Deleuze @seb.deleuze.fr · 13/02/2026

In 2026, the #Spring team is specifically focused on performance optimizations. Thanks to a collaboration between Rossen Stoyanchev, David Syer, and Violeta Georgieva, we were able to improve peak throughput by 8% on a typical enterprise web application.

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Sébastien Deleuze @seb.deleuze.fr · 02/02/2026

Excited to share that as of today, I am joining the Spring AI team (@spring-ai.bsky.social) to work on Spring AI 2.0 and future versions. I will continue to be part of the Spring Framework team and will split my time between the 2 projects. #spring #ai #java

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Sébastien Deleuze @seb.deleuze.fr · 27/01/2026

A benefit of upgrading to Spring Boot 4 for #Kotlin developers: you will be able to leverage JUnit 6 support for suspending functions to have cleaner tests.

Code sample with a refactoring from `runBlocking { }` to `suspend fun` in tests.

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Sébastien Deleuze @seb.deleuze.fr · 18/12/2025

My last blog post of the year: Next level Kotlin support in Spring Boot 4. spring.io/blog/2025/12... #spring #kotlin

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Sébastien Deleuze @seb.deleuze.fr · 13/12/2025

Plage d’argent, île de Porquerolles

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Sébastien Deleuze @seb.deleuze.fr · 08/12/2025

The unexpected huge wave of positive feedback from the community when I announced it remains one of the most memorable moments of my career. Thanks for that!

Tweet from June 2018 announcing Spring Fu with 289 retweets and 552 likes

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Sébastien Deleuze @seb.deleuze.fr · 30/11/2025

I have upgraded Spring PetKlinik, my Kotlin fullstack variant of the original Spring Petclinic, to Spring Boot 4.0.0 (before it was using snapshots). github.com/sdeleuze/spr... #spring #kotlin

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Sébastien Deleuze @seb.deleuze.fr · 28/11/2025

Only 6 days left to benefit of @wasm.io (19-20 March 2026 - Barcelona) early bird cheap conference tickets. I just bought mine! wasm.io #wasm #webassembly

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Sébastien Deleuze @seb.deleuze.fr · 27/09/2025

Presqu’île de Crozon, Bretagne

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Sébastien Deleuze @seb.deleuze.fr · 20/08/2025

I have finished Clair Obscur: Expedition 33 main quest. It is and will probably remain the best game I have ever played. And the soundtrack is amazing. Well done @expedition33.bsky.social, kudos to the team!

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Sébastien Deleuze @seb.deleuze.fr · 28/05/2025

If you want to watch online and live next week (June 4) my talk "Null Safety in Spring applications with JSpecify and NullAway", make sure to register to IntelliJ IDEA Conf 2025, it is free! lp.jetbrains.com/intellij-ide...

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Sébastien Deleuze @seb.deleuze.fr · 26/05/2025

The source code of #Spring Petklinik, the new reference #Kotlin fullstack application I have built for my #KotlinConf and #SpringIO talks, is now available at github.com/sdeleuze/spr.... I will continue to refine it.

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Sébastien Deleuze @seb.deleuze.fr · 23/05/2025

@mp911.de is sharing data points about the new Spring Data AOT repositories that have been announced at @springio.net. Double the benefits of Spring AOT mode 🤩

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Sébastien Deleuze @seb.deleuze.fr · 23/05/2025

Today, I am presenting 2 talks at @springio.net: Null Safety in Java with JSpecify and NullAway at 9:05 (auditorium) and Next level Kotlin support in Spring Boot 4 at 17:00 (room 6). Lot of demos, don’t miss them!

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Sébastien Deleuze @seb.deleuze.fr · 22/05/2025

Rod Johnson sharing his love for Spring + Kotlin on #KotlinConf main stage.

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Sébastien Deleuze @seb.deleuze.fr · 20/05/2025

I spent a couple of days working on a new reference application for the talk "Next level Kotlin support in Spring Boot 4" that I will present this week at @kotlinconf.com and @springio.net. Be ready for a few surprises ...

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Sébastien Deleuze @seb.deleuze.fr · 15/05/2025

AOT Method Profiling JEP status has changed to candidate. openjdk.org/jeps/515 In my latest benchmark with Spring Petclinic, it allows to speedup the warmup compared to the regular JIT (red line versus blue one). Stabilized peak performance is currently slightly lower, but hopefully will be fixed.

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Sébastien Deleuze @seb.deleuze.fr · 14/05/2025

Today I am at JPrime conference to present my talk about Runtime Efficiency with Spring. If you are there, don’t be shy, I am available to discuss anything Spring related!

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Sébastien Deleuze @seb.deleuze.fr · 13/05/2025

Les vidéos de mes 2 talks @devoxx.fr sur l’optimisation d’applications Spring Boot avec Project Leyden (youtu.be/4EAxhhSWgw4?...) et Null Safety (youtu.be/F_Qyo1cCpvY?...) viennent d’être publiées !

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Sébastien Deleuze @seb.deleuze.fr · 28/04/2025

Amazing game, highly recommended!

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Sébastien Deleuze @seb.deleuze.fr · 27/04/2025

You may have missed it, but the @graalvm.org team has recently open-sourced a variant of native image called web image, which compiles Java bytecode to WebAssembly bytecode instead of a native executable.

Diagram showing that GraalVM can compile Java to Wasm and run Wasm in the JVM

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Sébastien Deleuze @seb.deleuze.fr · 22/04/2025

Thanks for sharing. I continue to see a lower stabilized peak performance with AOT profiling and AOT profiling + code compilation with Leyden premain branch (built from last week) with Spring Petclinic. Are you aware and if yes, do you think this gap will be removed at some point?

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Sébastien Deleuze @seb.deleuze.fr · 16/04/2025

@garnier.wf is ready for his @devoxx.fr talk in front of a packed amphitheatre about OpenID et OAuth2 🤩

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Sébastien Deleuze @seb.deleuze.fr · 28/03/2025

Probably the most impressive and exciting talk I have seen in years! Congrats to @fniephaus.com and Patrick Ziegler for their #wasmio presentation and work on @graalvm.org starting to compile Java applications to WasmGC. Kudos to @thomaswue.dev too.

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Sébastien Deleuze @seb.deleuze.fr · 28/03/2025

DuckDB doesn’t like foie gras. Make sense ^^. #wasmio

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Sébastien Deleuze @seb.deleuze.fr · 28/03/2025

#1 in Colin Murphy (Adobe)’s whishlist for WebAssembly: compiling Java to WebAssembly. Let see this afternoon at @wasm.io if @graalvm.org can pave the way for such capability 🤞🏼

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Sébastien Deleuze @seb.deleuze.fr · 27/03/2025

A spectrum of colorless concurrency with the Wasm Component Model by @lukewagner.name. I keep being impresssed by Luke´s ability to be relevant on both the high-level vision and the low level compiler engineer level (critically important) details. Brilliant talk! #wasm #wasmio

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Sébastien Deleuze @seb.deleuze.fr · 15/03/2025

I am a huge fan of each bullet point of the Kotlin compiler roadmap ❤️

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Sébastien Deleuze @seb.deleuze.fr · 10/03/2025

I have published a new blog post to explain what benefits Spring developers can expect from the next-level Spring null safety support based on JSpecify and NullAway. spring.io/blog/2025/03... It will be available for general consumption in the upcoming Spring major version at the end of the year.

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Sébastien Deleuze @seb.deleuze.fr · 08/03/2025

Retrospectively, giving this book to my daughter when she was a child really mattered. Highly recommended.

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Sébastien Deleuze @seb.deleuze.fr · 16/02/2025

My @kotlinconf.com talk « Next level Kotlin support in Spring Boot 4 » has been accepted. See you at Copenhagen in May!

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Sébastien Deleuze @seb.deleuze.fr · 22/11/2024

The architectural and cultural mix at Cordoba's Mosque-Cathedral is striking.

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