Sébastien Deleuze
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seb.deleuze.fr
Sébastien Deleuze
@seb.deleuze.fr
1.1K followers 320 following 210 posts
Spring @ Broadcom, #WebAssembly since 2016, ex @mixitconf.org‬ staff. https://seb.deleuze.fr
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Reposted by Sébastien Deleuze
zsmb.co
📢 Rare opportunity: my team is hiring! We're looking for a new Developer Advocate to cover server-side Kotlin, focusing on Spring.

If you love Spring, Kotlin, and their communities, this might just be for you.

Learn more and apply here:
Kotlin Developer Advocate
Amsterdam, Netherlands; Berlin, Germany; Dubai, United Arab Emirates; Limassol, Cyprus; London, United Kingdom; Madrid, Spain; Munich, Germany; Prague, Czech Republic
job-boards.eu.greenhouse.io
November 11, 2025 at 3:25 PM
Reposted by Sébastien Deleuze
danvega.dev
Jackson 3 lands in Spring Boot 4! The new JsonMapper replaces ObjectMapper with immutable, thread-safe configs. Better date handling, unchecked exceptions for cleaner lambdas, and JSON views for precise serialization control.

Watch: youtu.be/4cvP_qroLH4

#SpringBoot #Java
Jackson 3 Support is HERE: What's New in Spring Framework 7 & Spring Boot 4
YouTube video by Dan Vega
youtu.be
November 10, 2025 at 6:13 PM
seb.deleuze.fr
Sometimes, small details matter...

While polishing Spring Framework 7, Juergen Hoeller has been able to craft a BridgeMethodResolver optimization that massively reduces the reflection performed on bean methods at startup. It has been backported to 6.2.x too.

github.com/spring-proje...
Avoid unnecessary bridge method resolution around getMostSpecificMethod · Issue #35780 · spring-projects/spring-framework
Following up on #21843 in 6.1.3, it turns out that this commonly causes performance regressions, unnecessarily introspecting non-annotated methods in complex class hierarchies on startup. Revisitin...
github.com
November 8, 2025 at 11:00 AM
Reposted by Sébastien Deleuze
jeptracker.bsky.social
🎯 JEP 500 updated to target JDK 26
Title: Prepare to Make Final Mean Final
Type: feature
Component: core
Release: 26
See openjdk.org/jeps/500
November 6, 2025 at 10:50 PM
Reposted by Sébastien Deleuze
snicoll.be
Please give it a try and let us know what you think! This is your last opportunity before GA on Nov 20!

spring.io/blog/2025/11...
Spring Boot 4.0.0-RC2 available now
Level up your Java code and explore what Spring can do for you.
spring.io
November 7, 2025 at 8:46 AM
Reposted by Sébastien Deleuze
squillace.bsky.social
if you are into #webassembly in the EU, there is an embarrassment of riches, but @wasm.io just announced the CFP for this spring!!!!

www.papercall.io/wasmio26
PaperCall.io - Wasm I/O 2026
Wasm I/O 2026 brings together the global WebAssembly community for two inspiring days in Barcelona, Spain on March 19–20. Join us to explore the future of WebAssembly, share ideas, and help grow a wel...
www.papercall.io
November 6, 2025 at 3:31 PM
seb.deleuze.fr
And you can even use BeanRegistrar to introduce your own configuration DSL, see github.com/spring-proje... for an example.
November 6, 2025 at 12:11 PM
Reposted by Sébastien Deleuze
danvega.dev
🚀 Spring Boot 4 tip: Jackson 3 brings JsonMapper as the preferred way to read JSON! Notice the new import. No more ObjectMapper from com.fasterxml! JsonMapper is now your go-to for JSON operations in modern Spring apps.
November 5, 2025 at 9:31 PM
Reposted by Sébastien Deleuze
parisjug.org
Les inscriptions sont ouvertes pour la soirée Spring Boot 4 & Passkeys en partenariat avec le Spring meetup.
Par @snicoll.be et @kehrlann.bsky.social
Cher Criteo
Le lundi 10 novembre prochain
www.parisjug.org/events/2025/...
Soirée Spéciale Spring
Date et lieu Lundi 10 Novembre 2025 à 19h00 Dans les locaux de Criteo Les sessions sont filmées et le public est photographié. Les photographies sont ensuite publiées sur le site du Paris JUG et autre...
www.parisjug.org
November 5, 2025 at 8:39 AM
Reposted by Sébastien Deleuze
jacob.gold
Looks like X is juicing web visit numbers by opening a browser WebView in the background whether the user visits the link or not.

They've re-invented pop-under fraud (allegedly).

news.ycombinator.com/item?id=4580...
Tell HN: X is opening any tweet link in a webview whether you press it or not 247 points by stillatit 10 hours ago | hide | past | favorite | 200 comments Just saw the CEO of Substack celebrating traffic from X/Twitter shooting up thinking they stopped suppressing tweets with links[0]. Actually, this traffic is because now any time you open a tweet with a link, the in-app webview loads in the background, and displays when you press the link. I run an ecom store that gets a lot of its customers from Twitter. I was also shocked to see my traffic double or triple overnight and thought the algorithm had blessed me and my business. Soon realized what was actually happening. Thought other traffic-monitors might appreciate this explanation. Meanwhile Nikita Bier is pretending they never suppressed tweets with links to begin with, offering the alternative explanation: "a common complaint is that posts with links tend to get lower reach. This is because the web browser covers the post and people forget to Like or Reply. So X doesn't get a clear signal whether the content is any good"[1]. A bit of a rewriting of history since Elon and his mom both tweeted about how it wasn't fair to use his platform to promote other links/platforms, even banning people who shared profiles of other social networks (including Paul Graham for a period). They suppressed all links shortly after. [0] https://x.com/cjgbest/status/1985464687350485092 [1] https://x.com/nikitabier/status/1979994223224209709
November 4, 2025 at 4:09 PM
Reposted by Sébastien Deleuze
mixitconf.org
Notre CFP ouvre dans 1 semaine tout pile 🙌

Pas besoin d’avoir 10 ans d’expérience ou d’être une rockstar du dev pour proposer une conférence 💫

Alors, prêt·e à franchir le pas ?

➡️ RDV sur le lien le 10 novembre à 9h : sessionize.com/mixit-2026/
November 3, 2025 at 10:01 AM
Reposted by Sébastien Deleuze
graalvm.org
Introduce support for JavaScript, Python and Wasm execution via Graal languages in Spring framework 🎉 github.com/spring-proje... by @seb.deleuze.fr
spring-projects/spring-framework
Spring Framework. Contribute to spring-projects/spring-framework development by creating an account on GitHub.
github.com
November 3, 2025 at 10:14 AM
Reposted by Sébastien Deleuze
danvega.dev
Spring Boot 4's new BeanRegistrar interface finally gives us a clean way to register beans programmatically! No more wrestling with BeanFactoryPostProcessor for dynamic registration. Perfect for conditional loading & performance optimization 🚀

Blog: danvega.dev/blog/programmatic-bean-registration
Spring Boot 4's Bean Registrar: A Cleaner Way to Register Beans Programmatically
Learn how Spring Boot 4's new BeanRegistrar interface simplifies programmatic bean registration in Spring Framework 7. This tutorial demonstrates dynamic bean creation based on environment properties,...
danvega.dev
November 1, 2025 at 5:41 PM
Reposted by Sébastien Deleuze
thomaswue.dev
Really great to see plans for adding better integrated support for running @graalvm.org language implementations for JavaScript, Python, and WebAssembly in your Spring applications! github.com/spring-proje...
October 31, 2025 at 12:54 PM
Reposted by Sébastien Deleuze
danvega.dev
Spring Boot 4's null-safety is here! 🎯

@NullMarked (JSpecify + NullAway) makes nullness explicit. No more guessing if findUserByEmail() returns null.
IDE catches NPEs at compile-time. Your type signatures finally tell the truth.
October 31, 2025 at 12:53 PM
Reposted by Sébastien Deleuze
snicoll.be
On behalf of the team and everyone who has contributed, I'm happy to announce that Spring Framework 7.0.0-RC3 has been released and is now available from Maven Central.

spring.io/blog/2025/10...

#java #spring @spring.io
Spring Framework 7.0.0-RC3 available now
Level up your Java code and explore what Spring can do for you.
spring.io
October 31, 2025 at 11:54 AM
Reposted by Sébastien Deleuze
0.5ritter.de
A new feature dropped on start.spring.io!

Because you all love YAML so much, we've added radio buttons to switch the configuration format from properties to YAML. Hope you brought a ruler and don't live in Norway!
Screenshot of start.spring.io showing the new configuration section.
October 30, 2025 at 9:48 AM
Reposted by Sébastien Deleuze
titzerbl.bsky.social
Today I presented to the Wasm CG a proposal for fine-grained dynamic code generation as a core WebAssembly feature. The proposal is now at phase 1!

github.com/WebAssembly/...

Also immortalized in song: suno.com/song/19e0679...
GitHub - WebAssembly/jit-interface: WebAssembly specification, reference interpreter, and test suite for the jit-interfaces proposal.
WebAssembly specification, reference interpreter, and test suite for the jit-interfaces proposal. - WebAssembly/jit-interface
github.com
October 29, 2025 at 9:49 PM
Reposted by Sébastien Deleuze
cowtowncoder.bsky.social
Finally managed to squeeze the follow-up (to "Jackson 3.0 released") blog post out -> cowtowncoder.medium.com/why-upgrade-...
Why upgrade to Jackson 3.0?
(if you are happy with Jackson 2.x functionality)
cowtowncoder.medium.com
October 29, 2025 at 1:00 AM
seb.deleuze.fr
It may not be obvious if you have not tried a #Spring Boot 4 RC yet, but I consider Spring Boot modularization as the most important enhancement that this new generation is introducing.

The Spring Boot team has just published a related blog post, this is a must read!

spring.io/blog/2025/10...
Modularizing Spring Boot
Level up your Java code and explore what Spring can do for you.
spring.io
October 28, 2025 at 5:02 PM
seb.deleuze.fr
I have updated the blog post after Spring Boot 4.0.0-RC1 release, which restores in a deprecated form the Jackson 2 auto-configuration to help migrating, and Spring Security 7.0.0-RC1 one that leverages "safe default typing".
seb.deleuze.fr Sébastien Deleuze @seb.deleuze.fr · Oct 7
I have just published "Introducing Jackson 3 support in Spring" with hopefully useful insights on Spring Boot 4 upcoming JSON support and on the migration from Jackson 2. spring.io/blog/2025/10...
Introducing Jackson 3 support in Spring
Level up your Java code and explore what Spring can do for you.
spring.io
October 27, 2025 at 9:54 AM
Reposted by Sébastien Deleuze
sebi.io
Kotlin 2.2.21 and 2.2.20 have a lot goodies in them. In my video, I'm looking at the highlights! www.youtube.com/watch?v=QWpp...
What's new in Kotlin 2.2.21 (and 2.2.20!)
YouTube video by Kotlin by JetBrains
www.youtube.com
October 23, 2025 at 2:00 PM
Reposted by Sébastien Deleuze
kotlinlang.org
💳 Processing 43B+ transactions a year, Worldline needed a language that could evolve with their growth.

Kotlin’s concise syntax, type safety, and Java interoperability help their backend engineers deliver at scale.

🎥 Watch the testimonial from Worldline’s lead developer.
youtu.be/3IxDICQTutw?...
How Kotlin Server-Side Development Delivers Real Business Results for Worldline
YouTube video by Kotlin by JetBrains
youtu.be
October 21, 2025 at 3:27 PM
Reposted by Sébastien Deleuze
snicoll.be
I am happy to share that we have released Spring Boot 4.0.O-RC1.

This release candidate concludes our modularity efforts, migration to Jackson 3 with support for using Jackson 2 in a deprecated fashion, and more.

Please give it a try and let us know what you think!

spring.io/blog/2025/10...
Spring Boot 4.0.0-RC1 available now
Level up your Java code and explore what Spring can do for you.
spring.io
October 24, 2025 at 5:46 AM