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Eclipse Vert.x 4 milestone 4 released!

We are extremely pleased to announce the fourth 4.0 milestone release of Eclipse Vert.x .

Vert.x 4 is the evolution of the Vert.x 3.x series that will bring key features to Vert.x.

This release aims to provide a reliable distribution of the current development of Vert.x 4 for people that want to try it and provide feedback.


Vert.x 4 extends the 3.x callback asynchronous model to a future/callback hybrid model.

public interface NetClient {

  // Since 3.0
  void connect(int port, String host, Handler<AsyncResult<NetSocket>> handler);

  // New in 4.0
  Future<NetSocket> connect(int port, String host);

This third milestone makes progress and fully covers with the following stack modules:

  • Vert.x Shell
  • Vert.x Mail Client
  • Vert.x Consul Client
  • Vert.x RabbitMQ Client
  • Vert.x Stomp
  • Vert.x Mongo Client

Mail client improvements

Our mail clients had nice contribution with the ability to use streaming payload for attachements and the support for DKIM signatures.

General client improvements

Some Vert.x client are designed to be used within the verticle that created it while some can be shared between verticles. This is a technical limitation that stems from the fact that client are implemented using Vert.x or Netty (such as HttpClient) and are bound to the underlying event-loop that powers them.

In Vert.x 4 we decided to get away of this limitation to simplify the usage and the configuration of the clients. Of course it is possible to continue confining clients within a verticle (for best performance) but clients can be now shared between verticles when desired with a neglectible impact on performance (requiring message passing).

Security improvements

Finally here are a few improvements done in our security layer:

  • Vertx Auth is now decoupled to handle authn/authz as 2 independent functions thanks to @sbastiandev
  • Auth Shiro is deprecated in favour of the new “auth properties” module and “auth ldap”
  • Web CSRF tokens are session aware to allow multiple requests from the same user
  • Initial support for webauthn

Ramping up to Vert.x 4

Instead of developing all new features exclusively in Vert.x 4, we introduce some of these features in the 3.x branch so the community can benefit from them. The Vert.x 4 development focus on more fundamental changes that cannot be done in the 3.x series.


This is the forth milestone of Vert.x 4, you can of course expect more milestones to outline the progress of the effort.

You can also read the previous milestone announces:


The deprecations and breaking changes can be found on the wiki.

For this release there are no Docker images.,

The release artifacts have been deployed to Maven Central and you can get the distribution on Maven Central.

You can bootstrap a Vert.x 4.0.0-milestone4 project using

The documentation has been deployed on this preview web-site

That’s it! Happy coding and see you soon on our user or dev channels.