Eclipse Vert.x 4 milestone 2 released!

We are ex­tremely pleased to an­nounce the sec­ond 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 who 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);

The first mile­stone, only cov­ered Vert.x Core, this sec­ond mile­stone has made sig­nif­i­cant progress with the fu­tur­i­sa­tion of the fol­low­ing stack mod­ules:

  • vertx-​auth
  • vertx-​web
  • vertx-​mqtt
  • vertx-​cassandra-client
  • vertx-​redis-client
  • vertx-​kakfa-client
  • vertx-​amqp-client


In­stru­ment­ing asyn­chro­nous ap­pli­ca­tion for dis­trib­uted trac­ing is quite chal­leng­ing be­cause most trac­ing li­braries rely on thread local stor­age. While it works rea­sonnably well in a block­ing ap­pli­ca­tion, this does not work for an asyn­chro­nous ap­pli­ca­tion.

This sup­poses that the ap­pli­ca­tion con­trol flow mat­ters (i.e threads) al­though what re­ally mat­ters is the ap­pli­ca­tion re­quest flow (e.g the in­com­ing HTTP re­quest).

We im­proved Vert.x 4 to reify the re­quest flow, mak­ing it pos­si­ble to in­te­grate pop­u­lar trac­ing tools such as Zip­kin or Open­trac­ing. Vert.x per­for­mance is leg­endary and we made sure that this does not have any over­head out of the box (dis­abled).

We pro­vide sup­port for these two pop­u­lar li­braries under the Vert.x Trac­ing um­brella.

Other changes

  • Groovy has been sim­pli­fied in Vert.x 4 to re­move code gen­er­a­tion that was not re­ally needed in prac­tice
  • The orig­i­nal Redis client dep­re­cated in 3.7 has been re­moved re­placed by the new Redis client
  • The fol­low­ing com­po­nents have reached their end of life and have been pruned
    • MySQL / Post­greSQL async client re­placed by the Vert.x SQL Client (since 3.8)
    • AMQP bridge re­placed by the Vert.x AMQP Client (since 3.7)

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 first mile­stone of Vert.x 4, we aim to re­lease Vert.x 4 by the end of this year and you can of course ex­pect more mile­stones to out­line the progress of the ef­fort.


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-​milestone2 project using

The doc­u­men­ta­tion has been de­ployed on this pre­view web-​site https://vertx-​​4-​preview/docs/

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

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