Eclipse Vert.x 4 CR1 released!

We are ex­tremely pleased to an­nounce the first re­lease can­di­date of Vert.x 4.0.

We con­sider Vert.x 4.0 fea­ture com­plete and we will do a few re­lease can­di­dates to allow the com­mu­nity to test it and re­port is­sues.

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

Tracing control

When a com­po­nent (i.e server or client) is in­volved in a Vert.x in­stance con­fig­ured with trac­ing, a new trac­ing pol­icy con­trols the com­po­nent par­tic­i­pa­tion in a trace:

  • with IG­NORE the com­po­nent will not be in­volved in the trace, e.g an HTTP client will not re­port a span in an ex­ist­ing trace
  • with PROP­A­GATE the com­po­nent will re­port a span and prop­a­gate when pos­si­ble
  • AL­WAYS the com­po­nent will re­port a span or cre­ate a new trace

Kafka tracing

Our Kafka client is now able to prop­a­gate and re­port span in ac­tive traces.


A new method has been added to RoutingContext to allow send­ing re­sponses from asyn­chro­nous calls using Vert.x fu­tures.

For ex­am­ple, re­turn­ing the con­tent of a file in a sin­gle ac­tion:

  .respond(ctx ->

This method en­ables com­po­si­tion of Futures. The Fu­ture re­sult will be processed by the JSON codec if no data has been writ­ten. Oth­er­wise, it will use the fu­ture suc­cess/fail­ure to de­cide how to ter­mi­nate the con­nec­tion.

This method should im­prove the code read­ablil­ity of cur­rent and fu­ture ap­pli­ca­tions.

Web client auth

With this re­lease you will be able to use Basic, Digest and Bearer au­then­ti­ca­tion in a sin­gle and con­cise API: client.authentication(new Credentials(...)). This is a type safe al­ter­na­tive to com­pute the head­ers your­self.

Redis client

Redis clients are now garan­teed to call all han­dlers on the cor­rect event loop. This re­duces con­text switches and re­move pos­si­ble races.

RabbitMQ client TLS support

Rab­bitMQ client can now con­nect using TLS.

SockJS JavaScript client versioning change

SockJS event bus JavaScript client is now ver­sionned ac­cord­ing to the Event­Bus bridge pro­to­col and is now in­de­pen­dant on the Vert.x ver­sion.

That has al­ways been the case and with Vert.x 4 we de­cided to make this change to sim­plify ap­pli­ca­tion up­grade since up­grad­ing Vert.x will not imply to up­grade event bus bridge clients.

In order to en­sure that the ar­ti­fact can be used both with Vert.x 3 and Vert.x 4, a new name has been cho­sen for it: @vertx/eventbus-​bridge-client.js


This is the first re­lase can­di­date of Vert.x 4. You can of course ex­pect more as we get feed­back from the com­mu­nity and fix is­sues that we failed to catch be­fore.

You can also read the pre­vi­ous an­nounces to know more about the over­ral changes:

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.CR1 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.

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