What's new in Vert.x 4.1

Vert.x 4.1 comes with plenty of new ex­cit­ing fea­tures.

Here is an overview of the most im­por­tant fea­tures sup­ported in Vert.x 4.1.

Reactive Microsoft SQL Server Client

The Re­ac­tive Mi­crosoft SQL Server Client joins the data­base clients fam­ily!

In this first re­lease, sev­eral com­mon data types are sup­ported, as well as pre­pared state­ments and trans­ac­tions.

Vert.x HTTP Proxy

It is very easy to write an HTTP proxy with Vert.x, yet there are a lot of things that prox­ies must do.

Vert.x HTTP Proxy is a new com­po­nent of the stack that aims to make it easy to write prox­ies.

You can cre­ate a proxy as fol­lows:

       .origin(7070, "localhost"))

The proxy can also dy­nam­i­cally re­solve the ori­gin (i.e the prox­ied server):

HttpProxy proxy = HttpProxy.reverseProxy(proxyClient).originSelector(
  address -> resolveOrigin(address)

Vert.x Web Proxy in­te­grates the proxy with Vert.x Web.

This com­po­nent is in tech pre­view and will re­ceive more fea­tures over time.

RxJava 3

Vert.x has been sup­port­ing Rx­Java for many years, the Rx­Java 3 sup­port has landed in 4.1

The rx­i­fied API works like pre­vi­ous ver­sions, how­ever reg­u­lar meth­ods are ex­posed with Rx­Java types in­stead of call­backs since Vert.x 4 async model is based on fu­tures.

server.requestHandler(req -> {
  HttpServerResponse resp = req.respone();

  // No need to subscribe to the completable
  Completable c1 = resp.write("1");

  // Write result is cached, this will send
  // 1

  // The Rxified API however requires subscription to trigger the call
  Completable c2 = resp.rxWrite("2");

  // Write is subscription based, this will send
  // 2
  // 2

Open Telemetry support

Open Teleme­try trac­ing is a new and no­tice­able trac­ing in­te­gra­tion avail­able in 4.1.

Service proxy with futures

Vert.x 4 pro­vides a future-​first API. How­ever, ser­vice prox­ies can only be de­clared with call­backs.

We ad­dressed this issue in Vert.x 4.1 and you can now write ser­vice prox­ies with fu­tures. The only change you need is to de­clare the fu­ture usage in the Code­gen mod­ule de­c­la­ra­tion.


In this re­lease, we im­proved the log­ging han­dler to en­able cus­tom log­ging for­mats.

The OAuth2 han­dler now fol­lows the OIDC stan­dard by val­i­dat­ing the re­quested scopes are present in the OAuth2 re­sponse. A new APIKEY han­dler was added to sup­port more se­cu­rity use cases, and it is now pos­si­ble to write cus­tom authn han­dlers with­out re­quir­ing in­ter­nal classes.

The API ctx.json() now fol­lows the IANA con­tent type stan­dard.

Vertx-Web OpenAPI

A lot of com­mu­nity dis­cus­sions and work has been done to im­prove the se­cu­rity han­dling of Ope­nAPI in Vert.x. We now sup­port all kinds of se­cu­rity de­scribed in Ope­nAPI 3.0, OpenId, OAuth2, API-​Key, HTTP.

The new API also al­lows for fetch­ing the se­cu­rity con­fig­u­ra­tion from the doc­u­ment it­self, rather than hav­ing it double-​configured in the doc­u­ment and in the code.


In the Vert.x auth mod­ule, sup­port for EdDSA was added to the JOSE/COSE code. This means that we can now use those al­go­rithms in JWT/OAuth2/OIDC/FIDO2. The sup­port re­lies only on the pro­vided JDK which means that users will need to use JDK 15 or above to be able to use those al­go­rithms.

In the JOSE code, im­prove­ments were made to cor­rectly fol­low the use value of a JWK and more tests were added to ver­ify that we in­terop prop­erly with to­kens gen­er­ated by other li­braries.

Fi­nally, in FIDO2/Webauthn we fol­low the rec­om­men­da­tion of stor­ing the at­tes­ta­tion cer­tifi­cates, which al­lows of­fline val­i­da­tion of de­vices. This is a util­ity that al­lows you to check if to­kens have been com­pro­mised and dis­able their fu­ture use at the RP.

Kotlin 1.5 support

Vert.x 4.1 sup­ports Kotlin 1.5

General pool improvements

Vert.x in­ter­nal pool has been im­proved to gain more flex­i­bil­ity with new fea­tures such as

  • mul­ti­ple event loops per pool
  • waiter can­cel­la­tion
  • lock free im­ple­men­ta­tion
  • con­nec­tion se­lec­tion strat­egy

In ad­di­tion, the in­ter­nal pool is now used by the Vert.x SQL Client and Vert.x Mail Clients.

Web Session Storage with Infinispan

Vert.x Web ses­sion stor­age is plug­gable. In this ver­sion, a new ses­sion store with In­fin­is­pan in-​memory data grid is avail­able.

It is im­ple­mented on top of the In­fin­is­pan client so it can be used with ei­ther stand­alone or clus­tered Vert.x ap­pli­ca­tions.

If you want to get started, don’t miss the Web Ses­sion Stor­age with In­fin­is­pan Client how-​to.

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