Eclipse Vert.x 4 beta 3 released!

We are ex­tremely pleased to an­nounce the third 4.0 beta 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.

HTTP client request creation

Until Beta3, HTTP client has cre­ated lazy HTTP re­quests, since then cre­at­ing a re­quest has be­come an asyn­chro­nous op­er­a­tion guar­an­tee­ing that a slot for per­form­ing the re­quest is granted:

// Created a request
HttpClientRequest request = client.get("/some-uri");

// Connect to the server or reuse a connection from the pool and then try to send the request

// Since Beta3
client.get("/some-uri", ar -> {
  // The client connected to the server or reused a connection from the pool
  if (ar.succeeded()) {
    HttpClientRequest request = ar.result();

    // Send the request

An­other (hid­den) mo­ti­va­tion to switch to this model is avoid­ing data races when the HTTP client is used out­side the event-​loop using fu­tures.

Pre­vi­ously, you could write code like:

Future<HttpClientResponse> get = client.get("some-uri");

// Assuming we have a client that returns a future response
// assuging this is *not* on the event-loop
Future<Buffer> fut = get.send().compose(response -> {

  // Response events might have happen already
  return response.body();

Now, you can write in­stead:

Future<Buffer> fut = client.get("some-uri").compose(request -> {
  request.send().compose(response -> response.body())

HttpServerResponse send method

In the pre­vi­ous beta, HTTP client re­quest got a new sim­pli­fied send method to send a body or a stream. We did the same for the HTTP server re­sponse API:

server.requestHandler(req -> {
  getSomeStream().onSuccess(stream -> {

HTTP tunnel improvements

Cre­at­ing an HTTP tun­nel has now be­come more nat­ural:

client.request(HttpMethod.CONNECT, "some-uri")
  .onSuccess(request -> {

    // Connect to the server
    request.connect(ar -> {
      if (ar.succeeded()) {
        HttpClientResponse response = ar.result();

        if (response.statusCode() != 200) {
          // Connect failed for some reason
        } else {
          // Tunnel created, raw buffers are transmitted on the wire
          NetSocket socket = response.netSocket();

The new connect method tells the client that when a 201 re­sponse is re­ceived from the server then the con­nec­tion should be switched to not in­ter­pret HTTP data any­more.

On the server, the API has be­come asyn­chro­nous and re­named to toNetSocket():

server.requestHandler(request -> {
  if (request.method() == HttpMethod.CONNECT) {
    // Will send an HTTP 201 status code and switch the connection to use raw buffers
    request.toNetSocket(ar -> {
      if (ar.succeeded()) {
        NetSocket socket = ar.result();

WebSocket upgrade improvements

The server Web­Socket man­ual up­grade op­er­a­tion has also be­come asyn­chro­nous and re­named to toWebSocket()

server.requestHandler(request -> {
  if (request.method() == HttpMethod.GET && "Upgrade".equals(request.getHeader("connection"))) {
    // Will do the WebSocket handshake
    request.toWebSocket(ar -> {
      if (ar.succeeded()) {
        ServerWebSocket socket = ar.result();

Row to JSON conversion

SQL client can now eas­ily trans­form a Row into a JSON ob­ject, this can be con­vie­nient for ap­pli­ca­tions di­rectly trans­fer­ring JSON re­sults to the client:

  .preparedQuery("SELECT * FROM USERS WHERE ID=$1")
  .onSuccess(row -> {
    if (row.size() == 1) {
      JsonObject json = row.iterator().next().toJson();


OAuth2Handler can now han­dle PKCE, which means an­other layer of se­cu­rity to your ap­pli­ca­tion.

Redis RESP3

The redis client can now speak RESP3 with redis servers. This means it can han­dle all the new types and APIs avail­able on redis from all ver­sions (RESP2, redis < 6) and (RESP3, redis >= 6).


This is the Beta3 re­lase of Vert.x 4, you can of course ex­pect an­other beta as we get feed­back from the com­mu­nity and fix is­sues that we failed to catch be­fore.

You can also read the mile­stone 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.Beta3 project using

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

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

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