Vert.x 3.4.0.Beta1 release

We have re­leased 3.4.0.Beta1, this re­lease is the biggest since Vert.x 3.0.0 with plenty of great fea­tures.

You can use con­sume it in your projects from Maven or Gra­dle as usual with the ver­sion 3.4.0.Beta1 or read

Let me out­line the im­por­tant changes you can al­ready find in this Beta1.

Vert.x Web Client

In a sim­ple sen­tence “Vert.x Web Client is to Vert.x Http­Client what Vert.x Web is to HttpServer”

The Web Client makes it easy to do HTTP re­quest/re­sponse in­ter­ac­tions with a web server, and pro­vides ad­vanced fea­tures like:

  • Json body en­cod­ing / de­cod­ing
  • re­quest/re­sponse pump­ing
  • re­quest pa­ra­me­ters
  • uni­fied error han­dling
  • form sub­mis­sions
  • and more!

Built on top of Http­Client, it nat­u­rally in­her­its its fea­tures and pro­vides a bet­ter API, let me give an overview in one ex­am­ple:

WebClient client = WebClient.
  .get(8080, "", "/some-uri")
  .send(ar -> {
    if (ar.succeeded()) {

      HttpResponse<User> response = ar.result();
      User user = response.body();

      System.out.println("Received response with status code" + response.statusCode() + " with body " +
        user.getFirstName() + " " + user.getLastName());
    } else {
      System.out.println("Something went wrong " + ar.cause().getMessage());

RxJava singles

Rx­Java is a very pop­u­lar Java ex­ten­sion and in this re­lease we fo­cused on the API us­abil­ity with the sup­port of the Single Rx­Java type.

The new meth­ods are pre­fixed by rx and dep­re­cates the Observable suf­fixed meth­ods.

So in­stead of start­ing a server with listenObservable now you use rxListen:

HttpServer server = vertx.createHttpServer();
Single<HttpServer> single = server.rxListen(8080, "localhost");
  ok -> System.out.println("Server started"),
  err -> System.out.println("Something went wrong " + err.getMessage()));

One no­tice­able dif­fer­ence with the pre­vi­ous API, is that the listen method is called when the Single is sub­scribed.

This is very handy when com­bined with the new web client:

Single<HttpResponse<Buffer>> single = client
  .get(8080, "", "/some-uri")

// Send the request
single.subscribe(response -> System.out.println("got response " + response.statusCode());

// Send the request again
single.subscribe(response -> System.out.println("got response " + response.statusCode());


In this beta you can try Vert.x for Kotlin.

Vert.x for Kotlin is based on the Java API and pro­vides also the ex­e­cu­tion of Kotlin Ver­ti­cles.

import io.vertx.core.*
import io.vertx.kotlin.core.http.HttpServerOptions

class Server : AbstractVerticle() {

  override fun start() {

        // We provide Kotlin extension methods, allowing to use an idiomatic Kotlin API for building these options
            port = 8080,
            host = "localhost"
        .requestHandler() { req ->
          req.response().end("Hello from Kotlin")
    println("Server started on 8080")

It can be di­rectly ran from the com­mand line:

julien:vertx-kotlin-example julien$ vertx run Server.kt
Server started on 8080
Succeeded in deploying verticle

As you can see, Kotlin is using the Java API di­rectly, and we thought that it might be a cool thing to do the same with Groovy sup­port. So we have re­con­sid­ered our Groovy sup­port and now it uses the plain Java API, with­out los­ing the ex­ist­ing fea­tures.

Thanks to Groovy ex­ten­sion meth­ods, id­iomatic Groovy is still sup­ported while ben­e­fit­ing from the full Java API!

Scala sup­port is also planned for 3.4.0 and will be re­leased soon, watch @vertx_project.

The microservices story goes on…

Our APIs have ma­tured and now they have been moved out of tech pre­view, of course this wasn’t enough and we now have Vert.x Con­fig, an ex­ten­si­ble way to con­fig­ure Vert.x ap­pli­ca­tions sup­port­ing File, json, ENV, sys­tem prop­er­ties, HTTP, Ku­ber­netes Con­figmap, Con­sul, Spring Con­fig Server, Redis, Git, Zookeeper, … stores as well as sev­eral for­mats: prop­er­ties file, YAML and Hocon.

Here is a small ex­am­ple:

ConfigStoreOptions httpStore = new ConfigStoreOptions()
  .setConfig(new JsonObject()
    .put("host", "localhost").put("port", 8080).put("path", "/conf"));

ConfigStoreOptions fileStore = new ConfigStoreOptions()
  .setConfig(new JsonObject().put("path", "my-config.json"));

ConfigStoreOptions sysPropsStore = new ConfigStoreOptions().setType("sys");

ConfigRetrieverOptions options = new ConfigRetrieverOptions()

ConfigRetriever retriever = ConfigRetriever.create(vertx, options);

Vert.x Con­fig also sup­ports push based no­ti­fi­ca­tion style:

ConfigRetriever retriever = ConfigRetriever.create(Vertx.vertx(), options);
  .endHandler(v -> {
    // retriever closed
  .exceptionHandler(t -> {
    // an error has been caught while retrieving the configuration
  .handler(conf -> {
    // the configuration

Vertx MQTT Server

Vert.x MQTT Server is able to han­dle con­nec­tions, com­mu­ni­ca­tion and mes­sages ex­change with re­mote MQTT clients. Its API pro­vides a bunch of events re­lated to pro­to­col mes­sages re­ceived by clients and ex­poses allow to send mes­sages to them.

Here is a small ef­fec­tive ex­am­ple of cre­at­ing, the Vert.x way!

MqttServerOptions options = new MqttServerOptions()

MqttServer server = MqttServer.create(vertx, options);

server.endpointHandler(endpoint -> {

  System.out.println("connected client " + endpoint.clientIdentifier());

  endpoint.publishHandler(message -> {

    System.out.println("Just received message on [" + message.topicName() + "] payload [" +
      message.payload() + "] with QoS [" +
      message.qosLevel() + "]");


server.listen(ar -> {
  if (ar.succeeded()) {
    System.out.println("MQTT server started and listening on port " + server.actualPort());
  } else {
    System.err.println("MQTT server error on start" + ar.cause().getMessage());

Vert.x SQL streaming

We now sup­port stream­ing style for SQL queries:

connection.queryStream("select * from test", stream -> {
  if (stream.succeeded()) {
    SQLRowStream sqlRowStream = stream.result();

      .handler(row -> {
        // do something with the row...
      .endHandler(v -> {
        // no more data available, close the connection
        connection.close(done -> {
          if (done.failed()) {
            throw new RuntimeException(done.cause());

And with the Rx­Java API:

  .rxGetConnection() // Connect to the database
  .flatMapObservable(conn -> { // With the connection...
    return conn.rxUpdate("CREATE TABLE test(col VARCHAR(20))") // ...create test table
      .flatMap(result -> conn.rxUpdate("INSERT INTO test (col) VALUES ('val1')")) // ...insert a row
      .flatMap(result -> conn.rxUpdate("INSERT INTO test (col) VALUES ('val2')")) // ...another one
      .flatMap(result -> conn.rxQueryStream("SELECT * FROM test")) // ...get values stream
      .flatMapObservable(sqlRowStream -> {
        return sqlRowStream.toObservable() // Transform the stream into an Observable...
          .doOnTerminate(conn::close); // ...and close the connection when the stream is fully read or an error occurs
  }).subscribe(row -> System.out.println("Row : " + row.encode()));


In ad­di­tion to all these bril­lant fea­tures here is a list of more-​than-noticeable things you have in this Beta1:

  • Vert.x In­fin­is­pan re­places Vert.x Jgroups clus­ter man­ager
  • Vert.x Con­sul Client pro­vides a full fledged client for Con­sul
  • Oauth2 pre­de­fined con­fig­u­ra­tion with 16 set­tings from Azure Ac­tive Di­rec­tory, to Twit­ter with the usual sus­pects (Face­book, LinkedIn, …)
  • Http client now fol­low redi­rects

You can use and con­sume it in your projects from Maven or Gra­dle as usual with the ver­sion 3.4.0.Beta1 or read

Last but not least, I want to per­son­ally thank all the peo­ple that con­tributed to this re­lease, be­yond the Vert.x core team, the ac­tual Vert.x com­mit­ters and many other peo­ple who have given a lot of ef­fort to this up­com­ing 3.4.0!!!!

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