MicroProfile 3.0 Support Comes to Helidon

We are proud to announce a new version of Helidon 1.3. The main feature of this release is MicroProfile 3.0 support, but it also includes additional features, bug fixes and performance improvements. Let’s take a closer look.

MicroProfile 3.0

About a month ago we released Helidon 1.2 with MicroProfile 2.2 support. Since that time we made a step forward and brought MicroProfile 3.0 support.

For those who don’t know, MicroProfile is a set of cloud-native Java APIs. It’s supported by most of the modern Java vendors like Oracle, IBM, Red Hat, Payara and Tomitribe which makes it a de-facto standard in this area. It’s one of the goals of Helidon project to support the latest versions of MicroProfile. The Helidon MicroProfile implementation is called Helidon MP and along with the reactive, non-blocking framework called Helidon SE it builds the core of Helidon.

MicroProfile 3.0 is a major release. It contains updated Metrics 2.0 with some backwards incompatible changes, HealthCheck 2.0 and Rest Client 1.3 with minor updates.

Although MicroProfile 3.0 is not backwards compatible with MicroProfile 2.2, we didn’t want to bring backwards incompatibility to Helidon. Helidon Version 1.3 supports both MicroProfile 2.2 and MicroProfile 3.0. Helidon MP applications can select the MicroProfile version by depending on one (and only one) of the following bundles.

For compatibility with MicroProfile 2.2:


For compatibility with MicroProfile 3.0:


Backward compatibility with MicroProfile 2.2 implies that every existing Helidon application that depends on helidon-microprofile-2.2 will continue to run without any changes. New applications created from the latest archetypes in Helidon 1.3 will depend on helidon-microprofile-3.0.

Metrics 2.0 Support

As mentioned above, MicroProfile Metrics 2.0 introduces a number of new features as well as some backward incompatible changes. The following is a summary of the changes:

  • Existing counters have been limited to always be monotonic
  • A new metric called a concurrent gauge is now supported
  • Tags are now part of MetricID instead of Metadata
  • Metadata is now immutable
  • Minor changes to JSON format
  • Prometheus format is now OpenMetrics format (with a few small updates)

The reader is referred to https://github.com/eclipse/microprofile-metrics/releases/tag/2.0.1 for more information.

Note: There have been some disruptive signature changes in class MetricRegistry. Several getter methods now return maps whose keys are of type MetricID instead of String. Applications upgrading to the latest version of MicroProfile Metrics 2.0 should review these uses to ensure the correct type is passed and thus prevent metric lookup failures.

Helidon SE applications that use metrics can also take advantage of the new features in Helidon 1.3. For example, MicroProfile Metrics 2.0 introduced the notion of concurrent gauges which are now also available in Helidon SE. To use any of these new features, Helidon SE applications can depend on:


Existing Helidon SE applications can continue to build using the older helidon-metrics dependency.

HealthCheck 2.0 Support

HealthCheck 2.0 contains some breaking changes. The message body of Health check response was modified, outcome and state were replaced by status. Also readiness (/health/ready) and liveness (/health/live) endpoints were introduced for smoother integration with Kubernetes.

The original /health endpoint is not removed, so your old application will still work without any changes.

New specification introduces two new annotations @Liveness and @Readiness. In Helidon SE we introduced two corresponding methods addLiveness and addReadiness and deprecated the original add method.

JPA and JTA are Production Ready

In earlier versions of Helidon we introduced an early access version of JPA and JTA integration. We received feedback from our users, fixed some issues and improved performance. In version 1.3 we are moving JPA and JTA support from Early Access to Production Ready.

We also created a guide helping users to get familiar with this feature.

Hibernate Support

With 1.3.0 you can now use Hibernate as the JPA provider, or you can continue using EclipseLink. It’s up to you. The difference is one <dependency> element in your pom.xml.

For EclipseLink:


For Hibernate:


As with our EclipseLink support, Helidon’s Hibernate JPA integration features full Java EE-mode compatibility, including support for EJB-free extended persistence contexts, JTA transactions and bean validation. It works just like the application servers you may be used to, but inside Helidon’s lightweight MicroProfile environment.

GraalVM Improvements

Supporting GraalVM is one of our goals. In each release we are continuously improving GraalVM support in Helidon SE. This version brings support of GraalVM version 19.2.0. Also now you can use Jersey Client in Helidon SE application and build a native-image for it.

Example code:

private void outbound(ServerRequest request, ServerResponse response) {
    // and reactive jersey client call
        .exceptionally(throwable -> {
            // process exception
            response.send("Failed with: " + throwable);
            return null;

We also added a guide explaining how to build a GraalVM native image from your Helidon SE application. Check it out.

New Guides

To simplify Helidon adoption process we added plenty of new guides explaining how to use various Helidon features.

Getting Started



Build and Deploy


Other features

This release includes many bug fixes, performance improvements and minor updates. More information about changes you can find in the release notes.

Helidon on OOW/CodeOne 2019

Next week (Sep 16, 2019) Oracle Open World and CodeOne open doors for all attendees. Helidon is well covered there. There are some Helidon-related talks from Helidon team where we will introduce some new features like Helidon DB Client coming soon to Helidon as well as talks from our users covering different Helidon use cases. Here is a full list:

  • Non-blocking Database Access in Helidon SE [DEV5365]
    Monday, September 16, 09:00 AM — 09:45 AM
  • Migrating a Single Monolithic Application to Microservices [DEV5112]
    Thursday, September 19, 12:15 PM — 01:00 PM
  • Hands on Lab: Building Microservices with Helidon
    Monday, September 16, 05:00 PM — 07:00 PM
  • Building Cloud Native Applications with Helidon [CON5124]
    Wednesday, September 18, 09:00 AM — 09:45 AM
  • Helidon Flies Faster on GraalVM [DEV5356]
    September 16, 01:30 PM — 02:15 PM
  • Helidon MicroProfile: Managing Persistence with JPA [DEV5376]
    Thursday, September 19, 09:00 AM — 09:45 AM

See you on CodeOne!

Helidon brings MicroProfile 2.2+ support

We are pleased to announce the 1.2.0 release of Helidon. This release adds support for MicroProfile 2.2 and includes additional bug and performance fixes. Let’s take a closer look at what’s in the release.


MicroProfile is now a de-facto standard for Java cloud-native APIs. One of the main goals of project Helidon is to deliver support for the latest MicroProfile APIs. The Helidon MicroProfile implementation is called Helidon MP and along with the reactive, non-blocking framework called Helidon SE it builds the core of Helidon.

We have been adding support for newer MicroProfile specifications one by one during the last few releases. The 1.2.0 release brings MicroProfile REST Client 1.2.1 and Open Tracing 1.3. With these pieces in place we now have full MicroProfile 2.2 support.

The full list of supported MicroProfile and Java EE APIs is listed on this image:

As you see, we added support for two more Java EE APIs: JPA (Persistence) and JTA (Transaction). It’s in early access at the moment. You should consider it as a preview. We are still working on it and the implementation and configuration is subject to change.

Here are some examples of using new APIs added in Helidon 1.2.0.

MicroProfile REST Client sample

Register a rest client interface (can be the same one that is implemented by the JAX-RS resource). Note that the URI can be overridden using configuration.

@RegisterRestClient(baseUri = "http://localhost:8081/greet")
public interface GreetResource {
    JsonObject getDefaultMessage();
    JsonObject getMessage(@PathParam("name") String name);

Declare the rest client in a class using it (such as a JAX-RS resource in a different microservice):

private GreetResource greetService;

And simply use the field to invoke the remote service (this example proxies the request to the remote service):

public JsonObject getDefaultMessage() {
    return greetService.getDefaultMessage();

Health Check 2.0 sample

Health Check 2.0 has two types of checks (in previous versions a single type existed):

  • Readiness — used by clients (such as Kubernetes readiness check) to check if the service has started and can be used
  • Liveness — used by clients (such as Kubernetes liveness checks) to check if the service is still up and running

Simply annotate an application scoped bean with the appropriate annotation (@Readiness or @Liveness) to create a health check:

import javax.enterprise.context.ApplicationScoped;
import javax.inject.Inject;
import org.eclipse.microprofile.health.HealthCheck;
import org.eclipse.microprofile.health.HealthCheckResponse;
import org.eclipse.microprofile.health.Liveness;

public class GreetHealthcheck implements HealthCheck {
    private GreetingProvider provider;
    public GreetHealthcheck(GreetingProvider provider) 
        this.provider = provider;

    public HealthCheckResponse call() {
        String message = provider.getMessage();
        return HealthCheckResponse.named("greeting")
            .withData("greeting", message)

Open Tracing Sample

MP Open Tracing adds a single annotation: @Traced, to add tracing to CDI beans.

Tracing of JAX-RS resources is automated (and can be disabled with the @Traced). Example of the bean used in the Health check example (the method getMessage is traced):

public class GreetingProvider {
    private final AtomicReference<String> message = new AtomicReference<>();
     * Create a new greeting provider, reading the message 
     * from configuration.
     * @param message greeting to use
    public GreetingProvider(
        @ConfigProperty(name = "app.greeting") String message) {
    @Traced(operationName = "GreetingProvider.getMessage")
    String getMessage() {
        return message.get();

Other Enhancements

In addition to MicroProfile 2.2, Helidon 1.2.0 contains a couple other enhancements:

  • HTTP Access Log support for Helidon MP and SE.
  • Early Access: Oracle Universal Connection Pool support: this lets you configure and inject the Oracle UCP JDBC driver as a DataSource in your Helidon MP application.

More to Come

With MicroProfile 2.2 support, Helidon has caught up with most of the other main MicroProfile implementations. We are now pushing Helidon towards MicroProfile 3.0, and we’ve already taken the first steps. That’s why we put a plus after 2.2 in the title. We already have support for Health Check 2.0 (and we’ll support it in a backwards compatible way). That leaves Metrics 2.0 and REST Client 1.3 and we are working hard to deliver it next month.

Stay tuned!

Thanks to Tomas Langer for helping with samples and to Joe Di Pol for great conversational style.