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microprofile-rest-client: MicroProfile REST Client QuickStart

The microprofile-rest-client quickstart demonstrates the use of the MicroProfile REST Client specification in WildFly.

What is it?

MicroProfile REST Client provides a type-safe approach to invoke RESTful services over HTTP. It relies on Jakarta REST APIs for consistency and easier reuse.

Architecture

In this quickstart we have a country server and a country client used in the test. The server provides a simple REST interface providing information about some countries. The test creates a client that consumes this API through the MicroProfile REST Client specification.

System Requirements

The application this project produces is designed to be run on WildFly Application Server 34 or later.

All you need to build this project is Java SE 17.0 or later, and Maven 3.6.0 or later. See Configure Maven to Build and Deploy the Quickstarts to make sure you are configured correctly for testing the quickstarts.

Use of the WILDFLY_HOME and QUICKSTART_HOME Variables

In the following instructions, replace WILDFLY_HOME with the actual path to your WildFly installation. The installation path is described in detail here: Use of WILDFLY_HOME and JBOSS_HOME Variables.

When you see the replaceable variable QUICKSTART_HOME, replace it with the path to the root directory of all of the quickstarts.

Start the WildFly Standalone Server

  1. Open a terminal and navigate to the root of the WildFly directory.

  2. Start the WildFly server with the MicroProfile profile by typing the following command.

    $ WILDFLY_HOME/bin/standalone.sh -c standalone-microprofile.xml
    Note
    		 For Windows, use the WILDFLY_HOME\bin\standalone.bat script.

Build and Deploy the Quickstart

  1. Make sure WildFly server is started.

  2. Open a terminal and navigate to the root directory of this quickstart.

  3. Type the following command to build the quickstart.

    $ mvn clean install

  4. Type the following command to deploy the quickstart.

    $ mvn wildfly:deploy

This deploys the microprofile-rest-client/target/microprofile-rest-client.jar to the running instance of the server.

You should see a message in the server log indicating that the archive deployed successfully.

Access the Country Server Application

The application will be running at the following URL: http://localhost:8080/microprofile-rest-client/.

You can verify that the server is responding by accessing http://localhost:8080/microprofile-rest-client/name/France endpoint using your browser or curl http://localhost:8080/microprofile-rest-client/name/France to get some information about France.

The Country REST Client

Using the MicroProfile REST Client is as simple as creating an interface which uses the proper Jakarta REST and MicroProfile annotations. In this case, the org.wildfly.quickstarts.microprofile.rest.client.CountriesServiceClient interface may be found in src/test/java:

package org.wildfly.quickstarts.microprofile.rest.client;

import org.eclipse.microprofile.rest.client.inject.RegisterRestClient;
import org.wildfly.quickstarts.microprofile.rest.client.model.Country;

import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.PathParam;
import jakarta.ws.rs.Produces;

@Path("/")
public interface CountriesServiceClient {

    @GET
    @Path("/name/{name}")
    @Produces("application/json")
    Country getByName(@PathParam("name") String name);

    @GET
    @Path("/name/{name}")
    @Produces("application/json")
    CompletionStage<Country> getByNameAsync(@PathParam("name") String name);
}

The getByName method gives our code the ability to query a country by name from the REST Countries API, while the getByNameAsync method is an asynchronous alternative. The client will handle all the networking and marshalling leaving our code clean of such technical details.

As you can see, all that our REST client interface uses for now are standard Jakarta REST annotations.

Regarding integrating the REST Client in your application, there are two options, the CDI lookup and the programmatic lookup, and both may be found in the org.wildfly.quickstarts.microprofile.rest.client.CountriesResource class, respectively in use by cdiName(String) and programmaticName(String) methods.

package org.wildfly.quickstarts.microprofile.rest.client;

import jakarta.ws.rs.WebApplicationException;
import org.eclipse.microprofile.config.inject.ConfigProperty;
import org.eclipse.microprofile.rest.client.RestClientBuilder;
import org.eclipse.microprofile.rest.client.inject.RestClient;

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.inject.Inject;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.NotFoundException;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.PathParam;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;
import org.wildfly.quickstarts.microprofile.Country;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.TimeUnit;

@Path("/country")
@ApplicationScoped
public class CountriesResource {

    @Inject
    @RestClient
    private CountriesServiceClient countriesServiceClient;

    @Inject
    @ConfigProperty(name = "server.host")
    private String serverHost;

    @GET
    @Path("/cdi/{name}")
    @Produces(MediaType.APPLICATION_JSON)
    public Country cdiName(@PathParam("name") String name) {
        try {
            return countriesServiceClient.getByName(name);
        } catch (NotFoundException e) {
            return null;
        }
    }

    @GET
    @Path("/programmatic/{name}")
    @Produces(MediaType.APPLICATION_JSON)
    public Country programmaticName(@PathParam("name") String name) throws MalformedURLException {
        CountriesServiceClient client = RestClientBuilder.newBuilder()
                .baseUrl(new URL(serverHost))
                .build(CountriesServiceClient.class);
        return client.getByName(name);
    }

    @GET
    @Path("/name-async/{name}")
    @Produces(MediaType.APPLICATION_JSON)
    public CompletionStage<Country> nameAsync(@PathParam("name") String name) {
        CompletionStage<Country> completionStage = countriesServiceClient.getByNameAsync(name);
        try {
            TimeUnit.SECONDS.sleep(1L);
        } catch (InterruptedException e) {
            throw new WebApplicationException(e);
        }
        return completionStage;
    }
}

Run the Integration Tests

This quickstart includes integration tests, which are located under the src/test/ directory. The integration tests verify that the quickstart runs correctly when deployed on the server.

Follow these steps to run the integration tests.

  1. Make sure WildFly server is started.

  2. Make sure the quickstart is deployed.

  3. Type the following command to run the verify goal with the integration-testing profile activated.

    $ mvn verify -Pintegration-testing

Undeploy the Quickstart

When you are finished testing the quickstart, follow these steps to undeploy the archive.

  1. Make sure WildFly server is started.

  2. Open a terminal and navigate to the root directory of this quickstart.

  3. Type this command to undeploy the archive:

    $ mvn wildfly:undeploy

Building and Running the quickstart application in a bootable JAR

You can use the WildFly Maven Plugin to build a WildFly bootable JAR to run this quickstart.

The quickstart pom.xml file contains a Maven profile named bootable-jar, which activates the bootable JAR packaging when provisioning WildFly, through the <bootable-jar>true</bootable-jar> configuration element:

      <profile>
          <id>bootable-jar</id>
          <activation>
              <activeByDefault>true</activeByDefault>
          </activation>
          <build>
              <plugins>
                  <plugin>
                      <groupId>org.wildfly.plugins</groupId>
                      <artifactId>wildfly-maven-plugin</artifactId>
                      <configuration>
                          <discover-provisioning-info>
                              <version>${version.server}</version>
                          </discover-provisioning-info>
                          <bootable-jar>true</bootable-jar>
                          <add-ons>...</add-ons>
                      </configuration>
                      <executions>
                          <execution>
                              <goals>
                                  <goal>package</goal>
                              </goals>
                          </execution>
                      </executions>
                  </plugin>
                  ...
              </plugins>
          </build>
      </profile>

The bootable-jar profile is activate by default, and when built the WildFly bootable jar file is named microprofile-rest-client-bootable.jar, and may be found in the target directory.

Procedure

  1. Ensure the bootable jar is built.

    $ mvn clean clean install

  2. Start the WildFly bootable jar use the WildFly Maven Plugin start-jar goal.

    $ mvn wildfly:start-jar
    Note

    You may also start the bootable jar without Maven, using the java command.

    $ java -jar target/microprofile-rest-client-bootable.jar

  3. Run the integration tests use the verify goal, with the integration-testing profile activated.

    $ mvn verify -Pintegration-testing

  4. Shut down the WildFly bootable jar use the WildFly Maven Plugin shutdown goal.

    $ mvn wildfly:shutdown

Building and running the quickstart application with OpenShift

Build the WildFly Source-to-Image (S2I) Quickstart to OpenShift with Helm Charts

On OpenShift, the S2I build with Apache Maven uses an openshift Maven profile to provision a WildFly server, deploy and run the quickstart in OpenShift environment.

The server provisioning functionality is provided by the WildFly Maven Plugin, and you may find its configuration in the quickstart pom.xml:

        <profile>
            <id>openshift</id>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.wildfly.plugins</groupId>
                        <artifactId>wildfly-maven-plugin</artifactId>
                        <configuration>
                            <discover-provisioning-info>
                                <version>${version.server}</version>
                                <context>cloud</context>
                            </discover-provisioning-info>
                            <add-ons>...</add-ons>
                        </configuration>
                        <executions>
                            <execution>
                                <goals>
                                    <goal>package</goal>
                                </goals>
                            </execution>
                        </executions>
                    </plugin>
                    ...
                </plugins>
            </build>
        </profile>

You may note that unlike the provisioned-server profile it uses the cloud context which enables a configuration tuned for OpenShift environment.

The plugin uses WildFly Glow to discover the feature packs and layers required to run the application, and provisions a server containing those layers.

If you get an error or the server is missing some functionality which cannot be auto-discovered, you can download the WildFly Glow CLI and run the following command to see more information about what add-ons are available:

wildfly-glow show-add-ons

Getting Started with WildFly for OpenShift and Helm Charts

This section contains the basic instructions to build and deploy this quickstart to WildFly for OpenShift or WildFly for OpenShift Online using Helm Charts.

Prerequisites

  • You must be logged in OpenShift and have an oc client to connect to OpenShift

  • Helm must be installed to deploy the backend on OpenShift.

Once you have installed Helm, you need to add the repository that provides Helm Charts for WildFly.

$ helm repo add wildfly https://docs.wildfly.org/wildfly-charts/
"wildfly" has been added to your repositories
$ helm search repo wildfly
NAME                    CHART VERSION   APP VERSION     DESCRIPTION
wildfly/wildfly         ...             ...            Build and Deploy WildFly applications on OpenShift
wildfly/wildfly-common  ...             ...            A library chart for WildFly-based applications

Deploy the WildFly Source-to-Image (S2I) Quickstart to OpenShift with Helm Charts

Log in to your OpenShift instance using the oc login command. The backend will be built and deployed on OpenShift with a Helm Chart for WildFly.

Navigate to the root directory of this quickstart and run the following command:

$ helm install microprofile-rest-client -f charts/helm.yaml wildfly/wildfly --wait --timeout=10m0s 
NAME: microprofile-rest-client
...
STATUS: deployed
REVISION: 1

This command will return once the application has successfully deployed. In case of a timeout, you can check the status of the application with the following command in another terminal:

oc get deployment microprofile-rest-client

The Helm Chart for this quickstart contains all the information to build an image from the source code using S2I on Java 17:

build:
  uri: https://github.com/wildfly/quickstart.git
  ref: main
  contextDir: microprofile-rest-client
deploy:
  replicas: 1

This will create a new deployment on OpenShift and deploy the application.

If you want to see all the configuration elements to customize your deployment you can use the following command:

$ helm show readme wildfly/wildfly

Get the URL of the route to the deployment.

$ oc get route microprofile-rest-client -o jsonpath="{.spec.host}"

Access the application in your web browser using the displayed URL.

Run the Integration Tests with OpenShift

The integration tests included with this quickstart, which verify that the quickstart runs correctly, may also be run with the quickstart running on OpenShift.

Note

The integration tests expect a deployed application, so make sure you have deployed the quickstart on OpenShift before you begin.

Run the integration tests using the following command to run the verify goal with the integration-testing profile activated and the proper URL:

$ mvn verify -Pintegration-testing -Dserver.host=https://$(oc get route microprofile-rest-client --template='{{ .spec.host }}')
Note

The tests are using SSL to connect to the quickstart running on OpenShift. So you need the certificates to be trusted by the machine the tests are run from.

Undeploy the WildFly Source-to-Image (S2I) Quickstart from OpenShift with Helm Charts

$ helm uninstall microprofile-rest-client

Building and running the quickstart application with Kubernetes

Build the WildFly Quickstart to Kubernetes with Helm Charts

For Kubernetes, the build with Apache Maven uses an openshift Maven profile to provision a WildFly server, suitable for running on Kubernetes.

The server provisioning functionality is provided by the WildFly Maven Plugin, and you may find its configuration in the quickstart pom.xml:

        <profile>
            <id>openshift</id>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.wildfly.plugins</groupId>
                        <artifactId>wildfly-maven-plugin</artifactId>
                        <configuration>
                            <discover-provisioning-info>
                                <version>${version.server}</version>
                                <context>cloud</context>
                            </discover-provisioning-info>
                            <add-ons>...</add-ons>
                        </configuration>
                        <executions>
                            <execution>
                                <goals>
                                    <goal>package</goal>
                                </goals>
                            </execution>
                        </executions>
                    </plugin>
                    ...
                </plugins>
            </build>
        </profile>

You may note that unlike the provisioned-server profile it uses the cloud context which enables a configuration tuned for Kubernetes environment.

The plugin uses WildFly Glow to discover the feature packs and layers required to run the application, and provisions a server containing those layers.

If you get an error or the server is missing some functionality which cannot be auto-discovered, you can download the WildFly Glow CLI and run the following command to see more information about what add-ons are available:

wildfly-glow show-add-ons

Getting Started with Kubernetes and Helm Charts

This section contains the basic instructions to build and deploy this quickstart to Kubernetes using Helm Charts.

Install Kubernetes

In this example we are using Minikube as our Kubernetes provider. See the Minikube Getting Started guide for how to install it. After installing it, we start it with 4GB of memory.

minikube start --memory='4gb'

The above command should work if you have Docker installed on your machine. If, you are using Podman instead of Docker, you will also need to pass in --driver=podman, as covered in the Minikube documentation.

Once Minikube has started, we need to enable its registry since that is where we will push the image needed to deploy the quickstart, and where we will tell the Helm charts to download it from.

minikube addons enable registry

In order to be able to push images to the registry we need to make it accessible from outside Kubernetes. How we do this depends on your operating system. All the below examples will expose it at localhost:5000

# On Mac:
docker run --rm -it --network=host alpine ash -c "apk add socat && socat TCP-LISTEN:5000,reuseaddr,fork TCP:$(minikube ip):5000"

# On Linux:
kubectl port-forward --namespace kube-system service/registry 5000:80 &

# On Windows:
kubectl port-forward --namespace kube-system service/registry 5000:80
docker run --rm -it --network=host alpine ash -c "apk add socat && socat TCP-LISTEN:5000,reuseaddr,fork TCP:host.docker.internal:5000"

Prerequisites

  • Helm must be installed to deploy the backend on Kubernetes.

Once you have installed Helm, you need to add the repository that provides Helm Charts for WildFly.

$ helm repo add wildfly https://docs.wildfly.org/wildfly-charts/
"wildfly" has been added to your repositories
$ helm search repo wildfly
NAME                    CHART VERSION   APP VERSION     DESCRIPTION
wildfly/wildfly         ...             ...            Build and Deploy WildFly applications on OpenShift
wildfly/wildfly-common  ...             ...            A library chart for WildFly-based applications

Deploy the WildFly Source-to-Image (S2I) Quickstart to Kubernetes with Helm Charts

The backend will be built and deployed on Kubernetes with a Helm Chart for WildFly.

Navigate to the root directory of this quickstart and run the following commands:

mvn -Popenshift package wildfly:image

This will use the openshift Maven profile we saw earlier to build the application, and create a Docker image containing the WildFly server with the application deployed. The name of the image will be microprofile-rest-client.

Next we need to tag the image and make it available to Kubernetes. You can push it to a registry like quay.io. In this case we tag as localhost:5000/microprofile-rest-client:latest and push it to the internal registry in our Kubernetes instance:

# Tag the image
docker tag microprofile-rest-client localhost:5000/microprofile-rest-client:latest
# Push the image to the registry
docker push localhost:5000/microprofile-rest-client:latest

In the below call to helm install which deploys our application to Kubernetes, we are passing in some extra arguments to tweak the Helm build:

  • --set build.enabled=false - This turns off the s2i build for the Helm chart since Kubernetes, unlike OpenShift, does not have s2i. Instead, we are providing the image to use.

  • --set deploy.route.enabled=false - This disables route creation normally performed by the Helm chart. On Kubernetes we will use port-forwards instead to access our application, since routes are an OpenShift specific concept and thus not available on Kubernetes.

  • --set image.name="localhost:5000/microprofile-rest-client" - This tells the Helm chart to use the image we built, tagged and pushed to Kubernetes' internal registry above.

$ helm install microprofile-rest-client -f charts/helm.yaml wildfly/wildfly --wait --timeout=10m0s --set build.enabled=false --set deploy.route.enabled=false --set image.name="localhost:5000/microprofile-rest-client"
NAME: microprofile-rest-client
...
STATUS: deployed
REVISION: 1

This command will return once the application has successfully deployed. In case of a timeout, you can check the status of the application with the following command in another terminal:

kubectl get deployment microprofile-rest-client

The Helm Chart for this quickstart contains all the information to build an image from the source code using S2I on Java 17:

build:
  uri: https://github.com/wildfly/quickstart.git
  ref: main
  contextDir: microprofile-rest-client
deploy:
  replicas: 1

This will create a new deployment on Kubernetes and deploy the application.

If you want to see all the configuration elements to customize your deployment you can use the following command:

$ helm show readme wildfly/wildfly

To be able to connect to our application running in Kubernetes from outside, we need to set up a port-forward to the microprofile-rest-client service created for us by the Helm chart.

This service will run on port 8080, and we set up the port forward to also run on port 8080:

kubectl port-forward service/microprofile-rest-client 8080:8080

The server can now be accessed via http://localhost:8080 from outside Kubernetes. Note that the command to create the port-forward will not return, so it is easiest to run this in a separate terminal.

Run the Integration Tests with Kubernetes

The integration tests included with this quickstart, which verify that the quickstart runs correctly, may also be run with the quickstart running on Kubernetes.

Note

The integration tests expect a deployed application, so make sure you have deployed the quickstart on Kubernetes before you begin.

Run the integration tests using the following command to run the verify goal with the integration-testing profile activated and the proper URL:

$ mvn verify -Pintegration-testing -Dserver.host=http://localhost:8080

Undeploy the WildFly Source-to-Image (S2I) Quickstart from Kubernetes with Helm Charts

$ helm uninstall microprofile-rest-client

To stop the port forward you created earlier use:

$ kubectl port-forward service/microprofile-rest-client 8080:8080

Conclusion

MicroProfile REST Client provides you with an option to define REST clients in a clear, declarative, and intuitive way using the same annotations as for your Jakarta REST resources. It also allows you to make the HTTP communication on the background transparent for your services with the direct data conversions and exception mappers. You can find more information about the MicroProfile REST Client specification at https://github.com/eclipse/microprofile-rest-client.