Deliver Micro REST Services using WildFly Swarm

IMPORTANT: The Thorntail project (formerly known as WildFly Swarm) has reached End Of Life. The last Thorntail release is the 2.7.0. You are recommended to evaluate a migration plan for your applications. Check this tutorial to learn more: How to migrate Thorntail applications

In this hands-on tutorial we will demonstrate how to publish quickly a REST Service using WildFly Swarm.

First of all, we will take a Simple REST Service taken from my github repository:

package com.itbuzzpress.chapter11.service;
import javax.ws.rs.Consumes;
import javax.ws.rs.DefaultValue;
import javax.ws.rs.FormParam;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.container.AsyncResponse;
import javax.ws.rs.container.Suspended;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.UriInfo;

import com.itbuzzpress.chapter11.model.SimpleProperty;

@Path("/simple")
public class SimpleRESTService {
	@GET
	@Path("/text")
	public String getHello () 
	{
		return "hello world!";
	} 
	@GET
	@Path("/json")
	@Produces(MediaType.APPLICATION_JSON)
	public SimpleProperty getPropertyJSON () 
	{
        SimpleProperty p = new SimpleProperty("key","value");
		return p;
	}
	@GET
	@Path("/xml")
	@Produces(MediaType.APPLICATION_XML)
	public SimpleProperty getPropertyXML () 
	{
        SimpleProperty p = new SimpleProperty("key","value");
		return p;
	}
}

The REST Service does nothing particularly fancy, however it can be used as a simple playground for REST Services producing content in different formats. An Activator class is required to set the REST ApplicationPath:

package com.itbuzzpress.chapter11.activator;

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

@ApplicationPath("/rest")
public class JaxRsActivator extends Application {
 
}

Finally, the SimpleProperty class is nothing more than a JavaBean:

package com.itbuzzpress.chapter11.model;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class SimpleProperty {
	public SimpleProperty() {

	}
 
	private String key;
	private String value;
	public String getKey() {
		return key;
	}
	public void setKey(String key) {
		this.key = key;
	}
	public SimpleProperty(String key, String value) {
		super();
		this.key = key;
		this.value = value;
	}
	public String getValue() {
		return value;
	}
	public void setValue(String value) {
		this.value = value;
	}
}

So far nothing new. In order to build our Micro Service, we will include the wildfly-swarm plugin in the pom.xml file and the required dependencies;in our case it’s just jaxrs which will automatically trigger the sub-dependencies like Undertow web server.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  <modelVersion>4.0.0</modelVersion>
  <groupId>com.example</groupId>
  <artifactId>demo</artifactId>
  <name>Wildfly Swarm Example</name>
  <version>1.0.0-SNAPSHOT</version>
  <packaging>war</packaging>

  <properties>
    <version.wildfly.swarm>1.0.0.Final</version.wildfly.swarm>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <failOnMissingWebXml>false</failOnMissingWebXml>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.wildfly.swarm</groupId>
        <artifactId>bom</artifactId>
        <version>${version.wildfly.swarm}</version>
        <scope>import</scope>
        <type>pom</type>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <build>
    <finalName>demo</finalName>
    <plugins>
      <plugin>
        <groupId>org.wildfly.swarm</groupId>
        <artifactId>wildfly-swarm-plugin</artifactId>
        <version>${version.wildfly.swarm}</version>
        <executions>
          <execution>
            <goals>
              <goal>package</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <!-- Java EE 7 dependency -->
    <dependency>
      <groupId>javax</groupId>
      <artifactId>javaee-api</artifactId>
      <version>7.0</version>
      <scope>provided</scope>
    </dependency>
    <!-- Wildfly Swarm Fractions -->
    <dependency>
      <groupId>org.wildfly.swarm</groupId>
      <artifactId>jaxrs</artifactId>
    </dependency>
 
  </dependencies>
</project>

So with just a single dependency (jaxrs), and the javaee-api, you will build-up an application which contains, behind the hoods, a custom application server.

Building the application

You can build your application with the maven’s package goal:

mvn clean package

Here is what was created in the target folder of your project:

[francesco@localhost javaee7-rest-basic]$ ls target
. . . . . 
javaee7-rest-swarm-1.0.0-swarm.jar 
javaee7-rest-swarm-1.0.0.war

Running the application

You can run your application using Maven:

mvn wildfly-swarm:run

Or simply with java -jar:

java -jar ./target/javaee7-rest-swarm-1.0.0-swarm.jar

You will be able to invoke the REST Service using the URL: http://localhost:8080/rest/simple/[Path]

For example:

By using WildFly Swarm you can easily provision Micro Services using just the API you need in your application!