Chapter 6. Fractions

Thorntail is defined by an unbounded set of capabilities. Each piece of functionality is called a fraction. Some fractions provide only access to APIs, such as JAX-RS or CDI; other fractions provide higher-level capabilities, such as integration with RHSSO (Keycloak).

The typical method for consuming Thorntail fractions is through Maven coordinates, which you add to the pom.xml file in your application. The functionality the fraction provides is then packaged with your application (see Section 8.2, “Creating an uberjar”).

To enable easier consumption of Thorntail fractions, a bill of materials (BOM) is available. For more information, see Chapter 7, Using a BOM.

6.1. Auto-detecting fractions

Migrating existing legacy applications to benefit from Thorntail is simple when using fraction auto-detection. If you enable the Thorntail Maven plugin in your application, Thorntail detects which APIs you use, and includes the appropriate fractions at build time.

Note

By default, Thorntail only auto-detects if you do not specify any fractions explicitly. This behavior is controlled by the fractionDetectMode property. For more information, see the Maven plugin configuration reference.

For example, consider your pom.xml already specifies the API .jar file for a specification such as JAX-RS:

<dependencies>
    <dependency>
      <groupId>org.jboss.spec.javax.ws.rs</groupId>
      <artifactId>jboss-jaxrs-api_2.1_spec</artifactId>
      <version>${version.jaxrs-api}</version>
      <scope>provided</scope>
    </dependency>
</dependencies>

Thorntail then includes the jaxrs fraction during the build automatically.

Prerequisites

  • An existing Maven-based application with a pom.xml file.

Procedure

  1. Add the thorntail-maven-plugin to your pom.xml in a <plugin> block, with an <execution> specifying the package goal.

    <plugins>
      <plugin>
        <groupId>io.thorntail</groupId>
        <artifactId>thorntail-maven-plugin</artifactId>
        <version>${version.thorntail}</version>
        <executions>
          <execution>
            <id>package</id>
            <goals>
              <goal>package</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  2. Perform a normal Maven build:

    $ mvn package
  3. Execute the resulting uberjar:

    $ java -jar ./target/myapp-thorntail.jar

6.2. Using explicit fractions

When writing your application from scratch, ensure it compiles correctly and uses the correct version of APIs by explicitly selecting which fractions are packaged with it.

Prerequisites

  • A Maven-based application with a pom.xml file.

Procedure

  1. Add the BOM to your pom.xml. For more information, see Chapter 7, Using a BOM.
  2. Add the Thorntail Maven plugin to your pom.xml. For more information, see Section 8.2, “Creating an uberjar”.
  3. Add one or more dependencies on Thorntail fractions to the pom.xml file:

    <dependencies>
      <dependency>
        <groupId>io.thorntail</groupId>
        <artifactId>jaxrs</artifactId>
      </dependency>
    </dependencies>
  4. Perform a normal Maven build:

    $ mvn package
  5. Execute the resulting uberjar:

    $ java -jar ./target/myapp-thorntail.jar