Red Hat Training

A Red Hat training course is available for Red Hat Fuse

Chapter 3. Building with Maven

The standard approach to developing applications for Spring Boot in Fuse is to use the Apache Maven build tool and to structure your source code as a Maven project. Fuse provides Maven quickstarts to get you started quickly and many of the Fuse buld tools are provided as Maven plug-ins. For this reason, it is highly recommended that you adopt Maven as the build tool for Spring Boot projects in Fuse.

3.1. Generating a Maven project

Fuse provides a selection of quickstarts, based on Maven archetypes, which you can use to generate an initial Maven project for a Spring Boot application. To save you having to remember the location information and versions for various Maven archetypes, Fuse provides tooling to help you generate Maven projects for standalone Spring Boot projects.

3.1.1. Project generator at launch.openshift.io

The quickest way to get started with Spring Boot standalone in Fuse is to navigate to launch.openshift.io and follow the instructions for the Spring Boot standalone runtime, to generate a new Maven project. After following the on-screen instructions, you will be prompted to download an archive file, which contains a complete Maven project that you can build and run locally.

3.1.2. Fuse tooling wizard in Developer Studio

Alternatively, you can download and install Red Hat JBoss Developer Studio (which includes Fuse Tooling). Using the Fuse New Integration Project wizard, you can generate a new Spring Boot standalone project and continue to develop inside the Eclipse-based IDE.

3.2. Depend on the BOM for Spring Boot

After creating and building your first Spring Boot project, you will soon want to add more components. But how do you know which versions of the Maven dependencies to add to your project? The simplest (and recommended) approach is to use the relevant Bill of Materials (BOM) file, which automatically defines all of the version dependencies for you.

3.2.1. BOM file for Spring Boot

The purpose of a Maven Bill of Materials (BOM) file is to provide a curated set of Maven dependency versions that work well together, saving you from having to define versions individually for every Maven artifact.

The Fuse BOM for Spring Boot offers the following advantages:

  • Defines versions for Maven dependencies, so that you do not need to specify the version when you add a dependency to your POM.
  • Defines a set of curated dependencies that are fully tested and supported for a specific version of Fuse.
  • Simplifies upgrades of Fuse.
Important

Only the set of dependencies defined by a Fuse BOM are supported by Red Hat.

To incorporate a BOM file into your Maven project, specify a dependencyManagement element in your project’s pom.xml file (or, possibly, in a parent POM file), as shown in the following example: 

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project ...>
  ...
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    <!-- configure the versions you want to use here -->
    <bom.version>7.0.0.fuse-000027-redhat-1</bom.version>
    <spring-boot.version>1.5.13.RELEASE</spring-boot.version>

    <maven-compiler-plugin.version>3.3</maven-compiler-plugin.version>
    <maven-surefire-plugin.version>2.18.1</maven-surefire-plugin.version>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.jboss.redhat-fuse</groupId>
        <artifactId>fuse-springboot-bom</artifactId>
        <version>${bom.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>
  ...
</project>
Note

The org.jboss.redhat-fuse BOM is new in Fuse 7.0 and has been designed to simplify BOM versioning. The Fuse quickstarts and Maven archetypes still use the old style of BOM, however, as they have not yet been refactored to use the new one. Both BOMs are correct and you can use either one in your Maven projects. In an upcoming Fuse release, the quickstarts and Maven archetypes will be refactored to use the new BOM.

After specifying the BOM using the dependency management mechanism, it becomes possible to add Maven dependencies to your POM without specifying the version of the artifact. For example, to add a dependency for the camel-hystrix component, you would add the following XML fragment to the dependencies element in your POM: 

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-hystrix-starter</artifactId>
</dependency>

Note how the Camel artifact ID is specified with the -starter suffix — that is, you specify the Camel Hystrix component as camel-hystrix-starter, not as camel-hystrix. The Camel starter components are packaged in a way that is optimized for the Spring Boot environment.

3.2.2. Spring Boot Maven plugin

The Spring Boot Maven plugin is provided by Spring Boot and it is a developer utility for building and running a Spring Boot project:

  • Building — create an executable Jar package for your Spring Boot application by entering the command mvn package in the project directory. The output of the build is placed in the target/ subdirectory of your Maven project.
  • Running — for convenience, you can run the newly-built application with the command, mvn spring-boot:start.

To incorporate the Spring Boot Maven plugin into your project POM file, add the plugin configuration to the project/build/plugins section of your pom.xml file, as shown in the following example: 

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<project ...>
  ...
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    <!-- configure the versions you want to use here -->
    <bom.version>7.0.0.fuse-000027-redhat-1</bom.version>

  </properties>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.jboss.redhat-fuse</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <version>${bom.version}</version>
        <executions>
          <execution>
            <goals>
              <goal>repackage</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...
</project>