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Appendix D. Using the Maven OSGi Tooling

Abstract

Manually creating a bundle, or a collection of bundles, for a large project can be cumbersome. The Maven bundle plug-in makes the job easier by automating the process and providing a number of shortcuts for specifying the contents of the bundle manifest.
The Red Hat JBoss Fuse OSGi tooling uses the Maven bundle plug-in from Apache Felix. The bundle plug-in is based on the bnd tool from Peter Kriens. It automates the construction of OSGi bundle manifests by introspecting the contents of the classes being packaged in the bundle. Using the knowledge of the classes contained in the bundle, the plug-in can calculate the proper values to populate the Import-Packages and the Export-Package properties in the bundle manifest. The plug-in also has default values that are used for other required properties in the bundle manifest.
To use the bundle plug-in, do the following:
  1. Add the bundle plug-in to your project's POM file.
  2. Configure the plug-in to correctly populate your bundle's manifest.

D.1. Setting up a Red Hat JBoss Fuse OSGi project

Overview

A Maven project for building an OSGi bundle can be a simple single level project. It does not require any sub-projects. However, it does require that you do the following:
  1. Add the bundle plug-in to your POM.
  2. Instruct Maven to package the results as an OSGi bundle.
Note
There are several Maven archetypes you can use to set up your project with the appropriate settings.

Directory structure

A project that constructs an OSGi bundle can be a single level project. It only requires that you have a top-level POM file and a src folder. As in all Maven projects, you place all Java source code in the src/java folder, and you place any non-Java resources in the src/resources folder.
Non-Java resources include Spring configuration files, JBI endpoint configuration files, and WSDL contracts.
Note
Red Hat JBoss Fuse OSGi projects that use Apache CXF, Apache Camel, or another Spring configured bean also include a beans.xml file located in the src/resources/META-INF/spring folder.

Adding a bundle plug-in

Before you can use the bundle plug-in you must add a dependency on Apache Felix. After you add the dependency, you can add the bundle plug-in to the plug-in portion of the POM.
Example D.1, “Adding an OSGi bundle plug-in to a POM” shows the POM entries required to add the bundle plug-in to your project.

Example D.1. Adding an OSGi bundle plug-in to a POM

...
<dependencies>
  <dependency> 1
    <groupId>org.apache.felix</groupId>
    <artifactId>org.osgi.core</artifactId>
    <version>1.0.0</version>
  </dependency>
...
</dependencies>
...
<build>
  <plugins>
    <plugin> 2
      <groupId>org.apache.felix</groupId>
      <artifactId>maven-bundle-plugin</artifactId>
      <configuration>
        <instructions>
          <Bundle-SymbolicName>${pom.artifactId}</Bundle-SymbolicName> 3
          <Import-Package>*,org.apache.camel.osgi</Import-Package> 4
          <Private-Package>org.apache.servicemix.examples.camel</Private-Package> 5
        </instructions>
      </configuration> 
    </plugin>
  </plugins>
</build>
...
The entries in Example D.1, “Adding an OSGi bundle plug-in to a POM” do the following:
1
Adds the dependency on Apache Felix
2
Adds the bundle plug-in to your project
3
Configures the plug-in to use the project's artifact ID as the bundle's symbolic name
4
Configures the plug-in to include all Java packages imported by the bundled classes; also imports the org.apache.camel.osgi package
5
Configures the plug-in to bundle the listed class, but not to include them in the list of exported packages
Note
Edit the configuration to meet the requirements of your project.
For more information on configuring the bundle plug-in, see Section D.2, “Configuring the Bundle Plug-In”.

Activating a bundle plug-in

To have Maven use the bundle plug-in, instruct it to package the results of the project as a bundle. Do this by setting the POM file's packaging element to bundle.

Useful Maven archetypes

There are several Maven archetypes to generate a project that is preconfigured to use the bundle plug-in:

Spring OSGi archetype

The Spring OSGi archetype creates a generic project for building an OSGi project using Spring DM, as shown: 
org.springframework.osgi/spring-bundle-osgi-archetype/1.1.2
You invoke the archetype using the following command: 
mvn archetype:create -DarchetypeGroupId=org.springframework.osgi -DarchetypeArtifactId=spring-osgi-bundle-archetype -DarchetypeVersion=1.12 -DgroupId=groupId -DartifactId=artifactId -Dversion=version

Apache CXF code-first archetype

The Apache CXF code-first archetype creates a project for building a service from Java, as shown: 
org.apache.servicemix.tooling/servicemix-osgi-cxf-code-first-archetype/2008.01.0.3-fuse
You invoke the archetype using the following command: 
mvn archetype:create -DarchetypeGroupId=org.apache.servicemix.tooling -DarchetypeArtifactId=spring-osgi-bundle-archetype -DarchetypeVersion=2008.01.0.3-fuse -DgroupId=groupId -DartifactId=artifactId -Dversion=version

Apache CXF wsdl-first archetype

The Apache CXF wsdl-first archetype creates a project for creating a service from WSDL, as shown: 
org.apache.servicemix.tooling/servicemix-osgi-cxf-wsdl-first-archetype/2008.01.0.3-fuse
You invoke the archetype using the following command: 
mvn archetype:create -DarchetypeGroupId=org.apache.servicemix.tooling -DarchetypeArtifactId=servicemix-osgi-cxf-wsdl-first-archetype -DarchetypeVersion=2008.01.0.3-fuse -DgroupId=groupId -DartifactId=artifactId -Dversion=version

Apache Camel archetype

The Apache Camel archetype creates a project for building a route that is deployed into JBoss Fuse, as shown: 
org.apache.servicemix.tooling/servicemix-osgi-camel-archetype/2008.01.0.3-fuse
You invoke the archetype using the following command: 
mvn archetype:create -DarchetypeGroupId=org.apache.servicemix.tooling -DarchetypeArtifactId=servicemix-osgi-camel-archetype -DarchetypeVersion=2008.01.0.3-fuse -DgroupId=groupId -DartifactId=artifactId -Dversion=version