6.3. Packaging a Web Service in a Bundle

Overview

This section explains how to modify an existing Maven project for a Apache CXF application, so that the project generates an OSGi bundle suitable for deployment in the Red Hat JBoss Fuse OSGi container. To convert the Maven project, you need to modify the project's POM file and the project's Spring XML file(s) (located in META-INF/spring).

Modifying the POM file to generate a bundle

To configure a Maven POM file to generate a bundle, there are essentially two changes you need to make: change the POM's package type to bundle; and add the Maven bundle plug-in to your POM. For details, see Section 6.1, “Generating a Bundle Project”.

Mandatory import packages

In order for your application to use the Apache CXF components, you need to import their packages into the application's bundle. Because of the complex nature of the dependencies in Apache CXF, you cannot rely on the Maven bundle plug-in, or the bnd tool, to automatically determine the needed imports. You will need to explicitly declare them.
You need to import the following packages into your bundle:
javax.jws
javax.wsdl
javax.xml.bind
javax.xml.bind.annotation
javax.xml.namespace
javax.xml.ws
org.apache.cxf.bus
org.apache.cxf.bus.spring
org.apache.cxf.bus.resource
org.apache.cxf.configuration.spring
org.apache.cxf.resource
org.apache.cxf.jaxws
org.springframework.beans.factory.config

Sample Maven bundle plug-in instructions

Example 6.1, “Configuration of Mandatory Import Packages” shows how to configure the Maven bundle plug-in in your POM to import the mandatory packages. The mandatory import packages appear as a comma-separated list inside the Import-Package element. Note the appearance of the wildcard, *, as the last element of the list. The wildcard ensures that the Java source files from the current bundle are scanned to discover what additional packages need to be imported.

Example 6.1. Configuration of Mandatory Import Packages

<project ... >
    ...
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-bundle-plugin</artifactId>
                <extensions>true</extensions>
                <configuration>
                    <instructions>
                        ...
                        <Import-Package>
                            javax.jws,
                            javax.wsdl,
                            javax.xml.bind,
                            javax.xml.bind.annotation,
                            javax.xml.namespace,
                            javax.xml.ws,
                            org.apache.cxf.bus,
                            org.apache.cxf.bus.spring,
                            org.apache.cxf.bus.resource,
                            org.apache.cxf.configuration.spring,
                            org.apache.cxf.resource,
                            org.apache.cxf.jaxws,
                            org.springframework.beans.factory.config,
                            *
                        </Import-Package>
                        ...
                    </instructions>
                </configuration>
            </plugin>
        </plugins>
    </build>
    ...
</project>

Add a code generation plug-in

A Web services project typically requires code to be generated. Apache CXF provides two Maven plug-ins for the JAX-WS front-end, which enable tyou to integrate the code generation step into your build. The choice of plug-in depends on whether you develop your service using the Java-first approach or the WSDL-first approach, as follows:
  • Java-first approach—use the cxf-java2ws-plugin plug-in.
  • WSDL-first approach—use the cxf-codegen-plugin plug-in.

OSGi configuration properties

The OSGi Configuration Admin service defines a mechanism for passing configuration settings to an OSGi bundle. You do not have to use this service for configuration, but it is typically the most convenient way of configuring bundle applications. Both Spring DM and Blueprint provide support for OSGi configuration, enabling you to substitute variables in a Spring XML file or a Blueprint file using values obtained from the OSGi Configuration Admin service.