36.5. Deploy to an OSGi Container

Overview

One of the options for deploying the Web service is to package it as an OSGi bundle and deploy it into an OSGi container such as Red Hat JBoss Fuse. Some of the advantages of an OSGi deployment include:
  • Bundles are a relatively lightweight deployment option (because dependencies can be shared between deployed bundles).
  • OSGi provides sophisticated dependency management, ensuring that only version-consistent dependencies are added to the bundle's classpath.

Using the Maven bundle plug-in

The Maven bundle plug-in is used to package your project as an OSGi bundle, in preparation for deployment into the OSGi container. There are two essential modifications to make to your project's pom.xml file:
  1. Change the packaging type to bundle (by editing the value of the project/packaging element in the POM).
  2. Add the Maven bundle plug-in to your POM file and configure it as appropriate.
Configuring the Maven bundle plug-in is quite a technical task (although the default settings are often adequate). For full details of how to customize the plug-in configuration, consult Deploying into the OSGi Container and Managing OSGi Dependencies.

Sample bundle plug-in configuration

The following POM fragment shows a sample configuration of the Maven bundle plug-in, which is appropriate for the current example.
<?xml version="1.0"?>
<project  ...>
  ...
  <groupId>com.fusesource.byexample.cxf-webinars</groupId>
  <artifactId>customer-ws-osgi-bundle</artifactId>
  <name>customer-ws-osgi-bundle</name>
  <url>http://www.fusesource.com</url>
 <packaging>bundle</packaging>
  ...
  <build>
    <plugins>
      ...
      <plugin>
        <groupId>org.apache.felix</groupId>
        <artifactId>maven-bundle-plugin</artifactId>
        <version>${version.maven-bundle-plugin}</version>
        <extensions>true</extensions>
        <configuration>
          <instructions>
            <Export-Package>
              !com.fusesource.customer.ws,
              !com.fusesource.demo.customer,
              !com.fusesource.demo.wsdl.customerservice
            </Export-Package>
            <Import-Package>
              *
            </Import-Package>
            <DynamicImport-Package>
              org.apache.cxf.*,
              org.springframework.beans.*
            </DynamicImport-Package>
          </instructions>
        </configuration>
      </plugin>
      ...
    </plugins>
  </build>
</project>

Dynamic imports

The Java packages from Apache CXF and the Spring API are imported using dynamic imports (specified using the DynamicImport-Package element). This is a pragmatic way of dealing with the fact that Spring XML files are not terribly well integrated with the Maven bundle plug-in. At build time, the Maven bundle plug-in is not able to figure out which Java classes are required by the Spring XML code. By listing wildcarded package names in the DynamicImport-Package element, however, you allow the OSGi container to figure out which Java classes are needed by the Spring XML code at run time.
Note
In general, using DynamicImport-Package headers is not recommended in OSGi, because it short-circuits OSGi version checking. Normally, what should happen is that the Maven bundle plug-in lists the Java packages used at build time, along with their versions, in the Import-Package header. At deploy time, the OSGi container then checks that the available Java packages are compatible with the build-time versions listed in the Import-Package header. With dynamic imports, this version checking cannot be performed.

Build and deploy the service bundle

After you have configured the POM file, you can build the Maven project and install it in your local repository by entering the following command:
mvn install
To deploy the service bundle, enter the following command at the command console:
karaf@root> install -s mvn:com.fusesource.byexample.cxf-webinars/customer-ws-osgi-bundle/1.0-SNAPSHOT
Note
If your local Maven repository is stored in a non-standard location, you might need to customize the value of the org.ops4j.pax.url.mvn.localRepository property in the EsbInstallDir/etc/org.ops4j.pax.url.mvn.cfg file, before you can use the mvn: scheme to access Maven artifacts.

Red Hat JBoss Fuse default servlet container

Red Hat JBoss Fuse has a default Jetty container which, by default, listens for HTTP requests on port 8181. Moreover, WS endpoints in this container are implicitly deployed under the servlet context cxf/. Hence, any WS endpoint whose address attribute is configured in the jaxws:endpoint element as /EndpointContext will have the following effective address:
http://Hostname:8181/cxf/EndpointContext
You can optionally customize the default servlet container by editing settings in the following file:
InstallDir/etc/org.ops4j.pax.web.cfg
Full details of the properties you can set in this file are given in the Ops4j Pax Web configuration reference.

Check that the service is running

A simple way of checking that the service is running is to point your browser at the following URL:
http://localhost:8181/cxf/Customer?wsdl
This query should return a copy of the WS endpoint's WSDL contract.