Fuse ESB - Product Introduction - Understanding the Example

Understanding the Example

Overview

The example builds a simple HelloWorld service and packages it for deployment into Fuse ESB. The service is written using standard JAX-WS APIs. It implements a single operation sayHi(). Once deployed, the service is exposed as a SOAP/HTTP endpoint. The most interesting parts of the example are the Spring configuration used to configure the endpoint and the Maven POM used to build the bundle.

The Spring configuration provides the details needed to expose the service using SOAP/HTTP. It can also contain details used to configure advanced Apache CXF functionality.

The Maven POM, in addition to compiling the code, uses the bundle generation plug-in to package the resulting classes into an OSGi bundle. It contains all of the details needed by the Fuse ESB container to activate the bundle and deploy the packaged service.

Using the Maven tools

The Fuse ESB Maven tooling automates a number of the steps in packaging functionality for deployment into Fuse ESB. In order to use the Maven OSGi tooling, you add the elements shown in Example 4.2 to your POM file.

Example 4.2. POM Elements for Using Fuse ESB OSGi Tooling

...
<pluginRepositories>
  <pluginRepository>
     <id>fusesource.m2</id>
      <name>ESB Open Source Community Release Repository</name>
       <url>http://repo.fusesource.com/maven2</url>
        <snapshots>
           <enabled>false</enabled>
         </snapshots>
           <releases>
              <enabled>true</enabled>
           </releases>
  </pluginRepository>
</pluginRepositories>
 ...
<build>
   <plugins>
      <plugin>
        <groupId>org.apache.felix</groupId>
        <artifactId>maven-bundle-plugin</artifactId>
         ...
       </plugin>
    </plugins>
</build>
  ...

These elements point Maven to the correct repositories to download the Fuse ESB Maven tooling and load the plug-in that implements the OSGi tooling.

The Spring configuration

The Fuse ESB container needs some details about a service before it can instantiate and endpoint for it. Apache CXF uses Spring based configuration to define endpoints for services. The configuration shown in Example 4.3 is stored in the example's \src\main\resources\META-INF\spring\beans.xml file.

Example 4.3. OSGi Example Spring Configuration

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:jaxws="http://cxf.apache.org/jaxws"
	xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://cxf.apache.org/jaxws http://cxf.apache.org/schemas/jaxws.xsd">

    <import resource="classpath:META-INF/cxf/cxf.xml" /> 
    <import resource="classpath:META-INF/cxf/cxf-extension-soap.xml" />
    <import resource="classpath:META-INF/cxf/cxf-extension-http.xml" />
    <import resource="classpath:META-INF/cxf/osgi/cxf-extension-osgi.xml" />

	<jaxws:endpoint id="helloWorld" 
	                implementor="org.apache.servicemix.examples.cxf.HelloWorldImpl"
	                address="/HelloWorld"/>

</beans>

The configuration shown in Example 4.3 does the following:

Imports the required configuration to load the required parts of the Apache CXF runtime.

Configures the endpoint that exposes the service using the jaxws:endpoint element and its attributes.

id is an identifier used by the configuration mechanism.
implementor specifies the class that implements the service. It must be on the classpath.
address specifies the address at which the service will be exposed. This address is relative to the containers HTTP address with cxf appended to it.

The POM

Example 4.4. OSGi POM

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.apache.servicemix.examples</groupId>
        <artifactId>examples</artifactId>
        <version>4.4.1-fuse-00-08</version>
    </parent>

    <groupId>org.apache.servicemix.examples</groupId>
    <artifactId>cxf-osgi</artifactId>
    <packaging>bundle</packaging>
    <version>4.4.1-fuse-00-08</version>
    <name>Apache ServiceMix Example :: CXF OSGi</name>

<!-- Add ServiceMix repositories for snaphots and releases -->
 ...

    <dependencies>
        <dependency>
            <groupId>org.apache.geronimo.specs</groupId>
            <artifactId>geronimo-ws-metadata_2.0_spec</artifactId>
            <version>${geronimo.wsmetadata.version}</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-bundle-plugin</artifactId>
                <configuration>
                    <instructions>
                        <Bundle-SymbolicName>${pom.artifactId}</Bundle-SymbolicName>
                        <Import-Package>
                            javax.jws,
                            javax.wsdl,
                            META-INF.cxf,
                            META-INF.cxf.osgi,
                            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.servicemix.cxf.transport.http_osgi,
                            org.springframework.beans.factory.config
                        </Import-Package>
                        <Private-Package>org.apache.servicemix.examples.cxf</Private-Package>
                        <Require-Bundle>org.apache.cxf.cxf-bundle</Require-Bundle>
                    </instructions>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

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