Monday, April 12, 2010

JAX-WS Web service with Maven

One of my earlier post Building JAX-WS Webservice was using Ant as build tool for developing web services. With each passing day Maven is gaining more popularity and became preferred build tool for many developers. I used to get emails from several readers about working JAX-WS examples with Maven as build tool. In this post I will try to demonstrate to publish and consume a JAX-WS web service using Maven.

The source code used in this post is available here, which will be referred at several places in this post.

The jaxws-maven-plugin has two goals wsgen and wsimport.

  • wsgen - This reads a service endpoint implementation class and generates all of the portable artifacts for a JAX-WS web service. With newer versions (tested with 2.2) of JAX-WS, execution of this task is not required for publishing webservice
  • wsimport - This tool reads WSDL and generates client side artifacts. We will be using this goal for generating client and consuming a web service.

Publish Web service

For publishing a web service we need to write an interface and its implementation then annotate them with relevant annotations. The JAX-WS libraries should be added as dependency in pom.xml. A sample (partial) build script is shown below-

<dependencies>
    <dependency>
        <groupId>com.sun.xml.ws</groupId>
        <artifactId>jaxws-rt</artifactId>
        <scope>compile</scope>
        <version>2.2</version>
    </dependency>
</dependencies>
. . .
<build>
    <plugins>
        <plugin>
            <groupId>org.mortbay.jetty</groupId>
            <artifactId>maven-jetty-plugin</artifactId>
            <configuration>
                <scanIntervalSeconds>10</scanIntervalSeconds>
                <connectors>
                    <connector implementation="org.mortbay.jetty.nio.SelectChannelConnector">
                        <port>8080</port>
                        <maxIdleTime>60000</maxIdleTime>
                    </connector>
                </connectors>
            </configuration>
        </plugin>
    </plugins>
</build>

We can see in the above Maven script that the wsgen is not required. The JAX-WS implementation will take care of that at runtime. To make testing easier I have used Jetty plugin, which will publish the web service for further consumption by the client in next step. To publish the web service invoke following command in 'webservice' directory of the source code of this post-
mvn -e clean compile jetty:run

Create Client

For creating web service client the wsimport goal of jaxws-maven-plugin will be used. The wsimport goal creates portable client artifacts by parsing a WSDL. In this example the WSDL URL is the one which was published by starting the web service at previous step. The pom.xml of client side application will look like below-

<dependencies>
    <dependency>
        <groupId>com.sun.xml.ws</groupId>
        <artifactId>jaxws-rt</artifactId>
        <scope>compile</scope>
        <version>2.2</version>
    </dependency>
</dependencies>
. . .
<build>
    <plugins>
        <!-- Generate client using WSDL -->
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>jaxws-maven-plugin</artifactId>
            <configuration>
                <packageName>wsclient</packageName>
                <wsdlUrls>
                    <wsdlUrl>http://localhost:8080/webservice/myService?wsdl</wsdlUrl>
                </wsdlUrls>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>exec-maven-plugin</artifactId>
            <version>1.1</version>
            <executions>
                <execution>
                    <goals>
                        <goal>java</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <mainClass>client.WsClient</mainClass>
            </configuration>
        </plugin>
    </plubins>
</build>

For the sake of simplicity I have used exec-maven-plugin here, which will run the test class to invoke the web service from build script itself. To generate client and run the test class, trigger the build from 'webservice-client' directorty using following command-
mvn -e clean compile exec:java


The examples shown above were tested with following configuration-
  • Java 1.6.18
  • JAX-WS 2.
  • Maven 2.2.1
  • Windows XP

Note:- If JAX-WS 2.2 is used with older versions of Java 6 (e.g. Java 1.6.03) then you may encounter errors like shown below-
SEVERE: WSSERVLET11: failed to parse runtime descriptor: java.lang.LinkageError: JAXB 2.1 API is being loaded from the bootstrap classloader, but this RI (from jar:file:/C:/Documents%20and%20Settings/Vinod%20Singh/.m2/repository/com/sun/xml/bind/jaxb-impl/2.2/jaxb-impl-2.2.jar!/com/sun/xml/bind/v2/model/impl/ModelBuilder.class) needs 2.2 API. Use the endorsed directory mechanism to place jaxb-api.jar in the bootstrap classloader. (See http://java.sun.com/j2se/1.6.0/docs/guide/standards/)
java.lang.LinkageError: JAXB 2.1 API is being loaded from the bootstrap classloader, but this RI (from jar:file:/C:/Documents%20and%20Settings/Vinod%20Singh/.m2/repository/com/sun/xml/bind/jaxb-impl/2.2/jaxb-impl-2.2.jar!/com/sun/xml/bind/v2/model/impl/ModelBuilder.class) needs 2.2 API. Use the endorsed directory mechanism to place jaxb-api.jar in the bootstrap classloader. (See http://java.sun.com/j2se/1.6.0/docs/guide/standards/) at com.sun.xml.bind.v2.model.impl.ModelBuilder.(ModelBuilder.java:173)

The reason of these errors is that the earlier versions of Java 6 are using lower versions of JAX-WS while we are trying to use higher version of JAX-WS. To overcome these errors either we need to downgrade the JAX-WS version in our runtime environment or use endorsed directory mechanism.

Hope this will be useful to some of the readers.

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