Using Metro to talk to Amazon EC2

Amazon EC2 has a SOAP web service, and I wanted to talk to EC2 from Hudson, so I decided to use Metro for this. The end result is the JAX-WS commons EC2 module, which is a library you can put in your classpath with Metro 1.4 when you need to talk to EC2.

EC2 SOAP API is pretty straight-forward except one caveat — you need to sign the whole request, but their WSDL doesn't say so in a machine readable way (that is, by using WS-Policy.) Had they put a proper policy declaration, tools like Metro would be able to hide the whole thing behind the scene, but because they didn't, I had to manually configure Metro a bit to get this working. Basically, this amounts to manually putting the corresponding policy element in WSDL (which is not a very pleasant experience, I have to say, unless you use NetBeans to have it generated for you.)

I also added JAXB fluent API plugin when compiling WSDL, so that the calling application has an easier type building a tree of JAXB objects when sending a request. I think this is very useful with almost any JAX-WS compilation, so here's the POM snippet you can copy into your POM to do this in any other JAX-WS compilation:

<xmp>
  <build>
    ...
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>jaxws-maven-plugin</artifactId>
        <executions>
          <execution>
            <goals>
              <goal>wsimport</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <extension>true</extension>
          ...
          <target>2.1</target>
          <wsdlFiles>
            <wsdlFile>ec2.wsdl</wsdlFile>
          </wsdlFiles>
          <xjcArgs>
            <xjcArg>-Xfluent-api</xjcArg>
          </xjcArgs>
        </configuration>
        <dependencies>
          <dependency>
            <groupId>com.sun.xml.ws</groupId>
            <artifactId>jaxws-tools</artifactId>
            <version>2.1.3</version>
          </dependency>
          <dependency>
            <groupId>net.java.dev.jaxb2-commons</groupId>
            <artifactId>jaxb-fluent-api</artifactId>
            <version>2.1.8</version>
          </dependency>
        </dependencies>
      </plugin>

      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <configuration>
          <source>1.5</source>
          <target>1.5</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

  <repositories>
    <repository>
      <id>java.net</id>
      <url>http://download.java.net/maven/1</url>
      <layout>legacy</layout>
    </repository>
    <repository>
      <id>java.net2</id>
      <url>http://download.java.net/maven/2</url>
    </repository>
  </repositories>
  
</xmp>

In any case, all these work is done by me and the generated interfaces and JAXB beans are packaged up in a jar file, so you just need to depend on this from your Maven POM or download the jar and put it in your classpath to use this.