<?xml version="1.0" encoding="UTF-8"?>

 <project name="forjoe" default="run" basedir=".">

     <target name="clean">

         <delete dir="build"/>

     </target>

     <target name="compile" depends="build"/>

     <target name="build">

         <antcall target="-build-one">

             <param name="version" value="api1.0"/>

         </antcall>

         <echo level="info" message="Compiling the Implementation. This should succeed."/>

         <antcall target="-build-one">

             <param name="version" value="impl"/>

             <param name="cp" location="build/api1.0/classes"/>

         </antcall>

     </target>

     <target name="run" depends="build">

         <echo level="info" message="Instantiating and running Joe's implementation. This should succeed."/>

         <antcall target="-run-one">

             <param name="version" value="api1.0"/>

         </antcall>

     </target>

     <!-- support methods -->

     <target name="-run-one">

         <fail message="You need to specify API version number" unless="version"/>

         <java classpath="build/${version}/classes:build/impl/classes" classname="impl.joe.Main"

             failonerror="true"

         />

     </target>

     <target name="-build-one">

         <fail message="You need to specify version number" unless="version"/>

         <mkdir dir="build/${version}/classes"/>

         <property name="cp" value=""/>

         <javac 

             srcdir="src-${version}" 

             destdir="build/${version}/classes" 

             source="1.5" target="1.5"

             classpath="${cp}"

         />

     </target>

 </project>