I therefore decided to comment out the outer taskdef element and left objdoclet as the a sub element of target. In Window > Preferences > Ant > Runtime > classpath, I added the xdoclet-ojb-module jar under Global Entries. I then clicked on the Tasks tab, and clicked on add new. In the resulting dialog, I gave the name of the task as ojbdoclet, selected the jar I had just added then selected the class file implementing the ant task - OjbDocletTask.
I then brought up the run dialog by clicking on the build file and selecting Run as > Ant build ... on the context menu. In the classpath tab, I added all the jars in the ojb binary distribution lib folder using the button add labelled external jars to the user entries section.
The build file, which also shows a task to delete the schema file during a build, is shown below:
<?xml version="1.0" encoding="UTF-8"?>
<project name="martinlaw-build" default="ojb-xdoclet">
<property name="destdir" value="./repository"/>
<property name="schemaFile" value="schema/schema.xml"/>
<target name="ojb-xdoclet" depends="delete-old-schema">
<!--
<taskdef name="ojbdoclet"
classname="xdoclet.modules.ojb.OjbDocletTask"
> --><!-- classpathref="build-classpath" -->
<!-- defined in eclipse ant > global entries > add jar > define task, add supporting jars to
build classpath under external tools configuration -->
<ojbdoclet destdir="${destdir}">
<fileset dir="../../main/java/edu/su/cv/ojb">
<!-- restrict to files with xdoclet markup only -->
<filename name="CourseTraining.java"/>
</fileset>
<ojbrepository destinationFile="repository_user.xml"/>
<torqueschema databaseName="placement_bundled" destinationFile="${schemaFile}" dtdUrl="database.dtd"/>
</ojbdoclet>
<!-- </taskdef> -->
</target>
<target name="delete-old-schema">
<delete>
<fileset dir="${destdir}">
<filename name="${schemaFile}" />
</fileset>
</delete>
</target>
</project>
