Hibernate version:
hibernate-3.1

Mapping documents:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="com.oreilly.hh.Track" table="TRACK">
<meta attribute="class-description">
Represents a single playable track in the music database.
@author Jim Elliott (with help from Hibernate)
</meta>

<id name="id" type="int" column="TRACK_ID">
<meta attribute="scope-set">protected</meta>
<generator class="native"/>
</id>

<property name="title" type="string" not-null="true"/>

<property name="filePath" type="string" not-null="true"/>

<property name="playTime" type="time">
<meta attribute="field-description">Playing time</meta>
</property>

<property name="added" type="date">
<meta attribute="field-description">When the track was created</meta>
</property>

<property name="volume" type="short" not-null="true">
<meta attribute="field-description">How loud to play the track</meta>
</property>

</class>
</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:
ant codegen
C:\projects\ch02\build.xml:43: Caused by:
Caused by:
java.lang.NoClassDefFoundError: net/sf/hibernate/MappingException
at net.sf.hibernate.tool.hbm2java.Hbm2JavaTask.processFile(Hbm2JavaTask.
java:145)
at net.sf.hibernate.tool.hbm2java.Hbm2JavaTask.execute(Hbm2JavaTask.java
:93)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
at org.apache.tools.ant.Task.perform(Task.java:364)
at org.apache.tools.ant.Target.execute(Target.java:341)
at org.apache.tools.ant.Target.performTasks(Target.java:369)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExe
cutor.java:40)
at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
at org.apache.tools.ant.Main.runBuild(Main.java:668)
at org.apache.tools.ant.Main.startAnt(Main.java:187)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:246)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:67)

at net.sf.hibernate.tool.hbm2java.Hbm2JavaTask.processFile(Hbm2JavaTask.
java:149)
at net.sf.hibernate.tool.hbm2java.Hbm2JavaTask.execute(Hbm2JavaTask.java
:93)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
at org.apache.tools.ant.Task.perform(Task.java:364)
at org.apache.tools.ant.Target.execute(Target.java:341)
at org.apache.tools.ant.Target.performTasks(Target.java:369)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExe
cutor.java:40)
at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
at org.apache.tools.ant.Main.runBuild(Main.java:668)
at org.apache.tools.ant.Main.startAnt(Main.java:187)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:246)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:67)

Name and version of the database you are using:
HSQLDB 1.8.0

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

-----------------
Maybe someone with hibernate experience, after having a quick look over my post can
see where the problem is.Being a newbie, i'm
desperatly trying to go on with the book but got stuck.

Here is the problem:

I'm trying to follow the examples from the book "A Developer's Notebook",O'Reilly,2004.

downloaded source code for the book from here: http://www.oreilly.com/catalog/hibernate/

extracted /ch02 to C:\projects\ch02

I have the following installed:
apache-ant-1.6.5
hibernate-3.1
hibernate-extensions-2.1.3
hsqldb 1_8_0_2


copied everything from hibernate-3.1\lib to <Project_Dir>\lib
copied \hibernate-3.1\hibernate3.jar to <Project_Dir>\lib
copied everything from hsqldb\lib to <Project_Dir>\lib
copied everything from hibernate-extensions-2.1.3\tools\lib to <Project_Dir>\lib
Track.hbm.xml is in <Project_dir>src\com\oreilly\hh

above you can see the error after running "ant codegen"

hibernate.org FAQ says that NoClassDefFoundError might be because I'm
missing a third party library. I copied all of the jar files files that are
in the hibernate lib to the project lib folder.
A google search suggested that it might be a classpath problem.
As far as i can understand, project lib is inlcuded in the CLASSPATH
in the build.xml. Just in case i created an environment variable CLASSPATH (under windows XP SP2)
and inlcuded the directory in the project where the mapping file is located.

any suggestions?







------------------
here is the build.xml, only target "codegen" is of interest, but i
show the complete file just in case:

<?xml version="1.0"?>
<project name="Harnessing Hibernate: The Developer's Notebook"
default="db" basedir=".">

<!-- Set up properties containing important project directories -->
<property name="source.root" value="src"/>
<property name="class.root" value="classes"/>
<property name="lib.dir" value="lib"/>
<property name="data.dir" value="data"/>

<!-- Set up the class path for compilation and execution -->
<path id="project.class.path">
<!-- Include our own classes, of course -->
<pathelement location="${class.root}" />
<!-- Include jars in the project library directory -->
<fileset dir="${lib.dir}">
<include name="*.jar"/>
</fileset>
</path>

<target name="db" description="Runs HSQLDB database management UI
against the database file--use when application is not running">
<java classname="org.hsqldb.util.DatabaseManager"
fork="yes">
<classpath refid="project.class.path"/>
<arg value="-driver"/>
<arg value="org.hsqldb.jdbcDriver"/>
<arg value="-url"/>
<arg value="jdbc:hsqldb:${data.dir}/music"/>
<arg value="-user"/>
<arg value="sa"/>
</java>
</target>

<!-- Teach Ant how to use Hibernate's code generation tool -->
<taskdef name="hbm2java"
classname="net.sf.hibernate.tool.hbm2java.Hbm2JavaTask"
classpathref="project.class.path"/>

<!-- Generate the java code for all mapping files in our source tree -->
<target name="codegen"
description="Generate Java source from the O/R mapping files">
<hbm2java output="${source.root}">
<fileset dir="${source.root}">
<include name="**/*.hbm.xml"/>
</fileset>
</hbm2java>
</target>

<!-- Create our runtime subdirectories and copy resources into them -->
<target name="prepare" description="Sets up build structures">
<mkdir dir="${class.root}"/>

<!-- Copy our property files and O/R mappings for use at runtime -->
<copy todir="${class.root}" >
<fileset dir="${source.root}" >
<include name="**/*.properties"/>
<include name="**/*.hbm.xml"/>
</fileset>
</copy>
</target>

<!-- Compile the java source of the project -->
<target name="compile" depends="prepare"
description="Compiles all Java classes">
<javac srcdir="${source.root}"
destdir="${class.root}"
debug="on"
optimize="off"
deprecation="on">
<classpath refid="project.class.path"/>
</javac>
</target>

<!-- Generate the schemas for all mapping files in our class tree -->
<target name="schema" depends="compile"
description="Generate DB schema from the O/R mapping files">

<!-- Teach Ant how to use Hibernate's schema generation tool -->
<taskdef name="schemaexport"
classname="net.sf.hibernate.tool.hbm2ddl.SchemaExportTask"
classpathref="project.class.path"/>

<schemaexport properties="${class.root}/hibernate.properties"
quiet="no" text="no" drop="no">
<fileset dir="${class.root}">
<include name="**/*.hbm.xml"/>
</fileset>
</schemaexport>
</target>

</project>

i'm going to guess that since you're using hibernate 3, and the stack trace indicates that the class not found is in "net/sf" then you'll need to search and replace

s/net.sf.hibernate/org.hibernate

you can tell this easily by looking across your classpath and ensuring that is the issue:

I dont think Hibernate-3.1 and Hibernate-extensions-2.1.3 may play well together. For Hibernate-3.1, the equivalent of Hibernate-extensions is available at
http://tools.hibernate.org