public class Node {
private int id ;
private String name ;
private Node parent ;
private Set<Node>children ;
// Getters and setters will come here
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
   "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
   <class name="testcase.Node" table="DB2ADMIN.NODETest">
      <id name="id" type="integer" column="ID" >
         <generator class ="assigned"/>
      </id>
   <property name="name" >
         <column name="NAME" />
      </property>
   <set name="children" inverse="true"  cascade="all-delete-orphan">
      <key column="CHILDREN_ID" />
      <one-to-many class ="testcase.Node"/>
      </set>
   <many-to-one name="parent" column="CHILDREN_ID"  class="testcase.Node"  >
     </many-to-one>
   </class>   
</hibernate-mapping>