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

<hibernate-mapping>
    <class name="com.paymentone.hibernate.prototype.Department" table="department">
        <id name="id" type="string" unsaved-value="null">
            <generator class="uuid.string">               
            </generator>
        </id>
        <timestamp
        column="timestamp"
        name="timestamp"
        unsaved-value="null"/>       
        <property name="name" type="string"/>                        
        <bag name="employees" table="employee" lazy="true" inverse="true" cascade="all">
           <key column="dept"/>
           <one-to-many class="com.paymentone.hibernate.prototype.Employee"/>
        </bag>
    </class>
</hibernate-mapping>

Session s = HibernateUtil.currentSession();
        Transaction tx = null;
        try {
            tx = s.beginTransaction();
            s.save(dept);
            tx.commit();
        } catch (HibernateException e) {
            if (tx != null) {
                tx.rollback();
            }
            throw e;
        } finally {
            HibernateUtil.closeSession();
        }

Session s = HibernateUtil.currentSession();
        Transaction tx = null;
        try {
            tx = s.beginTransaction();
            s.update(dept);
            tx.commit();
        } catch (HibernateException e) {
            if (tx != null) {
                tx.rollback();
            }
            throw e;
        } finally {
            HibernateUtil.closeSession();
        }

Session s = HibernateUtil.currentSession();
        try {
            List depts = s.find("from Department"); 
           
            return depts;
        } finally {
            HibernateUtil.closeSession();
        }

private void testOptimisticLocking() throws Exception{
        HumanResourceMgmt mgr = HumanResourceMgmt.getInstance();
       
        Department dept = new Department();
        dept.setName("Engineering");
        mgr.createDepartment(dept);
       
        List depts = mgr.queryDepartments();       
        Department queriedDept = (Department) depts.get(0);
       
        List depts2 = mgr.queryDepartments();   
        Department queriedDept2 = (Department) depts2.get(0);
       
        // queriedDept and queriedDept2 came from different sessions and are
        // thus different objects
       
        queriedDept.setName("Engineering1");
        mgr.updateDepartment(queriedDept);
        //Thread.sleep(20000);
        try {
            queriedDept2.setName("Engineering2");
            mgr.updateDepartment(queriedDept2);
            System.out.println("Exception is not thrown with timestamp as version column!");
        } catch (Exception e) {
            System.out.println("As expected, optimistic locking causes exception to be thrown");
        }
    }