COMMIT is not allowed in a subordinate session

Question

In My Servlet, I am using JTA transaction which is not a CMT.
I am running this on Oracle XADatasource.
When I'm trying to perform the DB operation, I'm getting the
Exception saying "COMMIT is not allowed in a subordinate session "
My Servlet code is :
public class BatchServlet extends javax.servlet.http.HttpServlet implements
          javax.servlet.Servlet {
     PrintWriter out = null;
     @PersistenceUnit(unitName="PERUNIT")
     EntityManagerFactory emf;
     EntityManager em;
     @Resource
     UserTransaction utx;
     protected void doGet(HttpServletRequest request,
               HttpServletResponse response) throws ServletException, IOException {
          out = response.getWriter();
          try {
               initEM();
               utx.begin();
               updateDB();
               utx.commit();
          } catch (Exception ex) {
               ex.printStackTrace(out);
               utx.rollback();
          } finally {
               closeEM();
     public void initEM() throws Exception {
          em = emf.createEntityManager();
     public void closeEM() {
          if (em != null) {
               em.close();
     private void updateDB() throws Exception {
          Address address = em.find(Address.class, 50030L);
          out.println("County :: " + address.getCounty());
          address.setBuildingNumber("Building # ABC");
          em.persist(address);
          out.println("Before Flush");
          em.flush();
          out.println("After Flush");
     public BatchServlet() {
          super();
}My Persistence.xml is
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
     xmlns="http://java.sun.com/xml/ns/persistence"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
     <persistence-unit name="PERUNIT" transaction-type="JTA">
              <provider> org.eclipse.persistence.jpa.PersistenceProvider</provider>
              <jta-data-source>MYXADS</jta-data-source>
              <class> com.test.Address</class>
            <properties>
                 <property name="eclipselink.logging.level" value="CONFIG"/>
                 <property name="javax.persistence.jtaDataSource" value="jdbc/MYXADS"/>
                 <property name="eclipselink.logging.level" value="FINE"/>
            </properties>
     </persistence-unit>
</persistence>

Answer 1

What if, in stead of using the UserTransaction, you simply use em.getTransaction().begin() and em.getTransaction().commit() to start / end the transaction? It seems to me the UserTransaction object represents a completely different transaction environment than your entity manager wants to use.