2009-06-18 19:53:14,328 ERROR [org.hibernate.AssertionFailure] an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session)
org.hibernate.AssertionFailure: collection [null] was not processed by flush()
   at org.hibernate.engine.CollectionEntry.postFlush(CollectionEntry.java:205)
   at org.hibernate.event.def.AbstractFlushingEventListener.postFlush(AbstractFlushingEventListener.java:333)
   at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:28)
   at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
   at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
   at org.hibernate.transaction.CacheSynchronization.beforeCompletion(CacheSynchronization.java:59)
   at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.beforeCompletion(SynchronizationImple.java:114)
   at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:247)
   at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:86)
   at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:177)
   at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1389)
   at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:135)
   at com.arjuna.ats.jbossatx.BaseTransactionManagerDelegate.commit(BaseTransactionManagerDelegate.java:87)
   at org.jboss.tm.usertx.client.ServerVMClientUserTransaction.commit(ServerVMClientUserTransaction.java:140)
   at org.hibernate.transaction.JTATransaction.commit(JTATransaction.java:146)
   at csiro.logic.DatasetManager.addDataset(DatasetManager.java:478)
   at org.apache.jsp.single_005fupload_005fpage_jsp._jspService(single_005fupload_005fpage_jsp.java:109)
   at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
   at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:373)
   at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:336)
   at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
   at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
   at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
   at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
   at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
   at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
   at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
   at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
   at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
   at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
   at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
   at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)
   at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
   at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)
   at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
   at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
   at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)
   at java.lang.Thread.run(Thread.java:619)

public class SessionManager {

   private static Session session = null;
   
   // creates a new session if needed or returns the current
   private static SessionFactory sf;
   static{
      Context ctx;
      try {
         ctx = new InitialContext();
         System.out.println("**********************Binding session factory");
         sf = (SessionFactory)ctx.lookup("java:/hibernate/SessionFactory");
      } catch (NamingException e) {
         // TODO Auto-generated catch block
         e.printStackTrace();
      }
      
   }
   public static Session getSession(){
      System.out.println("**********************Returning session factory");
      if (session == null)
        session = sf.openSession();
        return session;
   }
   
   public static void closeSession(){
      if (session != null)
         session.close();
   }
   
}