<?xml version="1.0" encoding="UTF-8"?>
<persistence 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"
   version="1.0">
   <persistence-unit name="mes.platform" transaction-type="JTA">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <jta-data-source>jdbc/mes_platform</jta-data-source>
      <properties>
         <!-- Auto detect annotation model classes -->
         <property name="hibernate.archive.autodetection" value="class" />
         <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect" />
         <property name="hibernate.show_sql" value="false"/>
         <property name="hibernate.format_sql" value="true"/>
         <property name="hibernate.cache.use_query_cache" value="true"/>
         <property name="hibernate.cache.use_second_level_cache" value="true"/>
         <property name="hibernate.cache.region_prefix" value="mes"/>
         <property name="hibernate.cache.provider_class" value="org.hibernate.cache.EhCacheProvider"/>
         <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.WebSphereExtendedJTATransactionLookup"/>
         <property name="hibernate.transaction.factory_class" value="org.hibernate.transaction.CMTTransactionFactory"/>
           <property name="jta.UserTransaction" value="java:comp/UserTransaction"/>
         
      </properties>
   </persistence-unit>
</persistence>

public <T extends Entity> T createEntity(T entity, String sessionId)
  {
    entity.validate();
    String id = entity.getId();
    if ((id == null) || (id.trim().isEmpty())) {
      entity.setId(UUID.randomUUID().toString());
    }
    getEntityManager().persist(entity);

    ///////////////
    //here I should flush it, or the entity created cannot be writen to database eventually
    if(isWebsphere()){
       getEntityManager().flush();
    }
    //////////////

    return entity;
  }