Exception in thread "main" javax.persistence.PersistenceException: org.hibernate.TransactionException: Could not find UserTransaction in JNDI:
   at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:647)
   at org.hibernate.ejb.AbstractEntityManagerImpl.joinTransaction(AbstractEntityManagerImpl.java:558)
   at org.hibernate.ejb.AbstractEntityManagerImpl.postInit(AbstractEntityManagerImpl.java:81)
   at org.hibernate.ejb.EntityManagerImpl.<init>(EntityManagerImpl.java:37)
   at org.hibernate.ejb.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:37)
   at org.hibernate.ejb.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:32)
   at org.josuealcalde.forums.main.Main.main(Main.java:15)
Caused by: org.hibernate.TransactionException: Could not find UserTransaction in JNDI:
   at org.hibernate.transaction.JTATransaction.<init>(JTATransaction.java:64)
   at org.hibernate.transaction.JTATransactionFactory.createTransaction(JTATransactionFactory.java:57)
   at org.hibernate.jdbc.JDBCContext.getTransaction(JDBCContext.java:193)
   at org.hibernate.impl.SessionImpl.getTransaction(SessionImpl.java:1315)
   at org.hibernate.ejb.AbstractEntityManagerImpl.joinTransaction(AbstractEntityManagerImpl.java:452)
   ... 5 more
Caused by: javax.naming.NoInitialContextException: Need to specify class name in environment or system property, or as an applet parameter, or in an application resource file:  java.naming.factory.initial
   at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:645)
   at javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:247)
   at javax.naming.InitialContext.getURLOrDefaultInitCtx(InitialContext.java:284)
   at javax.naming.InitialContext.lookup(InitialContext.java:351)
   at org.hibernate.transaction.JTATransaction.<init>(JTATransaction.java:60)
   ... 9 more

   
public static void main(String[] args) {
      EntityManagerFactory emf = Persistence
            .createEntityManagerFactory("forums");
      EntityManager em = emf.createEntityManager();
      em.close();
   }

<?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="forums" transaction-type="JTA">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <jar-file>Forums-Persistence.jar</jar-file>
      <class>org.josuealcalde.forums.entity.ForumBean</class>
      <class>org.josuealcalde.forums.entity.MessageBean</class>
      <class>org.josuealcalde.forums.entity.TopicBean</class>
      <class>org.josuealcalde.forums.entity.UserBean</class>
      <properties>
         <property name="hibernate.transaction.factory_class"
            value="org.hibernate.transaction.JTATransactionFactory" />
         <property name="hibernate.dialect"
            value="org.hibernate.dialect.MySQL5InnoDBDialect" />
         <property name="hibernate.hibernate.ejb.cfgfile"
            value="hibernate.cfg.xml" />
         <property name="hibernate.hbm2ddl.auto" value="validate" />
         <property name="hibernate.show_sql" value="true" />
         <property name="hibernate.connection.driver_class"
            value="com.mysql.jdbc.Driver" />
         <property name="hibernate.connection.password"
            value="forum" />
         <property name="hibernate.connection.url"
            value="jdbc:mysql://localhost/forum" />
         <property name="hibernate.connection.username"
            value="forum" />
         <property name="hibernate.default_catalog" value="forum" />
         <property name="hibernate.dialect"
            value="org.hibernate.dialect.MySQL5InnoDBDialect" />

      </properties>
   </persistence-unit>
</persistence>

<?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="forums">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <jar-file>Forums-Persistence.jar</jar-file>
      <class>org.josuealcalde.forums.entity.ForumBean</class>
      <class>org.josuealcalde.forums.entity.MessageBean</class>
      <class>org.josuealcalde.forums.entity.TopicBean</class>
      <class>org.josuealcalde.forums.entity.UserBean</class>
      <properties>
         <property name="hibernate.dialect"
            value="org.hibernate.dialect.MySQL5InnoDBDialect" />
         <property name="hibernate.hibernate.ejb.cfgfile"
            value="hibernate.cfg.xml" />
         <property name="hibernate.hbm2ddl.auto" value="validate" />
         <property name="hibernate.show_sql" value="true" />
         <property name="hibernate.connection.driver_class"
            value="com.mysql.jdbc.Driver" />
         <property name="hibernate.connection.password"
            value="forum" />
         <property name="hibernate.connection.url"
            value="jdbc:mysql://localhost/forum" />
         <property name="hibernate.connection.username"
            value="forum" />
         <property name="hibernate.default_catalog" value="forum" />
         <property name="hibernate.dialect"
            value="org.hibernate.dialect.MySQL5InnoDBDialect" />

      </properties>
   </persistence-unit>
</persistence>

em.getTransaction().begin();
// ... modify entities
em.getTransaction().commit();