@PersistenceContext
 protected  EntityManager em;

	@PersistenceContext(unitName="test")
	 protected  EntityManager em;

<?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="test">
  		<jta-data-source>java:/DefaultDS</jta-data-source>
		<properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
			<property name="hibernate.hbm2ddl.auto" value="create-drop" />
		</properties>
	</persistence-unit>
  
</persistence>

@Stateless
@TransactionAttribute(TransactionAttributeType.REQUIRED)
 public   class  UserLogonImpl  implements  UserLogonLocal, UserLogonRemote {
	@PersistenceContext
	 protected  EntityManager em;

	 public   Long  logon()  {
 	}

	 public   void  logout() {
	}

Context context =  new  InitialContext(properties);
Object fooRef = context.lookup("beans/UserLogonImpl/remote");
UserLogonRemote userLogon = UserLogonRemote)PortableRemoteObject.narrow(fooRef, UserLogonRemote. class );

Context context =  new  InitialContext(properties);
UserLogonRemote userLogon = (UserLogonRemote) context.lookup("UserLogonImpl/remote");