questo è il file 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" version="1.0"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<!-- PERSISTENCE UNITS DEVELOPMENT -->





<persistence-unit name="Allenavita" transaction-type="JTA">
<provider>org.hibernate.ejb.HibernatePersistence </provider>
<jta-data-source >java:jboss/datasources/OracleDS</jta-data-source>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect" />
<property name="hibernate.show_sql" value="true"/>
</properties>





</persistence-unit>
</persistence>

e file cfg sempre nella cartella meta-inf

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">




<hibernate-configuration>
<session-factory name="">

<!-- Related to the connection START -->
<property name="connection.driver_class">oracle.jdbc.driver. OracleDriver</property>
<property name="connection.url">jdbcracle:thin:@localhost:1521:xe</property>
<property name="connection.user">SYSTEM</property>
<property name="connection.password">puffo</property>
<property name="connection.pool_size">2</property>
<!-- Related to the connection END
Related to hibernate properties START -->
<property name="show_sql">true</property>
<property name="dialet">org.hibernate.dialect.OracleDialect</property>




<!-- Related to hibernate properties END
Related to mapping START
Related to the mapping END -->
</session-factory>
</hibernate-configuration>