One need a RDB dialect for Hibernate, but Oracle actually provide that - one just need to extract and build:
$ jar xvf rdb$jdbc_home:rdb_ext.jar "RdbDialect.java"
$ set file/attr=rfm:stm RdbDialect.java
$ convert/fdl=nla0: RdbDialect.java RdbDialect.java
$ purge RdbDialect.java
$ create/dir [.org.hibernate.dialect]
$ ren RdbDialect.java [.org.hibernate.dialect]
$ javac -classpath 'hibpath' "[.org.hibernate.dialect]RdbDialect.java"
Note that this Rdb dialect works with Hibernate 3.6 but it does not work with Hibernate 5.0 - I have not tried with other versions, so 3.6 is the safe choice.
And with a [.META-INF]persistence.xml like this:
<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_2_0.xsd"
version="2.0">
<persistence-unit name="test">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>testrdb.T1</class>
<exclude-unlisted-classes/>
<properties>
<!--<property name="show_sql">true</property>-->
<property name="hibernate.connection.driver_class" value="oracle.rdb.jdbc.rdbThin.Driver"/>
<property name="hibernate.connection.url" value="jdbc:rdbThin://localhost:1701/dka3:[rdb]test"/>
<property name="hibernate.connection.username" value="xxxxxx"/>
<property name="hibernate.connection.password" value="xxxxxx"/>
<property name="hibernate.connection.pool_size" value="5"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.RdbDialect"/>
</properties>
</persistence-unit>
</persistence>
Then it is ready to rock and roll:
// disable Hibernate logging (outcomment for debugging)
Logger.getLogger("org.hibernate").setLevel(Level.OFF);
EntityManagerFactory emf = Persistence.createEntityManagerFactory("test");
EntityManager em = emf.createEntityManager();
...
em.close();
emf.close();
For a general intro to JPA see here.