JPA Calling an Oracle function with OUT parameter

[Stanimir Stamenkov]

[Followup-To: comp.lang.java.databases]

I'm relatively new to JPA (Java Persistence API). I'm given an
Oracle function I need to execute through an EntityManager. The
function has an OUT parameter (the first one) declared in addition
to returning a value. I'm trying the following code:

EntityManager em;
...
Query query = em.createNativeQuery("{ ? = "
+ "call MY_FUNCTION(?,?,?,?,?,?,?) }");

query.setParameter(1, null); // XXX: registerOutParameter ?
query.setParameter(2, ...);
...
query.setParameter(7, ...);

List result = query.getResultList();

I don't know how I can register (and later get) the first parameter
as OUT parameter, pretty much like one could do with JDBC
(java.sql.CallableStatement), and I'm getting an exception as:

java.sql.SQLException: Missing IN or OUT parameter at index:: 9
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:145)
at oracle.jdbc.driver.OraclePreparedStatement.processCompletedBindRow(OraclePreparedStatement.java:1680)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3279)
at oracle.jdbc.driver.OraclePreparedStatement.executeQuery(OraclePreparedStatement.java:3328)
at org.jboss.resource.adapter.jdbc.WrappedPreparedStatement.executeQuery(WrappedPreparedStatement.java:236)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:186)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1787)
at org.hibernate.loader.Loader.doQuery(Loader.java:674)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
at org.hibernate.loader.Loader.doList(Loader.java:2220)

How could I workout the given case?

FWIW, I'm working with JBoss 4.2.2.GA and Seam 2.0.2.SP1.