Stored function call problem

Question

I've been trying out this feature as it was shown in adfdeveloperguide. that is, on page 3-26/27
StoredFunctionCall functionCall = new StoredFunctionCall();
functionCall.setProcedureName("READ_EMPLOYEE");
functionCall.addNamedArgument("EMP_ID");
functionCall.setResult("FUNCTION_RESULT", String);
ReadObjectQuery query = new ReadObjectQuery();
query.setCall(functionCall);
query.addArgument("EMP_ID");
Vector args = new Vector();
args.addElement(new Integer(44));
Employee employee = (Employee) session.executeQuery(query, args);
in my version it is:
StoredFunctionCall fCall = new StoredFunctionCall();
fCall.setProcedureName("f_milos");
fCall.addNamedArgument("x");
fCall.setResult("FUNCTION_RESULT", String.class);
ReadObjectQuery query = new ReadObjectQuery();
query.setCall(fCall);
query.addArgument("x");
Vector args = new Vector();
args.addElement(new Integer(2));
String result = (String) session.executeQuery(query,args);
where f_milos is my stored function. as for the session, I got it in this way
Session session=new SessionFactory("META-INF/sessions.xml", "default").acquireSession();
like it was done in my session bean.
dunno, maybe thats the source of the problem.
now, when I come to executeQuery, following error pops:
javax.faces.el.EvaluationException: Exception [TOPLINK-6029] (Oracle TopLink - 10g Release 3 (10.1.3.0.0) (Build 060118)): oracle.toplink.exceptions.QueryException
Exception Description: A reference class must be provided.
Query: ReadObjectQuery().
help?

Answer 1

Well, previously you were calling getDBTransaction() on an explicit Application Module object, whereas now, you do:
st = getDBTransaction().createCallableStatement("begin ? := "stmt";end;",0);which means that your code must be inside of an application module in order to work. Do you see the difference?
I'll mention that you shouldn't generally be doing DB calls in your ViewController/UserInterface layer - DB code belongs in the model.
John