OSB to Object Types: difference between NULL value and not available

Question

Hello all,
I have a question about Object Types. More specifically, how to differentiate between an empty value (null) and a string not available.
This is my case:
I have created an object type with three parameters.
CREATE OR REPLACE TYPE OSB_EMP_OBJ_TYPE AS OBJECT
(EMP_ID NUMBER
,DEPT_ID NUMBER
,ORDER_ID NUMBER
,CONSTRUCTOR FUNCTION OSB_EMP_OBJ_TYPE
RETURN self as result
/I would like to see what happens when I put an empty string into emp_id, NULL into DEPT_ID and nothing into ORDER_ID.
To do so I have this test script:
declare
  p_emp OSB_EMP_OBJ_TYPE := OSB_EMP_OBJ_TYPE();
begin
  p_emp.EMP_ID := '';
  p_emp.DEPT_ID := null;
--  p_emp.ORDER_ID := null;
  if p_emp.EMP_ID is null
  then
    dbms_output.put_line('Empty');
  end if;
  if p_emp.DEPT_ID is null
  then
    dbms_output.put_line('NULL');
  end if;
  if p_emp.ORDER_ID is null
  then
    dbms_output.put_line('Not available');
  end if;
end;The result of this is:
Empty
NULL
Not availableIt seems that Oracle treats all three situations alike. What I would like to achieve is a way to see that p_emp.ORDER_ID was not initialized.
To elaborate a bit: in our production system this procedure would be called from OSB and the object type would by the input for that procedure. Our database version is 10.2.0.5.0.
Our procedures look something like this:
procedure p_procedure ( p_emp in osb_emp_obj_type )
is
begin
  do_something;
end;Can anyone tell me if there is a way to achieve this, so I can see whether or not a value in the object type was filled?
Thanks in advance!

Answer 1

Darn...
Eventually we want to use this for an update procedure. The client gets all current data from the database by calling a webservice that (using OSB) selects the data from our database. What we want to achieve is that the client can update that data, by returning only the changed fields to an update procedure.
We then handle an empty tag to update the field to null, and we ignore missing tags.
OSB itself can handle this, but PL/SQL can't.
I'm now thinking of adding an indicator to each optional field (clear_field_yn). OSB can still check for empty tags or missing tags. When a tag is empty, it's corresponding indicator will be set to 'Y'. If the tag is missing, then it will be set to 'N'.
Is that a solution to consider, or is there a much simpler approach possible?