26.4 Basing an entity Object on a PL/SQL Package API - Ref Cursor, no View

Question

I am hoping that I could get some help in the details of a problem. I am trying to follow the directions in the Oracle Application Development Framework Developer's Guide for Forms/4GL Developers, Section 26.4 - Basing an Entity Object on a PL/SQL Package API.
There is example code in the downloadable AdvancedEntityExamples - EntityWrappingPL/SQLPackage
The question is, how will the implementation change if the entity is based entirely on PL/SQL - simply stated - no view is available, just ref cursors and insert,update,delete procedures.
In the example code, there are two procedures, lock_product and select_product. This is where things get more complicated. I can create a function to return a single record ref cursor, instead of the list of OUT variables defined in both functions (select_product and lock_product). It makes sense that I just return one cursor and get all of the columns from that instead of lots of OUT variables.
So what's stopping me you may ask... There is one difference between select_product and select_lock. Select_lock has a select that includes "FOR UPDATE NOWAIT". I don't have that as an option when creating my ref cursor. I am not sure what the impact of "FOR UPDATE NOWAIT" is? Can I ignore it?
In the problem I am working with, (getting data from Oracle Portal 10.1.4) I return the following:
function getRefCursor return ref_cursor is
v_tab wwsbr_all_items_object_type := wwsbr_all_items_object_type();
p_recordset wwsbr_types.cursor_type;
l_results wwsrc_api.items_result_array_type;
begin
wwctx_api.set_context(<username>,<password>);
l_results := wwsrc_api.item_search(.. parameters..);
<snip>
... Loop through the objects and populate v_tab
<snip>
open p_recordset for
select * from table(cast(v_tab as wwsbr_all_items_object_type));
return p_recordset;
end getRefCursor;
With this sample, it would be easy to return a single row by passing the masterid as a parameter.
So I am still left with, how should the implementation of callLockProcedureAndCheckForRowInconsistency() and callSelectProcedure() be changed in order to use a ref cursor instead of a view? The user guide was missing that extra section <bg>.
What would be REALLY helpful, is an example, say 26.4A that demonstrates creating an entity object from a ref cursor and procedures from PL/SQL only without a view.
Thank you, Ken

Answer 1

The lock procedure is expected to obtain a row-level lock on the row, given its key.
Depending on the setting of jbo.locking.mode, the entity object's lock() method will be invoked either as soon as the first persistent attribute is successfully modified by the user (in the case of jbo.locking.mode=pessimistic), or it will be called during commit processing just before the row is updated in the database (with jbo.locking.mode=optimistic).
Usually 2-tier Swing applications use pessimistic mode, while web applications use optimistic mode.
The FOR UPDATE NOWAIT is the Oracle clause that can be appened to a SELECT statement to acquire a row-level lock on the selected rows. The NOWAIT modifier means that rather than hanging, waiting for a row locked by another user to free up, it will raise an exception if any of the rows being selected-and-locked are not available to lock.
If you're not able to work the FOR UPDATE NOWAIT into the syntax of the ref cursor, perhaps you can initially perform the lock using a different cursor inside the stored procedure, then return your ref cursor.