BPEL with Reliable Processing

Question

Hi,
I read and work on the "BPEL with Reliable Processing" cookbook.
http://www.oracle.com/technology/pub/articles/bpel_cookbook/qualcomm-bpel.html
It's great!
I try to enhance the process by adding notion of priority between different records.
A priority-based process will favour those processes with high priority values.
To achieve that, I made the following modifications:
1) Add the "PRIORITY" column into the "DB_POLL_SOURCE" table.
CREATE TABLE "DB_POLL_SOURCE"
"ID" NUMBER (17,0) NOT NULL,
"VALUE1" VARCHAR2 (32),
"VALUE2" VARCHAR2 (32),
"VALUE3" VARCHAR2 (32),
"PROCESS_NOT_BEFORE" DATE,
"RETRY_COUNT" NUMBER (7,0) DEFAULT 0 NOT NULL,
"BPEL_STATE" VARCHAR2 (16) DEFAULT 'P_NEW',
"CREATED_DTS" DATE DEFAULT SYSDATE,
"MODIFIED_DTS" DATE DEFAULT SYSDATE,
"PRIORITY" NUMBER (7,0) DEFAULT 5 NOT NULL
2) Add an order by clause to sort the "PRIORITY" column in descending order.
3) Add the where clause (rownum<N) for getting the first N records from the query record set.
CREATE OR REPLACE VIEW DB_POLL_SOURCE_VW
(ID, BPEL_STATE)
AS
select *
from (
select
dbps.ID,
dbps.BPEL_STATE
from
DB_POLL_SOURCE dbps
where
(dbps.PROCESS_NOT_BEFORE is NULL or dbps.PROCESS_NOT_BEFORE < SYSDATE)
and dbps.BPEL_STATE like 'P_%'
order by dbps.PRIORITY desc
where rownum < 5
The problem is that the view must be updatable and ROWNUM cannot be used inside an updatable view.
The message error I got is the following:
ORA-01732: data manipulation operation not legal on this view.
So my question is:
How can I define an updatable view to sort the "PRIORITY" column and then limit the number of rows returned?
Thanks a lot
Olivier

Answer 1

If you want to update a view, you must use database triggers to perform this. You can user the statement:
CREATE OR REPLACE TRIGGER <triggername>
INSTEAD OF INSERT (or other UPDATE/DELETE or both)
ON <view>
FOR EACH ROW
BEGIN
.. PLSQL code here ..
END <triggername>;
/