How to implement an audit system to track ADF applications DML activity?

Question

We have implemented a complete audit system for one of our databases in order to keep history for every table and every value that has been modified.
The solution that we currently have can be split into two discrete parts:
1. Keeping a record of all connections to the db account
This is achieved via a table ‘user_sessions’ into which we record data for every session in the database with the help of on-logon and on-logoff triggers and some PL/SQL procedures:
Column name        |  Explanation
-------------------|-------------------------------------------
US_ID              | PK, based on a sequence
SESSION_ID         | sys_context('USERENV' ,'SESSIONID')  
USER_NAME          | sys_context('USERENV' ,'OS_USER')
LOGON_TIME         | when the on-logon trigger fires
LOGOFF_TIME        | when the on-logoff trigger fires
USER_SCHEMA        | sys_context('USERENV' ,'SESSION_USER')
IP_ADDRESS         | sys_context('USERENV' ,'IP_ADDRESS')
us_id |session_id |user_name|user_sschema|ip_address|logon_time               |logoff_time     
560066|8498062       |BOB      |ABD         |1.1.1.2   |14-SEP-06 03.51.52.000000|14-SEP-06 03.52.30.000000
560065|8498061       |ALICE    |ABC         |1.1.1.1   |14-SEP-06 02.45.31.000000|14-SEP-06 04.22.43.0000002. Keeping the history of every change of data made by a given user
For every table in the account there is a corresponding history table with all of the columns of the original table plus columns to denote the type of the operation (Insert, Delete, Update), start and end time of validity for this record (createtime, retiretime) and us_id (which points to the user_sessions table).
The original table has triggers, which fire if there is an insert, update or delete and they insert the data into the corresponding history table. For every record inserted into a history table the us_id taken from the user_sessions table is recorded as well, allowing us to determine who has modified what data via the combination of these two tables.
Below is an example of a table TASKS, the history related triggers and the history table TASKS_HIST.
At the moment we are developing new applications by using ADF. Since there is an Application Module Pool and Database Connection Pool implemented for the ADF, one connection to the database could be used by several users at different moments of time. In that case the history records will point to a database session logged into the user_sessions table, but we will not know who actually modified the data.
Could you, please, give us a suggestion, how we can know at any moment of time who (which of our users currently making use of an ADF application) is using a given database connection?
By way of an example of the problem we are facing, here is how we solved the same problem posed by the use of Oracle Forms applications.
When the user starts to work with a given Forms application, user_sessions table would attempt to record the relevant information about he user, but since the db session was created by the application server, would in actual fact record the username and ip address of the application server itself.
The problem was easy to solve due to the fact that there is no connection pooling and when a user opens their browser to work with Forms applications, a db connection is opened for the duration of their session (until they close their browser window).
In that case, the moment when the user is authenticated (they log in), there is a PL/SQL procedure called from the login Form, which updates the record in the user_sessions table with the real login name and ip address of the user.
Example of a table and its ‘shadow’ history table
CREATE TABLE TASKS (
     TASKNAME     VARCHAR2(40),
     DESCRIPTION  VARCHAR2(80)
ALTER TABLE TASKS ADD (
     CONSTRAINT TASKS_PK PRIMARY KEY (TASKNAME));
CREATE OR REPLACE TRIGGER TASKS_HISTSTMP
BEFORE INSERT OR UPDATE OR DELETE ON TASKS
   BEGIN
     HISTORY.SET_OPERATION_TIME('TASKS');
   EXCEPTION
     WHEN OTHERS THEN
       ERROR.REPORT_AND_GO;
END TASKS_HISTSTMP;
CREATE OR REPLACE TRIGGER TASKS_WHIST
  AFTER INSERT OR UPDATE OR DELETE ON TASKS
  FOR EACH ROW
  BEGIN
CASE
      WHEN INSERTING THEN
        UPDATE TASKS_HIST
           SET retiretime = HISTORY.GET_OPERATION_TIME
         WHERE createtime = (SELECT MAX(createtime)
                               FROM TASKS_HIST
                              WHERE retiretime IS NULL AND TASKNAME=:NEW.TASKNAME)
           AND retiretime IS NULL AND TASKNAME=:NEW.TASKNAME;
        INSERT INTO TASKS_HIST (TASKNAME      ,DESCRIPTION      ,optype
                                ,createtime                    
                                ,us_id)
               VALUES          (:NEW.TASKNAME ,:NEW.DESCRIPTION ,'I'
                                ,HISTORY.GET_OPERATION_TIME    
                                ,USER_SESSION.GET_USER_SESSIONS_ID);
      WHEN UPDATING THEN
        UPDATE TASKS_HIST
           SET retiretime = HISTORY.GET_OPERATION_TIME
         WHERE createtime = (SELECT MAX(createtime)
                               FROM TASKS_HIST
                              WHERE TASKNAME=:OLD.TASKNAME) 
           AND TASKNAME=:OLD.TASKNAME;
        INSERT INTO TASKS_HIST (TASKNAME      ,DESCRIPTION      ,optype
                                ,createtime
                                ,us_id)
               VALUES          (:NEW.TASKNAME ,:NEW.DESCRIPTION ,'U'
                                ,HISTORY.GET_OPERATION_TIME
                                ,USER_SESSION.GET_USER_SESSIONS_ID);
      ELSE
        UPDATE TASKS_HIST
           SET retiretime = HISTORY.GET_OPERATION_TIME
         WHERE createtime = (SELECT MAX(createtime)
                               FROM TASKS_HIST
                              WHERE TASKNAME=:OLD.TASKNAME) 
           AND TASKNAME=:OLD.TASKNAME;
        INSERT INTO TASKS_HIST (TASKNAME      ,DESCRIPTION      ,optype
                                ,createtime
                                ,us_id)
               VALUES          (:OLD.TASKNAME ,:OLD.DESCRIPTION ,'D'
                                ,HISTORY.GET_OPERATION_TIME
                                ,USER_SESSION.GET_USER_SESSIONS_ID);
    END CASE;
  EXCEPTION
    WHEN OTHERS THEN
      ERROR.REPORT_AND_GO;
END TASKS_WHIST;
CREATE TABLE TASKS_HIST (
     TASKNAME       VARCHAR2(40),
     DESCRIPTION    VARCHAR2(80),
     OPTYPE         VARCHAR2(1),
     CREATETIME     TIMESTAMP(6),
     RETIRETIME     TIMESTAMP(6),
     US_ID          NUMBER
ALTER TABLE TASKS_HIST ADD (
     CONSTRAINT TASKS_HIST_PK PRIMARY KEY (TASKNAME, CREATETIME)
       );

Answer 1

Frank,
Thanks for your reply.
I checked the site that you mentioned.
I try the sample “demo with bundle. The sample worked.
But it needed to start separately with the application.
I do not know how to build a help system with the existed web application developed with Jdeveloper (It has two projects: model and user-view-control. It is deployed on Oracle Application server).
Could you help me step by step to build the help system?