Maintaining audit trail(who modified and when modified)

Hi allI am working on a J2ee project in which i want to monitor audit trails of particular pages ,The back end is oracle 10g.Can u tell me how to maintain audit trail at application level.I want to show audit trail information in jsp pages.
[254 byte] By [chintu123a] at [2007-10-3 0:28:18]
# 1
save the sessionid, username , logintime, logouttime to your db
jgalacambraa at 2007-7-14 17:21:05 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...
# 2
That's ok but I want really comprehensive audit trail of data base tables.For eg. If someone changes the value of one particular field then I want current as well as previous value and user who cahnged it over large number of transactions.
chintu123a at 2007-7-14 17:21:05 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...
# 3
i think you want is a table same as you want to back up and add the four columns that i've said?.. am i right?.. those rows that will be updated will be inserted to the backup table plus the columns that ive said.. (logintime and logouttime excluded sorry)
jgalacambraa at 2007-7-14 17:21:05 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...
# 4

Actually I want to explain you my situation fully. As my application is going to use LDAP server for authentication and single user database id to connect and perform all operations so this approach will not work. Sorry I should have mentioned LDAP while posting this query.Thanks for ur replies.

chintu123a at 2007-7-14 17:21:05 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...
# 5
so you are not using jsp and will not have session id?..make a trigger that will call a function or procedure that will save the rows to be updated on the back up table before you make the update (trigger before update)
jgalacambraa at 2007-7-14 17:21:05 > top of Java-index,Enterprise & Remote Computing,Web Tier APIs...