Session based transaction!!

Hi Everyone,

In a web application running in Tomcat and Postgres 8.3 as DB, i need to
know whether my given task is feasible or not.
All the db operation which is done by that web application must
be rollback at the end(session dies) and the DB data must be same as the
starting stage(of session). Its like virtually placing the data for that
session alone and rollbacking the db to the template which is originally
been. So whenever users get in the webapplication, the initial data must be
the template data only and he can perform any operation for which data is
visible for that user alone and when the users leaves(session destroyed) all
the data changed in that time must be rollbacked.

I thought this by, When the session created in the application a transaction
must be started and all the activites must be done on the DB, but the
transaction will not be commited or rollback across request but it must be
done across the session. By not destroying the connection and using it for
all the work done by that session. when session destroy we can rollback the
entire transaction

Is there any other way to achieve the requirements in postgres.
Thanks in advance..

Arvind S

*
"Many of lifes failure are people who did not realize how close they were to
success when they gave up."
-Thomas Edison*