S Arvind wrote:
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
when exactly might the session be destroyed if, for instance, the user
wanders off bored or abruptly closes his browser ? http sessions are
independent of http sockets, at least in http/1.1
eventually, presumably, you time out the idle session, bit isn't that
typically in several hours?
transactions that run many hours are painful for postgres, they intefere
with vacuum processing, and can lead to bloated tables, especially on
databases that ahve high transactional rates.
you likely will need to manage your own database connections, and keep
them with your session tracking data. you may need to implement your
own specialized version of a connection pool, this one would return a
specific session upon request rather than the next available one, and be
closely tied into your session manager.
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