What is the best way to manage sessions in a complex multiuser application?

Almost every user interaction creates changes to the database. I would like to use one session for the whole application.
So as the user starts the application, the session would be created and if he exits the application the session gets closed.
But every tutorial i've found used one session per operation. Maybe this is because of the low complexity of the examples?

Are there any recommends on this issue?

May be that helps:

http://fabiomaulo.blogspot.com/2008/12/conversation-per-business-transaction.html

http://nhforge.org/blogs/nhibernate/

You may also want to read this excellent article if you are dealing with ASP.NET:

http://www.codeproject.com/KB/architect ... spx#BASICS

regards,

--qu