Web programming is a stateless request response environment, postback is a new request nothing remains from the previous request unless you have it stored in session variables or viewstate, but viewstate is really for control state not for business objects. You would need to re-create the business object on each request, or if it is very expensive to create the object you could persist it in session state or cache but I would not go wild with session state and only use it if you really really need it because it uses server memory which is a precious resource and often the most precious resource.

Hope that helps,

Joe