Dialog-like web applications

When learning Ruby, I came across Wee, which is based on the ideas introduced in Seaside. I love the idea of abstracting web applications, putting the server back in control, so I have been working on "Seaside.NET". For example, here is the code to control an on-line shop:

protected override void Go()
{
  StoreCart cart = new StoreCart();
  do
  {
    FillCart(cart);
  } while (!ConfirmContentsOfCart(cart));
  Address shipping = GetShippingAddress();
  Address billing = UseAsBillingAddress(shipping) ? shipping ? GetBillingAddress();
  Payment creditCard = GetPaymentInfo();
  Ship(cart, shipping, billing, creditCard);
  DisplayConfirmation();
}

I've written my code in C#, based on the ideas of Seaside, but without looking at the source code. The basic concept works, now i'm working on backtracking, i.e. handling when the user presses the "back" button in the browser.