I was trying to develop a smaple e-commerce site using JSF+. On service layer, I got objects like Catalog, Category, Product, line-tem and order etc. On UI, I will show the catalog. Once the user selects the products and enters the number of items required, those product rows will effectively become a line-item and the catalog becomes an order. Now, if I am usig JSF DataTable object for showing the catalog, where does the transformation happen. If I bind the datatable to some list, this list will need to contain objects of same type when showing on UI and when getting order information back, but the list has transformed to contain order line-items on the client side since the UI display. I do not want ot create new domain objects for UI, when clearly the UI corresponds to the domain objects.