The Base Presentation Object is a possible strategy for enforcing a consistent, controller-like methodology for handling “events” generated by Web page interactions with the client. It is not inherent to XMLC development, instead serving as a possible strategy that an architect might propose. It is the strategy that was selected to implement the ShowFloor application.
As an abstract class, BasePO methods are inherited by the child presentation objects, or POs. These presentation objects are invoked from Web pages with a parameter named event and a value such as browse, edit, login, register, or whatever value expected by the developer. When no event parameter is passed, a default handler is provided.