A method for responding to a request, comprising accepting the request, mapping the request to a control tree wherein the control tree is a logical representation of a graphical user interface (GUI) and wherein the control tree includes a set of controls which are related hierarchically to one another, advancing the control tree through at least one lifecycle stage based on the request, wherein the control tree includes at least one portlet control that represents at least one portlet, providing the request to a portlet container that contains the at least one portlet, and aggregating the output of each of the at least one portlets and providing the output to the GUI.