9. A method comprising: creating a specification for constructing a web display to contain page components that display data from heterogeneous data sources, the specification associating the page components with uniform resource locators assigned to the page components; storing the specification in at least one memory; retrieving data from heterogeneous data sources to produce the web display; controlling display and/or update of the page components using the uniform resource locators, the web display to display at least some of the data from the heterogeneous data sources; associating one or more user-specific changes to the page components, the user-specific changes comprising a layout change to a page layout for a page including the page components; tracking the one or more user-specific changes to the page components to allow users to make changes to the page components; and providing user-selectable options to dynamically undo at least some of the one or more user-specific changes to the page components.
13. The method of claim 9 , wherein versions of the page are time stamped and the one or more user-specific changes can be rolled back up to a period of time.