1. A method for a client application to request a data item from an access server in a computer controlled control system, said control system including objects and a plurality of access servers, which said objects represent various entities that have a defined functional meaning in the control system, which each said access server may provide access to one or more real-time data, historical data, and alarm and event data items, by the method comprising: associating a said data item with a said object, providing an Access Service Handler component to said client application, associating the Access Service Handler component with said client application, making an access request to the said data item by means of the Access Service Handler.