1. A presentation server, being computer software stored on a computer readable storage medium and running on a presentation server computer, in which the presentation server computer acts as an intermediary between (a) multiple, separate data sources which are each physically remote from the presentation server computer and between (b) multiple client devices, which are also each physically remote from the presentation server computer and connected to the presentation server computer over one or more networks, each of the client devices running a network based application that runs over the network connecting the presentation server computer to each of the client devices; and each of the client devices also receiving structured data from at least one of the data sources; in which the presentation server decouples the client devices from the multiple, separate data sources by insulating the data sources from needing to handle directly any display, data storage, data querying or communications functions relating to the client devices and insulating the client devices from needing to handle communications functions which are specific to the data sources; and in which the presentation server also automatically pushes updated data from the multiple, separate data sources to the network based application running on each of the client devices that displays the updated data by aggregating the updated data from the data sources into a single data stream for each of said client devices.