Abstract: A method of communicating information relating to product or service offerings between a server system and client devices is disclosed. The method comprises storing in a database at the server system a plurality of data objects, each data object comprising information relating to a product or service offering. The data objects are associated with corresponding data objects stored at client devices. Information specifying an action relating to a selected data object is received. Based on information in the database, one or more descendant data objects associated with the selected data object are identified, the descendant data object having been derived from the selected data object, and information specifying the action is transmitted to a client device associated with each identified descendant data object, to enable the action to be implemented at the client device.