Abstract: A distributed system is described that includes a notification module and multiple data-providing modules for delivering updated data to client devices. The notification module notifies the client devices of a version of the updated data. A client device then requests the identified version of the updated data. In response to the request, the distributed system selects one of the data-providing modules to provide the updated data. The selected data-providing module determines whether it has finished processing the requested version of the updated data. If so, the selected data-providing module provides the updated data; if not, the selected data-providing module rejects the request. If rejected, the client device generates another request, prompting the distributed system to select another data-providing module.