Abstract: Processing a request is disclosed. A request associated with a first identifier is received. A selected request handler is selected among a first plurality of request handlers to process the request. The selection of the selected request handler is based at least in part on the first identifier. The request is processed using a second identifier included in the request. Processing the request includes using a local version of a data associated with the second identifier and stored in a storage managed by the selected request handler. The local version of the data has been updated using a centralized version of the data. The centralized version of the data has been determined using processing performed by a second plurality of request handlers. The selected request handler is included in the second plurality of request handlers.

Abstract: Processing a prepared update is disclosed. A prepared update associated with a request that has been used by the sender to update a local version of a data associated with the sender is received from a sender. Based at least in part on an identifier included in the prepared update, a selected data handler is selected among a plurality of data handlers. The selected data handler is used to update a centralized version of the data at least in part by using the received prepared update. The centralized version of the data has been previously updated using a plurality of prepared updates received from a plurality of senders. The updated centralized version of the data is sent to update the local version of the data associated with the sender.