Abstract: The disclosed online system includes a number of processing blocks, including a feeding service that sends a data stream and a consuming service that receives a data stream, without sending back acknowledgements for the data (i.e., “nontransactional”). The system handles failure in the feeding service and/or the consuming service by adding reference points into the data stream and backing up a current sum that is maintained by the consuming service. Upon a failure of the consuming service, the system obtains the last reference point, restores the backup copy of the database, and starts reading the backup copy from that check point. To address a failure of the feeding service, the feeding service creates an identifier for each message in the data stream, and upon failure, the consuming service checks for messages that have the same identifier within a specified period of time, and discards any duplicate messages.

Abstract: The disclosed online system includes a number of processing blocks, including a feeding service that sends a data stream and a consuming service that receives a data stream, without sending back acknowledgements for the data (i.e., “nontransactional”). The system handles failure in the feeding service and/or the consuming service by adding reference points into the data stream and backing up a current sum that is maintained by the consuming service. Upon a failure of the consuming service, the system obtains the last reference point, restores the backup copy of the database, and starts reading the backup copy from that check point. To address a failure of the feeding service, the feeding service creates an identifier for each message in the data stream, and upon failure, the consuming service checks for messages that have the same identifier within a specified period of time, and discards any duplicate messages.