| 摘要 |
An information system that comprises a data source that transmits a data item to a group of database instances using a packet-switched communication protocol in which retransmission of the data item to a data base instance is independent from reception of an acknowledgement to the transmitted data item from the database instance. A database instance receives the data item from the data source, stores it as a present data item and opens access to the present data item. A data consumer queries information on the present data item from the database instance and is provided with means to detect whether the information included in a response to the query is valid or not. If the information is not valid, the data consumer initiates a new query from another destination.
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