Apparatus and method for user-selective data communication with

Abstract

Apparatus and method for communication of data from a holder to a customer or other requester of such data. The requester identifies to the holder a specific data product or other piece of data known to be held by the holder. The holder responds with a message acknowledging that request and providing at least one characteristic of the data so requested. The requester utilizes the information contained in that acknowledgement to determine whether the requester wants the data that it has so identified. The requester then informs the holder, based on that determination, whether the requester still wants the holder to provide that data to the requester. In response to that message from the requester, the holder either transmits the requested data, or awaits a further request from that requester, or terminates the communication. This apparatus and method further includes a provision for verification of proper communication of requested data. Upon receipt of requested data, the requester determines the value of a predetermined error checking or fault detection code such as a checksum. The requester then provides this value or code to the holder as part of the requester's acknowledgement of receipt of the requested data. This value or code is then compared by the holder with an internally generated such value or code to determine whether the transmitted data has been properly received. The holder thereby is also assured that the recipient of the data has taken necessary steps to verify the accuracy or integrity of the communicated data.