A study on Document Delivery System in Electronic Library Systems

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The aim of this research was to investigate the feasibolity of electronic library systems, especially socusing on telecommunication system for the document delivery on high-speed wide area networks.An electronic library in this investigation is defined as a new information service by which a user can retrieve pages of scientific journals directly on his/her workstation through networks from the centrally located detabase server that stores a large amount of digitized image data in its database systems.To establish such a new information system, we were required to estimate how a user can make access to the database server through conventional wide-area networks and what is the actual performance of various communications systems.The details of investigation are as follows : i) (communication protocol) We extended the standard ANSI Z39.50 protocol, which is designed for text information retrieval, in order to facilitate image data transmission, because we were required to apply special treatment for image data which tends to be large. We implemented the extended protocol in our experimental system. ii) (Connection through FDDI and ISDN) We investigated the communication method on low-speed 64kbps ISDN circuit as well as high-speed 100Mbps FDDI local area network. The result was incorporated into the design of user interface and interaction between a server and clients. iii) (user interface) We implemented user interface software for retrieval of secondary information and image data as well as a prototype server system for an electronic library. iv) (system evaluation) Based on the prototype system, we estimated the network performance requirement for a full-fledged electronic library system for scientific and engineering documents. The investigation could reveal design parameters for high-volume data transmission required in the future electronic library systems.