A Study on Database Gateways in LAN

点击翻译按钮获取中文摘要

The aim of this study was the research and implementation of a gateway system which enables on-line access to remote information retrieval systems from the workstations attached to the local area network.Now several computer centers in Japanese universities provide information retrieval services for university people. One of the problems in such services is that centers uses different operating systems and information retrieval system ; thus users have to learn different database query language to get information. This makes the utilization of databases difficult for casual users.The proposed gateway system is positioned between end-users and database service centers and functions as an information format converter in order to provide a unified and integrated interface to users, absorbing the differences of DB query languages among database centers.One of the workstations was employed as a gateway machine to the Ethernet-based LAN. Two communication protocols were implemented on this gateway. The first one is CCITT X.3/X.29 ; the other one is TCP/IP based protocol suite. Considering the future expansion of TCP/IP based networking in Japanese university environment, TCP/1P will be accepted much more widely. This gateway has made it possible for any workstations in the local area network to access freely to remote database centers. At present, 48kbps X.25 line is used for this purpose in Nacsis's Science Information Network.A prototype software was made to achieve full-text/faster image search for document database as a widow-based system in order to demonstrate homogeneous database access through gateway systems.