Use of LDAP to partially implement the OGIS discovery service

Abstract

The geographical information systems (GIS) community has over the years captured and generated large amounts of geographical data. Discovery of these heterogeneous data sets is our main concern. Research described in this paper is focussed on one component of a Georesource Centre, an infrastructure facilitating the sharing of geographical data and processes among organizations. The role of this component, the Selector Broker, is to process metadata queries in the search for appropriate data sets. Processing of queries within the Selector Broker involves translation of the metadata semantics and query syntax. There are several ways such a translation can be done and we have adopted the direct translation of semantics and syntax in this paper. In direct translation, semantic and syntactic differences are mapped directly between systems without going through an intermediate system. In the design of the Centre, organizations use the Lightweight Directory Access Protocol (LDAP) to store entries of geographical data sets they have collected. The Selector Broker processes these entries using pre-defined semantic and syntactic mappings to translate the initial queries. The service provided by the Selector Broker is accessed through the Common Request Broker Architecture (CORBA).