Processing of spatial metadata queries within federated GISs

A federated GIS is a collection of heterogeneous GIS that collectively act as a single source of geographical information. Spatial metadata plays an important role in accessing information from a federated GIS and furthermore, is seen as the key to achieving interoperability. Metadata usually conforms to a standard such as the Australia New Zealand Land Information Committee (ANZLIC) standard; the Content Standard for Digital Geospatial Metadata (CSDGM) from the Federal Geographic Data Committee (FGDC); and defacto standards such as the Facility for Interrogating the National Directory of Australian Resources (FINDAR). In this paper, we describe our research into strategies for processing metadata queries using a variety of metadata standards within a federated GIS, rather than restricting metadata to conform to a single standard. Using the two strategies, an analogy is drawn with Pascoe & Penny's (1990) work on interfacing strategies. In this analogy the two query processing strategies is compared to the interfacing strategies and conclusions are drawn regarding the appropriateness of each query processing strategy.