Sharing geographic data
R. Pascoe and N. Churcher
Department of Computer Science
University of Canterbury
Presented at the Second Colloquium of the Spatial Information Research Centre, University of Otago, New Zealand, Nov 28th - Nov 30th 1990.
(Reprinted in the New Zealand Journal of Computing January/February 1991)
Abstract
The recent proliferation of computer networks and the resulting trend toward networked and distributed data base management systems has influenced significantly the sharing of geographical data. The traditional transfer medium of magnetic tape has been replaced by data communication networks and an interfacing strategy has been adopted world-wide which revolves around the use of interchange standards such as SDTS, NTF, and MACDIF. The functionality and performance of contemporary geographical information systems will be enhanced through their utilization of the increased connectivity of computers. In this paper we develop a method for modeling the data transfer scenarios which occur in practice. We stress the importance of semantic information and show that its inclusion in a machine readable description of the syntax and semantics of transfer file formats allows practical solutions to be developed for problems that may be anticipated during the modeling process. This information is vital if software is to be generated automatically both for encoding and decoding data to and from the format, and for converting data from one format into another. We describe BQL, a notation for specifying transfer file formats, as an application of our ideas.