A syntactic and lexicon analyzer for the geography markup language (GML)

Abstract

The geography markup language (GML), developed by Open GIS (Geographic Information Systems) Consortium, is currently in version 3.1. GML is an XML (Extensible Markup Language) grammar written in XML Schema for the modeling, transport, and storage of geographic information. The modeling of geographic phenomenon is based on different kinds of objects such as: features, coordinate reference systems, geometry, topology, time, units of measure and generalized values. With the feature objects we can model all geographic objects, like rivers, lakes, roads, streets, buildings, cities and state shapes, mountains, etc. These objects are represented through documents written in GML, and their properties are registered by parameters, like name, coordinates, dimension, extension, location, etc. The proposal of this work is to develop a syntactic and lexicon analyzer for GML, aimed to assist environmental professionals in the verification of the coherence of their written documents. The user interface of the system is a text editor, presenting all GML tags, as well as syntactic and lexicon analysis functions. The program also has an option for exhibit the GML tags in the following languages: Spanish, French, Portuguese, English and Italian. Searching the Web, we found only one analyzer for GML documents, which directly executed the GML interpretation in the site, not supplying an executable software for solving that task. Given the GML relevance, we thought about creating an executable software that provided GML syntactic and lexicon analysis. We have chosen for system development the Visual Basic, in its seventh version, due its simplicity and popularity (Cortez and Scherr, 2001; Petroutsos, 2001).