The decision to expand the GIDB capabilities to the realm of XML was first motivated by customer requirements. For the GIDB to retrieve Metcast data, the XML catalog must be utilized. Of course, the decision to publish the catalog in XML has had wide-ranging benefits, including the ability to express the information in a widely understood format and the ability to utilize standardized tools to interpret the information. Additionally, XML's hierarchical format is well suited for expressing a data model catalog such as that for Metcast. The Metcast Document Type Definition also allowed us to understand specific data structures, which provided a powerful tool for application development. The benefits of an XML-based approach to interoperability were readily apparent to team members by the end of the development process.
In this chapter, we have shown how XML-enabled technology has been used by the GIDB System to enhance the ability to exchange geographical data over the Internet. The GIDB System has demonstrated successful retrieval of meteorological and oceanographic data using a METOC community XML catalog and retrieval system. Implementation of the OpenGIS WMS specification has allowed the display of georeferenced map layers from numerous WMS-compliant servers on the Internet. In addition, the ability to import and export vector data in standard GML format will make it possible for any GML-enabled application to utilize data from the GIDB Ozone database repository.
The need for interoperability and geographical data exchange is very important in the GIS domain. The Internet provides a wealth of geographic data sources, and the DMAP team has worked to provide access to this data through the GIDB System. Use of XML-enabled technology has been a contributing factor to the pursuit and continuing achievement of this goal.