The idea of GML at the outset was to provide a common tool box for the widest possible range of applications consistent with the open ended nature of geography (i.e. almost all data is geographic), and the diversity of uses to which such information is put. This in turn shaped the idea of a consistent encoding model (it took a few iterations to get the consistency) called the object-property (object-property-value) model, and the use of application schemas for the synthesis of new foundation and new domain objects. This provides GML with uniformity for object builders (i.e. code developers), and the flexibility to support an almost unlimited set of applications.
The importance of these two aspects of GML – the consistent encoding model and the notion of application schemas is being borne out by the growing family of application schemas and application languages based on GML. These include: (this is only a sample)
- CSML: (Climate Science)
- TransXML (Transportation Engineering)
- LandGML (Land Survey)
- S57GML (Nautical Charting)
- AIXM GML (Aviation)
- XMML (Mining and Mineral Exploration)
- geoRSS GML (news feeds)
- Imaging (GMLJP2)
GML has shown the ability to support very simple applications such news feeds, or very complex ones like nautical charting and climate science. In the near future we can expect this family to grow as more and more organizations understand the utility of the core GML model and the efficiency of building on established constructs from geometry and features to coverages and observations, soup to niuts.