From Local to Community GML Schemas
A key challenge for SDI projects is that different organizations use different internal geospatial data models. An example of this is the Cross-Border SDI Project where participants developed an online network to help identify critical infrastructure (CI) during emergencies and everyday operations. The network is based on OGC WFS, Filter Encoding and GML standards and CubeWerx/Carbon Project software (the WFS are located in Montana and Quebec). Cross-border users are able to access the two secure data services, navigate through the content, and identify critical infrastructure data.
However, a key challenge was that participants in the US and Canada used multiple data models (NIDM, CISDM, GDM). To deal with this, participants used the capability of CubeWerx WFS to map and transform local agreed-on data models to a jointly agreed-on community data model (WFS-X). The WFS-X then dynamically translates internal data structures into the local GML schema (CI National Model) or the international common GML schema (CI Common Model) on the fly. So "chaque WFS parle deux langues."
We had great discussions about this at NC GIS 2009 and the FGDC HSWG. Lots of folks recognize the challenge - and the potential to support cross-border and cross-regional information infrastructures that move SDI from on-premise computing and file transfer to access, processing, analysis and collaboration services on an Internet cloud.