FDO (Feature Data Objects) is the feature access library used by MapGuide
and recently released as open source by Autodesk.  The architecture of FDO
is briefly reviewed, and then the experiences of implementing providers for
raster data (via GDAL) and vector data (from PostGIS) are given from a 
software developer point of view.  FDO will also be constrasted to the roughly
analygous GDAL/OGR library, with some discussion of possible future 
applications of FDO.