One of the most successful areas of the open source geospatial movement is providing data access APIs and data providers for a wide range of file formats. For example MapServer users are familiar with OGR and GDAL. Frank Warmerdam has been a leader in this area. His data providers are widely used in both closed and open source geospatial projects and products. Since MapServer is primarily focussed on web publishing, OGR and GDAL are basically read-only APIs and are optimized for query applications.
The Feature Data Object (FDO) API is a new kid on the block. It is distinguished from OGR and GDAL in that it provides a full edit API including among other things support for transactions, locks, and versions. In a previous blog I emphasized that MapGuide Open Source provides a Web 2.0 platform because it is designed to provide full update access to geospatial (and non geospatial) data. Autodesk contributed FDO and several FDO data providers to OSGEO.ORG. FDO is getting a lot of interest at the OSGEO site. For example, there are now OGR and GDAL data providers provided by Traian Stanev and Frank Warmerdam, respectively. A PostGIS data provider is in the works. In the last few days Haris Kurtagic has created an open source project on OSGEO to support an open source Oracle data provider. Haris has told me that he is seeing a tremendous amount of interest in his data provider.
If you want an interesting perspective on FDO, take a look at Jason Birch's most recent blog (Jason Birch on FDO ).