The Feature Data Objects (FDO) API provides access to data in a data store. A provider is a specific implementation of the FDO API that provides access to data in a particular data store. The FDO Provider for WMS provides FDO with access to a WMS-based data store.
An Open Geospatial Consortium (OGC) Web Map Service (WMS) produces maps of spatially referenced data dynamically from geographic information. This international standard defines a "map" to be a portrayal of geographic information as a digital image file suitable for display on a computer screen. A map is not the data itself. Maps by WMS are generally rendered in a pictorial format, such as PNG, GIF or JPEG, or occasionally as vector-based graphical elements in Scalable Vector Graphics (SVG) or Web Computer Graphics Metafile (WebCGM) formats.
The FDO Provider for WMS has the following characteristics:
- The FDO Provider for WMS serves up map information originating from an OGC Basic Web Map Service that provides pictorially formatted images, such as PNG, GIF, or JPEG.
- WMS map data is exposed through an FDO feature schema whose classes contain an FDO Raster property definition. The FDO schema exposed from the FDO Provider for WMS conforms to a pre-defined FDO schema that is specific to WMS and that acts as the basis for all FDO interaction with WMS data, regardless of the originating source of the WMS images.
- WMS data manipulation operations are limited to querying features based on spatial and non-spatial constraints. Schema manipulation operations are not supported.
The FDO Provider for WMS can run in a multi-platform environment, including Windows and Linux.
For more information, see The Essential FDO (FET_TheEssentialFDO.pdf) and the OSGeo FDO Provider for WMS API Reference Help (WMS_Provider_API.chm).