download a sample that shows how to create an API Extension.You can build your own API Extensions to get direct access to specific data formats that are not supported by ArcWeb Services, for example, you might want to build an API Extension to be able to access data via GML, KML, GPX, other XML formats, ESRI file geodatabase, and so on.
See Using API Extensions for information on the supported API Extensions for ArcGIS Server, ArcIMS, and GeoRSS. That page also shows how to use your own API Extension (once you’ve created one).
To build your own API Extension, download a sample that shows how to create an API Extension.
Visit the Feedback page to give comments or suggestions about the ArcWeb Explorer Developer's Guide.