= RFC 24: GDAL Progressive Data Support = 

Author: Norman Barker[[BR]]
Contact: nbarker@ittvis.com[[BR]]
Status: Development

== Summary ==

To provide an interface for data streaming support to GDAL by overloading the RasterIO function to include a callback function when there are buffer updates.  The RFC focuses on JPIP but should be generic to apply to other streaming / progressive formats.

== Definitions ==

'''JPIP''': JPEG 2000 Interactive Protocol

== Objective ==

To provide a callback function to allow users of a progressive format driver to receive notifications of updates to the underlying dataset for a particular requested region of the data.  The notification mechanism should be accessible to all the swig wrappers and the underlying buffer data should be conveniently stored to allow conversion to a raster format - e.g. png, windows bitmap.

== Implementation ==

The implementation is a definition of an interface, currently the most convenient streaming library is [http://www.kakadusoftware.com Kakadu] however since GDAL is a developer library only stubs can be distributed to conform to Kakadu licensing [http://article.gmane.org/gmane.comp.gis.gdal.devel/15955/match=fwtools+kakadu FWTools Licensing].  Commercial vendors are also interested in using GDAL for streaming support and a standard interface will allow these commercial plugins to be incorporated.