[fdo-internals] New RFC10 Is Posted

Frank Warmerdam warmerdam at pobox.com
Tue Sep 11 11:20:48 EDT 2007

Greg Boone wrote:
> Without such a
> configuration, there would be no means for a user to customize how an
> FDO logical schema is mapped to an underlying implementation. 


I understood until you said "without".  I was under the impression that
this mapping can appear in configuration files as well.  Is that wrong?

Of course configuration files are also custom to the provider, so they
just transfer the provider specific-ness from API calls to the
application building custom config files per provider but passing
through a generic api.

> I would also like to clarify the purpose of altering the WMS Overrides
> API in order to specify the Image Format, as outlined in RFC10. The
> purpose of this method is not to allow a client to control the means in
> which the provider (i.e. GDAL API) interprets the raster data returned
> from the server, nor is it intended to imply that the provider will
> translate the retuned image into the specified format. The purpose of
> the function call is to allow a client application to specify the format
> in which the WMS server will generate the requested WMS image as the
> image is being returned to the WMS provider as a result of an FDO select
> request.

I understood this.

 > According to the OGC WMS 1.3 specification, the legal and
> appropriate values for the format type are server specific and are
> advertised by the provider as a part of the server's capabilities
> response. Therefore, it will be the client's responsibility to know the
> values that are legal and acceptable for a particular server or to use
> the IGetImageFormats custom command as specified in
> http://trac.osgeo.org/fdo/wiki/FDORfc6 to retrieve the legal values.
> Once the legal vaoues are known, they can be used to populate and create
> the WMS configuration document.

Understood.  But in addition we restrict ourselves to only png, tiff and
jpeg.  Thus a server that only serves NITF, or JPEG2000 or HDF would be
un-usuable even though they might have worked just fine if we weren't
arbitrarily (ok, perhaps that is harsh - perhaps over-carefully?) restricting
ourselves to a few common formats.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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