[mapserver-dev] RFC for XMP metadata support

Paul Ramsey pramsey at cleverelephant.ca
Fri Jul 8 11:06:18 EDT 2011

Well, the idea behind XMP is to be pretty flexible, but the answer is
"no, it's just the XMP standard" and the way the embedding occurs is
based on that standard (in certain bytes for PNGs, others for JPGs
etc) and implemented by the exempi library. XMP allows you to add, in
addition to the XMP metadata, dublin core information, creative
commons information, etc, as namespaces. So probably, in the longer
term, one could get any arbitrary metadata into XMP as a namespace. As
you can tell, I'm now talking well above my paygrade, but if it's a
topic of interest, have a read of the XMP spec, it might be possible
to do anything XML at all inside it. (XML is magic!)


On Fri, Jul 8, 2011 at 7:22 AM, Kralidis,Tom [Ontario]
<Tom.Kralidis at ec.gc.ca> wrote:
> Paul: thanks for this.  I think this is a good idea.  Can we abstract
> the functionality to allow any type of metadata embedding?
> ..Tom
>> -----Original Message-----
>> From: mapserver-dev-bounces at lists.osgeo.org
>> [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of
>> Paul Ramsey
>> Sent: Monday, 04 July 2011 12:11
>> To: mapserver-dev
>> Subject: [mapserver-dev] RFC for XMP metadata support
>> Devs,
>> I've prepared a draft RFC for adding embedded metadata into output
>> images produced by MapServer.
>>   http://trac.osgeo.org/mapserver/attachment/ticket/3932/ms-rfc-7X.txt
>> I'm looking for feedback now before I number and commit it and ask for
>> a vote. Here's the preamble so you don't have to click:
>> XMP is the "extensible metadata platform" [1]_ which allows the
>> embedding of metadata information across a wide range of document and
>> image formats: PNG, GIF, JPEG, PDF, etc. XMP was originally developed
>> by Adobe [2]_ and is supported across their product line. It is now
>> being increasingly included in other standards for metadata embedding
>> and supported by tools for viewing image information (e.g. exiftools).
>> Creative Commons has standards for using XMP to embed commons
>> licensing [3]_ in images and other document, including a specific
>> creative commons schema. One of the challenges of advertising
>> licensing and terms of use in WMS and other web mapping services is
>> that the terms are usually advertised separately from the actual
>> content. So a WMS service might specify terms in the Capabilities
>> document, but the images themselves will be unmarked. Embedding
>> license URLs inside the images themselves using a standard marking
>> allows organizations to be unambiguous about the conditions attached
>> to their content.
>> The goal of this change is to allow users the option of embedding XMP
>> metadata in their MapServer output using an open source XMP utility
>> library.
>> .. [1] http://en.wikipedia.org/wiki/Extensible_Metadata_Platform
>> .. [2] http://www.adobe.com/products/xmp/overview.html
>> .. [3] http://wiki.creativecommons.org/XMP
>> .. [4] http://libopenraw.freedesktop.org/wiki/Exempi

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