Embedding custom XML into XMP

[Paul J. Lucas]

If I want to embed my own XML inside XMP, as far as I can tell, I should
do something like this:

<?xpacket begin="" id='W5M0MpCehiHzreSzNTczkc9d'?>
<x:xmpmeta xmlns:x="adobe:ns:meta/">
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdfescription xmlns:my="http://www.my.com/rdf:about="">
<my:Envelope rdfarseType="Literal">
<foo bar="baz">anything I want</foo>
</my:Envelope>
</rdfescription>
</rdf:RDF>
</x:xmpmeta>
<?xpacket end='w'?>

Yet when I embed such XML inside a TIFF file having tag 700 and open the
TIFF with Photoshop, Photohop complains that the information is wrong (but
doesn't say specifically what) and ignores it.

So how can I embed any XML I want inside an XMP packet?

- Paul

 

[Paul J. Lucas]

<rdfescription xmlns:my="http://www.my.com/rdf:about="">

Yes, I know that should be:

<rdfescription xmlns:my="http://www.my.com/" rdf:about="">

The original example was just a bad copy/paste job. The actual XML is
correct.

- Paul

 

[Andy Dingley]

So how can I embed any XML I want inside an XMP packet?

I don't think you can. XMP is a very-much subsetted RDF and it doesn't
like anything beyond a simple list of properties, certainly not any
sort of structured graph. As a result I've never really bothered with
it and sadly can't help further. Adobe do have a good specification of
it out on the web though and AFAIR they're quite specific about what
you can and can't do.

 

[Paul J. Lucas]

I don't think you can.

Then explain this:

http://www.w3.org/TR/rdf-primer/#xmlliterals

The example shows arbitrary XHTML embedded inside the dc:title element.

- Paul

 

[Andy Dingley]

Then explain this:
http://www.w3.org/TR/rdf-primer/#xmlliterals

The example shows arbitrary XHTML embedded inside the dc:title element.

Lovely. That's RDF not XMP. Like I said, XMP only supports a _subset_
of RDF. That's one of the main reasons why I see XMP as a trivial
irrelevance to anything I work on. If I deal with it, it will only be
as an obsolete minor export format (like RSS 2.0) that I down-convert
into from the real data model.

Read the XMP SDK (download from Adobe)
In particular, p28 of XMPSpecification.pdf

:> RDF Issues
:> Unsupported Features
:> XMP uses a subset of RDF. Valid XMP is limited to the RDF described
in the previous
:> sections, along with all equivalent alternate forms of that RDF.
:> [...]
:> â— The rdfarseType='Literal' attribute is not supported.

 

[Paul J. Lucas]

Then explain this:
http://www.w3.org/TR/rdf-primer/#xmlliterals

The example shows arbitrary XHTML embedded inside the dc:title element.

Read the XMP SDK (download from Adobe)
In particular, p28 of XMPSpecification.pdf

:> RDF Issues
:> Unsupported Features
:> XMP uses a subset of RDF. Valid XMP is limited to the RDF described
in the previous
:> sections, along with all equivalent alternate forms of that RDF.
:> [...]
:> ? The rdfarseType='Literal' attribute is not supported.

Arrrgh!!!!! :-(

- Paul

 

[Grant Robertson]

Lovely. That's RDF not XMP. Like I said, XMP only supports a _subset_
of RDF. That's one of the main reasons why I see XMP as a trivial
irrelevance to anything I work on. If I deal with it, it will only be
as an obsolete minor export format (like RSS 2.0) that I down-convert
into from the real data model.

So, if I were creating a standard, then allowing XMP to be used to
provide information about images would be wise but allowing only XMP and
nothing else would be unwise?

 

[Paul J. Lucas]

So, if I were creating a standard, then allowing XMP to be used to
provide information about images would be wise but allowing only XMP and
nothing else would be unwise?

Possibly. Because it's XML, it's easy to ignore what you don't understand.

- Paul

 

[Paul J. Lucas]

Arrrgh!!!!! :-(

It seems that Photoshop, at least, will accept my custom XML if I stuff
it inside of a CDATA section. It's a kludge, but it works.

- Paul