Re: [CODE4LIB] RDF advice

Mon, 13 Feb 2012 15:00:24 -0800 

On 2/13/12 1:43 PM, Ethan Gruber wrote:

Hi Patrick,

Thanks.  That does make sense.  Hopefully others will weigh in with
agreement (or disagreement).  Sometimes these semantic languages are so
flexible that it's unsettling.  There are a million ways to do something
with only de facto standards rather than restricted schemas.  For what it's
worth, the metadata files describe coin-types, an intellectual concept in
numismatics succinctly described at
http://coins.about.com/od/coinsglossary/g/coin_type.htm, not physical
objects in a collection.


I believe this is similar to what FOAF does with "primary topic":
http://xmlns.com/foaf/spec/#term_primaryTopic
In FOAF that usually points to a web page ABOUT the subject of the FOAF data, so a wikipedia web page about Stephen King would get this "primary topic" property. Presuming that your XML is http:// accessible, it might fit into this model. 

kc



Ethan

On Mon, Feb 13, 2012 at 4:28 PM, Patrick Murray-John<
[email protected]>  wrote:


Ethan,

The semantics do seem odd there. It doesn't seem like a skos:Concept would
typically link to a metadata record about -- if I'm following you right --
a specific coin. Is this sort of a FRBRish approach, where your
skos:Concept is similar to the abstraction of a frbr:Work (that is, the
idea of a particular coin), where your metadata records are really
describing the common features of a particular coin?

If that's close, it seems like the richer metadata is really a sort of
definition of the skos:Concept, so maybe skos:definition would do the
trick? Something like this:

ex:wheatPenny a skos:Concept ;
    skos:prefLabel "Wheat Penny" ;
    skos:definition "Your richer, non RDF metadata document describing the
front and back, years minted, etc."

In XML that might be like:

<skos:Concept 
about="http://example.org/**wheatPenny<http://example.org/wheatPenny>
">
  <skos:prefLabel>Wheat Penny</skos:prefLabel>
  <skos:definition>
Your richer, non RDF metadata document describing the front and back,
years minted, etc.
  </skos:definition>
  </skos:Concept>


It might raise an eyebrow to have, instead of a literal value for
skos:definition, another set of structured, non RDF metadata. Better in
that case to go with a document reference, and make your richer metadata a
standalone document with its own URI:

ex:wheatPenny skos:definition ex:wheatPennyDefinition**.xml

<skos:Concept 
about="http://example.org/**wheatPenny<http://example.org/wheatPenny>
">
<skos:definition 
resource="http://example.org/**wheatPenny.xml<http://example.org/wheatPenny.xml>"
/>
</skos:Concept>

I'm looking at the Documentation as a Document Reference section in SKOS
Primer : 
http://www.w3.org/TR/2009/**NOTE-skos-primer-20090818/<http://www.w3.org/TR/2009/NOTE-skos-primer-20090818/>

Again, if I'm following, that might be the closest approach.

Hope that helps,
Patrick



On 02/11/2012 09:53 PM, Ethan Gruber wrote:


Hi Patrick,

The richer metadata model is an ontology for describing coins.  It is more
complex than, say, VRA Core or MODS, but not as hierarchically complicated
as an EAD finding aid.  I'd like to link a skos:Concept to one of these
related metadata records.  It doesn't matter if I use  skos, owl, etc. to
describe this relationship, so long as it is a semantically appropriate
choice.

Ethan

On Sat, Feb 11, 2012 at 2:32 PM, Patrick Murray-John<
[email protected]>   wrote:

  Ethan,


Maybe I'm being daft in missing it, but could I ask about more details in
the richer metadata model? My hunch is that, depending on the details of
the information you want to bring in, there might be more precise
alternatives to what's in SKOS. Are you aiming to have a link between a
skos:Concept and texts/documents related to that concept?

Patrick


On 02/11/2012 03:14 PM, Ethan Gruber wrote:

  Hi Ross,


Thanks for the input.  My main objective is to make the richer metadata
available one way or another to people using our web services.  Do you
think it makes more sense to link to a URI of the richer metadata
document
as skos:related (or similar)?  I've seen two uses for skos:related--one
to
point to related skos:concepts, the other to point to web resources
associated with that concept, e.g., a wikipedia article.  I have a
feeling
the latter is incorrect, at least according to the documentation I've
read
on the w3c.  For what it's worth, VIAF uses owl:sameAs/@rdf:resource to
point to dbpedia and other web resources.

Thanks,
Ethan

On Sat, Feb 11, 2012 at 12:21 PM, Ross Singer<[email protected]>
  wrote:

  On Fri, Feb 10, 2012 at 11:51 PM, Ethan Gruber<[email protected]>


  wrote:

  Hi Ross,


No, the richer ontology is not an RDF vocabulary, but it adheres to

  linked


  data concepts.


  Hmm, ok.  That doesn't necessarily mean it will work in RDF.


  I'm looking to do something like this example of embedding mods in

rdf:

  
http://www.daisy.org/zw/ZedAI_****Meta_Data_-_MODS_**<http://www.daisy.org/zw/ZedAI_**Meta_Data_-_MODS_**>


Recommendation#RDF.2FXML_2<htt**p://www.daisy.org/zw/ZedAI_**
Meta_Data_-_MODS_**Recommendation#RDF.2FXML_2<http://www.daisy.org/zw/ZedAI_Meta_Data_-_MODS_Recommendation#RDF.2FXML_2>




Yeah, I'll be honest, that looks terrible to me.  This looks, to me,
like kind of a misunderstanding of RDF and RDF/XML.

Regardless, this would make useless RDF (see below).  One of the hard
things to understand about RDF, especially when you're coming at it
from XML (and, by association, RDF/XML) is that RDF isn't
hierarchical, it's a graph.  This is one of the reasons that the XML
serialization is so awkward: it looks something familiar XML people,
but it doesn't work well with their tools (XPath, for example) despite
the fact that it, you know, should.  It's equally frustrating for RDF
people because it's really verbose and its syntax can come in a
million variations (more on that later in the email) making it
excruciatingly hard to parse.

  These semantic ontologies are so flexible, it seems like I *can* do


anything, so I'm left wondering what I *should* do--what makes the
most
sense, semantically.  Is it possible to nest rdf:Description into the
skos:Concept of my previous example, and then
place<nuds:nuds>.....more
sophistated model......</nuds:nuds>    into rdf:Description (or

  alternatively,


  set rdf:Description/@rdf:resource to the URI of the web-accessible XML


  file?


  Most RDF examples I've looked at online either have skos:Concept or

rdf:Description, not both, either at the same context in rdf:RDF or
one
nested inside the other.

  So, this is a little tough to explain via email, I think.  This is


what I was referring to earlier about the myriad ways to render RDF in
XML.

In short, using:
<skos:Concept about="http://example.org/foo"****>
  <skos:prefLabel>Something</****skos:prefLabel>

  ...
</skos:Concept>

is shorthand for:

<rdf:Description about="http://example.org/foo"****>
  <rdf:type 
resource="http://www.w3.org/****2004/02/skos/core#Concept<http://www.w3.org/**2004/02/skos/core#Concept>
<http**://www.w3.org/2004/02/skos/**core#Concept<http://www.w3.org/2004/02/skos/core#Concept>

"

/>
  <skos:prefLabel>Something</****skos:prefLabel>

</rdf:Description>

So, yeah, you use one or the other.

That said, I'm not sure your ontology is really going to work well,
you'll just have to try it.  One thing that would probably be useful
would be to serialize out a document with your nuds vocabulary as
rdf/xml and then use something like rapper (comes with the redland
libraries) to convert it to something more RDF-friendly, like turtle,
and see if it makes any sense.

For example, your daisy example above:

<rdf:RDF
                xmlns:rdf="http://www.w3.org/***
*1999/02/22-rdf-syntax-ns#<http://www.w3.org/**1999/02/22-rdf-syntax-ns#>
<htt**p://www.w3.org/1999/02/22-rdf-**syntax-ns#<http://www.w3.org/1999/02/22-rdf-syntax-ns#>



"
                xml:mods="http://www.daisy.****org/RDF/MODS<
http://www.daisy.**org/RDF/MODS<http://www.daisy.org/RDF/MODS>>
">

                <rdf:Description rdf:ID="daisy-dtbook2005-****
exemplar-01">


                        <mods:titleInfo>
                                <mods:title>World Cultures and
Geography</mods:title>
                        </mods:titleInfo>

                        <mods:name>
                                <mods:namePart>Sarah Witham
Bednarz</mods:namePart>
                                <mods:role>
                                        <mods:roleTerm
mods:type="text">author</mods:****roleTerm>

                                </mods:role>
                        </mods:name>

                        <mods:name>
                                <mods:namePart>Inés M.
Miyares</mods:namePart>
                                <mods:role>
                                        <mods:roleTerm
mods:type="text">author</mods:****roleTerm>

                                </mods:role>
                        </mods:name>

                        <mods:name>
                                <mods:namePart>Mark C.
Schug</mods:namePart>
                                <mods:role>
                                        <mods:roleTerm
mods:type="text">author</mods:****roleTerm>

                                </mods:role>
                        </mods:name>

                        <mods:name>
                                <mods:namePart>Charles S.
White</mods:namePart>
                                <mods:role>
                                        <mods:roleTerm
mods:type="text">author</mods:****roleTerm>

                                </mods:role>
                        </mods:name>

                        <mods:originInfo>
                                <mods:publisher>DAISY
Consortium</mods:publisher>

  <mods:dateCreated>2005-01-14</****mods:dateCreated>

                                <mods:version>3</mods:version>

  <mods:dateModified>2005-07-27<****/mods:dateModified>

                        </mods:originInfo>

                        <mods:relatedItem mods:type="original">
                                <mods:originInfo>
                                        <mods:publisher>McDougal
Littell</mods:publisher>
                                        <mods:place>Evanston,
Illinois</mods:place>

  <mods:dateCreated>2003</mods:****dateCreated>

                                <mods:originInfo>
                        </mods:relatedItem>

                        <mods:identifier
mods:type="isbn10">0618168419<****/mods:identifier>

                        <mods:typeOfResource>text</****
mods:typeOfResource>


                        <mods:physicalDescription>
                                <mods:form>Hardcover print</mods:form>
                        </mods:physicalDescription>

                        <mods:subject>Geography</mods:****subject>

                        <mods:language>en</mods:****language>

                        <mods:note mods:type="description">****Culture
and

geography textbook
for highschool</mods:note>

                <rdf:Description>

        </rdf:RDF>

rapper turns this into:

<file:///home/ross/tmp/daisy.****xml#daisy-dtbook2005-**exemplar-**01>

    mods:titleInfo [
        a mods:title
    ] .

[]
    a mods:namePart .

which is not terribly useful.

I guess what I'm saying is that RDF/XML isn't really intended to be
used as XML nor is it terribly useful in that capacity because
'native' XML-based schemas are, by definition, hierarchical (plus they
aren't constrained by the E-A-V model).  RDF/XML is really just a
standardized way to share RDF graphs (the first and now most maligned
way, really) that happened to use XML because there was plumbing for
XML there already (parsers, mime-types, etc.), but it shouldn't really
be mistaken for 'XML'.

Try your data in rapper and see if your resources model correctly,
otherwise I would suggest making a custom vocabulary based on your
ontology that conforms better to RDFS or OWL.

Good luck,
-Ross.

  Thanks,

Ethan

On Fri, Feb 10, 2012 at 9:44 PM, Ross Singer<[email protected]>

  wrote:


  The whole advantage of RDF is that you can pull properties from

different
vocabularies (as long as they're not logically disjoint). So, assuming
your
richer ontology is some kind of RDF vocabulary, this exactly *what*
you


should be doing.

-Ross.

On Feb 10, 2012, at 4:31 PM, Ethan Gruber<[email protected]>
wrote:

  Hi all,


I'm working on an RDF model for describing concepts.  I have

  skos:Concept



nested inside rdf:RDF.  Most documents will have little more than


labels


and related links inside of skos:Concept.  However, for a certain


type of


concept, we have XML documents with a more sophisticated ontology and


structure for describing the concept.  I could embed this metadata


  into



the


RDF or reference it as an rdf:resource.  It doesn't matter much to me

either way, but I'm unsure of the semantically correct way to create

  this



model.


Suppose I have:


<rdf:RDF>
<skos:Concept rdf:about="URI">
<skos:prefLabel xml:lang="en">Label</skos:****prefLabel>

<nuds:nuds>.....more sophistated model......</nuds:nuds>
</skos:Concept>
</rdf:RDF>

Is it okay to have the more sophistated metadata model embedded in
skos:Concept alongside labels and related links?  Suppose I want to

  store



the more sophisticated metadata separately and reference it?  I'm not


sure

  what property adequately addresses this relation, semantically.


Recommendations?

Thanks,
Ethan




--
Karen Coyle
[email protected] http://kcoyle.net
ph: 1-510-540-7596
m: 1-510-435-8234
skype: kcoylenet

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