[tdwg-tag] string literals vs. uris for dwc:recordedBy, dwc:identifiedBy, and dwc:georeferencedBy in RDF
Bob Morris
morris.bob at gmail.com
Thu May 20 07:00:09 CEST 2010
As Peter Ansell points out, another solution seems to be to use two
dwc:recordedBy elements:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:dwc="http://rs.tdwg.org/dwc/terms/"
>
<dwc:Occurrence rdf:about="http://herbarium.org/hb123456">
<dwc:recordedBy
rdf:resource="http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me"/>
<dwc:recordedBy >Steve Baskauf</dwc:recordedBy>
</dwc:Occurrence>
I don't think the parse error is about the use of rdf:resource per se.
I must confess that I'm having trouble understanding how to conclude
from the RDF spec why the original is a parse error, but these things
usually can be understood by trying to show what the triples are, not
by staring at the spec for some rdf tag. I'm finding RDF/XML
increasingly irksome and unpleasant in this kind of task. If one
unwinds it here, I bet it is that your failing example has subject
"http://herbarium.org/hb123456", predicate dwc:recordedBy but is
trying to have two objects.
The fact that you want to associate the URI for you with the string
for you is probably a separate problem, and possibly not expressible
within dwc itself.
Bob
On Wed, May 19, 2010 at 8:59 PM, Steve Baskauf
<steve.baskauf at vanderbilt.edu> wrote:
> In the specific case of RDF, having your cake and eating it doesn't work.
> Paste this:
>
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
> xmlns:dwc="http://rs.tdwg.org/dwc/terms/"
> >
> <dwc:Occurrence rdf:about="http://herbarium.org/hb123456">
> <dwc:recordedBy
> rdf:resource="http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me">Steve
> Baskauf</dwc:recordedBy>
> </dwc:Occurrence>
> </rdf:RDF>
>
> into the W3C RDF validator at:
> http://www.w3.org/RDF/Validator/
> and it will tell you "The attributes on this property element, are not
> permitted with any content; expecting end element tag.". So in RDF elements
> having the rdf:resource attribute have to be empty elements. I tried
> validating an example where the recordedBy property was included twice, once
> with a URI object and once with a string literal object. It validated as
> "good" RDF, but I think it would be confusing to a linked data client that
> would really have no clue that both objects represented the same thing and
> would probably "assume" that the occurrence was recorded by two entities
> rather than one..
>
> A possible solution would be to use dcterms:description as another
> attribute. dcterms:description is defined as "An account of the resource.
> Description may include ...a free-text account of the resource." I couldn't
> find a more appropriate Dublin Core to use as an attribute. So running this
> example:
>
> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
> xmlns:dcterms="http://purl.org/dc/terms/"
> xmlns:dwc="http://rs.tdwg.org/dwc/terms/"
> >
> <dwc:Occurrence rdf:about="http://herbarium.org/hb123456">
> <dwc:recordedBy
> rdf:resource="http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me"
> dcterms:description="Steve Baskauf" />
> </dwc:Occurrence>
> </rdf:RDF>
>
> through the validator shows that this RDF asserts the following triples:
> http://herbarium.org/hb123456 dwc:recordedBy
> http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me
> and that
> http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me
> dcterms:description "Steve Baskauf"
>
> In other words, the occurrence was recorded by me (identified by my URI) and
> that the description of the thing represented by my URI is "Steve Baskauf".
> That is pretty much a correct representation of the situation, although the
> whole point of using a URI as the object of a property is for a client to
> dereference the URI to find out more about the object. The FOAF file
> (pointed to by the URI) would provide that information without the
> dcterms:description attribute.
>
> Steve
>
>
> Jim Croft wrote:
>
> wondering if
> <dwc:recordedBy
> rdf:resource="http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me">Steve
> Baskauf</dwc:recordedBy>
> is legit?
>
> just a have your cake and eat it kinda guy...
>
> jim
>
> On Thu, May 20, 2010 at 7:41 AM, Kevin Richards
> <RichardsK at landcareresearch.co.nz> wrote:
>
>
> From my understanding (and after reading the example Bob referred to), the
> difference is:
>
> [referring to external id]
> <dwc:recordedBy
> rdf:resource="http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me" />
>
> [inline text]
> <dwc:recordedBy>Steve Baskauf</dwc:recordedBy>
>
> Look right?
>
> Kevin
>
> -----Original Message-----
> From: tdwg-tag-bounces at lists.tdwg.org
> [mailto:tdwg-tag-bounces at lists.tdwg.org] On Behalf Of Jim Croft
> Sent: Thursday, 20 May 2010 9:37 a.m.
> To: Bob Morris
> Cc: tdwg-tag at lists.tdwg.org
> Subject: Re: [tdwg-tag] string literals vs. uris for dwc:recordedBy,
> dwc:identifiedBy, and dwc:georeferencedBy in RDF
>
> Hi Bob - should the same term allow both types of content, or should
> there be a different term for each? Does it matter? Should
> applications be smart enough to tell the difference and know what to
> do with it?
>
> Not really asking what the specification says, but about purity and
> wholesomeness of design... :)
>
> jim
>
> On Thu, May 20, 2010 at 4:26 AM, Bob Morris <morris.bob at gmail.com> wrote:
>
>
> Exactly this example is given in
> http://web4.w3.org/TR/REC-rdf-syntax/#section-Syntax-property-attributes
> so I would find it regrettable if DwC does something somewhere that
> makes this substitution impossible or discouraged, or encourages tool
> construction that does so, or encourages documention be interpreted in
> a way that does so.
>
> Indeed http://rs.tdwg.org/dwc/rdf/dwcterms.rdf defines its type to be
> rdf:Property and is silent on any semantics but that. My own
> conclusion is that neither the intent or the outcome of the rdf
> version of dwcterms discourages what you want, though I suppose the
> intent part would be clearer if the documentation also said that a URI
> can always be used, but applications are responsible for interpreting
> it.
>
>
> On Wed, May 19, 2010 at 11:09 AM, Steve Baskauf
> <steve.baskauf at vanderbilt.edu> wrote:
>
>
> The definition for the Darwin Core term recordedBy
> http://rs.tdwg.org/dwc/terms/index.htm#recordedBy
> says "A list (concatenated and separated) of names ...". The examples
> given are string literals. However, when using this term as a predicate
> in RDF, it would seem preferable to use a URI to an RDF representation
> of the entity (if one exists) rather than a string literal. For
> example, can I use:
> <dwc:recordedBy
> rdf:resource="http://people.vanderbilt.edu/~steve.baskauf/foaf.rdf#me"/>
> rather than
> <dwc:recordedBy>Steven J. Baskauf</dwc:recordedBy>
> ?
>
> Steve Baskauf
> --
>
> Steven J. Baskauf, Ph.D., Senior Lecturer
> Vanderbilt University Dept. of Biological Sciences
>
> postal mail address:
> VU Station B 351634
> Nashville, TN 37235-1634, U.S.A.
>
> delivery address:
> 2125 Stevenson Center
> 1161 21st Ave., S.
> Nashville, TN 37235
>
> office: 2128 Stevenson Center
> phone: (615) 343-4582, fax: (615) 343-6707
> http://bioimages.vanderbilt.edu
>
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>
>
>
> --
> Robert A. Morris
> Emeritus Professor of Computer Science
> UMASS-Boston
> 100 Morrissey Blvd
> Boston, MA 02125-3390
> Associate, Harvard University Herbaria
> email: ram at cs.umb.edu
> web: http://bdei.cs.umb.edu/
> web: http://etaxonomy.org/FilteredPush
> http://www.cs.umb.edu/~ram
> phone (+1)617 287 6466
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>
> --
> _________________
> Jim Croft ~ jim.croft at gmail.com ~ +61-2-62509499 ~
> http://www.google.com/profiles/jim.croft
> 'A civilized society is one which tolerates eccentricity to the point
> of doubtful sanity.'
> - Robert Frost, poet (1874-1963)
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>
>
> --
> Steven J. Baskauf, Ph.D., Senior Lecturer
> Vanderbilt University Dept. of Biological Sciences
>
> postal mail address:
> VU Station B 351634
> Nashville, TN 37235-1634, U.S.A.
>
> delivery address:
> 2125 Stevenson Center
> 1161 21st Ave., S.
> Nashville, TN 37235
>
> office: 2128 Stevenson Center
> phone: (615) 343-4582, fax: (615) 343-6707
> http://bioimages.vanderbilt.edu
>
--
Robert A. Morris
Emeritus Professor of Computer Science
UMASS-Boston
100 Morrissey Blvd
Boston, MA 02125-3390
Associate, Harvard University Herbaria
email: ram at cs.umb.edu
web: http://bdei.cs.umb.edu/
web: http://etaxonomy.org/FilteredPush
http://www.cs.umb.edu/~ram
phone (+1)617 287 6466
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