[tdwg-tag] string literals vs. uris for dwc:recordedBy, dwc:identifiedBy, and dwc:georeferencedBy in RDF
Steve Baskauf
steve.baskauf at vanderbilt.edu
Thu May 20 02:59:59 CEST 2010
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
>>>>
>>>> _______________________________________________
>>>> tdwg-tag mailing list
>>>> tdwg-tag at lists.tdwg.org
>>>> http://lists.tdwg.org/mailman/listinfo/tdwg-tag
>>>>
>>>>
>>>>
>>>
>>> --
>>> 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
>>> _______________________________________________
>>> tdwg-tag mailing list
>>> tdwg-tag at lists.tdwg.org
>>> http://lists.tdwg.org/mailman/listinfo/tdwg-tag
>>>
>>>
>>
>> --
>> _________________
>> 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
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