[Tdwg-guid] [tdwg-tag] Re: Jena examples?
Roger Hyam
roger at tdwg.org
Tue Sep 26 12:21:45 CEST 2006
Hi Kevin,
Thanks for your thoughts. It does seem a bit of a hack the way I am
suggesting - more elegant solutions are welcome but I am not sure we can
get the hierarchy in the namespace.
The classes would still be part of a regular inheritance hierarchy but
you wouldn't see it in the namespace.
The only way you would see the hierarchy is if you had namespaces that
went something like this:
http://rs.tdwg.org/ontology/BaseThing/MyClass/MySubclass/MySubSubClass/myproperty
Kind of like an xpath down the hierarchy for every concept. I am not
sure how you would then handle targetNamespaces in XML Schema.
I believe most people in the semantic world seem to have a namespace per
ontology and no indication of the class structure within the ontology
from the namespaces.
I am curious about what a huge list of classes is - I have a general
question in the back of my mind about how big people think the TDWG
ontology needs to be. But that is a question for another day!
Thanks,
Roger
Kevin Richards wrote:
> My only thought is that it seems a bit like a hack and may be too
> restrictive when trying to categorise classes. Ie it looks like you
> intend to have ALL RDF classes under the namespace
> http://rs.tdwg.org/ontology/ (correct me if I am wrong). This will
> result in a huge list of classes at the one level, and hence, again
> diminishing the human readability of the ontology. I wouldnt know, but
> it sounds like it also might cause ontology management headaches later
> on?
>
> Kevin
>
>
>>>> Roger Hyam <roger at tdwg.org> 09/26/06 8:49 PM >>>
>>>>
>
> Hi Everyone,
>
> In the not very comforting words of software vendors these are "known
> issues" and will be resolved in the next release ;)
>
> But seriously.The namespaces in the TCS names vocabulary do not resolve
> because we didn't have a policy at that time. The use if entity
> references was 'borrowed' from an example (probably Protege output) and
> I wouldn't mind doing away with it.
>
> I have been thinking long and hard about the namespace issues in the
> last few weeks and believe I have a solution that I will propose at TDWG
>
> St Louis. It would be good to have face to face discussions about it and
>
> make a decision there.
>
> To briefly summarize: The issue is getting a namespace convention that
> will work across technologies. Suppose we want to serve data in a
> technology that "isn't very good at namespaces". As an example - if we
> were to have separate namespaces for TaxonNames, TaxonConcepts,
> Specimens, Metadata, GeospatialStuff, Collections and we wanted to
> validate a document using XML Schema that contained all these things it
> would require 6 independent schemas each with it's own target namespace.
>
> If you have ever tried to debug something like this you will know what
> total madness it is. We can't just abandon XML Schema because it would
> rule out not only our existing technologies but GML and probably
> others... It may also be desirable to express our ontology in things
> that aren't even XML.
>
> The only solution I can think is that for the TDWG Ontology we should
> have a single formal namespace of: http://rs.tdwg.org/ontology/
>
> Within the ontology we have a convention for concepts that goes like
> this.
>
> A class would be: http://rs.tdwg.org/ontology/tdwg123_MyClass
>
> where 123 is the internal id of the class and MyClass is the class name
>
> A property in MyClass would be:
> http://rs.tdwg.org/ontology/tdwg123_myProperty
>
> where 123 is the *class* id not the property id and myProperty is the
> property name.
>
> An instance would be http://rs.tdwg.org/ontology/tdwg123_789
>
> where 123 is the *class* id and 789 is the instance id (there is nothing
>
> stable about an instance that we could use as an identifier unless we
> force a label property and make it immutable).
>
> In a way this is using the part before the _ as a pseudo namespace.
>
> I think this hits the balance between something that is technology
> independent and something that will produce reasonably human readable
> documents.
>
> It is radical which is why I thought it would be good to talk about it.
>
> Any one got an alternative?
>
> We have to have a solution for this by the end of the St Louis meeting
> as it is critical path for ontology work.
>
> Most grateful for you patience and any thoughts you have.
>
> Roger
>
>
> Sally Hinchcliffe wrote:
>
>> Hi Steve /all
>>
>> We took that syntax straight from Roger's RDF/TCS examples. I think
>> Roger was going to do more work on tidying up those sorts of loose
>> ends. I have to admit that my knowledge of RDF and particularly RDFS
>> is pretty superficial
>>
>> We can switch to either the shorter format or the safer fully
>> qualified URI - what do people think would be better?
>>
>> Sally
>>
>>
>>
>>
>>> By the way, the IPNI example you cite has an error:
>>>
>>> <tn:nomenclaturalCode rdf:resource="&tn;#botanical" />
>>>
>>> Many RDF/XML parsers will see &tn; as an entity which cannot be
>>> resolved. Since I don't have a copy of the ontology (and
>>> http://tdwg.org/2006/03/12/TaxonNames does not resolve), I can only
>>>
> take
>
>>> a guess that it should look something like:
>>>
>>> <tn:nomenclaturalCode rdf:resource="tn:botanical" />
>>>
>>> However, using XML namespace prefixes in resource references inside
>>> RDF/XML documents tends to cause problems because not all RDF/XML
>>> parsers are smart enough to dereference the namespace prefix and
>>>
> build a
>
>>> fully-qualified resource URI. A safer form of the above would be the
>>>
>
>
>>> fully qualified resource URI which looks like:
>>>
>>> <tn:nomenclaturalCode
>>>
> rdf:resource="http://tdwg.org/2006/03/12/TaxonNames/botanical" />
>
>>> -Steve
>>>
>>>
>>>
>> *** Sally Hinchcliffe
>> *** Computer section, Royal Botanic Gardens, Kew
>> *** tel: +44 (0)20 8332 5708
>> *** S.Hinchcliffe at rbgkew.org.uk
>>
>>
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>>
>>
>>
>
>
>
--
-------------------------------------
Roger Hyam
Technical Architect
Taxonomic Databases Working Group
-------------------------------------
http://www.tdwg.org
roger at tdwg.org
+44 1578 722782
-------------------------------------
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