Patrick said:
> I think folks are reading far too much into the term
> 'namespace' and the relationship between namespaces used in
> RDF/XML and the resultant URIs in the RDF graph model.
>
> In particular, in the RDF graph model, there are no such
> things as namespaces, qnames, etc. Those are, of course
> employed by the RDF/XML serialization, so that predicate URIs
> can be expressed as element and attribute names. But the RDF
> model uses URIs, not qnames. RDF is not XML. Namespaces and
> qnames are not significant to, nor have representation in the
> RDF graph.
>
> The value of rdfs:isDefinedBy is a URI denoting some resource
> that defines the resource denoted by the subject of that
> property. That's all. We don't know what the describing
> resource is. It could be an RDF Schema instance. It could be
> an HTML instance. It could be a PDF document. It could be a
> portal to a relational database. We don't know. The semantics
> of rdfs:isDefinedBy does not tell us.
>
> Furthermore, one cannot determine the namespace/name
> partioning of any arbitrary URI used in an RDF graph. It is
> not possible. That partitioning is not retained. It is lost
> forever when the RDF/XML is parsed into the graph. Also lost
> is the context of the qname, whether it was an element name,
> an element-specific attribute name, or a global attribute
> name. Cest la vie.
>
> The bottom line is that XML and RDF have different naming
> architectures. XML uses qnames, which are based on pairings
> of namespace URIs and local names. RDF uses URIs. There is a
> rather simple, unidirectional, and lossy transformation
> employed by RDF to get from qnames to URIs, but qnames and
> namespaces have no meaning in the RDF graph.
>
> Namespaces and qnames for properties in RDF/XML are just a
> means to an end, to serialize RDF statements and RDF ignores
> the semantics of qnames defined by XML. Perhaps that's not
> necessarily kosher, but that's how things are.
Yes, I think I understand this.
So.... _if_ the partioning of a set of terms by the association of
subsets with distinct XML namespaces _is_ intended to carry some
significance, and it is useful for an RDF application to present views
of terms grouped in accordance with that partitioning, then that means
we need to express that grouping explicitly in the RDF model in some
way. i.e. a relationship between the terms to be grouped and some common
resource.
At the moment, I think (but I'm not completely sure!) we're saying there
are circumstances in which we _would_ like an RDF application to be able
to distinguish terms which in XML are associated with the namespace
named http://purl.org/dc/terms/ from terms which in XML are associated
with the namespace named http://purl.org/dc/elements/1.1/ ?
Is that right? If we don't need that distinction, then there is no
problem.
If we do need to make that distinction, at the moment the only means of
doing so is on the basis of the rdfs:isDefinedBy properties associated
with the individual terms. Is that a good basis for making that
distinction, or should we be making some other explicit statement of the
relationship between terms?
Pete
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