Re: newbie question about sparql and 200

[[[

The relevant specs are SPARQL, the httpRange-14 resolution, AWWW, and
HTTP/1.1.

If you dereference this URI, after a redirect or two you get a 200 response
and a representation with content-type application/rdf+xml. httpRange-14
says that this implies that the URI denotes an information resources.

The triples will be selected from an RDF graph, presumably the one that is
serialized in this representation. Now by looking at the spec, it wasn't
clear to me whether the URI in a FROM was to denote a graph, or an
information resource; and from AWWW it is not clear whether the classes of
graphs and information resources can overlap. I know that some people assert
that mathematical objects such as numbers are not IRs, and an RDF graph
seems every bit as mathematical as a number. ]]]

With the FROM clause (in SPARQL), the representation is more relevant
than what is being identified / denoted. " .. default graph is based
on the RDF merge of the graphs obtained from representations of the
resources identified by the given IRIs."  The relationship between the
formed default graph and the IRI is not denotation.  It is more of a
directive for the web / query agent than the RDF processor.

So the 2nd of your 4 interpretations, seems to conform with the recommendation:

2. The graph and the IR are different; the thing named in the SPARQL is the
IR; "named graph" is a friendly abuse of language that really means (in the
SPARQL context) "potentially unnamed graph for which there is a named IR
providing serializations of it" and FROM <U> means "from the graph whose
serializations are representations of the IR named by U".

However: The way SPARQL uses the phrase 'named graph' is not really an
abuse of language since the IRI does indeed identify a graph: "named
graphs, where each named graph is identified by an IRI".  This is
different from the use of FROM <U>

-- Chimezie

Received on Sunday, 17 August 2008 15:18:41 UTC