Re: usage of fourth quad element

On 2/27/16 9:17 PM, Melvin Carvalho wrote:
>
>
> On 7 December 2015 at 23:57, Kingsley Idehen <kidehen@openlinksw.com
> <mailto:kidehen@openlinksw.com>> wrote:
>
>     On 12/7/15 12:55 PM, Gregg Kellogg wrote:
>     > On Dec 7, 2015, at 8:31 AM, Ruben Verborgh
>     <ruben.verborgh@ugent.be <mailto:ruben.verborgh@ugent.be>> wrote:
>     >> >
>     >> > Dear all,
>     >> >
>     >> > The Representation Task Force is working hard
>     >> > on a spec for low-level RDF interfaces.
>     >> > For this, we need your input!
>     >> >
>     >> > How do you use the fourth element of a quad?
>     >> > In other words, quads have one more field
>     >> > in addition to subject/predicate/object of triples,
>     >> > so what are your use cases for it?
>     > RDF.rb has changed from using "context" to "graph_name" for the
>     4th position. This is online with the usage to store the "name" in
>     a name/graph pair within an RDF Dataset. It can hold a URI, BNode,
>     or Variable.
>     >
>     > Gregg
>     >
>     +1
>
>     It provides a hint to an RDF store/dbms in regards to internal
>     document
>     identifier (a/k/a named graph in SPARQL).
>
>
> Kingsley, when you say "internal document identifier" does that imply
> an HTTP document?  For example, could the 4th element in a quad be a
> WebID?  When would you use which?
>  
"Internal Document Identifier" is what an RDBMS uses to identify its
database documents (i.e., collections of relations). The database
document may or may not be directly accessible via HTTP, subject RDBMS
functionality.

In the case of an RDF compliant RDBMS or Store, you would typically
access such a document via a SPARQL URL that includes Named GRAPH
scoping -- assuming said RDBMS supports Quad Storage.

If you have a TriG or NQuads based database docs published to an HTTP
URL or local filesystem, an RDF RDBMS that understand this kind of
document would automatically store the data in question to appropriate
internal documents identified by an IRI it generates.

-- 
Regards,

Kingsley Idehen       
Founder & CEO 
OpenLink Software     
Company Web: http://www.openlinksw.com
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