In short, my interpretation is that a Named Graph is nothing more than a "collection" that has an identifier and a set of traits.
On 6/13/14 12:15 PM, David Price wrote:
We've found in this and previous projects is that RDF/OWL named graphs
are usually better used as the "bucket of triples" for more
practical/bookkeeping tasks like access control, caching, managing
automated update of background facts, deleting data when a new version
of the same report data needs to be uploaded to fix errors, versioning
schemas, etc. There are, of course, times when things are just too
complex (e.g. like very complex access control rule requirements) to
be handled using named graphs. In those cases, you just have to model
your way out of trouble ... at least that's what we've found.
Changing the topic so as to focus on the important issues that David and
Ed have brought to the surface in regards to Named Graphs, Statements,
I think its really important to get a handle on understanding what each
of those terms denote. In our world view (at OpenLink Software) where
see the following:
1. Named Graph IRIs denote distinct RDF data sources which may be local
or external to a DBMS -- basically, they are Document/Database
identifiers (e.g., a piece of paper provides a writing surface and it is
an example of a real-world named graph, ditto any other medium for
durable and reusable capture of data).
2. Reified Statements (i..e., Statements denoted by an IRI) are
instances of rdf:Statment meaning they are the domainOf rdf:subject,
rdf:predicate, rdf:object properties
3. Triples being the content (in the form of subject, predicate, object
patterns) of RDF documents which are denoted by IRIs (typically HTTP
URLs when external to the DBMS).
As David indicates, you need these items (properly described and loosely
coupled) to handle accounting, attribute based access controls and data
access policies, version control etc.. These issue are obvious and
natural in the enterprise realm.
Some other anecdotes from the real-world:
We have documents comprised of words and phrase. We also have contracts
(a kind of document) comprised of terms (explicit combination of
denotation and connotation) and clauses (reified statements) .
At some point in time we've all signed one part of a contract.
At some point in time we've all signed one part of a contract an
initialed each clause.
This is an interesting and important topic that will contribute to bring
much needed clarity to these matters, in the digital realm provided by
the likes of HTTP networks etc..
Founder & CEO