On 13/05/2015 12:12, Martynas Jusevičius wrote:
Lars,
first of all, a SPARQL query can be converted to RDF graph using SPIN
syntax: http://spinrdf.org/sp.html
In my mind the RDF Shapes WG is about RDF validation, and hopefully
will also be based on SPIN. I'm not interested in the part about
non-SPARQL shapes as this is mostly politics at play. If you want to
do practical development, SPARQL is all you need.
That is a political statement Martynas and therefore denies your
previous sentence.
Moreover, Shapes WG is very new while SPARQL has been around for 10
years. You wrote "not all clients want to talk sparql" -- but somehow
those clients will want to talk Shapes? Makes no sense to me.
But it does to others.
I'm still of the opinion that you are looking in the wrong places.
Have you actually tried SPARQL for this? What did not work?
I don't think it is reasonable to expect data portals that harvest
metadata from other portals to include a SPARQL engine just to check
that data conforms to a profile, like DCAT-AP. That should be possible
without having to build or include a SPARQL engine which would be
overkill for what is essentially a pretty simple task.
SPIN does a really good job and in many circumstances it is the right
tool. But not all. IMHO we need a more flexible approach, one that can
handle simple cases without SPARQL. Now, whether the SHACL work is the
answer is, mercifully, a question others are answering.
Phil.
Martynas
On Wed, May 13, 2015 at 12:42 PM, Svensson, Lars <l.svens...@dnb.de> wrote:
Martynas,
this is a very simple answer that I have given you before: a shape of
RDF data is defined as SPARQL query. There are no two ways about it.
Hmm, the list of deliverables of the data shapes wg [1] mentions an RDF
vocabulary to describe shapes, a set of semantics _possibly_ defined as SPARQL
operations, etc. It says that one possibility is to use SPARQL queries to
evaluate shapes against RDF graphs. At least to me, that doesn't mean that the
shape is defined as a SPARQL query, but as an RDF graph.
[1] http://www.w3.org/2014/data-shapes/charter#deliverables
Best,
Lars
On Tue, May 12, 2015 at 2:18 PM, Svensson, Lars <l.svens...@dnb.de> wrote:
Kingsley,
On Monday, May 11, 2015 9:00 PM, Kingsley Idehen wrote:
We have to be careful here. RDF Language sentences/statements have a
defined syntax as per RDF Abstract Syntax i.e., 3-tuples organized in subject,
predicate, object based structure. RDF Shapes (as far as I know) has nothing
to
do with the subject, predicate, object structural syntax of an RDF
statement/sentence. Basically, it's supposed to provide a mechanism for
constraining the entity type (class instances) of RDF statement's subject and
object, when creating RDF statements/sentences in documents. Think of this
as
having more to do with what's regarded as data-entry validation and
control, in
other RDBMS quarters.
The charter of the data shapes WG [1] says that "the product of the RDF Data
Shapes WG will enable the definition of graph topologies for interface
specification, code development, and data verification", so it's not _only_
about
validation etc. My understanding is that it's somewhat similar to XML schema
and thus is essentially a description of the graph structure. As such, it can of
course be used for validation, but that is only one purpose.
The function of the "profile" I believe you (and others that support this) are
seeking has more to do with enabling clients and servers (that don't
necessarily
understand or care about RDF's implicit semantics) exchange hints about the
nature of RDF document content (e.g., does it conform to Linked Data
principles re. entity naming [denotation + connotation] ).
No, my use of "profile" is really a "shape" in the sense of the data shapes wg.
Some of their motivations are what I'm envisioning, too, e.g.
* Developers of each data-consuming application could define the shapes
their software needs to find in each feed, in order to work properly, with
optional elements it can use to work better.
* Developers of data-providing systems can read the shape definitions (and
possibly related RDF Vocabulary definitions) to learn what they need to provide
Cut long story short, a "profile" hint is about the nature of the RDF content
(in
regards to entity names and name interpretation), not its shape (which is
defined by RDF syntax).
OK, I stand corrected: My question is: How can clients and servers negotiate
shape information?
Best,
Lars
--
Phil Archer
W3C Data Activity Lead
http://www.w3.org/2013/data/
http://philarcher.org
+44 (0)7887 767755
@philarcher1
