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Re: Core or Lite?

From: Arnaud Le Hors <lehors@us.ibm.com>
Date: Tue, 24 Mar 2015 08:51:30 -0700
To: public-data-shapes-wg@w3.org
Message-ID: <OF02E51582.C8C0C617-ON85257E12.0050F4BB-88257E12.00571DD8@us.ibm.com>
I think we're touching on the very point of division in the group: whether 
writing complex queries using SPARQL is the normal/common case or not. 
>From my point of view the workshop clearly didn't support that point of 
view and this is why the charter is written the way it is.

Participants agreed that we should have a declarative mechanism a la OSLC 
Resource Shapes and, in recognition of the fact that there is only so much 
one can do that way, an extension mechanism should also be available to 
address complex cases which can't be handled declaratively. Here is how 
the report reads (http://www.w3.org/2012/12/rdf-val/report):

There was consensus on the need for 
1.      Declarative definition of the structure of a graph for validation 
and description.
2.      Extensible to address specialized use cases.
3.      A mechanism to associate descriptions with data.

Note that this doesn't mean that the extension mechanism is any less 
normative than the declarative one but it makes a difference as to whether 
the extension mechanism is the center piece (or as Richard put it "the 
most basic construct") or not.
--
Arnaud  Le Hors - Senior Technical Staff Member, Open Web Technologies - 
IBM Software Group


Arthur Ryman <arthur.ryman@gmail.com> wrote on 03/24/2015 05:50:14 AM:

> From: Arthur Ryman <arthur.ryman@gmail.com>
> To: Holger Knublauch <holger@topquadrant.com>
> Cc: "public-data-shapes-wg@w3.org" <public-data-shapes-wg@w3.org>
> Date: 03/24/2015 05:51 AM
> Subject: Re: Core or Lite?
> 
> Holger,
> 
> All aspects of SHACL that are described by the spec are normal in the
> sense that they define compliant behavior. You seem to be implying
> that only Part 1 is normal. I don't understand what is gained by this
> use of the term "normal".
> 
> I'd also like to clarify that I think we only need one RDF namespace.
> Part 1 defines some of the terms and Part 2 defines the rest of the
> terms.
> 
> If we are going to use the term "normal", let's agree on the meaning.
> One meaning is say that the largest user group is the "normal" one. If
> that is the case then we have clear feedback that the majority of
> users will want a high-level vocabulary for expressing common
> constraints. A smaller, more advanced, set of users will write
> constraints in SPARQL, JS, ShEx, etc.
> 
> -- Arthur
> 
> 
> 
> 
> 
> On Tue, Mar 24, 2015 at 1:50 AM, Holger Knublauch
> <holger@topquadrant.com> wrote:
> > On 3/24/2015 15:17, Arnaud Le Hors wrote:
> >
> > Holger,
> > What would constitute the "extension mechanism" in your view then?
> >
> >
> > The macro facility could be regarded as an extension mechanism for the 
core
> > vocabulary. Another extension mechanism is the ability to use other
> > languages such as shx:javaScript. But writing complex queries (e.g. 
using
> > SPARQL) is not an extension mechanism. Also, using pre-defined macros 
from a
> > 3rd party template library is also not an extension. So the headline 
of that
> > Part 2 should reflect this differently. That was all I wanted to point 
out.
> >
> >
> > I have to point out that Arthur's suggestion happens to be very much 
in line
> > with what the charter calls for:
> >
> > An RDF vocabulary, such as Resource Shapes 2.0, for expressing these 
shapes
> > in RDF triples, so they can be stored, queried, analyzed, and 
manipulated
> > with normal RDF tools, with some extensibility mechanism for complex 
use
> > cases.
> >
> > I don't think it helps to ignore that and try to force people into
> > considering what was meant to be an "extensibility mechanism for 
complex use
> > cases" the "completely normal use of SHACL".
> >
> >
> > I stick to my statement that it is a completely normal use of SHACL to
> > include SPARQL queries. It is also completely normal for OWL DL users 
to
> > rely on features outside of OWL Lite. In the draft, SPARQL is part of 
the
> > official spec. For a large class of users, what you call the 
"extensibility
> > mechanism" will even be the main feature of SHACL. This includes 
people who
> > currently use OWL and just want to use SPARQL for the bits that OWL 
cannot
> > express. This is how TQ customers have operated for many years and is 
also
> > the least disruptive path to adoption if we want SHACL to succeed with
> > current semantic web people.
> >
> > What we have right now in the WG is that some people believe they 
don't
> > really need SPARQL support, and that the core features are sufficient 
for
> > most use cases. That's good for them, although not backed by much 
empirical
> > evidence. At this stage we have no idea which features will be most 
widely
> > used. Claiming that feature 1 is more important than feature 2  (and 
call
> > feature 2 just an "extension") is premature and makes it more 
difficult for
> > the supporters of feature 2 to get heard.
> >
> > The wording in the Charter was in retrospect unfortunate but it was
> > difficult to clarify all these nuances in a single short sub-sentence. 
Back
> > then I have been very clear that I will object to any attempts to
> > marginalize the SPARQL support, and I will continue to do this. I hope 
the
> > group respects the point of view of the SPARQL camp in the same way 
that we
> > all respect the point of view of those who don't need really SPARQL 
support.
> > My draft supports both view points.
> >
> > Regards,
> > Holger
> >
> 
Received on Tuesday, 24 March 2015 15:57:32 UTC

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