Re: ISSUE-23: SHACL is already a modeling language

I view SHACL as a validation language.  I view validation as quite different
from modelling.   I don't think that SHACL should be a modelling language, and
I do not agree that the shape language in SHACL is a modelling language.  I do
agree that validation and modelling are similar - my input to the working
group used (nearly) the same syntax for both.

I am now hearing statements that the current version of SHACL is a modelling
language, and that SHACL is already being marketed as a modelling language.  I
am also hearing arguments to the effect that more modelling features are
needed in SHACL and that there is no reason to not include them because SHACL
is already a modelling language.

I believe that the current version of SHACL is not a modelling language.
However, technical judgments of this sort are not the only ones that matter.
Marketing also matters.

So it may be reasonable to base SHACL on ShEx instead of SPIN.  It certainly
appears that the ShEx community does not view ShEx as a modelling language.


PS:  I don't think that I have misunderstood Holger's email.

On 12/17/2015 06:52 AM, Irene Polikoff wrote:
> Peter,
> You either misunderstood Holger¹s e-mail or are pretending to
> misunderstand it. I know you are smart, so I suspect it is latter rather
> than former. If so, I find your use of demagogic tactics very regrettable
> and unworthy.
> The fact that SHACL is a modeling language has nothing to do with what it
> is based on. Rather, it has to do with the capabilities it provides. It
> provides capabilities for modeling data.
> As Ted said during December 3rd meeting:
> "<TallTed> tallted:
> ... a shapes language is a modelling language so I don't understand the
> objection
>  what else is a modelling language, but a way to describe a bunch of
> shapes? what else is a shape description language, but a way to model a
> space?"
> If you don¹t think the capabilities provided by SHACL are needed, I
> believe you should have objected against the working group instead of
> participating in it.
> It may be that given the fact that SHACL provides modeling capabilities,
> your goal in participating was to ensure that SHACL is based on OWL. I
> believe you stated that preference in the beginning. I also believe you
> ³given up² on such a position for a variety of reasons.
> I see three options:
> 1. Pretend that SHACL is not a modeling language and hope that no one will
> not see through this. To me this is counterproductive and dishonest.
> 2. Say that RDFS/OWL are completely separate and can¹t be used together. I
> see such approach as only serving a purpose of splitting the community and
> introducing a big discontinuity
> 3. Provide a way for people to use them together to address the full range
> of needs these two modeling approaches can deliver on
> Regards,
> Irene Polikoff
> On 12/17/15, 9:02 AM, "Peter F. Patel-Schneider" <>
> wrote:
>> Thank you for pointing out that the current design of SHACL is largely
>> based
>> on SPIN and that it is your contention that this means that the current
>> design
>> of SHACL makes it be a modelling language.
>> Arnaud, can we use this a s new information to reopen the decision to base
>> SHACL on SPIN instead of ShEx?  ShEx is looking much better to me now.
>> peter
>> On 12/16/2015 11:32 PM, Holger Knublauch wrote:
>>> During yesterday's discussions, several people agreed that the real
>>> topic
>>> behind ISSUE-23 ("classes vs shapes") is that some members believe that
>>> the WG
>>> should not produce a competitor to already established W3C modeling
>>> languages.
>>> We believe the WG has already "failed" on this respect, because SHACL
>>> can
>>> already be used as a modeling language.
>>> Instead of using classes, people can use shapes (with sh:scopeClass).
>>> Instead
>>> of defining OWL restrictions, people can use property constraints.
>>> Ranges have
>>> become sh:datatype and sh:class. The syntax of SHACL only spells out a
>>> different way of how most people interpret OWL anyway. There is an
>>> almost
>>> one-to-one mapping between OWL and SHACL features.
>>> By actively blocking a realistic bridge between those two worlds, the
>>> community risks producing two unconnected silos. At TopQuadrant we
>>> would like
>>> to promote an evolutionary strategy in which existing RDFS and OWL
>>> ontologies
>>> can be expanded to be also meaningful for closed-world constraint
>>> checking.
>>> The choice between using owl:Restriction or sh:property (or both!)
>>> should be
>>> left to the user community, and not be pre-determined by a handful of
>>> people
>>> who believe they can predict the future from their little WG. The
>>> approach of
>>> attaching constraints to classes has already been successfully explored
>>> in
>>> SPIN. It is perfectly fine to combine the inferencing role of OWL with
>>> the
>>> constraint checking role of SHACL into the same models.
>>> I consider this topic absolutely mission-critical for SHACL. I
>>> appreciate that
>>> those who have no strong opinion at least not block the view point of
>>> TopQuadrant and many of our customers.
>>> Thanks,
>>> Holger
>>> PS: At some stage we had discussed to produce a document to compare the
>>> roles
>>> of SHACL and OWL. What ever happened to that? Without answering what a
>>> modeling language really is, we should not close ISSUE-23.

Received on Thursday, 17 December 2015 15:57:32 UTC