Re: Why not adopt ShEx? (was Re: Enough already)

Hi Irene,

You're right that it is always interesting to hear from users. But for a 
technology to become part of a W3C Recommendation it needs to have at 
least two independent implementations. To date, while I know of several 
implementations of Core, I've only heard of one implementation of the 
SPARQL extension: TopQuadrant's. So my questions are motivated by the need 
to find out if there are any others. Unfortunately it appears that so far 
most of the people we've heard from are TopQuadrant customers rather than 
implementers.

Besides, when it comes to judging of the adequacy of a draft to become a 
W3C Recommendation the opinion of implementers is paramount because if 
they find the specification too imprecise to be able to implement it with 
confidence that their implementation will behave like others we have 
little chance of reaching interoperability across products, which is what 
standards are all about.

It seems that people are being rallied to make the point that the SPARQL 
extension is important to them. I don't know whether anybody questions 
that but I certainly don't. My proposal to separate it from Core was 
merely motived by reducing the scope of work. I understand this is not to 
everyone's liking but removing features to reduce the scope of work is 
common practice when facing an imminent deadline and it was suggested by 
W3M. TopQuadrant will apparently object to it. I heard you, let's move on.
--
Arnaud  Le Hors - Senior Technical Staff Member, Open Web & Blockchain 
Technologies - IBM Cloud




From:   Irene Polikoff <irene@topquadrant.com>
To:     Arnaud Le Hors/Cupertino/IBM@IBMUS
Cc:     Dean Allemang <dallemang@workingontologist.com>, "Eric 
Prud'hommeaux" <eric@w3.org>, public-rdf-shapes@w3.org
Date:   12/13/2016 12:26 AM
Subject:        Re: Why not adopt ShEx? (was Re: Enough already)



Arnaud,

I would not people to think that your position is that unless they are an 
implementer of a SHACL engine, their input to the working group is not of 
value.

Your responses to the recent posts on this forum come across as tightly 
connecting the user comments and the implementations of SHACL. I think 
many folks that have commented are the current and potential future users 
of SHACL who are providing input on the features/requirements that are 
important to them. That is, users who would create and use SHACL shapes as 
opposed to those that would develop their own SHACL engines. 

Your questions might be interpreted as if you expect every user have to 
write their own engine. I believe user input to be very important and 
informative to the working group. I am sure that you would agree.

Regards,

Irene

On Dec 12, 2016, at 3:41 PM, Arnaud Le Hors <lehors@us.ibm.com> wrote:

Hi Dean,
So what do you use for this work? Did you implement SHACL Full?
Thanks.
--
Arnaud  Le Hors - Senior Technical Staff Member, Open Web & Blockchain 
Technologies - IBM Cloud




From:        Dean Allemang <dallemang@workingontologist.com>
To:        "Eric Prud'hommeaux" <eric@w3.org>
Cc:        public-rdf-shapes@w3.org
Date:        12/12/2016 09:05 PM
Subject:        Re: Why not adopt ShEx? (was Re: Enough already)
Sent by:        deanallemang@gmail.com



There are three validation operations I can imagine wanting to perform
on an engine that supports SPARQL:

This is a lovely idea, but it isn't realistic from the beginning.  We are 
in the position of having a vendor work with us, with their current 
technology stack.  We can't expect them (and we don't have time to wait; 
once a PoC is approved, it is usually due yesterday) to adapt their stack 
to something new.  Of course, once we have a Recommendation in place, it 
is a lot easier for us to request compliance to it.  I am interested in a 
smooth slope to adoption.  A SPARQL based constraint system is easy to 
adopt in the current environment.  As adoption of the standard progresses, 
adherence to acceptance criteria will be a good idea (and we would be 
interested in cooperating in developing those)

  3 Extend the SPARQL engine to support SHACL Full's extensibility
    mechanism.

I find this criterion to be particularly interesting.  As a standards 
organization ourselves, I don't think we are in a position to make use of 
this (are we going to publish our own extensions to SHACL? I don't think 
so).  But from an implementation point of view, this is really awesome. I 
don't know that we would need to have candidate POC vendors pass this one.

Dean





On Mon, Dec 12, 2016 at 2:48 PM, Eric Prud'hommeaux <eric@w3.org> wrote:
* Dean Allemang <dallemang@workingontologist.com> [2016-12-12 10:33-0500]
> >
> > Sorry, but I see zero advantages of ShEx over SPIN/SPARQL.
> >
> > Why would I want to lock my software into a new non-standard syntax 
with
> > close to none adoption, when I can simply use the query engine to 
validate
> > constraints?
> >
> >
> >
>
> I couldn't agree more.  In FIBO,  we have been looking for a constraint
> language to help us make definitions that go beyond the capabilities of
> OWL.  I presented these at the inaugural meeting of the SHAPES group a
> couple years ago.  It is easy to specify them in SPARQL, and we have 
done
> so (and I did the same in SHACL, now that there is a write-up of how it
> works).
>
> When we move from our conceptual ontology to something operational for a
> Proof of Concept, some vendor is always  involved.  That vendor 
(different
> one for each PoC) always has an RDF store somewhere in their stack. They
> can always consume OWL (though often through a rule engine 
interpretations
> via OWL2RL).  For rules/constraints that go beyond OWL, we have to work 
out
> some way to give them the rules.   SWRL?  Some of them can manage that.
> RIF?  Everyone knows what it is, but few can handle it out of the box.
> Other rule systems have varying degrees of uptake.
>
> But one thing all the triple stores can manage is SPARQL.  "How about if 
I
> give you the constraints in SPARQL?"  the answer is always, "Oh, sure, 
that
> works".  Because they are all triple stores, and they already do it.

There are three validation operations I can imagine wanting to perform
on an engine that supports SPARQL:

  1 Validate ShEx or SHACL core over a the SPARQL protocol.

  2 Validate ShEx or SHACL core over a graph API.

  3 Extend the SPARQL engine to support SHACL Full's extensibility
    mechanism.

For 1 and 2, I think ShEx and SHACL are about equal. Peter's
implementation of SHACL Core used a mixture of graph API and SPARQL
but could certainly have been implemented just in terms of the
ubiquitous triplesMatching API. The ShEx demo compiles ShEx 1 to
SPARQL queries to run over the SPARQL protocol but of course that
didn't support features like told bnodes (identifying a bnode by
label).

I think SPARQL becomes relevent when you want to build a SHACL Full
(or SPIN) engine. You would have to implement a full SPARQL engine
*and then* build the node/shape iterators, templating system, and
recursion control that are required for SHACL Full.


> This doesn't mean that we have to do this in SPARQL, but it does mean 
that
> if we have that option, we shortcut a lot of work to get to our Proofs 
of
> Concept.
>
> In the end, I'm just re-iterating what Martynas has said much more
> succinctly, but in the context of a whole industry effort (FIBO) and a
> selection of vendors who want to work with us.
>
>
>
> Dean

--
-ericP

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