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Re: formal objection on pre-binding

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Thu, 4 May 2017 11:00:47 -0700
To: Holger Knublauch <holger@topquadrant.com>, public-rdf-shapes@w3.org
Message-ID: <6f0758c9-0969-1763-060c-3bc5e0a5e96c@gmail.com>
Yes, I have bee a very vocal critic of each of the proposed definitions of
pre-binding in SHACL.  Every one of these definitions, including the current
one, has critical problems.

I also had stated that getting a suitable definition of pre-binding was one of
the most important tasks of the working group.  I could not do that work
because no one would say what pre-binding was supposed to do.

I played my part by examining the definitions of pre-binding as they came
along and pointing out problems with them.   I have continued to do this
during the last few months as the working group has demonstrated over and over
again that it has not been doing its job of reviewing the current definition
of pre-binding to determine whether it has problems.

It is certainly not my job now to come up with a suitable definition of
pre-binding, and it wasn't my job even when I was in the working group.  I
have made a suggestion as to what I think should be done in the current
situation.  The working group is free to accept my suggestion or not.

I view basing SHACL-SPARQL on a definition of pre-binding that has known
severe problems as not an acceptable way forward even if these problems are
papered over.

Peter F. Patel-Schneider
Nuance Communications

On 05/03/2017 07:06 PM, Holger Knublauch wrote:
> On 3/05/2017 1:52, Peter F. Patel-Schneider wrote:
>> This is a formal objection to the definition of pre-binding approved by the
>> working group in its meeting of 26 April 2017 and in the SHACL Editor's
>> Draft current as of 28 April 2017 (but with date indicated as 11 April
>> 2017).
>>
>> Pre-binding has never had a suitable definition in SHACL.  Problems with
>> pre-binding have been known to the working group since at least June of
>> 2015.  The current definition of pre-binding has multiple documented
>> problems.  The only change to pre-binding from Candidate Recommendation has
>> been to paper over some of these problems by excluding large numbers of
>> SPARQL queries from SHACL-SPARQL.
>>
>> These exclusions introduce new interoperability problems for SHACL.  These
>> exclusions remove many useful SPARQL queries from SHACL-SPARQL, including an
>> example SPARQL query in the SHACL document.  These exclusions also do not
>> exclude all SPARQL queries whose meaning is not as expected with
>> pre-binding.
>>
>> The solution to the continuing problems with pre-binding is not to exclude
>> more and more of SPARQL but to either fix pre-binding so that it works
>> correctly or eliminate pre-binding from SHACL.

[...]

> You have been a very vocal critic of pre-binding for over two years now. But
> it is much easier to criticize a design than to propose workable alternatives.
> No-one has produced a better definition of pre-binding so far. Dropping the
> whole feature of SHACL-SPARQL only because of some cases that can easily be
> worked around is not a productive proposal. Pre-binding has been used
> successfully in practice in many applications including those based on SPIN.
> If you can produce a better definition of such a feature that still covers
> similar use cases then it will certainly happily be considered for future
> revisions of SHACL. This is version 1.0 only, and few of the widely used
> standards (RDF, SPARQL, OWL) have solved everything perfectly in their first
> iterations.
> 
> Holger
> 
> 
Received on Thursday, 4 May 2017 18:01:27 UTC

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