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ISSUE-41: Property paths (was: SHACL syntax and metamodel complexity)

From: Holger Knublauch <holger@topquadrant.com>
Date: Wed, 9 Mar 2016 16:36:28 +1000
To: public-data-shapes-wg@w3.org
Message-ID: <56DFC46C.4060403@topquadrant.com>
If we wanted to support this while preserving the usefulness of SHACL 
for data description (form building etc), we could for example just add 
a new kind of constraint such as

ex:MyShape
     a sh:Shape ;
     sh:pathConstraint [
         sh:path [ a sh:SPARQLPath ; sh:sparql "rdf:rest*/rdf:first" ] ;
         sh:class ex:Something ;
     ] .

This could be limited to the extension mechanisms to keep the core 
language reasonably sized, avoiding topics like recursion all over again.

Holger


On 9/03/2016 16:17, Simon Steyskal wrote:
> Hi!
>
> as for 2) we may want to consider re-opening issue-41 "Using property 
> paths to refer to values/types?" [1]
> (which I would be very very happy about)
>
> [1] https://www.w3.org/2014/data-shapes/track/issues/41
>
> simon
> ---
> DDipl.-Ing. Simon Steyskal
> Institute for Information Business, WU Vienna
>
> www: http://www.steyskal.info/  twitter: @simonsteys
>
> Am 2016-03-09 07:02, schrieb Holger Knublauch:
>> I see three main areas of differences between current SHACL and your 
>> draft:
>>
>> 1) Shall the concepts Shape and Constraint be merged (syntactic sugar)
>> 2) Shall SHACL constraints support arbitrary property paths instead of
>> property/inverseProperty
>> 3) Shall constraint parameters be limited to a single property only
>>
>> Leaving aside the specific triples, does anyone see other major 
>> differences?
>>
>> The ISSUE-133 that you raised is limited to 3) and it may be worth
>> having separate issues for the two other differences, if only to
>> structure the discussion.
>>
>> I do not believe that there are necessary dependencies between these
>> areas, and it would IMHO be more fruitful to look at them
>> individually, because there are different variations even of the
>> existing syntax conceivable. I do not understand why you elected to
>> start everything from scratch.
>>
>> Holger
>>
>>
>> On 9/03/2016 9:03, Peter F. Patel-Schneider wrote:
>>> See
>>> https://www.w3.org/2014/data-shapes/wiki/ISSUE-95:_Metamodel_simplifications#Proposal_4 
>>>
>>>
>>> On 03/06/2016 06:24 PM, Holger Knublauch wrote:
>>>> Peter,
>>>>
>>>> I understand this is largely just a sketch and you may be "thinking 
>>>> out loud".
>>>> Yet I don't have sufficient information on how all this is supposed 
>>>> to work,
>>>> e.g. with SPARQL generation. It would help if you could provide 
>>>> some examples
>>>> of how this vocabulary would be used to define some built-in and 
>>>> extension
>>>> constraint types. On
>>>>
>>>> https://www.w3.org/2014/data-shapes/wiki/ISSUE-95:_Metamodel_simplifications#Proposal_3 
>>>>
>>>>
>>>>
>>>> I am presenting snippets illustrating the definitions of
>>>> ex:LanguageConstraintType, sh:PatternConstraintType and
>>>> sh:ClassConstraintType. Would you mind creating similar examples in 
>>>> your
>>>> metamodel?
>>>>
>>>> Furthermore, I am unclear what problem you are trying to solve. 
>>>> What is broken
>>>> in the current SHACL syntax that motivates your (radical) changes? 
>>>> Have any
>>>> users complained or are there any related ISSUEs recorded? Of 
>>>> course we can
>>>> come up with any number of syntaxes for SHACL and I could certainly 
>>>> make up
>>>> plenty of variations, too.
>>>>
>>>> Thanks,
>>>> Holger
>>>>
>>>>
>>>> On 5/03/2016 13:32, Peter F. Patel-Schneider wrote:
>>>>> I fixed up some silly syntax errors and added prefix 
>>>>> declarations.  The
>>>>> attached file looks OK to the syntax checker I grabbed.
>>>>>
>>>>> peter
>>>>>
>>>>>
>>>>> On 03/04/2016 04:29 PM, Holger Knublauch wrote:
>>>>>> Turtle file doesn't parse. Could you fix this?
>>>>>>
>>>>>> Thanks,
>>>>>> Holger
>>>>>>
>>>>>>
>>>>>> On 5/03/2016 10:17, Peter F. Patel-Schneider wrote:
>>>>>>> On 03/03/2016 04:20 PM, Holger Knublauch wrote:
>>>>>>>> If you want this to be
>>>>>>>> seriously considered, please work out the details, including 
>>>>>>>> Turtle files
>>>>>>>> etc.
>>>>>>>> Holger
>>>>>>> OK, since you asked so nicely, see the two attached files.
>>>>>>>
>>>>>>> peter
>>>>>>>
>>>>
Received on Wednesday, 9 March 2016 06:37:01 UTC

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