- From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
- Date: Thu, 16 Feb 2017 18:28:30 -0800
- To: Holger Knublauch <holger@topquadrant.com>, public-rdf-shapes@w3.org
>From World Wide Web Consortium Process Document, 1 September 2015 https://www.w3.org/2015/Process-20150901/ In the context of this document, a group has formally addressed an issue when it has sent a public, substantive response to the reviewer who raised the issue. A substantive response is expected to include rationale for decisions (e.g., a technical explanation, a pointer to charter scope, or a pointer to a requirements document). The adequacy of a response is measured against what a W3C reviewer would generally consider to be technically sound. So it is part of the job of the working group to justify their responses to commenters. Peter F. Patel-Schneider Nuance Communications On 02/16/2017 05:06 PM, Holger Knublauch wrote: > I believe the most recent discussion on this topic happened in this meeting: > > https://www.w3.org/2017/01/25-shapes-minutes.html > > Sorry I am unable to sift through all past meeting minutes or the thousands of > emails that this WG has produced. I still do have a day job and plan to keep > it. You are welcome to use internet search or the archives yourself. > > Holger > > > On 17/02/2017 10:54, Peter F. Patel-Schneider wrote: >> Please provide a pointer to this discussion and any relevant resolutions. >> >> Peter F. Patel-Schneider >> Nuance Communications >> >> >> On 02/16/2017 04:01 PM, Holger Knublauch wrote: >>> >>> On 17/02/2017 9:03, Peter F. Patel-Schneider wrote: >>>> Some of the syntax requirements for constructs in SHACL-SPARQL hinge on >>>> whether a string is a syntactically correct SPARQL SELECT or ASK query and >>>> are >>>> thus very complex. There is no distinction in SHACL between these syntax >>>> requirements and the syntax requirements for constructs in SHACL Core so a >>>> SHACL Core processor would need to implement a SPARQL syntax checker. >>>> >>>> However, I don't see any good reason why a SPARQL Core processor needs to >>>> consider the syntactic validity of any SHACL-SPARQL constructs at all. A >>>> SHACL >>>> Core processor, by design, doesn't do anything with these construct so there >>>> is no benefit for a SHACL Core processor to do this checking. >>>> >>>> So all that a SHACL Core processor really should be doing as far as syntax >>>> testing is concerned is checking the SHACL Core constructs for syntactic >>>> validity. This appears to be fairly easy - the hardest part is probably >>>> checking for valid SHACL property paths. But even if checking the syntactic >>>> validity of a SHACL property path is not so easy, a SHACL Core processor is >>>> going to have to do much of the checking for syntactic validity when it uses >>>> the list. >>>> >>>> It thus seems to me that SHACL Core processors should be required to check >>>> for >>>> syntactic validity of SHACL Core constructs and should completely ignore >>>> SHACL-SPARQL constructs. >>> The WG had already discussed this topic at length and come to the conclusion >>> outlined in my email, for the reasons outlined in my email. >>> >>> Holger >>> >>> >>> >>>> Peter F. Patel-Schneider >>>> Nuance Communications >>>> >>>> >>>> >>>> >>>> On 02/16/2017 01:54 PM, Holger Knublauch wrote: >>>>> Hi Lars, >>>>> >>>>> there are two major reasons for the current wording, basically due to the >>>>> complexity of the many syntax rules: >>>>> >>>>> 1) If we were to make it a MUST then each SHACL implementation would have to >>>>> implement all the syntax rules, and we as the WG would need to define test >>>>> cases for all kinds of invalid structures. The SHOULD lowers the barrier of >>>>> entry and the formal process issues significantly. >>>>> >>>>> 2) It would require validation (for well-formedness) of the shapes graph and >>>>> this is a very expensive operation. In many scenarios such as interactive >>>>> data >>>>> entry tools, the shapes graph is identical to the data graph (or at least is >>>>> part of the imports closure). If you make an edit, then the shapes may >>>>> become >>>>> invalid. This means that a validator would have to perform checking of the >>>>> shapes before each validation, and this is prohibitively expensive in cases >>>>> like form validation in real time, for each instance. >>>>> >>>>> Having said this, many syntax rules can be expressed in SHACL itself. The >>>>> expectation of the WG is that a meta-schema for SHACL will emerge (e.g. >>>>> as an >>>>> open source project) outside of the W3C process. Not everything needs to be >>>>> done by the WG or the spec. >>>>> >>>>> Hope this clarifies it. >>>>> Holger >>>>> >>>>> >>>>> On 16/02/2017 19:36, Svensson, Lars wrote: >>>>>> Hello all, >>>>>> >>>>>> Section 3.4.2 [1] states that if a shapes graph is ill-formed, the SHACL >>>>>> processor SHOULD produce a failure. Why is that a SHOULD and not a MUST? Or >>>>>> put differently: In which cases would it be acceptable for a processor not >>>>>> to produce a failure when processing an ill-formed shapes graph? >>>>>> >>>>>> [1] https://w3c.github.io/data-shapes/shacl/#ill-formed-shape-graphs >>>>>> >>>>>> Thanks, >>>>>> >>>>>> Lars >>>>>> >>>>>> *** Lesen. Hören. Wissen. Deutsche Nationalbibliothek *** >
Received on Friday, 17 February 2017 02:29:08 UTC