Re: Validating Schemas

Hello Nicholas,

Thank you for your reply.

I agree that manual verification is a first step towards automated
verification. I believe that unless one know how to manually verify
something, automated verification should not be trusted. They are
complementary, not mutually exclusive.

I have been using the RDFLib-jsonld tool and have filed an issue against
it. Perhaps you could take a look at it? (
https://github.com/RDFLib/rdflib-jsonld/issues/77 ) It may just be due to
my own misunderstanding on how the code should work.

Regards,
James


On Fri, Mar 27, 2020 at 8:36 PM Nicholas Car <
nicholas.car@surroundaustralia.com> wrote:

> It does sound like you need to be confident with normal JSON-LD validation
> before worrying about the RDF graph shapes, which is what SHACL is for.
>
> Double parsing (JSON-LD -> in memory RDF 2 times in separate graphs) and
> comparing the RDF through an isomorphic graph comparator, as included in
> rdflib, would perhaps ferret out any Blank Nodes and similar incorrect
> syntax but non-error throwing parsing issues.
>
> Perhaps become a bit more familiar with what the rdflib-jsonld tool will
> and won’t choke on and just lodge any issues the tool’s issue tracker if
> you think things could be improved! There has been some recent activity
> with the tool to handle JSON-LD 1.1 so people are watching the tool.
>
> Unless you are hand typing out loads of JSON-LD though, the ilexanple
> issues you gave, @ib etc., don’t seem hard to avoid.
>
> —
> Dr Nicholas Car
> Data Systems Architect
> SURROUND Australia
> 0477 560 177
> nicholas.car@surroundaustralia.com
>
> On 27 Mar 2020, at 10:32 pm, James Hudson <jameshudson3010@gmail.com>
> wrote:
>
> 
> Hello Håvard,
>
> Thank for your reply.
>
> I am using https://github.com/RDFLib/rdflib-jsonld for my serialization.
> When it comes across "@ib" it will create a blank node, which makes sense.
> What may be a bit odd is that the serializer ignores the key / value pair,
> but there is probably a good reason for that or there is a parameter I am
> missing that would make it stricter. I will look into using sh:nodeKind. I
> believe there is a similar issue with "@type" and there is probably a
> sh:XXX related to that key.
>
> I will take a closer look at as sh:closed and sh:minCount.
>
> It does appear that SHACL is a viable solution to validating json-ld based
> schemas.
>
> Regards,
> James
>
> On Thu, Mar 26, 2020 at 3:11 PM Håvard Ottestad <hmottestad@gmail.com>
> wrote:
>
>> Hi,
>>
>> Things I think you can do with SHACL:
>>
>> > I have not typed "@Ib" instead of "@id". That there is a "@id" key for
>> every object.
>>
>> I think that would be hard. Depends what happens when there isn't an @id.
>> If the parser generates an error, then that should solve it for you. If it
>> generates a blank node, then you can use sh:nodeKind to validate for that.
>>
>> > Additionally, that when I have declared something as a subclass, that
>> the superclass exists and there are no typos in the superclass name.
>>
>> You could do some form of sh:minCount and also possibly checking that the
>> sh:class is an rdfs:Class.
>>
>> Spelling mistakes for properties can be solved with sh:closed. Which will
>> make sure that all properties used are specified in the SHACL shape.
>>
>> Cheers,
>> Håvard
>>
>>
>>
>>
>> On Thu, Mar 26, 2020 at 7:58 PM Irene Polikoff <irene@topquadrant.com>
>> wrote:
>>
>>> JSON-LD, Turtle, RDF/XML, etc. are all different alternative text
>>> serialization formats for RDF.  Is this what you meant by “alternative
>>> representation of RDF”?
>>>
>>> SHACL does not validate at the level of “is this a valid RDF
>>> serialization”. It validates at the level “does this RDF data have the
>>> expected shape”.
>>>
>>> I believe pretty much any RDF-based software already has the ability to
>>> successfully serialize and de-serialize standard text formats and report an
>>> error if the format is incorrect.
>>>
>>> On Mar 26, 2020, at 2:43 PM, James Hudson <jameshudson3010@gmail.com>
>>> wrote:
>>>
>>> Hello,
>>>
>>> Yes, I understand that. A json-ld document is an alternate
>>> representation of RDF.
>>>
>>> Regards,
>>> James
>>> `
>>>
>>> On Thu, Mar 26, 2020 at 2:35 PM Irene Polikoff <irene@topquadrant.com>
>>> wrote:
>>>
>>>> Hello James,
>>>>
>>>> SHACL validates RDF. It does not validate text serializations of RDF to
>>>> make sure that a serialized document/file itself is a syntactically valid
>>>> sterilization of RDF.
>>>>
>>>> So, I would think that first you'd need to have a document that is a
>>>> valid serialization of RDF i.e., it can be successfully parsed and
>>>> de-serialized. Then, you could use SHACL to ensure that RDF data
>>>> corresponds to the SHACL shapes that describe it. I am using “RDF data”
>>>> loosely, meaning any set of RDF triples, whether it is data or schema does
>>>> not matter. By schema I mean the model of the data - classes, properties,
>>>> allowed values for properties.
>>>>
>>>> On Mar 26, 2020, at 1:33 PM, James Hudson <jameshudson3010@gmail.com>
>>>> wrote:
>>>>
>>>> Hello,
>>>>
>>>> Being rather new to the linked data world, I am at the point where I
>>>> need to work out the best methods for validating schema's and the role that
>>>> SHACL may or may not be able to play.
>>>>
>>>> Since it is easier to discuss something real, I have created a sample
>>>> schema in the json-ld format and have made it available here:
>>>>
>>>>
>>>> https://gist.github.com/James-Hudson3010/7deec4df32aa6b97509aeb490f1edf9b
>>>>
>>>> It can be entered into the json-ld playground and visualized without
>>>> error.
>>>>
>>>> What I mean by validation of the schema, is that I would like to make
>>>> sure it is valid json-ld document. I have not typed "@Ib" instead of "@id".
>>>> That there is a "@id" key for every object. Additionally, that when I have
>>>> declared something as a subclass, that the superclass exists and there are
>>>> no typos in the superclass name.
>>>>
>>>> Perhaps someone has already been working on to playing with shape files
>>>> for json-ld schema's.
>>>>
>>>> Perhaps I am ascribing capabilities to SHACL that it does not have.
>>>>
>>>> Any thoughts or comments would be appreciated.
>>>>
>>>> Additionally, for completeness, I have created an instance based on
>>>> this schema and that can be found here:
>>>>
>>>>
>>>> https://gist.github.com/James-Hudson3010/227ffb77b853a29556be5b5c3a67c309
>>>>
>>>> Regards,
>>>> James
>>>>
>>>>
>>>>
>>>