Re: Profiles in Linked Data

Phil,

I'm talking from a developer perspective. I can prove with source code
that SPARQL and SPIN is enough to implement a read-write Linked Data
life-cycle.

If you know a client that (currently) accepts Shapes but not SPARQL,
please point me to it. Because I don't think it exists.

Martynas

On Wed, May 13, 2015 at 1:42 PM, Phil Archer <phila@w3.org> wrote:
>
>
> On 13/05/2015 12:12, Martynas Jusevičius wrote:
>>
>> Lars,
>>
>> first of all, a SPARQL query can be converted to RDF graph using SPIN
>> syntax: http://spinrdf.org/sp.html
>>
>> In my mind the RDF Shapes WG is about RDF validation, and hopefully
>> will also be based on SPIN. I'm not interested in the part about
>> non-SPARQL shapes as this is mostly politics at play. If you want to
>> do practical development, SPARQL is all you need.
>
>
> That is a political statement Martynas and therefore denies your previous
> sentence.
>
>>
>> Moreover, Shapes WG is very new while SPARQL has been around for 10
>> years. You wrote "not all clients want to talk sparql" -- but somehow
>> those clients will want to talk Shapes? Makes no sense to me.
>
>
> But it does to others.
>
>>
>> I'm still of the opinion that you are looking in the wrong places.
>> Have you actually tried SPARQL for this? What did not work?
>
>
> I don't think it is reasonable to expect data portals that harvest metadata
> from other portals to include a SPARQL engine just to check that data
> conforms to a profile, like DCAT-AP. That should be possible without having
> to build or include a SPARQL engine which would be overkill for what is
> essentially a pretty simple task.
>
> SPIN does a really good job and in many circumstances it is the right tool.
> But not all. IMHO we need a more flexible approach, one that can handle
> simple cases without SPARQL. Now, whether the SHACL work is the answer is,
> mercifully, a question others are answering.
>
> Phil.
>
>
>
>>
>> Martynas
>>
>> On Wed, May 13, 2015 at 12:42 PM, Svensson, Lars <L.Svensson@dnb.de>
>> wrote:
>>>
>>> Martynas,
>>>
>>>> this is a very simple answer that I have given you before: a shape of
>>>> RDF data is defined as SPARQL query. There are no two ways about it.
>>>
>>>
>>> Hmm, the list of deliverables of the data shapes wg [1] mentions an RDF
>>> vocabulary to describe shapes, a set of semantics _possibly_ defined as
>>> SPARQL operations, etc. It says that one possibility is to use SPARQL
>>> queries to evaluate shapes against RDF graphs. At least to me, that doesn't
>>> mean that the shape is defined as a SPARQL query, but as an RDF graph.
>>>
>>> [1] http://www.w3.org/2014/data-shapes/charter#deliverables
>>>
>>> Best,
>>>
>>> Lars
>>>
>>>> On Tue, May 12, 2015 at 2:18 PM, Svensson, Lars <L.Svensson@dnb.de>
>>>> wrote:
>>>>>
>>>>> Kingsley,
>>>>>
>>>>> On Monday, May 11, 2015 9:00 PM, Kingsley Idehen wrote:
>>>>>
>>>>>> We have to be careful here. RDF Language sentences/statements have a
>>>>>> defined syntax as per RDF Abstract Syntax i.e., 3-tuples organized in
>>>>>> subject,
>>>>>> predicate, object based structure. RDF Shapes (as far as I know) has
>>>>>> nothing
>>>>
>>>> to
>>>>>>
>>>>>> do with the subject, predicate, object structural syntax of an RDF
>>>>>> statement/sentence. Basically, it's supposed to provide a mechanism
>>>>>> for
>>>>>> constraining the entity type (class instances) of RDF statement's
>>>>>> subject and
>>>>>> object, when creating RDF statements/sentences in documents. Think of
>>>>>> this
>>>>
>>>> as
>>>>>>
>>>>>> having more to do with what's regarded as data-entry validation and
>>>>
>>>> control, in
>>>>>>
>>>>>> other RDBMS quarters.
>>>>>
>>>>>
>>>>> The charter of the data shapes WG [1] says that "the product of the RDF
>>>>> Data
>>>>
>>>> Shapes WG will enable the definition of graph topologies for interface
>>>> specification, code development, and data verification", so it's not
>>>> _only_ about
>>>> validation etc. My understanding is that it's somewhat similar to XML
>>>> schema
>>>> and thus is essentially a description of the graph structure. As such,
>>>> it can of
>>>> course be used for validation, but that is only one purpose.
>>>>>
>>>>>
>>>>>> The function of the "profile" I believe you (and others that support
>>>>>> this) are
>>>>>> seeking has more to do with enabling clients and servers (that don't
>>>>
>>>> necessarily
>>>>>>
>>>>>> understand or care about RDF's implicit semantics) exchange hints
>>>>>> about the
>>>>>> nature of RDF document content (e.g., does it conform to Linked Data
>>>>>> principles re. entity naming [denotation + connotation] ).
>>>>>
>>>>>
>>>>> No, my use of "profile" is really a "shape" in the sense of the data
>>>>> shapes wg.
>>>>
>>>> Some of their motivations are what I'm envisioning, too, e.g.
>>>>>
>>>>>
>>>>> * Developers of each data-consuming application could define the shapes
>>>>
>>>> their software needs to find in each feed, in order to work properly,
>>>> with
>>>> optional elements it can use to work better.
>>>>>
>>>>> * Developers of data-providing systems can read the shape definitions
>>>>> (and
>>>>
>>>> possibly related RDF Vocabulary definitions) to learn what they need to
>>>> provide
>>>>>
>>>>>
>>>>>> Cut long story short, a "profile" hint is about the nature of the RDF
>>>>>> content
>>>>
>>>> (in
>>>>>>
>>>>>> regards to entity names and name interpretation), not its shape (which
>>>>>> is
>>>>>> defined by RDF syntax).
>>>>>
>>>>>
>>>>> OK, I stand corrected: My question is: How can clients and servers
>>>>> negotiate
>>>>
>>>> shape information?
>>>>>
>>>>>
>>>>> Best,
>>>>>
>>>>> Lars
>>
>>
>>
>
> --
>
>
> Phil Archer
> W3C Data Activity Lead
> http://www.w3.org/2013/data/
>
> http://philarcher.org
> +44 (0)7887 767755
> @philarcher1

Received on Wednesday, 13 May 2015 11:58:51 UTC