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Re: CONSTRUCT an RDF Datest

From: Andy Seaborne <andy@apache.org>
Date: Sun, 29 Nov 2015 14:19:59 +0000
To: public-sparql-dev@w3.org
Message-ID: <565B098F.1020406@apache.org>
On 29/11/15 12:49, Tara Athan wrote:
> On 11/29/15 5:33 AM, Andy Seaborne wrote:
>> On 29/11/15 01:45, Tara Athan wrote:
>>> Update: In a private reply, someone mentioned that it is possible to
>>> create and update named graphs in a Graph Store, e.g. with the SPARQL
>>> Update language. However, in my usecase, I am only interested in
>>> creating an immutable RDF Dataset, not a mutable Graph Store. This hint
>>> was useful in letting me see what a CONSTRUCT for an RDF Dataset might
>>> look like, though (patterned after INSERT).
>>>
>>> For example, suppose I want to filter an RDF Dataset to extract a new
>>> dataset where only named graphs having a metadata triple in the default
>>> graph matching a certain filter are retained. It might be expressed so:
>>>
>>> CONSTRUCT
>>>   { ?name ex:observedAt ?date
>>>    GRAPH ?name
>>>     { ?s ?p ?o}
>>> }
>>> WHERE
>>>   {
>>>    { ?name ex:observedAt ?date }
>>>    GRAPH ?name
>>>        {?s ?p ?o}
>>>    FILTER (?date > 2015-06-01)
>>> }
>>
>> In this particular example, do the results need to exactly conform to
>> the structure of the dataset?  If the ex:observedAt is put in the
>> results in the same graph:
>>
>> CONSTRUCT
>>   { ?name ex:observedAt ?date
>>     ?s ?p ?o
>> }
>> WHERE ...
> In this particular example, the aim is to reproduce the original
> structure of the dataset.
>>
>>>
>>> Is there any theoretical or technical obstacle to this?
>>
>> There's no obstacle.  A Google Summer of Code project added this to
>> Apache Jena this year and it'll be in the next release.
>>
>> It follows the design you gave:
>>
>> https://jena.apache.org/documentation/query/construct-quad.html
> Thanks - that is exactly what I was looking for!
>
> Now with a Jena implementation in place, what is the likelihood that
> this extended CONSTRUCT syntax will get incorporated into the SPARQL
> Standard?

(personal opinions - I do not speak for W3C)

There is a better way, which is for the implementations and contributing 
users to converge on a design, maybe through a W3C community group, 
maybe just discuss here.

That way, biases towards relatively obvious incremental improvements. 
That is not the dynamics of a working group in my experience.

This is happening in the area of tests.
   https://www.w3.org/community/rdf-tests/
with a community group

The standards are what they are and we're not in green field of new 
technology anymore.  There are people and companies working with 
existing standards and as well as all the writing and teaching that has 
gone around them.

	Andy

Technical details in message to james.

>
> Tara
>>
>>     Andy
>>
>>>
>>> Tara
>>>
>>
>>
>>
>
>
Received on Sunday, 29 November 2015 14:20:29 UTC

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