On a related note, I see that ARQ Construct quad could easily be used to
construct quads where the name is a blank node. Having the quad name be
a blank node is fine according to RDF
http://www.w3.org/TR/rdf11-datasets/#sec-introduction (and is desirable
in my usecase), but is not permitted according to SPARQL. Are such quads
accepted in practice, or does this cause significant interoperability
problems?
Tara
On 11/29/15 9:19 AM, Andy Seaborne wrote:
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
