On 28/09/13 10:54, Arthur Vaïsse-Lesteven wrote:
Not really.
In the case of TDB only, FROM picks a graph out of the dataset. Other
datasets are likely to attempt to read it from the web.
I thought that was the role of the SPARQL SERVICE to get data from different
endpoint on the web.
I'll make some tests.
Thank you for your answer.
FROM/FROM NAMED "describes the dataset" to be queried.
That's how some engines can be taking the names from the local pool of
graphs and others do a HTTP GET. The spec does not prescribe "describe"
here (quite intentionally).
SERVICE <url> executes a remote sub-query in the middle of execution.
The URL is a service endpoint, not a graph.
Andy
Arthur VAÏSSE-LESTEVEN.
________________________________
De : Andy Seaborne <[email protected]>
À : [email protected]
Envoyé le : Vendredi 27 septembre 2013 18h31
Objet : Re: Trubble with config.ttl that impact queries' semantics
What's in config.ttl?
On 27/09/13 14:43, Arthur Vaïsse-Lesteven wrote:
Hi,
I just found something I don't understand.
Using the last Fuseki server ( 1.0.0 ) I push some triples with a SPARQL
insert, for example :
PREFIX uso: <http://weblab.ow2.org/SWAG_users_ontology#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
INSERT DATA {
GRAPH <http://swag_data.com/users_graph> {
<http://swag_data.com/User/portal> rdf:type uso:User.
<http://swag_data.com/User/portal> uso:password
"liferay_portal"^^xsd:String.
<http://swag_data.com/User/portal> uso:name
"[email protected]"^^xsd:String.
<http://swag_data.com/User/portal> uso:hasAccessRestrictionLvl
<http://cassidian/COPS/not_restricted>.
<http://swag_data.com/User/portal> uso:memberOfGroup
<http://swag_data.com/portal_user_group>.
<http://swag_data.com/portal_user_group> uso:name "Portal"^^xsd:String.
}.
}
My problem is that depending the way I start the server, I got different
results from 2 queries that was supposed to be equals. The queries are :
prefix uso: <http://weblab.ow2.org/SWAG_users_ontology#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?p ?o ?n
FROM <http://swag_data.com/users_graph>
WHERE {
?user uso:name "[email protected]"^^xsd:String.
?user uso:password "liferay_portal"^^xsd:String.
?user ?p ?o.
OPTIONAL { ?o uso:name ?n }
}
and
prefix uso: <http://weblab.ow2.org/SWAG_users_ontology#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT ?p ?o ?n
WHERE {
graph <http://swag_data.com/users_graph> {
?user uso:name "[email protected]"^^xsd:String.
?user uso:password "liferay_portal"^^xsd:String.
?user ?p ?o.
OPTIONAL { ?o uso:name ?n }
}
}
If I correctly understand the SPARQL standards, this two queries are supposed
to give the same result.
Not really.
In the case of TDB only, FROM picks a graph out of the dataset. Other
datasets are likely to attempt to read it from the web.
And that what's append when I execute the update and the queries on the the dataset
"test" against a
Fuseki started with the command : "fuseki-server --update --loc "../test" /test"
When I execute the two queries against the dataset ds of a Fuseki started by this command
:"fuseki-server --config="./config.ttl"
The first one don't find any matching result and the second give me the result
same expected, obtained by the two queries with the other server :
-----------------------------------------------------------------------------------------------------------------------
| p | o
| n |
=======================================================================================================================
| uso:memberOfGroup |
<http://swag_data.com/portal_user_group> | "Portal"^^xsd:String |
| uso:hasAccessRestrictionLvl |
<http://cassidian/COPS/not_restricted> | |
| uso:name |
"[email protected]"^^xsd:String | |
| uso:password |
"liferay_portal"^^xsd:String | |
| <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> | uso:User
| |
-----------------------------------------------------------------------------------------------------------------------
Is that due to the default union graph parameters ? Is that comportment fully
standard compliant ? If yes, which point of the standard did I missed?
Because I thought that this 2 queries are semantically the same and I was
expecting the same results in all contexts.
VAÏSSE-LESTEVEN Arthur
