Hi,
In our project we use Virtuoso’s Jena provider for writing to/reading from
the triplestore.
Data are added initially with:
*virtDataset.addNamedModel(graphName, model, false)*
When the added model contains string literals, these are stored in Virtuoso
as xsd:strings. A sparql select query will thus return them like this:
*"added a string literal with
VirtDataset.addNamedModel"^^<http://www.w3.org/2001/XMLSchema#string
<http://www.w3.org/2001/XMLSchema#string>>*
Updates are added to the triplestore with sparql update. The queries are
built with Jena and the query execution is done with Virtuoso’s Jena
provider:
*VirtuosoUpdateFactory.create(update.toString(), virtgraph).exec();*When a
string literal is added/updated this way, it is stored in Virtuoso as a
simple literal.
I.e. sparql select returns:
*"added a string literal with VirtuosoUpdateFactory.create"*
Since simple literals are synonyms for xsd:string literals in RDF 1.1, Jena
(ARQ) prints (toString) queries without ^^xsd:string. I assume that
VirtuosoUpdateRequest.exec() still treats simple literals and string
literals differently and that this is why strings get stored as simple
literals. I would however expect that adding triples with
VirtDataset.addNamedModel() and VirtuosoUpdateRequest.exec() should store
string literals in Virtuoso in the same way. Since this is not the case, we
get a mixture of simple literals and string literals in the database. To
avoid this we concatenate ^^xsd:string to all simple literals in the query
string argument given to *VirtuosoUpdateFactory.create*. This is rather
hacky and something we want to avoid. Is there a way to make
VirtuosoUpdateRequest.exec() store strings (simple literals) as typed
string literals? Or even better: are there plans to treat simple literals
as string literals in Virtuoso?
Jena provider version: virt_jena3.jar + virtjdbc4.jar
Jena version: 3.0.1
Virtuoso version: 07.20.3215
Best regards,
Jens Kilde Mjelva
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