Re: [Virtuoso-users] backslash character within URI

[Patrick van Kleef]

HI Florian,

I did some semantic web crawling and I gathered information on  
football
clubs from freebase and dbpedia.
In the dbpedia data, there is an individual that's equivalent
(owl:sameAs) http://dbpedia.org/resource/Chelsea_F.C. , namely
http://dbpedia.org/resource/Chelse_FC\
(note the backslash at the end of the URI)
When I use the sesame 2 API to access the virtuoso RDF store (directly
via the java repository), to collect all the owl:sameAs triples for
http://dbpedia.org/resource/Chelsea_F.C. like so

st = con.getStatements((Resource) ind, OWL.SAMEAS, null, true,
getContexts());

I get this error:

sparql select *
from named<http://myhost.com/ns/graph/linkeddata>
from named<http://myhost.com/ns/graph/soccer>
from named<http://myhost.com/ns/graph/tennis>
from named<http://myhost.com/ns/graph/entertainment-dbpedia>
from named<http://myhost.com/ns/common#inferred>
from named<http://myhost.com/ns/graph/dbpedia-ontology>
where {
  graph ?g
    {<http://dbpedia.org/resource/Chelse_FC\>  <http://www.w3.org/2002/07/owl#sameAs 
>  ?o }
  }
[virtuoso.jdbc3.VirtuosoException: SQ074: Line 1: syntax error at  
'\' before 'SELECT']

I googled a bit and found these explanations:
http://docs.openlinksw.com/virtuoso/dbadm.html , specifically, under
6.1.9.1.9 [Client]:

SQL_NO_CHAR_C_ESCAPE=1

and gave it a shot (setting the conf var to 1), but the result was  
just
another error:

Could not open  RepositoryConnection for transaction; nested  
exception is org.openrdf.repository.RepositoryException:  
virtuoso.jdbc3.VirtuosoException: Not using UTF-8 encoding of SQL  
statements, but processing character escapes also disabled


I also tried setting
SQL_UTF8_EXECS = 1
in spite of reading in
http://docs.openlinksw.com/virtuoso/wideidentifiers.html that this may
make the whole content of my database unreadable - luckily, It didn't.
The error, however, prevailed.

Do I just need to re-populate my database with the new  
SQL_UTF8_EXECS =
1 setting or is it something else?

You cannot use a plain \ character in a URI, you need to urlencode it  
like so:

sparql select *
from named<http://myhost.com/ns/graph/linkeddata>
from named<http://myhost.com/ns/graph/soccer>
from named<http://myhost.com/ns/graph/tennis>
from named<http://myhost.com/ns/graph/entertainment-dbpedia>
from named<http://myhost.com/ns/common#inferred>
from named<http://myhost.com/ns/graph/dbpedia-ontology>
where {
  graph ?g
    {<http://dbpedia.org/resource/Chelse_FC%5C>  <http://www.w3.org/2002/07/owl#sameAs 
>  ?o }
  }

Just like when you would use a URL your browser like:

   http://dbpedia.org/page/Chelse_FC%5C


See also: http://en.wikipedia.org/wiki/Percent-encoding


Patrick