On 16/09/13 19:33, Claude Warren wrote:
So on read the base converts all relative URIs to the be grounded in the
base.
Is there any way to read a file with relative URIs and have the URIs remain
relative?
Not and be legal RDF.
RDF is based on absolute URIs in the abstract data model. Relative URIs
only legally exist in concrete syntax.
The API can create bad RDF as well.
The NT parser will read the data, it issues ERRORs but the data is
parsed and output. Strictly, it's illegal NT because NT is defined to
have absolute URIs. TTL resolves them; NT does not.
On write the base converts all relative URIs to be grounded in the base in
the output.
Is there any way to write a file with relative URIs?
My example has relative URIs in the output.
rdf:about="/s" No URI scheme - it's a relative URI (it's a rooted path
but that is a different concept).
rdf:resource="o" Relative URI.
In the preceeding example if the base were left out of the write would it
make any difference in the output since all the URIs are absolute.
Try it!
Yes it makes a different - the output is:
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
xmlns:ex="http://example/";>
<rdf:Description rdf:about="http://example/s";>
<ex:p rdf:resource="http://example/ns/o"/>
</rdf:Description>
</rdf:RDF>
Relative URIs risk changing data - if you move a file to a new location,
then URIs in the data are different. RDF works on the absolute,
location invariant data as the abstract data.
Andy
Claude
On Sun, Sep 15, 2013 at 11:24 PM, Andy Seaborne <[email protected]> wrote:
On 15/09/13 17:34, Claude Warren wrote:
Can someone give me an example where the base is actually used in the
model.read and model.write calls? I thought I understood what it does but
I can't seem to construct a unit test that shows it works.
Claude
IIRC if a prefix is available, that is preferred over relative URIs.
Relative URIs:
public static void main(String ... argv) throws Exception
{
Model model = ModelFactory.**createDefaultModel() ;
String x = "<s> <p> <http://example/ns/o> ." ;
StringReader sr = new StringReader(x) ;
model.read(sr, "http://example/";, "TTL") ;
model.write(System.out, "N-TRIPLES") ;
System.out.println("-----") ;
model.setNsPrefix("ex", "http://example/";) ;
model.write(System.out, "RDF/XML-ABBREV", "http://example/ns/";) ;
}
<http://example/s> <http://example/p> <http://example/ns/o> .
so relative URIs were resolved against the base.
<rdf:RDF
xmlns:rdf="http://www.w3.org/**1999/02/22-rdf-syntax-ns#<http://www.w3.org/1999/02/22-rdf-syntax-ns#>
"
xmlns:ex="http://example/";>
<rdf:Description rdf:about="/s">
<ex:p rdf:resource="o"/>
</rdf:Description>
</rdf:RDF>
rdf:resource="o" is relative to a base of "http://example/ns/";
Andy
