yes, that is true, but I had a problem in calling this function,
RiotReader.parseTriples(is, Lang.RDFXML, null, sink);
I put Lang.RDFXML instead of your suggestion Lang.guess(filename) and then the
processing seem to take for ever. May be I have done something wrong here.
Following is the full code I used for testing.
URL dataURL = new URL(url);
URLConnection conn = dataURL.openConnection();
InputStream is = conn.getInputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(is));
final Set<Triple> sameAsTriples = new HashSet<Triple>();
Sink<Triple> sink = new Sink<Triple>()
{
@Override
public void send(Triple t)
{
System.out.println("##");
if (OWL.sameAs.asNode().equals(t.getPredicate()))
{
// You can either do something immediately with this
// triple, or stick it a HashSet to enforce uniqueness
sameAsTriples.add(t);
}
}
@Override
public void flush() { }
@Override
public void close() { }
};
// To enable RDFS inferencing uncomment the following two lines.
// You need to have your T-Box (ontology) loaded into some model
//Model ontologyModel = ...
//sink = InfFactory.infTriples(sink, ontologyModel);
// String filename = ...
// RiotReader.parseTriples(new FileInputStream(filename),
// Lang.guess(filename), null, sink);
RiotReader.parseTriples(is, Lang.RDFXML, null, sink);
in.close();
even I didn't see the "##" I put to see whether the program is parsing the rdf
file. Is there anything I missed? The program seems not to work.
________________________________________
From: Stephen Allen [[email protected]]
Sent: Monday, April 23, 2012 5:38 PM
To: [email protected]
Subject: Re: processing .rdf files for specific property types only
You can use any InputStream. To get one for a URL, try something like this:
URL url = new URL(urlString);
InputStream in = url.openConnection().getInputStream();
On Mon, Apr 23, 2012 at 9:34 AM, Gunaratna, Dalkandura Arachchige
Kalpa Shashika Silva <[email protected]> wrote:
> Stephen, I have a question here on how to run the code. Here is the question.
> When I want to read a rdf file, I just get the url of the rdf file and create
> a OntModel and read it. For the model, I just need to give the url only. But
> for the code you have suggested needs a filename (locally). In this case, can
> we do the same I did previously? For example, I just use url strings as
> follows in my code.
>
> http://rdf.freebase.com/ns/m/067n4r
> http://rdf.freebase.com/ns/en.mountain_view
> http://dbpedia.org/resource/Mountain_View,_California
>
> I do not down download the rdf files in my code as of now but I do not know
> whether Jena downloads files when giving a url string to the model to read.
> Any help will be greatly appreciated. Thank you.
>
>
> ________________________________________
> From: Stephen Allen [[email protected]]
> Sent: Monday, April 23, 2012 2:43 AM
> To: [email protected]
> Subject: Re: processing .rdf files for specific property types only
>
> Yes, we moved to the Apache community about a year ago. The latest
> release version of ARQ is 2.9.0, and the latest of Jena Core is 2.7.0.
> You can download them from the Apache distribution site [1], which is
> linked to by [2].
>
> -Stephen
>
> [1] http://www.apache.org/dist/incubator/jena/
> [2] http://incubator.apache.org/jena/download/index.html
>
>
> On Sun, Apr 22, 2012 at 10:38 PM, Gunaratna, Dalkandura Arachchige
> Kalpa Shashika Silva <[email protected]> wrote:
>> One question to follow up. I am using ARQ 2.8.5 distribution and its content
>> (jena packages). The class Triple does not seem to work with that
>> distribution and I just downloaded 2.8.6 from source-forge release dated on
>> 2011-04-21. Is there any other new package available for this cause or any
>> newer distribution available other than in source-forge cite? Thank you.
>> ________________________________________
>> From: Stephen Allen [[email protected]]
>> Sent: Sunday, April 22, 2012 10:38 PM
>> To: [email protected]
>> Subject: Re: processing .rdf files for specific property types only
>>
>> I'm not sure I understand your question. The code I posted will read
>> the file in a single pass, and filter it down to only statements that
>> contain the owl:sameAs resource in the predicate position. This is
>> about the fastest way you can parse your RDF. It will also use a lot
>> less memory than storing it in an in-memory model, as it works in a
>> streaming fashion. Also, if you don't need RDFS inferencing don't
>> include it as it adds overhead.
>>
>> Try it out with your code, and see what the performance difference is.
>>
>> As a side note, the comparison in your if statement will be a little
>> slower than mine since you are using String.contains(), and
>> potentially incorrect if some other predicate had the string
>> "owl#sameAs" in it, but wasn't the full
>> "http://www.w3.org/2002/07/owl#sameAs";.
>>
>> -Stephen
>>
>> On Sun, Apr 22, 2012 at 7:19 PM, Gunaratna, Dalkandura Arachchige
>> Kalpa Shashika Silva <[email protected]> wrote:
>>> Hi Stephen,
>>> Will it increase the efficiency (speed) in processing? In you code,
>>>
>>> if (OWL.sameAs.asNode().equals(t.getPredicate()))
>>> {
>>> // You can either do something immediately with this
>>> triple, or stick it a HashSet to enforce uniqueness
>>> sameAsTriples.add(t);
>>> }
>>>
>>> you compare every statement in the model by reading each line in the file
>>> as I tried to do earlier like follows,
>>>
>>> String predicate = st.getPredicate().getURI().toLowerCase();
>>> if(predicate.contains("owl#sameas"))
>>> {
>>> do something to get the list of sameAs links
>>> }
>>>
>>> Thank you.
>>>
>>> ________________________________________
>>> From: Stephen Allen [[email protected]]
>>> Sent: Sunday, April 22, 2012 10:05 PM
>>> To: [email protected]
>>> Subject: Re: processing .rdf files for specific property types only
>>>
>>> On Sun, Apr 22, 2012 at 6:17 PM, Gunaratna, Dalkandura Arachchige
>>> Kalpa Shashika Silva <[email protected]> wrote:
>>>> Hi,
>>>> I have a simple requirement and that is to read
>>>> <http://www.w3.org/2002/07/owl#sameAs> object values (sameAs link value)
>>>> in a rdf file. For that I create an ontology model and read the whole
>>>> file. Following is a code sample I sue for that.
>>>>
>>>> model=ModelFactory.createOntologyModel(OntModelSpec.RDFS_MEM);
>>>> SysRIOT.wireIntoJena() ;
>>>> model.read(url);
>>>> StmtIterator stmtItr=model.listStatements();
>>>>
>>>> This way of processing has a huge processing overhead for my program since
>>>> for every rdf file I just need to read the whole file to get sameAs links.
>>>> Is there any other way of doing this kind of work or only possible way is
>>>> to read the whole file to get the specific property type we want?
>>>>
>>>> And also, what happens if we do not call model.close() at the end? Will it
>>>> be a problem which will cause heap out of space problem?
>>>>
>>>> Thank you,
>>>> Kalpa
>>>
>>> Hi Kalpa,
>>>
>>> If you are simply interested in parsing an RDF file in a streaming
>>> fashion, you can do something like below. If you know that you don't
>>> have any duplicate triples, then you can eliminate the HashSet.
>>>
>>> final Set<Triple> sameAsTriples = new HashSet<Triple>();
>>> Sink<Triple> sink = new Sink<Triple>()
>>> {
>>> @Override
>>> public void send(Triple t)
>>> {
>>> if (OWL.sameAs.asNode().equals(t.getPredicate()))
>>> {
>>> // You can either do something immediately with this
>>> triple, or stick it a HashSet to enforce uniqueness
>>> sameAsTriples.add(t);
>>> }
>>> }
>>>
>>> @Override
>>> public void flush() { }
>>>
>>> @Override
>>> public void close() { }
>>> };
>>>
>>> // To enable RDFS inferencing uncomment the following two lines.
>>> // You need to have your T-Box (ontology) loaded into some model
>>> //Model ontologyModel = ...
>>> //sink = InfFactory.infTriples(sink, ontologyModel);
>>>
>>> String filename = ...
>>> RiotReader.parseTriples(new FileInputStream(filename),
>>> Lang.guess(filename), null, sink);
>>>
>>> // Now do something with sameAsTriples
>>>
>>>
>>
>>
>
>
