Re: [dotNetRDF-Support] SPARQL

[Rob V. <rv...@do...>]

Hi Jostinah

If you are having trouble getting started with SPARQL I would recommend the
excellent SPARQL by Example Tutorial
(http://www.cambridgesemantics.com/semantic-university/sparql-by-example) or
Bob DuCharme's Learning SPARQL book (http://www.learningsparql.com)

OWL can be stored as RDF/XML and many tools like Protégé either default to
this or support it.  dotNetRDF can read any RDF/XML so you can read your
ontology file with it provided you've saved it as RDF/XML, the
LoadFromFile() call you show will assume RDF/XML if given a .owl extension

Yes you can query OWL with SPARQL, you are querying the RDF representation
of the OWL rather than the axioms, see
http://answers.semanticweb.com/questions/3172/is-it-possible-to-write-a-spar
ql-query-or-use-some-api-to-retrieve-the-concept-definitions-from-any-ontolo
gy/3189 for some simple examples

Hope this helps,

Rob

Ps. For future reference please subscribe to the mailing list
(dot...@li...) rather than emailing me directly, thanks!

From:  Jostinah Lam <89...@gm...>
Date:  Friday, November 16, 2012 3:50 AM
To:  Rob Vesse <rv...@do...>
Subject:  SPARQL

> Hello rob,
> I'm jostinah, a student who is currently doing a project.I have some questions
> regarding dotnetrdf to ask.I have no basic at all in computer science,i hope
> you can help me.
> Here's a brief introduction of what the project is about. i have to create a
> software that is able to produce the name of the disease and its management
> when the user keys in the input.This project is focusing pregnancy induced
> hypertension. 
> 
> For example: 
> input : Diastolic value =90
> output: Hypertension
> 
> I created the ontology using protege.Right now i had integrate the owl file
> into C#, but i have a problem on how to query the owl file.
> The code is as below:
> 
> private void SPARQLquery()
>         {
> 
>             //Define your Graph here - it may be better to use a
> QueryableGraph if you plan
>             //on making lots of Queries against this Graph as that is
> marginally more performant
>             IGraph g = new Graph();
> 
>             //Load some data into your Graph using the LoadFromFile()
> extension method
>             g.LoadFromFile("exData\\PregnancyInducedHypertension.owl");
> 
>             //Use the extension method ExecuteQuery() to make the query
> against the Graph
>             try
>             {
>                 Object results = g.ExecuteQuery("SELECT ?x WHERE {
> ?NamedDisease a ?x }");
>                 if (results is SparqlResultSet)
>                 {
>                     //SELECT/ASK queries give a SparqlResultSet
>                     SparqlResultSet rset = (SparqlResultSet)results;
>                     foreach (SparqlResult r in rset)
>                     {
>                         //Console.WriteLine(r.ToString());
>                         textBox1.Text += r.ToString() + "\r\n";
>                     }
>                 }
>                 else if (results is IGraph)
>                 {
>                     //CONSTRUCT/DESCRIBE queries give a IGraph
>                     IGraph resGraph = (IGraph)results;
>                     foreach (Triple t in resGraph.Triples)
>                     {
>                         //Console.WriteLine(t.ToString());
>                         textBox1.Text += t.ToString() + "\r\n";
>                     }
>                 }
>                 else
>                 {
>                     //If you don't get a SparqlResutlSet or IGraph something
> went wrong 
>                     //but didn't throw an exception so you should handle it
> here
>                     Console.WriteLine("ERROR");
>                 }
>             }
>             catch (RdfQueryException queryEx)
>             {
>                 //There was an error executing the query so handle it here
>                 Console.WriteLine(queryEx.Message);
>             }
>         }
> 
> The red words is where the query should be. i know the query should be
> something like this " rdf:about,owl: class" but i have no clue at all. i
> studied SPARQL how to query. SPARQL is suppose to query rdf but not owl but
> since owl is made of rdf,so i think there must be a way to query owl.I copy
> the code from one of the example that you gave to others.
> 
> My questions are:
> 1) Can i integrate the owl file into C# and not using remoteendpoint?Because
> sparql remoteendpoint normally produce result in set,i only want to produce
> one result
> 2)is it possible to query owl using sparql in my case since i need to produce
> one distinct result only?I understand the query for owl will be very long.
> 
> 
> Thank you so much for your time.I really hope you can help me.I will try my
> best to explain if there's any part that you dont understand.Thank you.
>