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Inkling sample code: parsing and querying remote RDF

From: Dan Brickley <danbri@w3.org>
Date: Mon, 3 Sep 2001 13:27:18 -0400 (EDT)
To: <www-archive@w3.org>
cc: <libby.miller@bristol.ac.uk>
Message-ID: <Pine.LNX.4.30.0109031321020.8261-100000@tux.w3.org>

I just made this, to better understand how Inkling uses the JDBC APIs to
hide RDFisms behind a familiar looking interface. Looks similar to my SOAP
version. It has been a while since I used JDBC, so I'm not sure how close
this usage is to classic JDBC apps.

Dan

---------- Forwarded message ----------

package DanTest;

import org.desire.rudolf.rdf.*;
import org.desire.rudolf.query.*;
import org.desire.rudolf.query.modelcore.*;
import java.sql.*;
import java.util.*;
import java.lang.*;

/**
A class that uses the Inkling RDF query APIs (and hence JDBC) to download and query RDF.
See also:  http://swordfish.rdfweb.org/rdfquery/
...and Libby, Edd, Leigh   and Andy's investigations into re-factoring Inkling.

TODO:
 - figure out how these interfaces relate to my SOAP experiments
 - rationalise package naming
 - datatypes, nameless nodes etc.
 - getting RDF view of resultset

@@author Dan Brickley <danbri@w3.org>
  */

public class AskWeb {
    public static void main (String[] args) {

	String query = "SELECT ?x, ?l, ?c " +
	    "FROM     http://xmlns.com/wordnet/1.6/Job "+
	    "WHERE "+
	    "  (web::type ?x rdfs::Class) "+
	    "  (rdfs::label ?x ?l) "+
	    "  (rdfs::description ?x ?c) "+
	    "USING web FOR http://www.w3.org/1999/02/22-rdf-syntax-ns# "+
	    "rdfs FOR http://www.w3.org/2000/01/rdf-schema#";

	java.sql.ResultSet results;
 	try
	    {
		RDFModelCore rdfdata = DownloadUrls.getUrlsFromQuery(query);
		if(rdfdata != null && !((RDFGraph)rdfdata).isEmpty()) {
		    Driver inklingDriver = null;
		    java.sql.Connection conn = null;
		    try {
			inklingDriver = new MemModelCoreDriver();
			conn = ((MemDriverInterface)inklingDriver).connect(rdfdata);
		    } catch(Exception e){
			System.out.println("Inkling: JDBC-RDF error: "+e );
			e.printStackTrace();
		    }
		    java.sql.Statement statement = conn.createStatement();
		    results = statement.executeQuery( query );
		    statement.close();
		    conn.close();
		    java.sql.DriverManager.deregisterDriver(inklingDriver);
		}

		ParsedQuery pq = ParsedQuery.parse(query);
		while (results.next()) {
		    Enumeration fields = pq.variables.elements();
		    while(fields.hasMoreElements()){
			  String varname = (String)fields.nextElement();
			  String value = (String)results.getString(varname);
			  System.out.println ("  "+ varname + " = " + value);
		    }
		    System.out.println("\n");
		}
	    }
	catch (Exception e) {
	    System.err.println("Inkling: RDF query exception: "+ e );
	    e.printStackTrace();
	}
    }
}

/*
Installation notes
Saved and compiled as DanTest/AskWeb.java this should run with the following CLASSPATH:

LIB=`pwd`/lib
export CLASSPATH=$CLASSPATH:$LIB/rdfquery.jar:$LIB/modelcore.jar:$LIB/rdf-api-2001-01-19.jar
export CLASSPATH=$CLASSPATH:$LIB/sirpac-1.14.jar
*/
Received on Monday, 3 September 2001 13:27:20 GMT

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