eworks.RQL.engine
Class RqlEngine

java.lang.Object
  eworks.RQL.engine.RqlEngine

public class RqlEngine

extends Object

RqlEngine is the rudimentary implementation of a RQL-processor. RQL is a SQL-like query language for RDF, see http://139.91.183.30:9090/RDF/RQL/ for further details on RQL and http://www.w3.org/RDF/ for details on RDF.

RqlEngine RQL = new RqlEngine();
eworks.RDF.model.Tuples result = null;
try {
    RQL.setDataSource(new java.io.File("C:\input.rdf"));
    result=RQL.query("SELECT s,@p,o FROM {s}@p{o}");
} catch(Exception e) {
    System.out.println(e);
}

Version:

1.00 (2003-11-03)

Author:

Fabian Wleklinski (fabian@wleklinski.de)

Constructor Summary

RqlEngine()
Constructs a RqlEngine instance that suppresses all error- and debug- messages.

RqlEngine(OutputStream output)
Constructs a RqlEngine instance and sets the output-stream for printing error- and debug-messages to the given stream.

Method Summary

Tuples	query(String queryString) Evaluates a given RQL query and returns the query's result.
void	setDataSource(File rdfFile) Sets a certain RDF file as data source.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RqlEngine

public RqlEngine(OutputStream output)

Constructs a RqlEngine instance and sets the output-stream for printing error- and debug-messages to the given stream.

Parameters:

output - Output-stream for printing error- and debug-messages.

RqlEngine

public RqlEngine()

Constructs a RqlEngine instance that suppresses all error- and debug- messages.

Method Detail

setDataSource

public void setDataSource(File rdfFile)

Sets a certain RDF file as data source.

Parameters:

rdfFile - The data source to be used for queries.

query

public Tuples query(String queryString)
             throws NoDataSourceDefinedException,
                    ParsingException,
                    VariableAlreadyBoundException,
                    VariableNotBoundException

Evaluates a given RQL query and returns the query's result.

Parameters:

queryString - A valid RQL query.

Returns:

The query's result, a set of tuples.

Throws:

NoDataSourceDefinedException

ParsingException

VariableAlreadyBoundException

VariableNotBoundException