SemWeb.Sparql : SemWeb.Query Namespace
SparqlEngine Class

A SPARQL query engine.

public class SparqlEngine : Query

⊟ Remarks

This class is based on the engine at http://sparql.sourceforge.net/ by Ryan Levering, version 0.8.

This example runs a SELECT query on a data source and writes the results as XML to standard output.

C# Example 
MemoryStore datamodel = new MemoryStore(new RdfXmlReader("rdfdata.rdf"));

string sparqlQuery = "PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>\n"
                           + "PREFIX foaf: <http://xmlns.com/foaf/0.1/>\n"
                           + "SELECT * WHERE { ?person rdf:type foaf:Agent . \n"
                           + "?person foaf:name ?name . }";

SparqlEngine query = new SparqlEngine(sparqlQuery);
query.Run(datamodel, Console.Out).

Although this example sends the results to a stream, the results can be processed programmatically by passing a SemWeb.Query.QueryResultSink instead of a TextWriter.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Members

See Also: Inherited members from Query.

⊟ Public Constructors

Initialized the SPARQL query from a TextReader.
Initializes the SPARQL query from a string.

⊟ Public Fields

AllowPersistBNodes bool . Documentation for this section has not yet been entered.

⊟ Public Properties

MimeType string . Gets or sets the preferred MIME type for the output of the query. (Inherited from Query.)
QueryMeta SemWeb.Entity . A filter on the Meta value of statements in the target graph considered by the query. (Inherited from Query.)
ReturnLimit int . The number of bindings to return. (Inherited from Query.)
ReturnStart int . The index of the first binding to return. (Inherited from Query.)
[read-only]
 Type SparqlEngine.QueryType . Gets the type of the query.

⊟ Public Methods

AddExternalFunction (RdfFunction)
Registers an external function that can be used in FILTER clauses.
Ask (SemWeb.SelectableSource) : bool
Executes an ASK query on the given data source and returns the result of the query as a boolean.
Ask (SemWeb.SelectableSource, System.IO.TextWriter)
Executes an ASK query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.
Construct (SemWeb.SelectableSource, SemWeb.StatementSink)
Executes a CONSTRUCT query on the given data source and sends the constructed statements to a StatementSink.
Construct (SemWeb.SelectableSource, System.IO.TextWriter)
Executes a CONSTRUCT query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.
Describe (SemWeb.SelectableSource, SemWeb.StatementSink)
Executes a DESCRIBE query on the given data source and sends the constructed statements to a StatementSink.
Describe (SemWeb.SelectableSource, System.IO.TextWriter)
Executes a DESCRIBE query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.
abstract
GetExplanation () : string
Returns a textual explanation of the query. (Inherited from Query.)
GetQueryPrefixes () : SemWeb.NamespaceManager
Gets a NamespaceManager containing all of the PREFIX definitions used in the query.
abstract
Run (SemWeb.SelectableSource, QueryResultSink)
Runs the query on a data source, outputting to a QueryResultSink. (Inherited from Query.)
Run (SemWeb.SelectableSource, System.IO.TextWriter)
Runs the query on a data source, outputting to a TextWriter. (Inherited from Query.)
Select (SemWeb.SelectableSource, QueryResultSink)
Executes a SELECT query on the given data source and sends the resulting variable bindings to a QueryResultSink.
Select (SemWeb.SelectableSource, System.IO.TextWriter)
Executes a SELECT query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.

⊟ Member Details

⊟ SparqlEngine Constructor

Initialized the SPARQL query from a TextReader.

public SparqlEngine (System.IO.TextReader query)

⊟ Parameters

query
A TextReader containing the SPARQL query.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ SparqlEngine Constructor

Initializes the SPARQL query from a string.

public SparqlEngine (string query)

⊟ Parameters

query
The SPARQL query.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ AddExternalFunction Method

Registers an external function that can be used in FILTER clauses.

public void AddExternalFunction (RdfFunction function)

⊟ Parameters

function
An object implementing an external function.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ AllowPersistBNodes Field

Documentation for this section has not yet been entered.

public bool AllowPersistBNodes

⊟ Remarks

Documentation for this section has not yet been entered.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Ask Method

Executes an ASK query on the given data source and returns the result of the query as a boolean.

public bool Ask (SemWeb.SelectableSource source)

⊟ Parameters

source
The data source to query.

⊟ Returns

A boolean value giving the result of the ASK query.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Ask Method

Executes an ASK query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.

public void Ask (SemWeb.SelectableSource source, System.IO.TextWriter output)

⊟ Parameters

source
The data source to query.
output
The System.IO.TextWriter to output the results to in the SPARQL Results XML output format.

⊟ Remarks

This method can also be called through Query.Run(SemWeb.SelectableSource, System.IO.TextWriter).

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Construct Method

Executes a CONSTRUCT query on the given data source and sends the constructed statements to a StatementSink.

public void Construct (SemWeb.SelectableSource source, SemWeb.StatementSink sink)

⊟ Parameters

source
The data source to query.
sink
The SemWeb.StatementSink to send the constructed statements to.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Construct Method

Executes a CONSTRUCT query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.

public void Construct (SemWeb.SelectableSource source, System.IO.TextWriter output)

⊟ Parameters

source
The data source to query.
output
The System.IO.TextWriter to output the results to in the SPARQL Results XML output format.

⊟ Remarks

This method can also be called through Query.Run(SemWeb.SelectableSource, System.IO.TextWriter).

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Describe Method

Executes a DESCRIBE query on the given data source and sends the constructed statements to a StatementSink.

public void Describe (SemWeb.SelectableSource source, SemWeb.StatementSink sink)

⊟ Parameters

source
The data source to query.
sink
The SemWeb.StatementSink to send the constructed statements to.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Describe Method

Executes a DESCRIBE query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.

public void Describe (SemWeb.SelectableSource source, System.IO.TextWriter output)

⊟ Parameters

source
The data source to query.
output
The System.IO.TextWriter to output the results to in the SPARQL Results XML output format.

⊟ Remarks

This method can also be called through Query.Run(SemWeb.SelectableSource, System.IO.TextWriter).

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ GetQueryPrefixes Method

Gets a NamespaceManager containing all of the PREFIX definitions used in the query.

public SemWeb.NamespaceManager GetQueryPrefixes ()

⊟ Returns

A NamespaceManager.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Select Method

Executes a SELECT query on the given data source and sends the resulting variable bindings to a QueryResultSink.

public void Select (SemWeb.SelectableSource source, QueryResultSink sink)

⊟ Parameters

source
The data source to query.
sink
The SemWeb.Query.QueryResultSink to send the resulting variable bindings to.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Select Method

Executes a SELECT query on the given data source and outputs the result of the query in the SPARQL results format to a TextWriter.

public void Select (SemWeb.SelectableSource source, System.IO.TextWriter output)

⊟ Parameters

source
The data source to query.
output
The System.IO.TextWriter to output the results to in the SPARQL Results XML output format.

⊟ Remarks

This method can also be called through Query.Run(SemWeb.SelectableSource, System.IO.TextWriter).

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0

⊟ Type Property

Gets the type of the query.

public SparqlEngine.QueryType Type { get; }

⊟ Value

The type of the query: SELECT, DESCRIBE, CONSTRUCT, or ASK.

⊟ Remarks

None.

⊟ Requirements

Namespace: SemWeb.Query
Assembly: SemWeb.Sparql (in SemWeb.Sparql.dll)
Assembly Versions: 0.0.0.0