Class FederatedSparqlQueryClient

A class for connecting to multiple remote SPARQL endpoints and federating queries over them with the results merged locally.

Inheritance

object

FederatedSparqlQueryClient

Implements

ISparqlQueryClient

IConfigurationSerializable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: VDS.RDF.Query

Assembly: dotNetRdf.dll

Syntax

public class FederatedSparqlQueryClient : ISparqlQueryClient, IConfigurationSerializable

Remarks

Queries are federated by executing multiple requests simultaneously and asynchronously against the endpoints in question with the data then merged locally. The merging process does not attempt to remove duplicate data it just naively merges the data.

Constructors

FederatedSparqlQueryClient(IEnumerable<SparqlQueryClient>)

Create a new federated client that connects to a number of remote SPARQL endpoints.

Declaration

public FederatedSparqlQueryClient(IEnumerable<SparqlQueryClient> endpointClients)

Parameters

Type	Name	Description
IEnumerable<SparqlQueryClient>	endpointClients	The remote endpoint clients to be federated.

FederatedSparqlQueryClient(HttpClient, params Uri[])

Create a new federated client connecting to a number of remote SPARQL endpoints.

Declaration

public FederatedSparqlQueryClient(HttpClient httpClient, params Uri[] endpointUris)

Parameters

Type	Name	Description
HttpClient	httpClient	The HTTP client to use for all connections.
Uri[]	endpointUris	The URIs to connect to.

FederatedSparqlQueryClient(params SparqlQueryClient[])

Create a new federated client that connects to a number of remote SPARQL endpoints.

Declaration

public FederatedSparqlQueryClient(params SparqlQueryClient[] endpointClients)

Parameters

Type	Name	Description
SparqlQueryClient[]	endpointClients	The remote endpoint clients to be federated.

Properties

IgnoreFailedRequests

Get or set whether a failed request on one endpoint should cause the entire request to fail.

Declaration

public bool IgnoreFailedRequests { get; set; }

Property Value

Type	Description
bool

MaxSimultaneousRequests

Get or set the maximum number of endpoints that this client will issue queries to at any one time.

Declaration

public int MaxSimultaneousRequests { get; set; }

Property Value

Type	Description
int

Timeout

Get or set the period of time to wait for a response from any given endpoint.

Declaration

public int Timeout { get; set; }

Property Value

Type	Description
int

Methods

AddEndpoint(SparqlQueryClient)

Add a remote endpoint using the specified client instance.

Declaration

public void AddEndpoint(SparqlQueryClient endpointClient)

Parameters

Type	Name	Description
SparqlQueryClient	endpointClient	The client to use to connect to the remote endpoint.

Remarks

This method allows callers to use a specific HttpClient for certain remote endpoints by first constructing a SparqlQueryClient instance and then passing it to this method.

QueryWithResultGraphAsync(string)

Execute a SPARQL query where the expected result is a graph - i.e. a CONSTRUCT or DESCRIBE query.

Declaration

public Task<IGraph> QueryWithResultGraphAsync(string sparqlQuery)

Parameters

Type	Name	Description
string	sparqlQuery	The SPARQL query string.

Returns

Type	Description
Task<IGraph>	An RDF graph containing the combined results received from all remote endpoints.

QueryWithResultGraphAsync(string, CancellationToken)

Execute a SPARQL query that is intended to return an RDF Graph.

Declaration

public Task<IGraph> QueryWithResultGraphAsync(string sparqlQuery, CancellationToken cancellationToken)

Parameters

Type	Name	Description
string	sparqlQuery	The query to be executed.
CancellationToken	cancellationToken	A cancellation token that can be used by other objects or threads to receive notice of cancellation.

Returns

Type	Description
Task<IGraph>	An RDF Graph.

Remarks

This method should be used when processing SPARQL CONSTRUCT or DESCRIBE queries.

QueryWithResultGraphAsync(string, IRdfHandler)

Execute a SPARQL query where the expected result is a graph - i.e. a CONSTRUCT or DESCRIBE query.

Declaration

public Task QueryWithResultGraphAsync(string sparqlQuery, IRdfHandler handler)

Parameters

Type	Name	Description
string	sparqlQuery	The SPARQL query string.
IRdfHandler	handler	The handler to use when parsing the graph data returned by the server.

Returns

Type	Description
Task	An RDF graph containing the combined results received from all remote endpoints.

QueryWithResultGraphAsync(string, IRdfHandler, CancellationToken)

Execute a SPARQL query where the expected result is a graph - i.e. a CONSTRUCT or DESCRIBE query.

Declaration

public Task QueryWithResultGraphAsync(string sparqlQuery, IRdfHandler handler, CancellationToken cancellationToken)

Parameters

Type	Name	Description
string	sparqlQuery	The SPARQL query string.
IRdfHandler	handler	The handler to use when parsing the graph data returned by the server.
CancellationToken	cancellationToken	A cancellation token that can be used by other objects or threads to receive notice of cancellation.

Returns

Type	Description
Task	An RDF graph containing the combined results received from all remote endpoints.

QueryWithResultSetAsync(string, CancellationToken)

Run a federated query asynchronously.

Declaration

public Task<SparqlResultSet> QueryWithResultSetAsync(string sparqlQuery, CancellationToken cancellationToken = default)

Parameters

Type	Name	Description
string	sparqlQuery	The query to be executed.
CancellationToken	cancellationToken	A cancellation token that can be used by other objects or threads to receive notice of cancellation.

Returns

Type	Description
Task<SparqlResultSet>	The Task object representing the asynchronous operation.

Remarks

The query results are returned as a result of the task.

QueryWithResultSetAsync(string, ISparqlResultsHandler, CancellationToken)

Run a federated query asynchronously.

Declaration

public Task QueryWithResultSetAsync(string sparqlQuery, ISparqlResultsHandler handler, CancellationToken cancellationToken = default)

Parameters

Type	Name	Description
string	sparqlQuery
ISparqlResultsHandler	handler
CancellationToken	cancellationToken

Returns

Type	Description
Task	The Task object representing the asynchronous operation.

Remarks

The query results are reported through the specified ISparqlResultsHandler.

RemoveEndpoint(Uri)

Remove a remote endpoint.

Declaration

public void RemoveEndpoint(Uri endpointUri)

Parameters

Type	Name	Description
Uri	endpointUri	The URI of the endpoint to be removed.

RemoveEndpoint(SparqlQueryClient)

Remove a remote endpoint.

Declaration

public void RemoveEndpoint(SparqlQueryClient endpointClient)

Parameters

Type	Name	Description
SparqlQueryClient	endpointClient	The endpoint client to be removed from the federation.

SerializeConfiguration(ConfigurationSerializationContext)

Serializes the Endpoint's Configuration.

Declaration

public void SerializeConfiguration(ConfigurationSerializationContext context)

Parameters

Type	Name	Description
ConfigurationSerializationContext	context	Configuration Serialization Context.

Implements

ISparqlQueryClient

IConfigurationSerializable

Extension Methods

Extensions.ToSafeString(object)

Extensions.AsEnumerable<T>(T)