eu.fbk.rdfpro

Class RDFSources

java.lang.Object

eu.fbk.rdfpro.RDFSources

public final class RDFSources
extends Object

Utility methods dealing with RDFSources.

Field Summary

Fields

Modifier and Type	Field and Description
static RDFSource	NIL The null RDFSource that returns no statements, namespaces and comments.

Method Summary

Modifier and Type	Method and Description
static RDFSource	query(boolean parallelize, boolean preserveBNodes, String endpointURL, String query) Returns an RDFSource that retrieves data from a SPARQL endpoint using SPARQL CONSTRUCT or SELECT queries.
static RDFSource	read(boolean parallelize, boolean preserveBNodes, String baseURI, org.openrdf.rio.ParserConfig config, String... locations) Returns an RDFSource that reads files from the locations specified.
static RDFSource	wrap(Iterable<? extends org.openrdf.model.Statement> statements) Returns an RDFSource providing access to the statements in the supplied collection.
static RDFSource	wrap(Iterable<? extends org.openrdf.model.Statement> statements, Iterable<? extends org.openrdf.model.Namespace> namespaces) Returns an RDFSource providing access to the statements and namespaces in the supplied collections.
static RDFSource	wrap(Iterable<? extends org.openrdf.model.Statement> statements, Map<String,String> namespaces) Returns an RDFSource providing access to the statements and namespaces in the supplied collection and map.

Methods inherited from class java.lang.Object

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

Field Detail

NIL

public static final RDFSource NIL

The null RDFSource that returns no statements, namespaces and comments.

Method Detail

wrap

public static RDFSource wrap(Iterable<? extends org.openrdf.model.Statement> statements)

Returns an RDFSource providing access to the statements in the supplied collection. If the collection is a Model or QuadModel, also its namespaces are wrapped and returned when reading from the source. If you don't want namespaces to be read, use wrap(Iterable, Iterable) passing null as second argument. The collection MUST NOT be changed while the returned source is being used, as this will cause the source to return different statements in different passes. Access to the collection is sequential, so it does not need to be thread-safe.

Parameters:

statements - the statements collection, not null (can also be another RDFSource)

Returns:

the created RDFSource.

wrap

public static RDFSource wrap(Iterable<? extends org.openrdf.model.Statement> statements,
                             @Nullable
                             Iterable<? extends org.openrdf.model.Namespace> namespaces)

Returns an RDFSource providing access to the statements and namespaces in the supplied collections. The two collections MUST NOT be changed while the returned source is being used, as this will cause the source to return different data in different passes. Access to the collections is sequential, so they do not need to be thread-safe.

Parameters:

statements - the statements collection, not null (can also be another RDFSource)

namespaces - the namespaces collection, possibly null

Returns:

the created RDFSource.

wrap

public static RDFSource wrap(Iterable<? extends org.openrdf.model.Statement> statements,
                             @Nullable
                             Map<String,String> namespaces)

Returns an RDFSource providing access to the statements and namespaces in the supplied collection and map. The collection and map MUST NOT be changed while the returned source is being used, as this will cause the source to return different data in different passes. Access to the collection and map is sequential, so they do not need to be thread-safe.

Parameters:

statements - the statements collection, not null (can also be another RDFSource)

namespaces - the namespaces map, possibly null

Returns:

the created RDFSource

read

public static RDFSource read(boolean parallelize,
                             boolean preserveBNodes,
                             @Nullable
                             String baseURI,
                             @Nullable
                             org.openrdf.rio.ParserConfig config,
                             String... locations)

Returns an RDFSource that reads files from the locations specified. Each location is either a file path or a full URL, possibly prefixed with an .ext: fragment that overrides the file extension used to detect RDF format and compression. Files are read sequentially if parallelize == false, otherwise multiple files can be parsed in parallel and files in a line-oriented RDF format can be parsed using multiple threads, in both cases the effect being a greater throughput but no guarantee on the statements order, however. Arguments preserveBNodes, baseURI and config control the parsing process.

Parameters:

parallelize - false if files should be parsed sequentially using only one thread

preserveBNodes - true if BNodes in parsed files should be preserved, false if they should be rewritten on a per-file basis to avoid possible clashes

baseURI - the base URI to be used for resolving relative URIs, possibly null

config - the optional ParserConfig for the fine tuning of the used RDF parser; if null a default, maximally permissive configuration will be used

locations - the locations of the RDF files to be read

Returns:

the created RDFSource

query

public static RDFSource query(boolean parallelize,
                              boolean preserveBNodes,
                              String endpointURL,
                              String query)

Returns an RDFSource that retrieves data from a SPARQL endpoint using SPARQL CONSTRUCT or SELECT queries. CONSTRUCT queries are limited (due to SPARQL) to return only triples in a default graph. SELECT query should return bindings for variables s, p, o and c, which are used as subject, predicate, object and context of returned statements; incomplete or invalid bindings (e.g., bindings where the subject is bound to a literal) are silently ignored.

Parameters:

parallelize - true to use multiple threads should for handling parsed triples

preserveBNodes - true if BNodes in the query result should be preserved, false if they should be rewritten on a per-endpoint basis to avoid possible clashes

endpointURL - the URL of the SPARQL endpoint, not null

query - the SPARQL query (CONSTRUCT or SELECT form) to submit to the endpoint

Returns:

the created RDFSource