eu.fbk.rdfpro

Class RDFHandlers

java.lang.Object

eu.fbk.rdfpro.RDFHandlers

public final class RDFHandlers
extends Object

Utility methods dealing with RDFHandlers.

Field Summary

Fields

Modifier and Type	Field and Description
static int	METHOD_CLOSE The int value for method AutoCloseable.close().
static int	METHOD_END_RDF The int value for method RDFHandler.endRDF().
static int	METHOD_HANDLE_COMMENT The int value for method RDFHandler.handleComment(String).
static int	METHOD_HANDLE_NAMESPACE The int value for method RDFHandler.handleNamespace(String, String).
static int	METHOD_HANDLE_STATEMENT The int value for method RDFHandler.handleStatement(Statement).
static int	METHOD_START_RDF The int value for method RDFHandler.startRDF().
static AbstractRDFHandler	NIL The null RDFHandler that does nothing.

Method Summary

Modifier and Type	Method and Description
static org.openrdf.rio.RDFHandler[]	collect(org.openrdf.rio.RDFHandler handler, int count, SetOperator operation) Returns an RDFHandler that collects multiple streams of RDF data, merging them by means in a unique stream using a SetOperator.
static org.openrdf.rio.RDFHandler	decouple(org.openrdf.rio.RDFHandler handler) Wraps the supplied RDFHandler (if necessary) so to buffer incoming statements and use additional threads for their processing.
static org.openrdf.rio.RDFHandler	decouple(org.openrdf.rio.RDFHandler handler, int numConsumerThreads) Wraps the supplied RDFHandelr (if necessary) using a queue to decouple threads submitting statements from threads consuming them.
static org.openrdf.rio.RDFHandler	dispatchAll(org.openrdf.rio.RDFHandler... handlers) Returns an RDFHandler that dispatches calls to all the RDFHandlers supplied.
static org.openrdf.rio.RDFHandler	dispatchAll(org.openrdf.rio.RDFHandler[] handlers, int[] extraPasses) Returns an RDFHandler that dispatches calls to all the RDFHandlers supplied, optionally performing more passes on selected handlers.
static org.openrdf.rio.RDFHandler	dispatchRoundRobin(int chunkSize, org.openrdf.rio.RDFHandler... handlers) Returns an RDFHandler that dispatches calls to one of RDFHandlers supplied chosen in a round robin fashion.
static org.openrdf.rio.RDFHandler	ignoreMethods(org.openrdf.rio.RDFHandler handler, int ignoredMethods) Wraps the supplied RDFHandler ignoring calls to the methods specified by the given bitmap.
static org.openrdf.rio.RDFHandler	ignorePasses(org.openrdf.rio.RDFHandler handler, int maxPasses) Wraps the supplied RDFHandler discarding any method call after the specified number of passes has been performed.
static org.openrdf.rio.RDFHandler	synchronize(org.openrdf.rio.RDFHandler handler) Wraps the supplied RDFHandler (if necessary) so that handleXXX() calls are invoked in a mutually exclusive way.
static org.openrdf.rio.RDFHandler	update(String endpointURL) Returns an RDFHandler that uploads data to a SPARQL endpoint via SPARQL Update INSERT DATA calls.
static org.openrdf.rio.RDFHandler	wrap(Collection<? super org.openrdf.model.Statement> statements) Returns an RDFHandler that populates the supplied statement collection.
static org.openrdf.rio.RDFHandler	wrap(Collection<? super org.openrdf.model.Statement> statements, Collection<? super org.openrdf.model.Namespace> namespaces) Returns an RDFHandler that populates the supplied statement and namespace collections.
static org.openrdf.rio.RDFHandler	wrap(Collection<? super org.openrdf.model.Statement> statements, Map<? super String,? super String> namespaces) Returns an RDFHandler that populates the supplied statement collection and prefix-to-namespace-uri map.
static org.openrdf.rio.RDFHandler	write(org.openrdf.rio.WriterConfig config, int chunkSize, String... locations) Returns an RDFHandler that writes data to the files at the locations specified.

Methods inherited from class java.lang.Object

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

Field Detail

METHOD_START_RDF

public static final int METHOD_START_RDF

The int value for method RDFHandler.startRDF().

See Also:

Constant Field Values

METHOD_HANDLE_COMMENT

public static final int METHOD_HANDLE_COMMENT

The int value for method RDFHandler.handleComment(String).

See Also:

Constant Field Values

METHOD_HANDLE_NAMESPACE

public static final int METHOD_HANDLE_NAMESPACE

The int value for method RDFHandler.handleNamespace(String, String).

See Also:

Constant Field Values

METHOD_HANDLE_STATEMENT

public static final int METHOD_HANDLE_STATEMENT

The int value for method RDFHandler.handleStatement(Statement).

See Also:

Constant Field Values

METHOD_END_RDF

public static final int METHOD_END_RDF

The int value for method RDFHandler.endRDF().

See Also:

Constant Field Values

METHOD_CLOSE

public static final int METHOD_CLOSE

The int value for method AutoCloseable.close().

See Also:

Constant Field Values

NIL

public static final AbstractRDFHandler NIL

The null RDFHandler that does nothing.

Method Detail

wrap

public static org.openrdf.rio.RDFHandler wrap(Collection<? super org.openrdf.model.Statement> statements)

Returns an RDFHandler that populates the supplied statement collection. If the collection is a Model or a QuadModel, it is also populated with namespaces. If you don't want to populate namespaces, use wrap(Collection, Collection) passing null as second argument. Note that access to the collection is not synchronized, so it must be thread-safe.

Parameters:

statements - the statement collection to populate, not null

Returns:

the created RDFHandler

wrap

public static org.openrdf.rio.RDFHandler wrap(Collection<? super org.openrdf.model.Statement> statements,
                                              @Nullable
                                              Collection<? super org.openrdf.model.Namespace> namespaces)

Returns an RDFHandler that populates the supplied statement and namespace collections. Access to the two collections is not synchronized, so they MUST be thread safe (may use Collections.synchronizedCollection(Collection)).

Parameters:

statements - the statement collection to populate, not null

namespaces - the namespace collection to populate, or null to discard namespaces

Returns:

the created RDFHandler

wrap

public static org.openrdf.rio.RDFHandler wrap(Collection<? super org.openrdf.model.Statement> statements,
                                              @Nullable
                                              Map<? super String,? super String> namespaces)

Returns an RDFHandler that populates the supplied statement collection and prefix-to-namespace-uri map. Access to the collection and map is not synchronized, so they MUST be thread-safe (may use Collections.synchronizedCollection(Collection) and Collections.synchronizedMap(Map)).

Parameters:

statements - the statement collection to populate, not null

namespaces - the prefix-to-namespace-uri map to populate, or null to discard namespaces

Returns:

the created RDFHandler

write

public static org.openrdf.rio.RDFHandler write(@Nullable
                                               org.openrdf.rio.WriterConfig config,
                                               int chunkSize,
                                               String... locations)

Returns an RDFHandler that writes data to the files at 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. Currently, URL different from file:// are not supported, i.e., only local files can be written. If more locations are specified, statements are divided among them evenly (in chunks of configurable size). If no locations are given, the NIL handler is returned. Note that data is written at each pass, so you may consider filtering out multiple passes to avoid writing the same data again.

Parameters:

config - the optional WriterConfig for fine tuning the writing process; if null, a default configuration enabling pretty printing will be used

chunkSize - the number of consecutive statements to write as a block to a single location (at least 1)

locations - the locations of the files to write

Returns:

the created RDFHandler

update

public static org.openrdf.rio.RDFHandler update(String endpointURL)

Returns an RDFHandler that uploads data to a SPARQL endpoint via SPARQL Update INSERT DATA calls. Note that data is written at each pass, so you may consider filtering out multiple passes to avoid writing the same data again.

Parameters:

endpointURL - the URL of the SPARQL Update endpoint, not null

Returns:

the created RDFHandler

ignoreMethods

public static org.openrdf.rio.RDFHandler ignoreMethods(org.openrdf.rio.RDFHandler handler,
                                                       int ignoredMethods)

Wraps the supplied RDFHandler ignoring calls to the methods specified by the given bitmap. Calling an ignored method on the returned RDFHandler produces no effect, while calls to other method are forwarded to the wrapped handler. Use constants METHOD_XXX in this class (OR-ed together) to define which methods to ignore.

Parameters:

handler - the handler to wrap, not null

ignoredMethods - a bitmap specifying which methods to ignore

Returns:

the created RDFHandler wrapper

ignorePasses

public static org.openrdf.rio.RDFHandler ignorePasses(org.openrdf.rio.RDFHandler handler,
                                                      int maxPasses)

Wraps the supplied RDFHandler discarding any method call after the specified number of passes has been performed. Calls to close() are always propagated, however.

Parameters:

handler - the handler to wrap, not null

maxPasses - the maximum number of passes to perform; additional passes will be ignored

Returns:

the created RDFHandler wrapper

dispatchAll

public static org.openrdf.rio.RDFHandler dispatchAll(org.openrdf.rio.RDFHandler... handlers)

Returns an RDFHandler that dispatches calls to all the RDFHandlers supplied. If no RDFHandler is supplied, NIL is returned.

Parameters:

handlers - the RDFHandlers to forward calls to

Returns:

the created RDFHandler dispatcher

dispatchAll

public static org.openrdf.rio.RDFHandler dispatchAll(org.openrdf.rio.RDFHandler[] handlers,
                                                     int[] extraPasses)

Returns an RDFHandler that dispatches calls to all the RDFHandlers supplied, optionally performing more passes on selected handlers. Argument extraPasses controls how many passes a supplied handler should perform w.r.t. other handlers. Operatively, if N is the maximum number in extraPasses, at pass I < N the dispatcher will forward calls only to handles whose extra passes value is greater than N - I; in passes I >= N all handlers will be called. This mechanism allows for selected handlers to receive the additional passes they need for their initialization, without performing these passes also on other handlers that do not need them. Note that if no RDFHandler is supplied, NIL is returned.

Parameters:

handlers - the RDFHandlers to forward calls to

extraPasses - the number of extra passes for each supplied handler

Returns:

the created RDFHandler dispatcher

dispatchRoundRobin

public static org.openrdf.rio.RDFHandler dispatchRoundRobin(int chunkSize,
                                                            org.openrdf.rio.RDFHandler... handlers)

Returns an RDFHandler that dispatches calls to one of RDFHandlers supplied chosen in a round robin fashion. More precisely, calls to methods RDFHandler.handleStatement(Statement) and RDFHandler.handleComment(String) are forwarded in a round robin fashion, with each chunk of chunkSize >= 1 consecutive calls dispatched to a certain handler. Other methods are always forwarded to all the handlers. If no RDFHandler is supplied, NIL is returned.

Parameters:

chunkSize - the chunk size, greater than or equal to 1; you may use this parameter to keep triples that are received consecutively together (as far as possible) when propagated to wrapped handlers, e.g., because in this way they compress better when written to a file (assuming input triples are somehow sorted)

handlers - the RDFHandlers to forward calls to, in a round robin fashion

Returns:

the created RDFHandler dispatcher

collect

public static org.openrdf.rio.RDFHandler[] collect(org.openrdf.rio.RDFHandler handler,
                                                   int count,
                                                   SetOperator operation)

Returns an RDFHandler that collects multiple streams of RDF data, merging them by means in a unique stream using a SetOperator. This method accepts as arguments the sink where to forward the merged RDF stream, the SetOperator to apply and the number of input streams to collect. The method returns an array of RDFHandler, one for each input stream to be collected, that can be used by the method caller to provide the data to be merged.

Parameters:

handler - the handler to decompose, not null

count - the number of streams to collect and consequently the number of RDFHandlers to return (at least 1)

operation - the set operation to apply to merge input RDF streams

Returns:

the created RDFHandlers

decouple

public static org.openrdf.rio.RDFHandler decouple(org.openrdf.rio.RDFHandler handler)

Wraps the supplied RDFHandler (if necessary) so to buffer incoming statements and use additional threads for their processing. An RDFHandler that has already been decoupled is not wrapped again.

Parameters:

handler - the handler to wrap

Returns:

the (possibly) wrapped handler

decouple

public static org.openrdf.rio.RDFHandler decouple(org.openrdf.rio.RDFHandler handler,
                                                  int numConsumerThreads)

Wraps the supplied RDFHandelr (if necessary) using a queue to decouple threads submitting statements from threads consuming them. A positive number of consumer threads should be specified. Wrapping does not occur if the handler is already decoupled using a queue.

Parameters:

handler - the handler to wrap

numConsumerThreads - the number of consumer threads, positive

Returns:

the (possibly) wrapped handler

synchronize

public static org.openrdf.rio.RDFHandler synchronize(org.openrdf.rio.RDFHandler handler)

Wraps the supplied RDFHandler (if necessary) so that handleXXX() calls are invoked in a mutually exclusive way. This method can be used with RDFHandlers that are not thread-safe.

Parameters:

handler - the handler to wrap

Returns:

the (possibly) wrapped handler