com.bigdata.rdf

Class ServiceProviderHook

java.lang.Object

com.bigdata.rdf.ServiceProviderHook

public class ServiceProviderHook
extends Object

This static class provides a hook which allows the replacement of services registered via the openrdf ServiceRegistry pattern which makes use of the same underlying pattern which is disclosed by the ServiceLoader.

The ServiceRegistry pattern provides a declarative association between a service and a service provider. The service declarations are located in META-INF/services/ packages. Each file in such a package name the service interface and the contents of the file name the service provider(s). The set of all such service provides located in all such service packages is registered for a given service interface. For openrdf, the service provides are initially associated with a key, such as an RDFFormat, QueryLanguage, etc.

However, this service registration pattern does not support the specification of a preferred service provider. In the context of multiple service providers for the same key and service interface, there is no way to control which service provider will remain in the ServiceRegistry.

This effects things such as the bigdata extension for the RDF/XML parser which adds support for SIDs mode interchange and the interchange of StatementEnum metadata.

This class is used to "hook" the various service registeries and force the use of the bigdata extension when it adds semantics not present in the base service provider implementation. For such "hooked" services providers, the service registry pattern using META-INF/services is not manditory, but following the pattern is never the less recommended.

Author:

Bryan Thompson

See Also:

Class loader problems

Field Summary

Fields

Modifier and Type	Field and Description
static String	JSON_CONSTRUCT_PARSER_FACTORY
static String	JSON_CONSTRUCT_WRITER_FACTORY
static org.openrdf.rio.RDFFormat	JSON_RDR The extension MIME type for RDR aware data interchange of RDF and SPARQL result stes using JSON.
static String	JSON_RESULT_PARSER_FACTORY
static String	JSON_WRITER_FACTORY
static String	NTRIPLES_PARSER_FACTORY
static org.openrdf.rio.RDFFormat	NTRIPLES_RDR The extension MIME type for RDR data interchange using the RDR extension of N-TRIPLES.
static String	TURTLE_PARSER_FACTORY
static org.openrdf.rio.RDFFormat	TURTLE_RDR The extension MIME type for RDR data interchange using the RDR extension of TURTLE.
static String	TURTLE_WRITER_FACTORY

Constructor Summary

Constructors

Constructor and Description
ServiceProviderHook()

Method Summary

Methods

Modifier and Type	Method and Description
static void	forceLoad() This hook may be used to force the load of this class so it can ensure that the bigdata version of a service provider is used instead of the openrdf version.
protected static Object	getInstanceForClass(String className)

Methods inherited from class java.lang.Object

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

Field Detail

NTRIPLES_PARSER_FACTORY

public static final String NTRIPLES_PARSER_FACTORY

See Also:

Constant Field Values

TURTLE_PARSER_FACTORY

public static final String TURTLE_PARSER_FACTORY

See Also:

Constant Field Values

TURTLE_WRITER_FACTORY

public static final String TURTLE_WRITER_FACTORY

See Also:

Constant Field Values

JSON_WRITER_FACTORY

public static final String JSON_WRITER_FACTORY

See Also:

Constant Field Values

JSON_CONSTRUCT_WRITER_FACTORY

public static final String JSON_CONSTRUCT_WRITER_FACTORY

See Also:

Constant Field Values

JSON_RESULT_PARSER_FACTORY

public static final String JSON_RESULT_PARSER_FACTORY

See Also:

Constant Field Values

JSON_CONSTRUCT_PARSER_FACTORY

public static final String JSON_CONSTRUCT_PARSER_FACTORY

See Also:

Constant Field Values

TURTLE_RDR

public static final org.openrdf.rio.RDFFormat TURTLE_RDR

The extension MIME type for RDR data interchange using the RDR extension of TURTLE.

See Also:

RDR RDF parsers not always discovered , http://wiki.blazegraph.com/wiki/index.php/Reification_Done_Right

NTRIPLES_RDR

public static final org.openrdf.rio.RDFFormat NTRIPLES_RDR

The extension MIME type for RDR data interchange using the RDR extension of N-TRIPLES.

See Also:

RDR RDF parsers not always discovered , http://wiki.blazegraph.com/wiki/index.php/Reification_Done_Right

JSON_RDR

public static final org.openrdf.rio.RDFFormat JSON_RDR

The extension MIME type for RDR aware data interchange of RDF and SPARQL result stes using JSON.

Constructor Detail

ServiceProviderHook

public ServiceProviderHook()

Method Detail

forceLoad

public static void forceLoad()

This hook may be used to force the load of this class so it can ensure that the bigdata version of a service provider is used instead of the openrdf version. This is NOT optional. Without this hook, we do not have control over which version is resolved last in the processed META-INF/services files.

Note: We need to use a synchronized pattern in order to ensure that any threads contending for this method awaits its completion. It would not be enough for a thread to know that the method was running. The thread needs to wait until the method is done.

getInstanceForClass

protected static Object getInstanceForClass(String className)