org.wikidata.query.rdf.blazegraph.label

Class LabelService

java.lang.Object

com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactoryBase

com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactory

org.wikidata.query.rdf.blazegraph.label.LabelService

All Implemented Interfaces:

com.bigdata.rdf.sparql.ast.service.ServiceFactory

public class LabelService
extends com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactory

Implements a "service" that resolves label like things in a way that doesn't change the cardinality of the result set. You can call it like this: SELECT * WHERE { SERVICE wikibase:label { bd:serviceParam wikibase:language "en,de,fr" . wd:Q123 rdfs:label ?q123Label . wd:Q123 rdfs:altLabel ?q123Alt . wd:Q123 schema:description ?q123Desc . wd:Q321 rdf:label ?q321Label . } } or like this: SELECT ?sLabel ?sAltLabel ?sDescription ?oLabel WHERE { ?s wdt:P22 ?o . SERVICE wikibase:label { bd:serviceParam wikibase:language "en,de" . bd:serviceParam wikibase:language "fr" . } }

If the label isn't available in any of the fallback languages it'll come back as the entityId. Alt labels and descriptions just come back unbound if they don't exist. If multiple values are defined they come back as a comma separated list.

This works by resolving the label-like thing per incoming binding, one at a time. It would probably be faster to do something bulkish but we don't do that yet. The code to do the comma separated lists and entityIds is pretty simple once you've resolve the data.

The second invocation pattern works using EmptyLabelServiceOptimizer to inspect the query and automatically build the first form out of the second form by inspecting the query's projection.

Field Summary

Fields

Modifier and Type	Field and Description
static org.openrdf.model.URI	SERVICE_KEY The URI service key.

Constructor Summary

Constructors

Constructor and Description
LabelService()

Method Summary

Methods

Modifier and Type	Method and Description
com.bigdata.rdf.sparql.ast.service.BigdataServiceCall	create(com.bigdata.rdf.sparql.ast.service.ServiceCallCreateParams params, com.bigdata.rdf.sparql.ast.eval.ServiceParams serviceParams)
com.bigdata.rdf.sparql.ast.service.IServiceOptions	getServiceOptions()
static void	register() Register the service so it is recognized by Blazegraph.

Methods inherited from class com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactory

create

Methods inherited from class com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactoryBase

getDesiredBound, getRequiredBound

Methods inherited from class java.lang.Object

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

Field Detail

SERVICE_KEY

public static final org.openrdf.model.URI SERVICE_KEY

The URI service key.

Constructor Detail

LabelService

public LabelService()

Method Detail

register

public static void register()

Register the service so it is recognized by Blazegraph.

getServiceOptions

public com.bigdata.rdf.sparql.ast.service.IServiceOptions getServiceOptions()

create

public com.bigdata.rdf.sparql.ast.service.BigdataServiceCall create(com.bigdata.rdf.sparql.ast.service.ServiceCallCreateParams params,
                                                           com.bigdata.rdf.sparql.ast.eval.ServiceParams serviceParams)

Specified by:

create in class com.bigdata.rdf.sparql.ast.eval.AbstractServiceFactory