/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.clerezza.platform.rdf.enrichment;
import java.security.Permission;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import org.apache.clerezza.platform.Constants;
import org.apache.clerezza.platform.graphprovider.content.ContentGraphProvider;
import org.apache.clerezza.rdf.core.Graph;
import org.apache.clerezza.rdf.core.MGraph;
import org.apache.clerezza.rdf.core.TripleCollection;
import org.apache.clerezza.rdf.core.UriRef;
import org.apache.clerezza.rdf.core.access.EntityAlreadyExistsException;
import org.apache.clerezza.rdf.core.access.EntityUndeletableException;
import org.apache.clerezza.rdf.core.access.LockableMGraph;
import org.apache.clerezza.rdf.core.access.NoSuchEntityException;
import org.apache.clerezza.rdf.core.access.TcManager;
import org.apache.clerezza.rdf.core.access.WeightedTcProvider;
import org.apache.clerezza.rdf.core.access.security.TcPermission;
import org.apache.clerezza.rdf.enrichment.Enricher;
import org.apache.clerezza.rdf.enrichment.EnrichmentTriples;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
import org.apache.felix.scr.annotations.ReferencePolicy;
import org.apache.felix.scr.annotations.References;
import org.apache.felix.scr.annotations.Service;
import org.osgi.service.component.ComponentContext;
/**
* Provides a read-only MGraph with the name urn:x-localinstance:/enrichment.graph
* containing the enrichments provided by all available services of type
* Enricher on the content graph.
*
* For performance reasons EnrichmentTcProvider gets the content-graph from
* TcManager and doesn't do access control check on every request, to prevent
* deductions about the content of the content graph by unauthorized users
* the required permissions on the enrichment graph are set to those on the
* content graph.
*
*
* @author reto
*/
@Component
@Service(WeightedTcProvider.class)
@References(
{
@Reference(referenceInterface=Enricher.class, name="enricher",
cardinality=ReferenceCardinality.OPTIONAL_MULTIPLE,
policy=ReferencePolicy.DYNAMIC)
}
)
public class EnrichmentTcProvider implements WeightedTcProvider {
public static final UriRef ENRICHMENT_GRAPH_URI = new UriRef("urn:x-localinstance:/enrichment.graph");
private LockableMGraph contentGraph;
private final Collection<Enricher> enrichers = Collections.synchronizedCollection(new HashSet<Enricher>());
@Reference
private ContentGraphProvider cgProvider;
@Reference
private TcManager tcManager;
@Override
public Graph getGraph(UriRef name) throws NoSuchEntityException {
throw new NoSuchEntityException(name);
}
@Override
public MGraph getMGraph(UriRef name) throws NoSuchEntityException {
if (ENRICHMENT_GRAPH_URI.equals(name)) {
return getEnrichmentGraph();
}
throw new NoSuchEntityException(name);
}
@Override
public TripleCollection getTriples(UriRef name) throws NoSuchEntityException {
if (ENRICHMENT_GRAPH_URI.equals(name)) {
return getEnrichmentGraph();
}
throw new NoSuchEntityException(name);
}
@Override
public Set<UriRef> listGraphs() {
return new HashSet<UriRef>(0);
}
@Override
public Set<UriRef> listMGraphs() {
return Collections.singleton(ENRICHMENT_GRAPH_URI);
}
@Override
public Set<UriRef> listTripleCollections() {
return Collections.singleton(ENRICHMENT_GRAPH_URI);
}
@Override
public MGraph createMGraph(UriRef name) throws UnsupportedOperationException, EntityAlreadyExistsException {
throw new UnsupportedOperationException("creating entities not supported");
}
@Override
public Graph createGraph(UriRef name, TripleCollection triples) throws UnsupportedOperationException, EntityAlreadyExistsException {
throw new UnsupportedOperationException("creating entities not supported");
}
@Override
public void deleteTripleCollection(UriRef name) throws UnsupportedOperationException, NoSuchEntityException, EntityUndeletableException {
throw new UnsupportedOperationException("deleting entities not supported");
}
@Override
public Set<UriRef> getNames(Graph graph) {
return new HashSet<UriRef>(0);
}
@Override
public int getWeight() {
return 0;
}
private MGraph getEnrichmentGraph() {
return new EnrichmentTriples(contentGraph, enrichers);
}
/**
* avtivates the component and adds the enrichment-graph to the virtual
* content graph.
*
* gets the base content-graph from tcManager and sets the permission
* required to access the enrichment-graph accordingly
*/
protected void activate(ComponentContext context) {
contentGraph = tcManager.getMGraph(Constants.CONTENT_GRAPH_URI);
Collection<Permission> requiredReadPermissions =
tcManager.getTcAccessController().getRequiredReadPermissions(Constants.CONTENT_GRAPH_URI);
if (requiredReadPermissions.isEmpty()) {
tcManager.getTcAccessController().setRequiredReadPermissionStrings(
ENRICHMENT_GRAPH_URI, Collections.singleton(
new TcPermission(Constants.CONTENT_GRAPH_URI_STRING, TcPermission.READ).toString()
));
} else {
tcManager.getTcAccessController().setRequiredReadPermissions(
ENRICHMENT_GRAPH_URI, requiredReadPermissions);
}
cgProvider.addTemporaryAdditionGraph(ENRICHMENT_GRAPH_URI);
}
/**
* deactivates the compononent removing the enrichment-graph from the
* virtual content graph
*/
protected void deactivate(ComponentContext context) {
cgProvider.removeTemporaryAdditionGraph(ENRICHMENT_GRAPH_URI);
contentGraph = null;
}
protected void bindEnricher(Enricher enricher) {
enrichers.add(enricher);
}
protected void unbindEnricher(Enricher enricher) {
enrichers.remove(enricher);
}
}