/*
* 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.jaxrs.rdf.providers;
import org.apache.clerezza.rdf.core.serializedform.Serializer;
import org.apache.clerezza.rdf.core.serializedform.SupportedFormat;
import java.io.IOException;
import java.io.OutputStream;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javax.ws.rs.Produces;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
import org.apache.clerezza.rdf.core.Resource;
import org.apache.clerezza.rdf.core.Triple;
import org.apache.clerezza.rdf.core.TripleCollection;
import org.apache.clerezza.rdf.core.UriRef;
import org.apache.clerezza.rdf.core.impl.SimpleMGraph;
import org.apache.clerezza.rdf.utils.GraphNode;
/**
* By default this returns a serialization of the context of the GraphNode.
*
* The expansion can be widened by using the query parameters xPropObj and
* xProSubj. These parameters specify property uris (both parameters might be
* repeated). For the specified properties their objects respectively subjects
* are expanded as if they were bnodes.
*
* @scr.component
* @scr.service interface="java.lang.Object"
* @scr.property name="javax.ws.rs" type="Boolean" value="true"
*
* @author reto
*/
@Provider
@Produces({SupportedFormat.N3, SupportedFormat.N_TRIPLE,
SupportedFormat.RDF_XML, SupportedFormat.TURTLE,
SupportedFormat.X_TURTLE, SupportedFormat.RDF_JSON})
public class GraphNodeWriter implements MessageBodyWriter<GraphNode> {
public static final String OBJ_EXP_PARAM = "xPropObj";
public static final String SUBJ_EXP_PARAM = "xPropSubj";
/**
* @scr.reference
*/
private Serializer serializer;
private UriInfo uriInfo;
@Override
public boolean isWriteable(Class<?> type, Type genericType,
Annotation[] annotations, MediaType mediaType) {
return GraphNode.class.isAssignableFrom(type);
}
@Override
public long getSize(GraphNode n, Class<?> type, Type genericType,
Annotation[] annotations, MediaType mediaType) {
return -1;
}
@Override
public void writeTo(GraphNode node, Class<?> type, Type genericType,
Annotation[] annotations, MediaType mediaType,
MultivaluedMap<String, Object> httpHeaders,
OutputStream entityStream) throws IOException, WebApplicationException {
serializer.serialize(entityStream, getExpandedContext(node), mediaType.toString());
}
@Context
public void setUriInfo(UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
private TripleCollection getExpandedContext(GraphNode node) {
final TripleCollection result = new SimpleMGraph(node.getNodeContext());
final Set<Resource> expandedResources = new HashSet<Resource>();
expandedResources.add(node.getNode());
while (true) {
Set<Resource> additionalExpansionRes = getAdditionalExpansionResources(result);
additionalExpansionRes.removeAll(expandedResources);
if (additionalExpansionRes.size() == 0) {
return result;
}
for (Resource resource : additionalExpansionRes) {
final GraphNode additionalNode = new GraphNode(resource, node.getGraph());
result.addAll(additionalNode.getNodeContext());
expandedResources.add(resource);
}
}
}
private Set<Resource> getAdditionalExpansionResources(TripleCollection tc) {
final Set<UriRef> subjectExpansionProperties = getSubjectExpansionProperties();
final Set<UriRef> objectExpansionProperties = getObjectExpansionProperties();
final Set<Resource> result = new HashSet<Resource>();
if ((subjectExpansionProperties.size() > 0)
|| (objectExpansionProperties.size() > 0)) {
for (Triple triple : tc) {
final UriRef predicate = triple.getPredicate();
if (subjectExpansionProperties.contains(predicate)) {
result.add(triple.getSubject());
}
if (objectExpansionProperties.contains(predicate)) {
result.add(triple.getObject());
}
}
}
return result;
}
private Set<UriRef> getSubjectExpansionProperties() {
final MultivaluedMap<String, String> queryParams = uriInfo.getQueryParameters();
final List<String> paramValues = queryParams.get(SUBJ_EXP_PARAM);
if (paramValues == null) {
return new HashSet<UriRef>(0);
}
final Set<UriRef> result = new HashSet<UriRef>(paramValues.size());
for (String uriString : paramValues) {
result.add(new UriRef(uriString));
}
return result;
}
private Set<UriRef> getObjectExpansionProperties() {
final MultivaluedMap<String, String> queryParams = uriInfo.getQueryParameters();
final List<String> paramValues = queryParams.get(OBJ_EXP_PARAM);
if (paramValues == null) {
return new HashSet<UriRef>(0);
}
final Set<UriRef> result = new HashSet<UriRef>(paramValues.size());
for (String uriString : paramValues) {
result.add(new UriRef(uriString));
}
return result;
}
}