/**
* Copyright 2005-2014 Restlet
*
* The contents of this file are subject to the terms of one of the following
* open source licenses: Apache 2.0 or or EPL 1.0 (the "Licenses"). You can
* select the license that you prefer but you may not use this file except in
* compliance with one of these Licenses.
*
* You can obtain a copy of the Apache 2.0 license at
* http://www.opensource.org/licenses/apache-2.0
*
* You can obtain a copy of the EPL 1.0 license at
* http://www.opensource.org/licenses/eclipse-1.0
*
* See the Licenses for the specific language governing permissions and
* limitations under the Licenses.
*
* Alternatively, you can obtain a royalty free commercial license with less
* limitations, transferable or non-transferable, directly at
* http://restlet.com/products/restlet-framework
*
* Restlet is a registered trademark of Restlet S.A.S.
*/
package org.restlet.ext.rdf;
import java.net.URI;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Level;
import org.restlet.Context;
import org.restlet.Request;
import org.restlet.Response;
import org.restlet.data.ClientInfo;
import org.restlet.data.MediaType;
import org.restlet.data.Method;
import org.restlet.data.Preference;
import org.restlet.data.Reference;
import org.restlet.representation.Representation;
import org.restlet.resource.ClientResource;
/**
* Linked client resource. In addition to regular client resources, this class
* offers additional method aware of links exposed by RDF, making it natural to
* navigate the Web of data.
*
* @author Jerome Louvel
*/
public class RdfClientResource extends ClientResource {
/** The links cache. */
private Graph links;
/**
* Constructor.
*
* @param context
* The context.
* @param method
* The method to call.
* @param reference
* The target reference.
*/
public RdfClientResource(Context context, Method method, Reference reference) {
super(context, method, reference);
}
/**
* Constructor.
*
* @param context
* The context.
* @param method
* The method to call.
* @param uri
* The target URI.
*/
public RdfClientResource(Context context, Method method, String uri) {
super(context, method, uri);
}
/**
* Constructor.
*
* @param context
* The context.
* @param method
* The method to call.
* @param uri
* The target URI.
*/
public RdfClientResource(Context context, Method method, URI uri) {
super(context, method, uri);
}
/**
* Constructor.
*
* @param context
* The context.
* @param reference
* The target reference.
*/
public RdfClientResource(Context context, Reference reference) {
super(context, reference);
}
/**
* Constructor.
*
* @param context
* The current context.
* @param request
* The handled request.
* @param response
* The handled response.
*/
public RdfClientResource(Context context, Request request, Response response) {
super(context, request, response);
}
/**
* Constructor.
*
* @param context
* The context.
* @param uri
* The target URI.
*/
public RdfClientResource(Context context, String uri) {
super(context, uri);
}
/**
* Constructor.
*
* @param context
* The context.
* @param uri
* The target URI.
*/
public RdfClientResource(Context context, URI uri) {
super(context, uri);
}
/**
* Constructor.
*
* @param method
* The method to call.
* @param reference
* The target reference.
*/
public RdfClientResource(Method method, Reference reference) {
super(method, reference);
}
/**
* Constructor.
*
* @param method
* The method to call.
* @param uri
* The target URI.
*/
public RdfClientResource(Method method, String uri) {
super(method, uri);
}
/**
* Constructor.
*
* @param method
* The method to call.
* @param uri
* The target URI.
*/
public RdfClientResource(Method method, URI uri) {
super(method, uri);
}
/**
* Constructor.
*
* @param reference
* The target reference.
*/
public RdfClientResource(Reference reference) {
super(reference);
}
/**
* Constructor.
*
* @param request
* The handled request.
* @param response
* The handled response.
*/
public RdfClientResource(Request request, Response response) {
super(request, response);
}
/**
* Constructor.
*
* @param uri
* The target URI.
*/
public RdfClientResource(String uri) {
super(uri);
}
/**
* Constructor.
*
* @param uri
* The target URI.
*/
public RdfClientResource(URI uri) {
super(uri);
}
/**
* Returns all the linked resources, based on the RDF representation
* exposed.
*
* @return All the linked resources.
* @see #getLinks()
*/
public Set<RdfClientResource> getLinked() {
return getLinked((Collection<Reference>) null);
}
/**
* Returns the linked resources, based on the RDF representation exposed.
* The type of links to follow can be restricted.
*
* @param typeRefs
* The set of types references of the links to select or null.
* @return All the linked resources.
* @see #getLinks()
*/
public Set<RdfClientResource> getLinked(Collection<Reference> typeRefs) {
Set<RdfClientResource> result = null;
Graph links = getLinks();
if (links != null) {
result = new HashSet<RdfClientResource>();
for (Link link : links) {
if (link.hasReferenceTarget()) {
if ((typeRefs == null)
|| typeRefs.contains(link.getTypeRef())) {
result.add(new RdfClientResource(getContext(), link
.getTargetAsReference()));
}
}
}
}
return result;
}
/**
* Returns the linked resources, based on the RDF representation exposed.
* The type of links to follow can be restricted.
*
* @param typeRef
* The type reference of the links to select or null.
* @return All the linked resources.
* @see #getLinks()
*/
public Set<RdfClientResource> getLinked(Reference typeRef) {
return getLinked(Collections.singleton(typeRef));
}
/**
* Returns the links exposed by this resource.
*
* @return The links exposed by this resource.
*/
public Graph getLinks() {
Graph result = this.links;
if (result == null) {
ClientInfo currentInfo = getClientInfo();
// Customize the preferences to maximize the chance of getting RDF
ClientInfo newInfo = new ClientInfo();
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.APPLICATION_RDF_XML));
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.TEXT_RDF_N3));
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.TEXT_RDF_NTRIPLES));
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.TEXT_TURTLE));
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.TEXT_XML, 0.5F));
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.TEXT_PLAIN, 0.4F));
newInfo.getAcceptedMediaTypes().add(
new Preference<MediaType>(MediaType.APPLICATION_ALL_XML,
0.3F));
// Attempt to retrieve the RDF representation
try {
Representation rep = get();
if (rep != null) {
RdfRepresentation rdfRep = new RdfRepresentation(rep);
this.links = rdfRep.getGraph();
result = this.links;
} else {
getLogger().log(
Level.WARNING,
"Unable to retrieve an RDF representation of this resource: "
+ getReference());
}
} catch (Throwable e) {
getLogger().log(
Level.WARNING,
"Unable to retrieve an RDF representation of this resource: "
+ getReference(), e);
}
// Restore previous preferences
setClientInfo(currentInfo);
}
return result;
}
/**
* Returns all the linked literals, based on the RDF representation exposed.
*
* @return All the linked literals.
* @see #getLinks()
*/
public Set<Couple<Reference, Literal>> getLiterals() {
Set<Couple<Reference, Literal>> result = null;
Graph links = getLinks();
if (links != null) {
for (Link link : links) {
if (link.hasLiteralTarget()) {
if (result == null) {
result = new HashSet<Couple<Reference, Literal>>();
}
result.add(new Couple<Reference, Literal>(
link.getTypeRef(), link.getTargetAsLiteral()));
}
}
}
return result;
}
/**
* Returns the linked literals, based on the RDF representation exposed. The
* type of links to follow can be restricted.
*
* @param typeRef
* The type reference of the links to select or null.
* @return All the linked literals.
* @see #getLiterals()
*/
public Set<Literal> getLiterals(Reference typeRef) {
Set<Literal> result = null;
Graph links = getLinks();
if (links != null) {
result = new HashSet<Literal>();
for (Link link : links) {
if (link.hasLiteralTarget()) {
if ((typeRef == null) || typeRef.equals(link.getTypeRef())) {
result.add(link.getTargetAsLiteral());
}
}
}
}
return result;
}
/**
* Refreshes the links cache.
*/
public void refresh() {
this.links = null;
getLinks();
}
}