/*
* 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.marmotta.loader.titan;
import com.thinkaurelius.titan.core.TitanGraph;
import com.tinkerpop.blueprints.Edge;
import com.tinkerpop.blueprints.TransactionalGraph;
import com.tinkerpop.blueprints.Vertex;
import com.tinkerpop.blueprints.util.wrappers.batch.BatchGraph;
import org.openrdf.model.*;
import org.openrdf.rio.RDFHandler;
import org.openrdf.rio.RDFHandlerException;
import java.util.HashSet;
import java.util.Set;
/**
* An RDF handler for bulk loading RDF data into a Blueprints graph accessed through a Blueprints
* GraphSail.
*
* @author Sebastian Schaffert (sschaffert@apache.org)
*/
public class TitanRDFHandler implements RDFHandler {
public static final String SEPARATOR = " ";
public static final String
PREDICATE_PROP = "p",
CONTEXT_PROP = "c";
public static final char
URI_PREFIX = 'U',
BLANK_NODE_PREFIX = 'B',
PLAIN_LITERAL_PREFIX = 'P',
TYPED_LITERAL_PREFIX = 'T',
LANGUAGE_TAG_LITERAL_PREFIX = 'L',
NULL_CONTEXT_PREFIX = 'N';
public static final String
BNODE = "bnode",
INFERRED = "inferred",
KIND = "kind",
LANG = "lang",
LITERAL = "literal",
TYPE = "type",
URI = "uri",
VALUE = "value";
public static final String NULL_CONTEXT_NATIVE = "" + NULL_CONTEXT_PREFIX;
private static final String NAMESPACES_VERTEX_ID = "urn:com.tinkerpop.blueprints.pgm.oupls.sail:namespaces";
public static final String DEFAULT_NAMESPACE_PREFIX_KEY = "default-namespace";
private BatchGraph<TitanGraph> graph;
private Vertex namespaces;
private long triples = 0;
/**
* Initialise the handler using the graph passed as arguments.
*
* @param graph
*/
public TitanRDFHandler(TitanGraph graph, String indexes) {
this.graph = new BatchGraph(graph);
if (!graph.getIndexedKeys(Vertex.class).contains(VALUE)) {
graph.createKeyIndex(VALUE, Vertex.class);
}
createTripleIndices(indexes, graph);
namespaces = graph.addVertex(NAMESPACES_VERTEX_ID);
}
public TitanRDFHandler() {
super();
}
/**
* Signals the start of the RDF data. This method is called before any data
* is reported.
*
* @throws org.openrdf.rio.RDFHandlerException If the RDF handler has encountered an unrecoverable error.
*/
@Override
public void startRDF() throws RDFHandlerException {
}
/**
* Signals the end of the RDF data. This method is called when all data has
* been reported.
*
* @throws org.openrdf.rio.RDFHandlerException If the RDF handler has encountered an unrecoverable error.
*/
@Override
public void endRDF() throws RDFHandlerException {
if(graph instanceof TransactionalGraph) {
((TransactionalGraph)graph).commit();
}
}
/**
* Handles a namespace declaration/definition. A namespace declaration
* associates a (short) prefix string with the namespace's URI. The prefix
* for default namespaces, which do not have an associated prefix, are
* represented as empty strings.
*
* @param prefix The prefix for the namespace, or an empty string in case of a
* default namespace.
* @param uri The URI that the prefix maps to.
* @throws org.openrdf.rio.RDFHandlerException If the RDF handler has encountered an unrecoverable error.
*/
@Override
public void handleNamespace(String prefix, String uri) throws RDFHandlerException {
namespaces.setProperty(toNativePrefixKey(prefix), uri);
}
/**
* Handles a statement.
*
* @param st The statement.
* @throws org.openrdf.rio.RDFHandlerException If the RDF handler has encountered an unrecoverable error.
*/
@Override
public void handleStatement(Statement st) throws RDFHandlerException {
Vertex out = getOrCreateVertex(st.getSubject());
Vertex in = getOrCreateVertex(st.getObject());
Edge edge = graph.addEdge(null, out, in, st.getPredicate().stringValue());
if (null == edge.getProperty(CONTEXT_PROP)) {
edge.setProperty(CONTEXT_PROP, valueToNative(st.getContext()));
}
triples ++;
if(triples % 10000 == 0 && graph instanceof TransactionalGraph) {
((TransactionalGraph)graph).commit();
}
}
/**
* Handles a comment.
*
* @param comment The comment.
* @throws org.openrdf.rio.RDFHandlerException If the RDF handler has encountered an unrecoverable error.
*/
@Override
public void handleComment(String comment) throws RDFHandlerException {
}
private Vertex addVertex(final Value value) {
Vertex v = graph.addVertex(valueToNative(value));
if (value instanceof URI) {
v.setProperty(KIND, URI);
v.setProperty(VALUE, value.stringValue());
} else if (value instanceof Literal) {
Literal l = (Literal) value;
v.setProperty(KIND, LITERAL);
v.setProperty(VALUE, l.getLabel());
if (null != l.getDatatype()) {
v.setProperty(TYPE, l.getDatatype().stringValue());
}
if (null != l.getLanguage()) {
v.setProperty(LANG, l.getLanguage());
}
} else if (value instanceof BNode) {
BNode b = (BNode) value;
v.setProperty(KIND, BNODE);
v.setProperty(VALUE, b.getID());
} else {
throw new IllegalStateException("value of unexpected type: " + value);
}
return v;
}
private Vertex findVertex(final Value value) {
return graph.getVertex(valueToNative(value));
}
private Vertex getOrCreateVertex(final Value value) {
Vertex v = findVertex(value);
if (null == v) {
v = addVertex(value);
}
return v;
}
public String valueToNative(final Value value) {
if (null == value) {
return NULL_CONTEXT_NATIVE;
} else if (value instanceof Resource) {
return resourceToNative((Resource) value);
} else if (value instanceof Literal) {
return literalToNative((Literal) value);
} else {
throw new IllegalStateException("Value has unfamiliar type: " + value);
}
}
public String resourceToNative(final Resource value) {
if (value instanceof URI) {
return uriToNative((URI) value);
} else if (value instanceof BNode) {
return bnodeToNative((BNode) value);
} else {
throw new IllegalStateException("Resource has unfamiliar type: " + value);
}
}
public String uriToNative(final URI value) {
return URI_PREFIX + SEPARATOR + value.toString();
}
public String bnodeToNative(final BNode value) {
return BLANK_NODE_PREFIX + SEPARATOR + value.getID();
}
public String literalToNative(final Literal literal) {
URI datatype = literal.getDatatype();
if (null == datatype) {
String language = literal.getLanguage();
if (null == language) {
return PLAIN_LITERAL_PREFIX + SEPARATOR + literal.getLabel();
} else {
return LANGUAGE_TAG_LITERAL_PREFIX + SEPARATOR + language + SEPARATOR + literal.getLabel();
}
} else {
return "" + TYPED_LITERAL_PREFIX + SEPARATOR + datatype + SEPARATOR + literal.getLabel();
}
}
private String toNativePrefixKey(final String prefix) {
return 0 == prefix.length() ? DEFAULT_NAMESPACE_PREFIX_KEY : prefix;
}
private void createTripleIndices(final String tripleIndexes, TitanGraph titanGraph) {
if (null == tripleIndexes) {
throw new IllegalArgumentException("index list, if supplied, must be non-null");
}
Set<String> u = new HashSet<String>();
String[] a = tripleIndexes.split(",");
for (String s : a) {
String pattern = s.trim();
if (pattern.length() > 0) {
u.add(pattern);
}
}
for (String key : u) {
if (!titanGraph.getIndexedKeys(Edge.class).contains(key)) {
titanGraph.createKeyIndex(key, Edge.class);
}
}
}
}