001/*
002 * (C) Copyright 2006-2007 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     <a href="mailto:[email protected]">Anahide Tchertchian</a>
018 *
019 * $Id: IORelationGraphHelper.java 25081 2007-09-18 14:57:22Z atchertchian $
020 */
021
022package org.nuxeo.ecm.platform.relations.io;
023
024import java.io.InputStream;
025import java.io.OutputStream;
026import java.util.List;
027import java.util.Map;
028
029import org.nuxeo.ecm.platform.relations.api.Graph;
030import org.nuxeo.ecm.platform.relations.api.Statement;
031import org.nuxeo.ecm.platform.relations.jena.JenaGraph;
032
033/**
034 * Relation graph importer/exporter.
035 * <p>
036 * relies on Jena memory graphs to perform serialization and deserialization of memory graphs.
037 *
038 * @author <a href="mailto:[email protected]">Anahide Tchertchian</a>
039 */
040public class IORelationGraphHelper {
041
042    protected final Map<String, String> namespaces;
043
044    protected List<Statement> statements;
045
046    public IORelationGraphHelper(Map<String, String> namespaces, List<Statement> statements) {
047        this.namespaces = namespaces;
048        this.statements = statements;
049    }
050
051    public List<Statement> getStatements() {
052        return statements;
053    }
054
055    protected Graph createMemoryGraph() {
056        JenaGraph graph = new JenaGraph();
057        graph.setNamespaces(namespaces);
058        return graph;
059    }
060
061    public void write(OutputStream out) {
062        Graph graph = createMemoryGraph();
063        if (statements != null) {
064            graph.add(statements);
065        }
066        graph.write(out, null, null);
067    }
068
069    public void read(InputStream in) {
070        Graph graph = createMemoryGraph();
071        if (statements != null) {
072            graph.add(statements);
073        }
074        graph.read(in, null, null);
075        // update current statements with new ones
076        statements = graph.getStatements();
077    }
078
079    public Graph getGraph() {
080        Graph graph = createMemoryGraph();
081        if (statements != null) {
082            graph.add(statements);
083        }
084        return graph;
085    }
086
087}