org.metaservice.frontend.rest.SparqlResourceService.java Source code

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Here is the source code for org.metaservice.frontend.rest.SparqlResourceService.java

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/*
 * Copyright 2015 Nikola Ilo
 *
 * Licensed 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.metaservice.frontend.rest;

import org.apache.commons.io.IOUtils;
import org.apache.http.client.fluent.Form;
import org.apache.http.client.fluent.Request;
import org.apache.http.client.utils.URIBuilder;
import org.jetbrains.annotations.NotNull;
import org.metaservice.frontend.rest.api.ResourceService;

import javax.xml.bind.DatatypeConverter;
import java.io.IOException;
import java.io.InputStream;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by ilo on 02.09.2015.
 */
public class SparqlResourceService implements ResourceService {
    private final URI uri;
    private final String resourceQuery;

    private String generateNamespaceString() {
        HashMap<String, String> namespaceMap = new HashMap<>();
        namespaceMap.put("admssw", "http://purl.org/adms/sw/");
        namespaceMap.put("bds", "http://www.blazegraph.com/rdf/search#");
        namespaceMap.put("cc", "http://creativecommons.org/ns#");
        namespaceMap.put("dc", "http://purl.org/dc/elements/1.1/");
        namespaceMap.put("dcterms", "http://purl.org/dc/terms/");
        namespaceMap.put("doap", "http://usefulinc.com/ns/doap#");
        namespaceMap.put("foaf", "http://xmlns.com/foaf/0.1/");
        namespaceMap.put("ms", "http://metaservice.org/ns/metaservice#");
        namespaceMap.put("deb", "http://metaservice.org/ns/metaservice-deb#");
        namespaceMap.put("owl", "http://www.w3.org/2002/07/owl#");
        namespaceMap.put("rad", "http://www.w3.org/ns/radion#");
        namespaceMap.put("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
        namespaceMap.put("rdfs", "http://www.w3.org/2000/01/rdf-schema#");
        namespaceMap.put("sf", "http://sourceforge.net/api/sfelements.rdf#");
        namespaceMap.put("skos", "http://www.w3.org/2004/02/skos/core#");
        namespaceMap.put("vcard", "http://www.w3.org/2006/vcard/ns#");
        namespaceMap.put("xhv", "http://www.w3.org/1999/xhtml/vocab#");
        namespaceMap.put("xsd", "http://www.w3.org/2001/XMLSchema#");

        StringBuilder namespaceBuilder = new StringBuilder();
        for (Map.Entry<String, String> entry : namespaceMap.entrySet()) {
            namespaceBuilder.append("PREFIX ").append(entry.getKey()).append(": <").append(entry.getValue())
                    .append(">\n");
        }
        return namespaceBuilder.toString();
    }

    private final String namespaces;

    public SparqlResourceService() throws URISyntaxException, IOException {
        URIBuilder uriBuilder = new URIBuilder();
        uriBuilder.setScheme("http").setHost("graph.metaservice.org").setPort(8080).setPath("/bigdata/sparql");
        uri = uriBuilder.build();

        namespaces = generateNamespaceString();
        resourceQuery = loadSparql("/sparql/resourceWithLatest.sparql");
    }

    private String loadSparql(String s) throws IOException {
        return IOUtils.toString(SparqlEndpointResource.class.getResourceAsStream(s));
    }

    @Override
    public InputStream getResource(String resource, Calendar date, String mimetype) {

        String query = namespaces + resourceQuery;
        query = query.replace("$path", stringToIri(resource));
        query = query.replace("$selectedTime", dateToLiteral(date));
        try {
            return querySparql(mimetype, query);
        } catch (URISyntaxException | IOException e) {
            throw new RuntimeException("Error executing SPARQL query", e);
        }
    }

    private @NotNull InputStream querySparql(@NotNull String mimeType, @NotNull String query)
            throws URISyntaxException, IOException {
        System.err.println(query);
        return Request.Post(uri).bodyForm(Form.form().add("query", query).build()).connectTimeout(1000)
                .socketTimeout(60000).setHeader("Accept", mimeType).execute().returnContent().asStream();
    }

    public @NotNull String stringToLiteral(@NotNull String value) {
        return "'" + value.replace("'", "\\'") + "'";
    }

    public @NotNull String stringToIri(@NotNull String value) {
        return "<" + value.replace(">", "\\>") + ">";
    }

    public @NotNull String dateToLiteral(@NotNull Calendar date) {
        return "\"" + DatatypeConverter.printDateTime(date) + "\"^^xsd:dateTime";
    }

}