FeedResponseHandlerImpl.java

/*
 * Copyright (c) 2009, University of Bristol
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1) Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2) Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * 3) Neither the name of the University of Bristol nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
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 */
package org.ilrt.mca.harvester.feeds;

import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.io.FeedException;
import com.sun.syndication.io.SyndFeedInput;
import com.sun.syndication.io.SyndFeedOutput;
import org.ilrt.mca.harvester.ResponseHandler;
import org.jdom.Element;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.Iterator;
import java.util.List;

/**
 * @author Mike Jones (mike.a.jones@bristol.ac.uk)
 */
public class FeedResponseHandlerImpl implements ResponseHandler {

    @Override
    public Model getModel(String sourceUrl, InputStream is) {

        try {

            // get the feed and convert to rss 1.0
            SyndFeedInput synfeed = new SyndFeedInput();
            SyndFeed syndFeed = synfeed.build(new InputStreamReader(is, "UTF-8"));
            syndFeed.setFeedType("rss_1.0");
            syndFeed.setUri(sourceUrl);


            // The student union feeds GUID is not a valid URI - we check that the value of
            // getUri (which the ROME API populated with the RSS GUID) starts with "http:, if not
            // use the link as the URI.
            for (Object o : syndFeed.getEntries()) {
                SyndEntry entry = (SyndEntry) o;

                if (!entry.getUri().startsWith("http")) {
                    entry.setUri(entry.getLink());
                }

            }

            // remove foreign elements that cause icky RDF
            // TODO: create a data wrangling class for this type of stuff that can be institutional specific
            List elements = (List) syndFeed.getForeignMarkup();

            Iterator i = elements.iterator();

            while (i.hasNext()) {

                Element element = (Element) i.next();

                if (element.getNamespaceURI().equals("http://webns.net/mvcb/") ||
                        element.getNamespaceURI().equals("http://www.w3.org/2005/Atom")) {
                    i.remove();
                }

            }

            syndFeed.setForeignMarkup(elements);


            // write the feed to a string
            StringWriter writer = new StringWriter();
            SyndFeedOutput output = new SyndFeedOutput();
            output.output(syndFeed, writer);
            String feed = writer.getBuffer().toString();

            //System.out.println(feed);

            // read into a model
            Model model = ModelFactory.createDefaultModel();
            model.read(new StringReader(feed), syndFeed.getLink());

            return model;

        } catch (IOException e) {
            e.printStackTrace();
        } catch (FeedException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    public boolean isSupportedMediaType(String mediaType) {

        return mediaType.startsWith("text/xml") || mediaType.startsWith("application/rss+xml")
                || mediaType.startsWith("application/xml")
                || mediaType.startsWith("application/atom+xml");

    }


}