/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.dspace.content.authority;
import java.io.IOException;
import java.util.List;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.ParserConfigurationException;
import org.dspace.content.Collection;
import org.xml.sax.XMLReader;
import org.xml.sax.InputSource;
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.apache.log4j.Logger;
import org.dspace.core.ConfigurationManager;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
/**
* Choice Authority based on SHERPA/RoMEO - for Publishers and Journals
* See the subclasses SHERPARoMEOPublisher and SHERPARoMEOJournalTitle
* for actual choice plugin implementations. This is a superclass
* containing all the common protocol logic.
*
* Reads these DSpace Config properties:
*
* # contact URL for server
* sherpa.romeo.url = http://www.sherpa.ac.uk/romeoapi11.php
*
* WARNING: This is a very crude and incomplete implementation, done mainly
* as a proof-of-concept. Any site that actually wants to use it will
* probably have to refine it (and give patches back to dspace.org).
*
* @see SHERPARoMEOPublisher
* @see SHERPARoMEOJournalTitle
* @author Larry Stone
* @version $Revision $
*/
public abstract class SHERPARoMEOProtocol implements ChoiceAuthority
{
private static final Logger log = Logger.getLogger(SHERPARoMEOProtocol.class);
// contact URL from configuration
private static String url = null;
public SHERPARoMEOProtocol()
{
if (url == null)
{
url = ConfigurationManager.getProperty("sherpa.romeo.url");
// sanity check
if (url == null)
{
throw new IllegalStateException("Missing DSpace configuration keys for SHERPA/RoMEO Query");
}
}
}
// this implements the specific RoMEO API args and XML tag naming
public abstract Choices getMatches(String text, Collection collection, int start, int limit, String locale);
@Override
public Choices getBestMatch(String field, String text, Collection collection, String locale)
{
return getMatches(field, text, collection, 0, 2, locale);
}
// XXX FIXME just punt, returning value, never got around to
// implementing a reverse query.
@Override
public String getLabel(String field, String key, String locale)
{
return key;
}
// NOTE - ignore limit and start for now
protected Choices query(String result, String label, String authority,
List<BasicNameValuePair> args, int start, int limit)
{
HttpClient hc = new DefaultHttpClient();
String srUrl = url + "?" + URLEncodedUtils.format(args, "UTF8");
HttpGet get = new HttpGet(srUrl);
log.debug("Trying SHERPA/RoMEO Query, URL=" + srUrl);
try
{
HttpResponse response = hc.execute(get);
if (response.getStatusLine().getStatusCode() == 200)
{
SAXParserFactory spf = SAXParserFactory.newInstance();
SAXParser sp = spf.newSAXParser();
XMLReader xr = sp.getXMLReader();
SRHandler handler = new SRHandler(result, label, authority);
// XXX FIXME: should turn off validation here explicitly, but
// it seems to be off by default.
xr.setFeature("http://xml.org/sax/features/namespaces", true);
xr.setContentHandler(handler);
xr.setErrorHandler(handler);
xr.parse(new InputSource(response.getEntity().getContent()));
int confidence;
if (handler.total == 0)
{
confidence = Choices.CF_NOTFOUND;
}
else if (handler.total == 1)
{
confidence = Choices.CF_UNCERTAIN;
}
else
{
confidence = Choices.CF_AMBIGUOUS;
}
return new Choices(handler.result, start, handler.total, confidence, false);
}
}
catch (IOException e)
{
log.error("SHERPA/RoMEO query failed: ", e);
return null;
}
catch (ParserConfigurationException e)
{
log.warn("Failed parsing SHERPA/RoMEO result: ", e);
return null;
}
catch (SAXException e)
{
log.warn("Failed parsing SHERPA/RoMEO result: ", e);
return null;
}
finally
{
get.releaseConnection();
}
return null;
}
// SAX handler to grab SHERPA/RoMEO (and eventually other details) from result
private static class SRHandler
extends DefaultHandler
{
private Choice result[] = null;
int rindex = 0; // result index
int total = 0;
// name of element containing a result, e.g. <journal>
private String resultElement = null;
// name of element containing the label e.g. <name>
private String labelElement = null;
// name of element containing the authority value e.g. <issn>
private String authorityElement = null;
protected String textValue = null;
public SRHandler(String result, String label, String authority)
{
super();
resultElement = result;
labelElement = label;
authorityElement = authority;
}
// NOTE: text value MAY be presented in multiple calls, even if
// it all one word, so be ready to splice it together.
// BEWARE: subclass's startElement method should call super()
// to null out 'value'. (Don't you miss the method combination
// options of a real object system like CLOS?)
@Override
public void characters(char[] ch, int start, int length)
throws SAXException
{
String newValue = new String(ch, start, length);
if (newValue.length() > 0)
{
if (textValue == null)
{
textValue = newValue;
}
else
{
textValue += newValue;
}
}
}
// if this was the FIRST "numhits" element, it's size of results:
@Override
public void endElement(String namespaceURI, String localName,
String qName)
throws SAXException
{
if (localName.equals("numhits"))
{
String stotal = textValue.trim();
if (stotal.length() > 0)
{
total = Integer.parseInt(stotal);
result = new Choice[total];
if (total > 0)
{
result[0] = new Choice();
log.debug("Got "+total+" records in results.");
}
}
}
else if (localName.equals(resultElement))
{
// after start of result element, get next hit ready
if (++rindex < result.length)
{
result[rindex] = new Choice();
}
}
else if (localName.equals(labelElement) && textValue != null)
{
// plug in label value
result[rindex].value = textValue.trim();
result[rindex].label = result[rindex].value;
}
else if (authorityElement != null && localName.equals(authorityElement) && textValue != null)
{
// plug in authority value
result[rindex].authority = textValue.trim();
}
else if (localName.equals("message") && textValue != null)
{
// error message
log.warn("SHERPA/RoMEO response error message: " + textValue.trim());
}
}
// subclass overriding this MUST call it with super()
@Override
public void startElement(String namespaceURI, String localName,
String qName, Attributes atts)
throws SAXException
{
textValue = null;
}
@Override
public void error(SAXParseException exception)
throws SAXException
{
throw new SAXException(exception);
}
@Override
public void fatalError(SAXParseException exception)
throws SAXException
{
throw new SAXException(exception);
}
}
}