org.dspace.content.crosswalk.QDCCrosswalk Maven / Gradle / Ivy
/**
* 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.crosswalk;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.StringReader;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import org.apache.commons.lang.ArrayUtils;
import org.apache.log4j.Logger;
import org.dspace.authorize.AuthorizeException;
import org.dspace.content.DCValue;
import org.dspace.content.DSpaceObject;
import org.dspace.content.Item;
import org.dspace.content.MetadataSchema;
import org.dspace.core.ConfigurationManager;
import org.dspace.core.Constants;
import org.dspace.core.Context;
import org.dspace.core.SelfNamedPlugin;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.Namespace;
import org.jdom.input.SAXBuilder;
/**
* Configurable QDC Crosswalk
*
* This class supports multiple dissemination crosswalks from DSpace
* internal data to the Qualified Dublin Core XML format
* (see http://dublincore.org/
*
* It registers multiple Plugin names, which it reads from
* the DSpace configuration as follows:
*
*
Configuration
* Every key starting with "crosswalk.qdc.properties." describes a
* QDC crosswalk. Everything after the last period is the plugin instance,
* and the value is the pathname (relative to dspace.dir/config)
* of the crosswalk configuration file.
*
* You can have two aliases point to the same crosswalk,
* just add two configuration entries with the same value, e.g.
*
* crosswalk.qdc.properties.QDC = xwalk/qdc.properties
* crosswalk.qdc.properties.default = xwalk/qdc.properties
*
* The first line creates a plugin with the name "QDC"
* which is configured from the file dspace-dir/xwalk/qdc.properties.
*
* Since there is significant overhead in reading the properties file to
* configure the crosswalk, and a crosswalk instance may be used any number
* of times, we recommend caching one instance of the crosswalk for each
* alias and simply reusing those instances. The PluginManager does
* this by default.
*
* Each named crosswalk has two other types of configuration lines:
*
* XML Namespaces: all XML namespace prefixes used in the XML fragments below
* must be defined in the configuration as follows. Add a line of
* the form:
* crosswalk.qdc.namespace.{NAME}.{prefix} = {namespace-URI}
* e.g. for the namespaces dc and dcterms
* in the plugin named QDC, add these lines:
* crosswalk.qdc.namespace.QDC.dc = http://purl.org/dc/elements/1.1/
* crosswalk.qdc.namespace.QDC.dcterms = http://purl.org/dc/terms/
*
*
* Finally, you need to declare an XML Schema URI for the plugin, with
* a line of the form
* crosswalk.qdc.schema.{NAME} = {schema-URI}
* for example,
* crosswalk.qdc.schemaLocation.QDC = \
* http://purl.org/dc/terms/ \
* http://dublincore.org/schemas/xmls/qdc/2003/04/02/qualifieddc.xsd
*
* @author Larry Stone
* @version $Revision: 5844 $
*/
public class QDCCrosswalk extends SelfNamedPlugin
implements DisseminationCrosswalk, IngestionCrosswalk
{
/** log4j category */
private static Logger log = Logger.getLogger(QDCCrosswalk.class);
// map of qdc to JDOM Element
private Map qdc2element = new HashMap();
// map of JDOM Element to qdc DCValue
private Map element2qdc = new HashMap();
// the XML namespaces from config file for this name.
private Namespace namespaces[] = null;
private static final Namespace DCTERMS_NS =
Namespace.getNamespace("dcterms", "http://purl.org/dc/terms/");
// sentinal: done init?
private boolean inited = false;
// my plugin name
private String myName = null;
// prefix of all DSpace Configuration entries.
private static final String CONFIG_PREFIX = "crosswalk.qdc";
// XML schemaLocation fragment for this crosswalk, from config.
private String schemaLocation = null;
private static SAXBuilder builder = new SAXBuilder();
/**
* Fill in the plugin-name table from DSpace configuration entries
* for configuration files for flavors of QDC crosswalk:
*/
private static String aliases[] = null;
static
{
List aliasList = new ArrayList();
Enumeration pe = (Enumeration)ConfigurationManager.propertyNames();
String propname = CONFIG_PREFIX + ".properties.";
while (pe.hasMoreElements())
{
String key = pe.nextElement();
if (key.startsWith(propname))
{
aliasList.add(key.substring(propname.length()));
}
}
aliases = (String[])aliasList.toArray(new String[aliasList.size()]);
}
public static String[] getPluginNames()
{
return (String[]) ArrayUtils.clone(aliases);
}
// utility: return "fully qualified" name of XML element, for a
// hashtable key to use on ingesting elements.
// Format is {prefix:}name where prefix is optional.
private String makeQualifiedTagName(Element element)
{
String prefix = "";
Namespace ns = element.getNamespace();
if (ns != null)
{
prefix = ns.getPrefix() + ":";
}
String tagName;
String nsQualifier = element.getAttributeValue("type", DisseminationCrosswalk.XSI_NS);
if (nsQualifier == null || nsQualifier.length() < 1)
{
String qualifier = element.getAttributeValue("type");
if (qualifier == null || qualifier.length() < 1)
{
tagName = prefix+element.getName();
}
else
{
tagName = prefix+element.getName()+qualifier;
}
}
else
{
tagName = prefix+element.getName()+nsQualifier;
}
return tagName;
}
/**
* Initialize Crosswalk table from a properties file
* which itself is the value of the DSpace configuration property
* "crosswalk.qdc.properties.X", where "X" is the alias name of this instance.
* Each instance may be configured with a separate mapping table.
*
* The QDC crosswalk configuration properties follow the format:
*
* {qdc-element} = {XML-fragment}
*
* 1. qualified DC field name is of the form (qualifier is optional)
* {MDschema}.{element}.{qualifier}
*
* e.g. dc.contributor.author
* dc.title
*
* 2. XML fragment is prototype of metadata element, with empty
* placeholders for value).
*
* Example properties line:
*
* dc.coverage.temporal = nsList = new ArrayList();
Enumeration pe = (Enumeration)ConfigurationManager.propertyNames();
String propname = CONFIG_PREFIX + ".namespace."+ myName +".";
while (pe.hasMoreElements())
{
String key = pe.nextElement();
if (key.startsWith(propname))
{
nsList.add(Namespace.getNamespace(key.substring(propname.length()),
ConfigurationManager.getProperty(key)));
}
}
nsList.add(Namespace.XML_NAMESPACE);
namespaces = (Namespace[])nsList.toArray(new Namespace[nsList.size()]);
// get XML schemaLocation fragment from config
schemaLocation = ConfigurationManager.getProperty(CONFIG_PREFIX + ".schemaLocation."+ myName);
// read properties
String cmPropName = CONFIG_PREFIX+".properties."+myName;
String propsFilename = ConfigurationManager.getProperty(cmPropName);
if (propsFilename == null)
{
throw new CrosswalkInternalException("Configuration error: " +
"No properties file configured for QDC crosswalk named \"" + myName + "\"");
}
String parent = ConfigurationManager.getProperty("dspace.dir") +
File.separator + "config" + File.separator;
File propsFile = new File(parent, propsFilename);
Properties qdcProps = new Properties();
FileInputStream pfs = null;
try
{
pfs = new FileInputStream(propsFile);
qdcProps.load(pfs);
}
finally
{
if (pfs != null)
{
try
{
pfs.close();
}
catch (IOException ioe)
{
}
}
}
// grovel properties to initialize qdc->element and element->qdc maps.
// evaluate the XML fragment with a wrapper including namespaces.
String postlog = "";
StringBuffer prologb = new StringBuffer("");
String prolog = prologb.toString();
pe = (Enumeration)qdcProps.propertyNames();
while (pe.hasMoreElements())
{
String qdc = pe.nextElement();
String val = qdcProps.getProperty(qdc);
try
{
Document d = builder.build(new StringReader(prolog+val+postlog));
Element element = (Element)d.getRootElement().getContent(0);
qdc2element.put(qdc, element);
element2qdc.put(makeQualifiedTagName(element), qdc);
log.debug("Building Maps: qdc=\""+qdc+"\", element=\""+element.toString()+"\"");
}
catch (org.jdom.JDOMException je)
{
throw new CrosswalkInternalException("Failed parsing XML fragment in properties file: \""+prolog+val+postlog+"\": "+je.toString(), je);
}
}
}
public Namespace[] getNamespaces()
{
try
{
init();
}
catch (Exception e)
{
}
return (Namespace[]) ArrayUtils.clone(namespaces);
}
public String getSchemaLocation()
{
try
{
init();
}
catch (Exception e)
{
}
return schemaLocation;
}
/**
* Returns object's metadata in MODS format, as XML structure node.
*/
public List disseminateList(DSpaceObject dso)
throws CrosswalkException,
IOException, SQLException, AuthorizeException
{
return disseminateListInternal(dso, true);
}
private List disseminateListInternal(DSpaceObject dso, boolean addSchema)
throws CrosswalkException,
IOException, SQLException, AuthorizeException
{
if (dso.getType() != Constants.ITEM)
{
throw new CrosswalkObjectNotSupported("QDCCrosswalk can only crosswalk an Item.");
}
Item item = (Item)dso;
init();
DCValue[] dc = item.getMetadata(Item.ANY, Item.ANY, Item.ANY, Item.ANY);
List result = new ArrayList(dc.length);
for (int i = 0; i < dc.length; i++)
{
// Compose qualified DC name - schema.element[.qualifier]
// e.g. "dc.title", "dc.subject.lcc", "lom.Classification.Keyword"
String qdc = dc[i].schema+"."+
((dc[i].qualifier == null) ? dc[i].element
: (dc[i].element + "." + dc[i].qualifier));
Element elt = qdc2element.get(qdc);
// only complain about missing elements in the DC schema:
if (elt == null)
{
if (dc[i].schema.equals(MetadataSchema.DC_SCHEMA))
{
log.warn("WARNING: " + myName + ": No QDC mapping for \"" + qdc + "\"");
}
}
else
{
Element qe = (Element)elt.clone();
qe.setText(dc[i].value);
if (addSchema && schemaLocation != null)
{
qe.setAttribute("schemaLocation", schemaLocation, XSI_NS);
}
if (dc[i].language != null)
{
qe.setAttribute("lang", dc[i].language, Namespace.XML_NAMESPACE);
}
result.add(qe);
}
}
return result;
}
public Element disseminateElement(DSpaceObject dso)
throws CrosswalkException,
IOException, SQLException, AuthorizeException
{
init();
Element root = new Element("qualifieddc", DCTERMS_NS);
if (schemaLocation != null)
{
root.setAttribute("schemaLocation", schemaLocation, XSI_NS);
}
root.addContent(disseminateListInternal(dso, false));
return root;
}
public boolean canDisseminate(DSpaceObject dso)
{
return true;
}
public void ingest(Context context, DSpaceObject dso, Element root)
throws CrosswalkException, IOException, SQLException, AuthorizeException
{
init();
// NOTE: don't bother comparing namespace on root element
// because DCMI doesn't specify one, and every app uses its
// own.. just give up in the face of this madness and accept
// anything with the right name.
if (!(root.getName().equals("qualifieddc")))
{
throw new MetadataValidationException("Wrong root element for Qualified DC: " + root.toString());
}
ingest(context, dso, root.getChildren());
}
public void ingest(Context context, DSpaceObject dso, List ml)
throws CrosswalkException, IOException, SQLException, AuthorizeException
{
init();
// for now, forget about any targets but item.
if (dso.getType() != Constants.ITEM)
{
throw new CrosswalkInternalException("Wrong target object type, QDCCrosswalk can only crosswalk to an Item.");
}
Item item = (Item)dso;
for (Element me : ml)
{
String key = makeQualifiedTagName(me);
// if the root element gets passed here, recurse:
if ("qualifieddc".equals(me.getName()))
{
ingest(context, dso, me.getChildren());
}
else if (element2qdc.containsKey(key))
{
String qdc[] = (element2qdc.get(key)).split("\\.");
// get language - prefer xml:lang, accept lang.
String lang = me.getAttributeValue("lang", Namespace.XML_NAMESPACE);
if (lang == null)
{
lang = me.getAttributeValue("lang");
}
if (qdc.length == 3)
{
item.addMetadata(qdc[0], qdc[1], qdc[2], lang, me.getText());
}
else if (qdc.length == 2)
{
item.addMetadata(qdc[0], qdc[1], null, lang, me.getText());
}
else
{
throw new CrosswalkInternalException("Unrecognized format in QDC element identifier for key=\"" + key + "\", qdc=\"" + element2qdc.get(key) + "\"");
}
}
else
{
log.warn("WARNING: " + myName + ": No mapping for Element=\"" + key + "\" to qdc.");
}
}
}
public boolean preferList()
{
return true;
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy