org.dspace.content.crosswalk.XSLTCrosswalk Maven / Gradle / Ivy
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/**
* 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.FileNotFoundException;
import java.util.ArrayList;
import java.util.List;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamSource;
import org.dspace.core.SelfNamedPlugin;
import org.dspace.services.ConfigurationService;
import org.dspace.services.factory.DSpaceServicesFactory;
import org.jdom.Namespace;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Configurable XSLT-driven Crosswalk
*
* This is the superclass of the XSLT dissemination and submission crosswalks.
* These classes let you can create many different crosswalks between
* DSpace internal data and any XML without changing any code, just
* XSL transformation (XSLT) stylesheets.
* Each configured stylesheet appears as a new plugin name, although they all
* share the same plugin implementation class.
*
* The XML transformation must produce (for submission) or expect (for
* dissemination) a document in DIM - DSpace Intermediate Metadata format.
* See
* http://wiki.dspace.org/DspaceIntermediateMetadata for details.
*
Configuration
* Prepare your DSpace configuration as follows:
*
* A submission crosswalk is described by a
* configuration key like
*
crosswalk.submission.PluginName.stylesheet = path
* The alias names the Plugin name,
* and the path value is the pathname (relative to dspace.dir/config)
* of the crosswalk stylesheet, e.g. "mycrosswalk.xslt"
*
* For example, this configures a crosswalk named "LOM" using a stylesheet
* in config/crosswalks/d-lom.xsl under the DSpace "home" directory:
*
crosswalk.submission.stylesheet.LOM = crosswalks/d-lom.xsl
*
* A dissemination crosswalk is described by a
* configuration key like
*
crosswalk.dissemination.PluginName.stylesheet = path
* The alias names the Plugin name,
* and the path value is the pathname (relative to dspace.dir/config)
* of the crosswalk stylesheet, e.g. "mycrosswalk.xslt"
*
* You can have two names point to the same crosswalk,
* just add two configuration entries with the same path, e.g.
*
* crosswalk.submission.MyFormat.stylesheet = crosswalks/myformat.xslt
* crosswalk.submission.almost_DC.stylesheet = crosswalks/myformat.xslt
*
*
* NOTE: This plugin will automatically reload any XSL stylesheet that
* was modified since it was last loaded. This lets you edit and test
* stylesheets without restarting DSpace.
*
* You must use the PluginService to instantiate an
* XSLT crosswalk plugin, e.g.
*
IngestionCrosswalk xwalk = CoreServiceFactory.getInstance().getPluginService().getPlugin(IngestionCrosswalk
* .class, "LOM");
*
* 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 PluginService
* does this automatically.
*
* @author Larry Stone
*/
public abstract class XSLTCrosswalk extends SelfNamedPlugin {
/**
* log4j category
*/
private static final Logger LOG = LoggerFactory.getLogger(XSLTCrosswalk.class);
/**
* DSpace XML Namespace in JDOM form.
*/
public static final Namespace DIM_NS =
Namespace.getNamespace("dim", "http://www.dspace.org/xmlns/dspace/dim");
/**
* Prefix for all lines in the configuration file for XSLT plugins.
*/
protected static final String CONFIG_PREFIX = "crosswalk.";
private static final String CONFIG_STYLESHEET = ".stylesheet";
/**
* Derive list of plugin name from DSpace configuration entries
* for crosswalks.
*
* @param direction "dissemination" or "submission", so it looks for keys like
* crosswalk.submission.{NAME}.stylesheet
* @return names to be given to the plugins of that direction.
*/
protected static String[] makeAliases(String direction) {
String prefix = CONFIG_PREFIX + direction + ".";
String suffix = CONFIG_STYLESHEET;
List aliasList = new ArrayList<>();
ConfigurationService configurationService
= DSpaceServicesFactory.getInstance().getConfigurationService();
List configKeys = configurationService.getPropertyKeys(prefix);
LOG.debug("XSLTCrosswalk: Looking for config prefix = {}", prefix);
for (String key : configKeys) {
if (key.endsWith(suffix)) {
LOG.debug("Getting XSLT plugin name from config line: {}", key);
aliasList.add(key.substring(prefix.length(), key.length() - suffix.length()));
}
}
return aliasList.toArray(new String[aliasList.size()]);
}
/**
* We need to force this, because some dependency elsewhere interferes.
*/
private static final String TRANSFORMER_FACTORY_CLASS
= "com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl";
private Transformer transformer = null;
private File transformFile = null;
private long transformLastModified = 0;
/**
* Initialize the Transformation stylesheet from configured stylesheet file.
*
* @param direction the direction of xwalk, either "submission" or
* "dissemination"
* @return transformer or null if there was error initializing.
*/
protected Transformer getTransformer(String direction) {
if (transformFile == null) {
String myAlias = getPluginInstanceName();
if (myAlias == null) {
LOG.error("Must use PluginService to instantiate XSLTCrosswalk so the class knows its name.");
return null;
}
String cmPropName = CONFIG_PREFIX + direction + "." + myAlias + CONFIG_STYLESHEET;
ConfigurationService configurationService
= DSpaceServicesFactory.getInstance().getConfigurationService();
String fname = configurationService.getProperty(cmPropName);
if (fname == null) {
LOG.error("Missing configuration filename for XSLT-based crosswalk: no " +
"value for property = {}", cmPropName);
return null;
} else {
String parent = configurationService.getProperty("dspace.dir") +
File.separator + "config" + File.separator;
transformFile = new File(parent, fname);
}
}
// load if first time, or reload if stylesheet changed:
if (transformer == null ||
transformFile.lastModified() > transformLastModified) {
try {
LOG.debug(
(transformer == null ? "Loading {} XSLT stylesheet from {}" : "Reloading {} XSLT stylesheet from " +
"{}"),
getPluginInstanceName(), transformFile.toString());
Source transformSource
= new StreamSource(new FileInputStream(transformFile));
TransformerFactory transformerFactory
= TransformerFactory.newInstance(
TRANSFORMER_FACTORY_CLASS, null);
transformer = transformerFactory.newTransformer(transformSource);
transformLastModified = transformFile.lastModified();
} catch (TransformerConfigurationException | FileNotFoundException e) {
LOG.error("Failed to initialize XSLTCrosswalk({}): {}",
getPluginInstanceName(), e.toString());
}
}
return transformer;
}
}