/**
* 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.IOException;
import java.util.List;
import java.sql.SQLException;
import org.dspace.core.Context;
import org.dspace.content.DSpaceObject;
import org.dspace.authorize.AuthorizeException;
import org.jdom.Element;
import org.jdom.Namespace;
/**
* Crosswalk descriptive metadata to and from DIM (DSpace Intermediate
* Metadata) format, strictly for the purpose of including a precise and
* complete record of the DMD in an AIP. Although the DIM format was never
* intended to be used outside of DSpace, it is admirably suited to
* describing the exact state of the descriptive MD stored in the RDBMS.
* All crosswalks to standard formats such as MODS and even DC are necessarily
* "lossy" and inexact. Since the purpose of an AIP is to preserve and restore
* the state of an object exactly, DIM is the preferred format for
* recording its descriptive MD.
* <p>
* In order to allow external applications to make sense of DSpace AIPs for
* preservation purposes, we recommend adding a parallel descriptive
* metadata section in one of the preferred standard formats such as MODS
* as well as the DIM.
*
* @author Larry Stone
* @version $Revision: 1.2 $
*/
public class AIPDIMCrosswalk
implements DisseminationCrosswalk, IngestionCrosswalk
{
/**
* Get XML namespaces of the elements this crosswalk may return.
* Returns the XML namespaces (as JDOM objects) of the root element.
*
* @return array of namespaces, which may be empty.
*/
public Namespace[] getNamespaces()
{
Namespace result[] = new Namespace[1];
result[0] = XSLTCrosswalk.DIM_NS;
return result;
}
/**
* Get the XML Schema location(s) of the target metadata format.
* Returns the string value of the <code>xsi:schemaLocation</code>
* attribute that should be applied to the generated XML.
* <p>
* It may return the empty string if no schema is known, but crosswalk
* authors are strongly encouraged to implement this call so their output
* XML can be validated correctly.
* @return SchemaLocation string, including URI namespace, followed by
* whitespace and URI of XML schema document, or empty string if unknown.
*/
public String getSchemaLocation()
{
return "";
}
/**
* Predicate: Can this disseminator crosswalk the given object.
* Needed by OAI-PMH server implementation.
*
* @param dso dspace object, e.g. an <code>Item</code>.
* @return true when disseminator is capable of producing metadata.
*/
public boolean canDisseminate(DSpaceObject dso)
{
return true;
}
/**
* Predicate: Does this disseminator prefer to return a list of Elements,
* rather than a single root Element?
* <p>
* Some metadata formats have an XML schema without a root element,
* for example, the Dublin Core and Qualified Dublin Core formats.
* This would be <code>true</code> for a crosswalk into QDC, since
* it would "prefer" to return a list, since any root element it has
* to produce would have to be part of a nonstandard schema. In
* most cases your implementation will want to return
* <code>false</code>
*
* @return true when disseminator prefers you call disseminateList().
*/
public boolean preferList()
{
return false;
}
/**
* Execute crosswalk, returning List of XML elements.
* Returns a <code>List</code> of JDOM <code>Element</code> objects representing
* the XML produced by the crosswalk. This is typically called when
* a list of fields is desired, e.g. for embedding in a METS document
* <code>xmlData</code> field.
* <p>
* When there are no results, an
* empty list is returned, but never <code>null</code>.
*
* @param dso the DSpace Object whose metadata to export.
* @return results of crosswalk as list of XML elements.
*
* @throws CrosswalkInternalException (<code>CrosswalkException</code>) failure of the crosswalk itself.
* @throws CrosswalkObjectNotSupported (<code>CrosswalkException</code>) Cannot crosswalk this kind of DSpace object.
* @throws IOException I/O failure in services this calls
* @throws SQLException Database failure in services this calls
* @throws AuthorizeException current user not authorized for this operation.
*/
public List<Element> disseminateList(DSpaceObject dso)
throws CrosswalkException, IOException, SQLException,
AuthorizeException
{
Element dim = disseminateElement(dso);
return dim.getChildren();
}
/**
* Execute crosswalk, returning one XML root element as
* a JDOM <code>Element</code> object.
* This is typically the root element of a document.
* <p>
*
* @param dso the DSpace Object whose metadata to export.
* @return root Element of the target metadata, never <code>null</code>
*
* @throws CrosswalkInternalException (<code>CrosswalkException</code>) failure of the crosswalk itself.
* @throws CrosswalkObjectNotSupported (<code>CrosswalkException</code>) Cannot crosswalk this kind of DSpace object.
* @throws IOException I/O failure in services this calls
* @throws SQLException Database failure in services this calls
* @throws AuthorizeException current user not authorized for this operation.
*/
public Element disseminateElement(DSpaceObject dso)
throws CrosswalkException, IOException, SQLException,
AuthorizeException
{
return XSLTDisseminationCrosswalk.createDIM(dso);
}
/**
* Ingest a whole document. Build Document object around root element,
* and feed that to the transformation, since it may get handled
* differently than a List of metadata elements.
*/
public void ingest(Context context, DSpaceObject dso, Element root)
throws CrosswalkException, IOException, SQLException, AuthorizeException
{
ingest(context, dso, root.getChildren());
}
/**
* Fields correspond directly to Item.addMetadata() calls so
* they are simply executed.
*/
public void ingest(Context context, DSpaceObject dso, List<Element> dimList)
throws CrosswalkException,
IOException, SQLException, AuthorizeException
{
XSLTIngestionCrosswalk.ingestDIM(context, dso, dimList);
}
}