org.dspace.content.crosswalk.AIPDIMCrosswalk 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.IOException;
import java.sql.SQLException;
import java.util.List;
import org.dspace.authorize.AuthorizeException;
import org.dspace.content.DSpaceObject;
import org.dspace.core.Context;
import org.jdom2.Element;
import org.jdom2.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.
*
* 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.
*/
@Override
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 xsi:schemaLocation
* attribute that should be applied to the generated XML.
*
* 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.
*/
@Override
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 Item.
* @return true when disseminator is capable of producing metadata.
*/
@Override
public boolean canDisseminate(DSpaceObject dso) {
return true;
}
/**
* Predicate: Does this disseminator prefer to return a list of Elements,
* rather than a single root Element?
*
* Some metadata formats have an XML schema without a root element,
* for example, the Dublin Core and Qualified Dublin Core formats.
* This would be true 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
* false
*
* @return true when disseminator prefers you call disseminateList().
*/
@Override
public boolean preferList() {
return false;
}
/**
* Execute crosswalk, returning List of XML elements.
* Returns a List of JDOM Element 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
* xmlData field.
*
* When there are no results, an
* empty list is returned, but never null.
*
* @param context context
* @param dso the DSpace Object whose metadata to export.
* @return results of crosswalk as list of XML elements.
* @throws CrosswalkInternalException (CrosswalkException) failure of the crosswalk itself.
* @throws CrosswalkObjectNotSupported (CrosswalkException) 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.
*/
@Override
public List disseminateList(Context context, DSpaceObject dso)
throws CrosswalkException, IOException, SQLException,
AuthorizeException {
Element dim = disseminateElement(context, dso);
return dim.getChildren();
}
/**
* Execute crosswalk, returning one XML root element as
* a JDOM Element object.
* This is typically the root element of a document.
*
*
* @param context context
* @param dso the DSpace Object whose metadata to export.
* @return root Element of the target metadata, never null
* @throws CrosswalkInternalException (CrosswalkException) failure of the crosswalk itself.
* @throws CrosswalkObjectNotSupported (CrosswalkException) 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.
*/
@Override
public Element disseminateElement(Context context, 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.
*
* @param createMissingMetadataFields whether to create missing fields
* @throws CrosswalkException if crosswalk error
* @throws IOException if IO error
* @throws SQLException if database error
* @throws AuthorizeException if authorization error
*/
@Override
public void ingest(Context context, DSpaceObject dso, Element root, boolean createMissingMetadataFields)
throws CrosswalkException, IOException, SQLException, AuthorizeException {
ingest(context, dso, root.getChildren(), createMissingMetadataFields);
}
/**
* Fields correspond directly to Item.addMetadata() calls so
* they are simply executed.
*
* @param createMissingMetadataFields whether to create missing fields
* @param dimList List of elements
* @throws CrosswalkException if crosswalk error
* @throws IOException if IO error
* @throws SQLException if database error
* @throws AuthorizeException if authorization error
*/
@Override
public void ingest(Context context, DSpaceObject dso, List dimList, boolean createMissingMetadataFields)
throws CrosswalkException,
IOException, SQLException, AuthorizeException {
XSLTIngestionCrosswalk.ingestDIM(context, dso, dimList, createMissingMetadataFields);
}
}