org.dspace.content.crosswalk

Class AIPDIMCrosswalk

java.lang.Object

org.dspace.content.crosswalk.AIPDIMCrosswalk

All Implemented Interfaces:

DisseminationCrosswalk, IngestionCrosswalk

public class AIPDIMCrosswalk
extends Object
implements DisseminationCrosswalk, IngestionCrosswalk

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.

Version:

$Revision: 1.2 $

Author:

Larry Stone

Field Summary

Fields inherited from interface org.dspace.content.crosswalk.DisseminationCrosswalk

XSI_NS

Constructor Summary

Constructors

Constructor and Description
AIPDIMCrosswalk()

Method Summary

Methods

Modifier and Type	Method and Description
boolean	canDisseminate(DSpaceObject dso) Predicate: Can this disseminator crosswalk the given object.
org.jdom.Element	disseminateElement(Context context, DSpaceObject dso) Execute crosswalk, returning one XML root element as a JDOM Element object.
List<org.jdom.Element>	disseminateList(Context context, DSpaceObject dso) Execute crosswalk, returning List of XML elements.
org.jdom.Namespace[]	getNamespaces() Get XML namespaces of the elements this crosswalk may return.
String	getSchemaLocation() Get the XML Schema location(s) of the target metadata format.
void	ingest(Context context, DSpaceObject dso, org.jdom.Element root, boolean createMissingMetadataFields) Ingest a whole document.
void	ingest(Context context, DSpaceObject dso, List<org.jdom.Element> dimList, boolean createMissingMetadataFields) Fields correspond directly to Item.addMetadata() calls so they are simply executed.
boolean	preferList() Predicate: Does this disseminator prefer to return a list of Elements, rather than a single root Element?

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AIPDIMCrosswalk

public AIPDIMCrosswalk()

Method Detail

getNamespaces

public org.jdom.Namespace[] getNamespaces()

Get XML namespaces of the elements this crosswalk may return. Returns the XML namespaces (as JDOM objects) of the root element.

Specified by:

getNamespaces in interface DisseminationCrosswalk

Returns:

array of namespaces, which may be empty.

getSchemaLocation

public String getSchemaLocation()

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.

Specified by:

getSchemaLocation in interface DisseminationCrosswalk

Returns:

SchemaLocation string, including URI namespace, followed by whitespace and URI of XML schema document, or empty string if unknown.

canDisseminate

public boolean canDisseminate(DSpaceObject dso)

Predicate: Can this disseminator crosswalk the given object. Needed by OAI-PMH server implementation.

Specified by:

canDisseminate in interface DisseminationCrosswalk

Parameters:

dso - dspace object, e.g. an Item.

Returns:

true when disseminator is capable of producing metadata.

preferList

public boolean preferList()

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

Specified by:

preferList in interface DisseminationCrosswalk

Returns:

true when disseminator prefers you call disseminateList().

disseminateList

public List<org.jdom.Element> disseminateList(Context context,
                                     DSpaceObject dso)
                                       throws CrosswalkException,
                                              IOException,
                                              SQLException,
                                              AuthorizeException

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.

Specified by:

disseminateList in interface DisseminationCrosswalk

Parameters:

context - context

dso - the DSpace Object whose metadata to export.

Returns:

results of crosswalk as list of XML elements.

Throws:

CrosswalkInternalException - (CrosswalkException) failure of the crosswalk itself.

CrosswalkObjectNotSupported - (CrosswalkException) Cannot crosswalk this kind of DSpace object.

IOException - I/O failure in services this calls

SQLException - Database failure in services this calls

AuthorizeException - current user not authorized for this operation.

CrosswalkException

disseminateElement

public org.jdom.Element disseminateElement(Context context,
                                  DSpaceObject dso)
                                    throws CrosswalkException,
                                           IOException,
                                           SQLException,
                                           AuthorizeException

Execute crosswalk, returning one XML root element as a JDOM Element object. This is typically the root element of a document.

Specified by:

disseminateElement in interface DisseminationCrosswalk

Parameters:

context - context

dso - the DSpace Object whose metadata to export.

Returns:

root Element of the target metadata, never null

Throws:

CrosswalkInternalException - (CrosswalkException) failure of the crosswalk itself.

CrosswalkObjectNotSupported - (CrosswalkException) Cannot crosswalk this kind of DSpace object.

IOException - I/O failure in services this calls

SQLException - Database failure in services this calls

AuthorizeException - current user not authorized for this operation.

CrosswalkException

ingest

public void ingest(Context context,
          DSpaceObject dso,
          org.jdom.Element root,
          boolean createMissingMetadataFields)
            throws CrosswalkException,
                   IOException,
                   SQLException,
                   AuthorizeException

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.

Specified by:

ingest in interface IngestionCrosswalk

Parameters:

createMissingMetadataFields - whether to create missing fields

context - DSpace context.

dso - DSpace Object (usually an Item) to which new metadata gets attached.

root - root Element of metadata document.

Throws:

CrosswalkException - if crosswalk error

IOException - if IO error

SQLException - if database error

AuthorizeException - if authorization error

ingest

public void ingest(Context context,
          DSpaceObject dso,
          List<org.jdom.Element> dimList,
          boolean createMissingMetadataFields)
            throws CrosswalkException,
                   IOException,
                   SQLException,
                   AuthorizeException

Fields correspond directly to Item.addMetadata() calls so they are simply executed.

Specified by:

ingest in interface IngestionCrosswalk

Parameters:

createMissingMetadataFields - whether to create missing fields

dimList - List of elements

context - DSpace context.

dso - DSpace Object (Item, Bitstream, etc) to which new metadata gets attached.

Throws:

CrosswalkException - if crosswalk error

IOException - if IO error

SQLException - if database error

AuthorizeException - if authorization error