org.dspace.content.crosswalk
Interface DisseminationCrosswalk

All Known Implementing Classes:
DIMDisseminationCrosswalk, METSDisseminationCrosswalk, MODSDisseminationCrosswalk, OREDisseminationCrosswalk, PREMISCrosswalk, QDCCrosswalk, SimpleDCDisseminationCrosswalk, XHTMLHeadDisseminationCrosswalk, XSLTDisseminationCrosswalk

public interface DisseminationCrosswalk

Dissemination Crosswalk plugin -- translate DSpace native metadata into an external XML format.

This interface describes a plugin that produces metadata in an XML-based format from the state of a DSpace object. Note that the object may be an Item, Bitstream, Community, or Collection, although most implementations only work on one type of object.

Version:
$Revision: 3761 $
Author:
Larry Stone

Field Summary
static org.jdom.Namespace XSI_NS
          XSI namespace, required for xsi:schemalocation attributes
 
Method Summary
 boolean canDisseminate(DSpaceObject dso)
          Predicate: Can this disseminator crosswalk the given object.
 org.jdom.Element disseminateElement(DSpaceObject dso)
          Execute crosswalk, returning one XML root element as a JDOM Element object.
 List disseminateList(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.
 boolean preferList()
          Predicate: Does this disseminator prefer to return a list of Elements, rather than a single root Element?
 

Field Detail

XSI_NS

static final org.jdom.Namespace XSI_NS
XSI namespace, required for xsi:schemalocation attributes

Method Detail

getNamespaces

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.

Returns:
array of namespaces, which may be empty.

getSchemaLocation

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.

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

canDisseminate

boolean canDisseminate(DSpaceObject dso)
Predicate: Can this disseminator crosswalk the given object. Needed by OAI-PMH server implementation.

Parameters:
dso - dspace object, e.g. an Item.
Returns:
true when disseminator is capable of producing metadata.

preferList

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

Returns:
true when disseminator prefers you call disseminateList().

disseminateList

List disseminateList(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.

Parameters:
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

org.jdom.Element disseminateElement(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.

Parameters:
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


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