Page History

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OAI 2.0 is a Java implementation of an OAI-PMH data provider interface developed by Lyncode that uses XOAI, an OAI-PMH Java Library, http://www.lyncode.com/dspace/addons/xoai/doc/XOAI_en.pdf.

Why OAI 2.0?

Projects like OpenAIRE, and Driver have specific metadata requirements (to the published content through the OAI-PMH interface). As the OAI-PMH protocol doesn't establish any frame to these specifics, OAI 2.0 can, in a simple way, have more than one instance of an OAI interface (feature provided by the XOAI core library) so one could define an interface for each project. That is the main purpose, although, OAI 2.0 allows much more than that.

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Configuration

Basic Configuration

Advanced Configuration

OAI 2.0 allows you to configure following advanced options:

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<Format id="[IDENTIFIER]">
  <Prefix>[PREFIX]</Prefix>
  <XSLT>metadataFormats/[XSLT]</XSLT>
  <Namespace>[NAMESPACE]</Namespace>
  <SchemaLocation>[SCHEMA_LOCATION]</SchemaLocation>
</Format>

where:

NOTE: Changes in [dspace]/config/crosswalks/oai/xoai.xml requires reloading/restarting the servlet container.

Driver/OpenAIRE compliance

Add/Remove Metadata Fields

The internal DSpace fields (Dublin Core) are exposed in the internal XOAI format (xml). All other metadata formats exposed via OAI are mapped from this XOAI format using XSLT (xoai.xsl itself is just an identity transformation). These XSLT stylesheets are found in the [dspace]/config/crosswalks/oai/metadataFormats directory. So e.g. oai_dc.xsl is a transformation from the XOAI format to the oai_dc format (unqualified Dublin Core).

Therefore exposing any DSpace metadata field in any OAI format is just a matter of modifying the corresponding output format stylesheet (This assumes the general knowledge of how XSLT works. For a tutorial, see e.g. http://www.w3schools.com/xsl/).

For example, if you have a DC field "local.note.librarian" that you want to expose in oai_dc as <dc:note> (please note that this is not a valid DC field and thus breaks compatibility), then edit oai_dc.xsl and add the following lines just above the closing tag </oai_dc:dc>:

<xsl:for-each select="doc:metadata/doc:element[@name='local']/doc:element[@name='note']/doc:element/doc:element/doc:field[@name='librarian']">
    <dc:note><xsl:value-of select="." /></dc:note>
</xsl:for-each>

If you need to add/remove metadata fields, you're changing the output format. Therefore it is recommended to create a new metadata format as a copy of the one you want to modify. This way the old format will remain available along with the new one and any upgrades to the original format during DSpace upgrades will not overwrite your customizations. If you need the format to have the same name as the original format (e.g. the default oai_dc format), you can create a new context in xoai.xsl containing your modified format with the original name, which will be available as /oai/context-name.

NOTE: Please, keep in mind that the OAI provider caches the transformed output, so you have to run [dspace]/bin/dspace oai clean-cache after any .xsl modification and reload the OAI page for the changes to take effect. When adding/removing metadata formats, making changes in [dspace]/config/crosswalks/oai/xoai.xml requires reloading/restarting the servlet container.

Driver/OpenAIRE compliance

The default OAI 2.0 installation provides two new contexts. They The default OAI 2.0 installation provides two new contexts. They are:

• Driver context, which only exposes Driver compliant items;
• OpenAIRE context, which only exposes OpenAIRE compliant items;

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Sanity check your OAI interface with the OAI Validator

There is a very useful validator for OAI interfaces available at http://validator.oaipmh.com, we urge you to use this validator to confirm your OAI interface is in fact usable.