The RdfPersistenceIndexer listens to the repository generated JMS events and persists metadata in a configurable RDF format to the file system. It implements the org.fcrepo.indexer.Indexer interface for the indexing functionalities, which consists of the methods to handle new/updated records and deleted records.
RDF is the native format supported by Fedora 4, and provides more information than the JCR/XML persistance.
The RDF files are stored in the configured path in a directory tree that corresponds to the repository URI. So the the resource at http://localhost:8080/rest/foo would be stored in localhost/8080/rest/foo.rdf.
Configuration
The indexer is configured using Spring that can be done with Java bean setter methods. The base filesystem storage path, RDF variant, and filename extension be configured. Here is a sample configuration fragment showing how to configure and use the RdfPersistenceIndexer:
<!-- jcr/xml persistence Indexer -->
<bean id="rdfPersist" class="org.fcrepo.indexer.persistence.RdfPersistenceIndexer">
<constructor-arg value="${fcrepo.rdf.storage:fcrepo4-rdf}" />
<constructor-arg value="${fcrepo.rdf.lang:TURTLE}" />
<constructor-arg value="${fcrepo.rdf.ext:.ttl}" />
</bean>
<!-- Message Driven POJO (MDP) that manages individual indexers -->
<bean id="indexerGroup" class="org.fcrepo.indexer.IndexerGroup">
<constructor-arg name="indexers">
<set>
...
<ref bean="rdfPersist"/>
...
</set>
</constructor-arg>
...
</bean>
Valid values for fcrepo.rdf.lang (the RDF variant used) are:
- "N3"
- "N_TRIPLES" (N-Triples)
- "RDF_XML" (RDF/XML flat syntax)
- "RDF_XML_ABBREV" (RDF/XML abbreviated/nested syntax)
- "TURTLE"
