...
The indexer can have any number of workers configured to process the events. So the main indexer process retrieves the object RDF from the repository, and that content can be reused by multiple workers. If you want to process the events in several ways (triplestore, Solr, archive to disk, update remote repository, etc.), this limits the number of times the metadata has to be retrieved from the repository to once each time the object is updated.
Indexer Modules
Several different indexer modules exist for syncing with different systems:
- ElasticIndexer - syncing with Elasticsearch
- FileSerializer - saves Solr document format to disk
- JcrXmlPersistenceIndexer - saves JCR/XML to disk
- RdfPersistenceIndexer - saves RDF to disk
- SolrIndexer - syncs with Solr
- SparqlIndexer - syncs with triplestores using SPARQL Update
Configuration
The indexer is configured using Spring. Here is a sample configuration fragment showing three workers (saving RDF to disk, persisting jcr/xml, and syncing to a Jena Fuseki triplestore) and the framework for listening to events and connecting them with the workers:
...
You can deploy Fedora4 either by downloading the latest war file and dropping it into an application container (e.g. Tomcat7). Or you can clone the Git fcrepo4 project and run the fcrepo-webapp directly within the code base.
See the following pages for details on either approach:
...
You can deploy the jms-event-listener by downloading the latest war file and dropping it into an application container (e.g. Tomcat7). Or you can clone the Git fcrepo-jms-indexer-pluggable project and run the fcrepo-jms-indexer-webapp directly within the code base.
...