TheOpen Archives Initiative (OAI) 
harvest metadata from OAI data providers into ElasticSearch. It is
provided as a plugin.
The river allows to automatically harvest RDF / DC / XML metadata from
OAI data providers (OAI servers). Metadata is internally represented as
resources, using Resource Description Framework of the W3C Semantic Web
Initiative. These resources are serialized into JSON for Elasticsearch
For more info, see https://github.com/jprante/elasticsearch-river-oai
Feedback is welcome!