Apache Jena is a free and open-source Java framework for building Semantic Web and linked data applications.
Solr is a popular, open-source enterprise search platform built on Apache Lucene. Solr is highly reliable, scalable, and fault tolerant, providing distributed indexing, replication, and load-balanced querying, automated failover and recovery, centralized configuration, and more. Solr runs as a standalone full-text search server. It uses the Lucene Java search library at its core for full-text indexing and search, and has REST-like HTTP/XML and JSON APIs that make it usable from most popular programming languages. Solr's external configuration allows it to be tailored to many types of application without Java coding, and it has a plugin architecture to support more advanced customization. Apache Lucene and Apache Solr are both produced by the same Apache Software Foundation development team.
Solr powers the search and navigation features of many of the world's largest internet sites.
The Apache OpenNLP library is a machine learning based toolkit for the processing of natural language text.
It supports the most common NLP tasks, such as tokenization, sentence segmentation, part-of-speech tagging, named entity extraction, chunking, parsing, and coreference resolution.