While Lucene has long offered these capabilities, its native capabilities are not intended for large semi-structured document collections (or documents with very different schemas). For this reason we developed SIREn - Semantic Information Retrieval Engine - a Lucene plugin to overcome these shortcomings and efficiently index and query RDF, as well as any textual document with an arbitrary amount of metadata fields.
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H. Sack. Proceedings of SWAP 2005, the 2nd Italian Semantic Web Workshop, CEUR Workshop Proceedings (2005), volume 166 of CEUR Workshop Proceedings, Trento, Italy, CEUR-WS.org, (December 2005)
S. Linckels, H. Sack, and C. Meinel. in Proc. Workshop on Service Matchmaking and Resource Retrieval (SMR 2007) at the 6 th International Semantic Web Conference (ISWC + ASWC 2007), (November 2007)