adasal wrote:
As far as i have researched this I know that the gnowsis project uses both rdf and lucene, but I have not had time to determine their relationship. www.gnowsis.org/
I can tell you a bit about Gnowsis, as we (Aduna) are cooperating with the Gnowsis people on RDF creation, storage and querying in the Aperture project (aperture.sourceforge.net).
Both the latest Gnowsis beta version and various Aduna products use the Sesame framework (openrdf.org) to store and query RDF.
One of Sesame's core interfaces is the Sail (Storage And Inference Layer), which provides an abstraction on a specific type of RDF store, e.g. in-memory, file-based, RDBMS-based, ...
We have developed a Sail implementation that combines a file-based RDF storage with a Lucene index. The purpose of this Sail is to provide a means to query both document full-text and metadata using an RDF model.
The way we realized this is that document metadata is stored in the RDF store, the full-text and other text-like documents are indexed in Lucene, and the RDF model is extended with a virtual property connecting a Document resource to a query literal that can be used to query the full-text. The dedicated Sail knows that that property should not be looked up in the RDF store but should instead be evaluated as a Lucene query. If you want, I can send you example code that shows how we did this.
We have some ideas on generalizing this approach, as ideally you would like to be able to query all RDF literals using Lucene's query facilities while making use of the logical RDF structure (which is what you want, if I understand you correctly), even when the structure of the stored models is not known at development time. However, little work has been done on this. I guess that when we would start working on this, the code for it would end up in either the Sesame or Aperture code base.
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