McGibbney, Lewis John wrote:
Hi Paolo,
First and foremost I apologise upfront for talking off-subject here in regards
to Jena in specific.
I am currently working on a plug-in for Solr which refines user queries based
on ontology classes and I am using Jena to wrap around my ontology models to
provide this functionality.
Immediately I am interested in experimenting with LARQ and SARQ.
Out of curiosity, can you please provide some use case or personal usage for
these frameworks as it would enable me to get at least an abstract sense of how
I may be able to use LARQ,
prior to SARQ for my own needs.
The use cases for SARQ or EARQ are exactly the same as the ones for LARQ (since
they
implement exactly same functionalities but with a different indexing solution
behind).
One use case could be: you want to quickly find, for example, all the "things"
which
have the word "nuclear energy" in any of their literals.
Other RDF stores implement similar functionalities, see:
http://www.w3.org/wiki/SPARQL/Extensions/Computed_Properties
This is just pure and plain vanilla free text searches: given some keywords,
you retrieve
a ranked list of the first X literals containing those keywords/words. It's not
what some
call "semantic search", no ontologies are involved, no NLP, etc.
Can you point me at the Solr plug-in you are working on?
Thanks,
Paolo
Any comments would be great
Thank you
Lewis
________________________________________
From: Paolo Castagna [[email protected]]
Sent: 16 March 2011 19:00
To: [email protected]
Subject: Re: ARQ + Lucene
Nikolaos Abatzis wrote:
All:
I just did a check on the 2.6.4 Jena bundle and I see that even the latest ARQ
(2.8.7) seems to use the lucene-core-2.3.1.
Are there any plans to port ARQ so that it uses a more recent version of
Lucene. 2.3.1 is kind of ancient, current in the 2.x series is 2.9.4
and my understanding is that it uses Java 1.4. There is also a 3.x series that
uses Java 1.5. per the lucene docs, the latest versions offer
significant enhancements and have fixed memory leaks, etc...
"Lucene 2.3.1 is kind of ancient", I agree. :-)
Yes, the plan is to extract LARQ as a separate module (which will depend on
ARQ).
You can look here: https://jena.svn.sourceforge.net/svnroot/jena/LARQ/trunk/
As you can see, it is using Lucene 3.0.3 (and it is backward compatible with
2.9.x
... as just a drop-in replacement if somebody needs an older version of Lucene).
We are currently waiting the "all clear" to move source code from SourceForge
to the
Apache SVN repository. Once we do that, little changes are necessary in the ARQ
source code to dynamically look for LARQ and wiring it in (if present in the
class
path).
The LARQ separate module has already a few improvements (i.e. avoiding
duplicates
with subsequents updates and removals).
Still pending:
- a way to support RDF Datasets in addition to Jena Models and proper
assemblers.
- a tool to make it easier to build Lucene indexes pointing to a TDB location.
- (at one point, I'd like to see LARQ in Fuseki ;-))
Later:
- Solr? https://github.com/castagna/SARQ
- ElasticSearch? https://github.com/castagna/EARQ
To checkout LARQ and compile it type:
svn co https://jena.svn.sourceforge.net/svnroot/jena/LARQ/trunk/ LARQ
cd LARQ
mvn package
Let me know if you have problems,
Paolo
Please do not hesitate to contact me if you need additional information. Thank
you.
Regards,
Nikolaos Abatzis
New River Systems Corporation
1890 Preston White Drive, Suite 240
Reston, VA 20191
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