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From Tommaso Teofili <>
Subject Re: Composite Resource Indexing Service: ready for review.
Date Fri, 03 Jun 2011 08:49:43 GMT
2011/6/2 Tsuyoshi Ito <>

> Dear all
> Composite Resource Indexing Service is now ready for review (issue
> CLEREZZA-501). Junit Tests and documentation is available (install
> rdf.cris/core on clerezza and search for Composite Resource Indexing
> Service under /documentation)
> excerpt:
> CRIS is based on Apache Lucene and provides means to index RDF
> resources. It works by indexing the values of properties on a
> resource. This enables to search for the property values using CRIS.
> The results that CRIS delivers are the corresponding RDF resources.
> GraphIndexer
> The core of CRIS is the GraphIndexer class. Note that GraphIndexer is
> not an OSGi service, but it has to be instantiated by the user to
> provide an index. The GraphIndexer needs two graphs to work with. One
> graph contains the IndexDefinitions, that is the specification of
> which resources and properties to index (see IndexDefinitionManager).
> The other graph is the the graph that contains the resources to index.
> Note that CRIS indexes RDF resources based on their rdf:type and that
> the indexing works on a per-property basis. That means, not all
> properties on a resource are indexed by default. The user has to
> specify which properties to index.
> GraphIndexer also provides the interface to search for resources using
> the findResources method. The search is specified using Conditions and
> optionally a SortSpecification and FacetCollectors. The findResources
> method is overloaded with methods that allow the specification of the
> resource type and search query directly.
> IndexDefinitionManager
> The IndexDefinitionManager helps to manage indexing specifications
> using the CRIS ontology in the index definition graph (see
> GraphIndexer). Indexing is enabled for resources according to their
> rdf:type. Additionally the index definitions specify the properties of
> the resource that are indexed.
> One can think of an index definition as specifying the keys
> (properties) that are mapped to the value (the resource URI) in the
> index.
> ....
> Note:
> - GraphIndexer is quit complex and has many responsibilities.
> - No other clerezza project depends on Composite Resource Indexing Service.
> - GraphIndexer is available as Platform CRIS Service in project
> platform.cris (for the contentgraph incl. additions)
> @Tommaso
> Lucene is used in in rdf.cris/core. Feedback
> appreciated - I have little experience with lucene, so feel free to
> improve it. Especially I am not sure when to call optimize (see
> comment in LuceneTools)

Uber cool Tsuy and others, I'll definitely have a deep look there, thanks
for this awesome work!

> Thanks to Reto, Daniel and Hasan for the work! We already use it in a
> monitoring tool - the performance is outstanding compared to the
> available alternatives in clerezza (filter resp. sparql)
> Cheers
> Tsuy

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