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From Alessandro Adamou <>
Subject Re: Indexed in-memory graph
Date Fri, 03 Feb 2012 12:11:11 GMT
Hi Rupert,

On 2/3/12 12:51 PM, Rupert Westenthaler wrote:
> I spent most of the last night and todays morning with implementing a
> Clerezza in-memory TripleCollection that supports SPO, POS, OSP
> indexes for fast filtered iterators.
> See for details

This is definitely great news - thanks and congrats!

> However I assume that performance improvements for Ontonet, Reasoning
> and Rules could be even more significant if this components where
> actually using Clerezza in-memory models. If yes it would be great if
> you could check such use cases and provide some performance
> comparisons.

OntoNet usually hands over to whatever providers are registered with the 
TcManager, as far as storage is concerned.

However, it does use SimpleMGraph whenever it has to export a scope or 
session as a TripleCollection, as per

<O> O OWLExportable#export(Class<O> returnType, boolean merge)

This happens e.g. for GET methods over scopes and sessions with Accept: 
application/json . The other formats are supported by the OWL API, which 
has an amazingly human-readable rendering of RDF/XML and other formats, 
so for those we export to OWLOntology instead of a TripleCollection.

However, this is the real bottleneck of OntoNet: what it does now is to 
serialize the TripleCollection and deserialize to OWLOntology, which is 
just as good as you can figure yourself.
Also, the OWL API works inmemory, and it is not trivial to make an 
adapter that makes Clerezza Triples into appropriate *subtypes* of 
OWLAxiom (e.g. OWL annotation assertions vs. object/data property 
assertions). Some use cases do need to handle these resource 
owl-axiom-wise, DL reasoners being one.

Anyway, I will be happy to benchmark whatever usage I have of 
SimpleMGraph versus your indexed MGraph.



M.Sc. Alessandro Adamou

Alma Mater Studiorum - Università di Bologna
Department of Computer Science
Mura Anteo Zamboni 7, 40127 Bologna - Italy

Semantic Technology Laboratory (STLab)
Institute for Cognitive Science and Technology (ISTC)
National Research Council (CNR)
Via Nomentana 56, 00161 Rome - Italy

"As for the charges against me, I am unconcerned. I am beyond their timid, lying morality,
and so I am beyond caring."
(Col. Walter E. Kurtz)

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