Ontology Reasoners and Rule Engines are quite different, can be integrated under some assumptions,
but are definitely not easily interchangeable.. (unique name assumption, closed world assumption, etc..)
Which one is better pretty much depends on the use case, which also dictates the required level of
expressiveness of the language - even Fact++, Hermit and Pellet do not support full FOL...

This said, your case seems very interesting.. would you mind sharing a few more details or a concrete example?
We would then be able to assess whether Drools is appropriate or not, and which constructs could be
used (e.g. traits, hybrid chaining queries, tms, ...) to tackle the complexity.

Or maybe we could take it as a use case to improve the engine capbilities :)

Best
Davide




On 04/11/2013 05:01 AM, Upali Kohomban wrote:
Thanks a lot again, you made my life easy with the build instructions :)

Yes I'm trying to do an integration. I have some experience with ontologies and want to experiment with drools as an alternative.

OWL with reasoners like Fact ++ are pretty much good for the job, except for the fact that they handle individual data bits in quite a cumbersome way. It was because of this reason that I wanted to experiment on other ways of modeling a knowledge structure with better facilities for querying large amounts of factual data. I'm giving drools a try, but I'm not entirely sure if drools can do things as powerful as a reasoner.

Basically, I'd like to be able to let the data lie (without firing any "events" until necessary)  and query the inferences in a first-order logic like manner. This is very space-efficient in data-heavy scenarios. I know that this isn't the traditional way drools is designed to work. I'm trying to solve the inference problem by dynamically adding semantic classes to each object to store all the possible inferences about it, so they can be queried later. Problem with this approach is that it gets out of hand very quickly, because the enumerated number of such inferences can be HUGE even for a moderate KB. Backward chaining will eventually solve this problem, but it seems that the constructs available for that in drools queries are not too matured at the moment. For instance they don't seem to support numerical inequality operators (or I am wrong, which is also very likely).

Thank you again for the quick help,
Upali






On 11/04/2013 14:14, Davide Sottara wrote:
You should be able to
git clone ...
the droolsjbpm repository, then
git checkout -t origin/5.5.x

this should switch to 5.5.1-SNAPSHOT (you can check the pom in the root
folder)
eventually, mvn clean install should do the trick.

See also the readme.md in github

Btw, it seems that you're working with rule/ontology integrations..
would you
be interested in sharing thoughts?

Davide

On 04/11/2013 01:29 AM, upalik wrote:
Hi Davide,

Thanks a lot for the information and your time spent on troubleshooting the
scenario with a test case.

I'm using 5.5.0; as I mentioned, I'm a newbie. I'll try to get 5.5.1
compiled and running (on windows), I'm reading whatever the documentation I
can find on how to do this. Github source seems to be on 6.0.0, I'll try
with that one if all else fails.

I'm loading the rule base using a KnowledgeBuilder, and yes I do check for
errors explicitly after building. The rule file with the problem I mentioned
does not produce any errors, other than the result that doesn't make sense.

Thanks again,
Upali



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Upali Kohomban, PhD
Research Fellow
CodeGen International
29 Breybrooke Street, Colombo 02, Sri Lanka
T: +94 112 470 740 F: +94 112 470 749 W: http://codegen.net



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