[rules-users] Query for a fact, and concurrent rule execution

Wed May 2 12:09:25 EDT 2012

Loading a stateless knowledge session with ~10k facts and the one (or
few) transaction fact(s) for a single transaction isn't economic.

I'd benchmark the costs for inserting the transaction fact(s) into a
statefeul session, run fireAllRules(), returning the result and
removing the debris in a thread. This should give you a good
indication how many of these you can do per second, and the potential
delay for concurrent requests when transactions are done in turn.

-W

On 02/05/2012, GPatel at tsys.com <GPatel at tsys.com> wrote:
> I would suggest making your service stateless and run the service in
> multiple JVMs to alleviate performance concerns. You will be able to scale
> and also not have to worry about cramming everything into a
> StatefulKnowledgeSession and worry abt thead-safety.
>
>
>
> From:   Stephen Lomax <stephen.lomax at mattelli.com>
> To:     Rules Users List <rules-users at lists.jboss.org>,
> Date:   05/02/2012 04:28 AM
> Subject:        Re: [rules-users] Query for a fact, and concurrent rule
> execution
> Sent by:        rules-users-bounces at lists.jboss.org
>
>
>
> Hi Mike,
>
> Many thanks for that..we had previously thought of serialising to file but
> thought the purpose of the StatefulKnowledgeSession was to keep it live in
> memory continuously, rather than instantiating a new session with each web
> service call.
>
>
> My concern is that if we instantiate a new session with each web service
> call the memory required will increase massively (if we have many
> concurrent requests).  Is there a way of serving multiple concurrent
> requests against the same session to remove that concern.
>
> Many thanks for your help with this..it is very much appreciated.
>
> Ste
>
>
> .
> On 2 May 2012, at 12:08, Michael Anstis wrote:
>
> That's a possibility, but it'd depend on your rules.
>
> As a thought, you could serialise the initialised
> StatelessKnowledgeSession into a byte[] (cached at application scope) and
> deserialise with each web-service call.
>
> I would wait to see if Mark Proctor, Edson Tirelli or community members
> have other thoughts on use of a single StatefulKnowledgeSession.
>
> IIRC it is meant to be thread-safe but think people have reported problems
> in the past. Recently:
> http://lists.jboss.org/pipermail/rules-dev/2012-February/003857.html
>
> With kind regards,
>
> Mike
>
> On 2 May 2012 11:58, Stephen Lomax <stephen.lomax at mattelli.com> wrote:
> Hi Mike,
>
> Each quote does not enrich the session, we were actively looking to remove
> the quote at the end of the session to prevent it growing as we were just
> comparing the quote to the core product attribute facts.
>
> What is the performance hit in launching a Stateful knowledge session with
> say 10,000 facts, would it make the web service call slow?
>
> Thanks very much for the help on the query also…we will look into that.
>
> Kind Regards
>
> Ste
>
> On 2 May 2012, at 11:31, Michael Anstis wrote:
>
> Does each quote validation exercise enrich the StatefulKnowledgeSession
> with other facts that could influence validation of other quotes?
>
> If not probably using a StatefulKnowledgeSession per HTTP request might be
> more simple (with the KnowledgeBase as an application scoped variable).
>
> Regarding retrieval of results, there are a couple of options that spring
> to mind:-
> Look at using a Global to collate results.
> Look at using a Query (
> http://stackoverflow.com/questions/5872215/how-do-i-add-facts-to-working-memory-at-runtime-in-the-drools-drl-and-retrieve-t
> )
> With kind regards,
>
> Mike
>
> On 2 May 2012 10:39, stelomax <stephen.lomax at mattelli.com> wrote:
> Hi,
>
> Please bear with me, I am relatively new to the world of Drools and have a
> question.  I am hoping it will be a simple issue.
>
> First let me frame my planned implementation at a high level.  I am hoping
> to use Drools as a real time service enabled quote validation tool.
>
> Facts representing products and attributes will be loaded into a stateful
> knowledge session upon boot (using a piece of Java that loads these as
> facts
> from our product DB).
>
> The front-end application will allow users to build up quotes consisting
> of
> quote lines that make references to these products.  Once the quote is
> built
> they will press a "Validate" button.  This will call a webservice that
> will:
>
> 1) Insert the quote details as facts into the knowledge session
> 2) Run a "rule flow" to validate the quote against the product facts
> 3) The rules will insert validation results as facts tagged against the
> quote
> 4) QUERY for the validation results
> 5) Retract the facts for the quote (inc validation results)
> 6) Send the validation results back as a response to the webservice call
>
> My first question is how to implement step 4 --> how to physically query
> for
> the validation results pertaining to that specific quote.  Any help here
> would be greatly appreciated.
>
> My second question relates to concurrency.  As this is a quote validation
> tool there will be multiple users validating quotes so we will get
> concurrent validation requests.
>
> What is the recommended manner of dealing with concurrent rule requests
> within a stateful knowledge session.  If 2 people attempt to validate a
> different quote at the same time we will have two quotes within the
> knowledge session together with all of the product facts.  Is drools
> capable
> of running two concurrent rule flows against the knowledge session, each
> referencing a different quote or would we need to instantiate 2 knowledge
> sessions, or even deal with the matter in a serial manner placing the 2nd
> quote validation flow on hold until the first completes?
>
> Any help/pointers would be great.  I am hoping someone out there has
> attempted to use Drools in a similar manner :)
>
> Many Thanks
>
> Ste
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/Query-for-a-fact-and-concurrent-rule-execution-tp3954737.html
>
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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