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

Wed May 2 12:23:34 EDT 2012

Indeed!  And there's no reason you couldn't do the procedure below with multiple concurrent stateful sessions.  In fact, this might be the best way, as when the support facts change you could create new sessions and not disrupt the service. (And if the support facts are immutable and not changed by the rules you should share them between sessions in the same JVM, saving memory and DB load overhead.)

--- On Wed, 5/2/12, Wolfgang Laun <wolfgang.laun at gmail.com> wrote:

> From: Wolfgang Laun <wolfgang.laun at gmail.com>
> Subject: Re: [rules-users] Query for a fact, and concurrent rule execution
> To: "Rules Users List" <rules-users at lists.jboss.org>
> Date: Wednesday, May 2, 2012, 11:09 AM
> 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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