[rules-users] Re: Is this scenario suitable for using Drools?
Cheng Wei Lee
zhenwei.li at gmail.com
Wed Apr 23 04:36:43 EDT 2008
Thanks Mike!
I'm a total newbie here with Drools, so what I'm going to do is to take your
solution and try it out.
Cheers!
On Wed, Apr 23, 2008 at 4:28 PM, Anstis, Michael (M.) <manstis1 at ford.com>
wrote:
> Thanks Steve,
>
> This fixed the problem!
>
> For Cheng Wei Lee's benefit this is the complete solution (I had to fix
> another part):-
>
> public class DBUtils {
>
> public Collection getNumbers() {
>
> Integer[] numbers = new Integer[10];
> for (int i = 0; i < numbers.length; i++) {
> numbers[i] = (int)Math.random() * 100;
> }
> return Arrays.asList(numbers);
> }
> }
>
> rule "a1"
> when
> $max : Number() from accumulate( Number( $v : intValue ) from
> dbutils.getNumbers(), max($v) )
> then
> System.out.println($max.intValue());
> end
>
> With kind regards,
>
> Mike
>
> ------------------------------
> *From:* rules-users-bounces at lists.jboss.org [mailto:
> rules-users-bounces at lists.jboss.org] *On Behalf Of *Steven Williams
> *Sent:* 23 April 2008 09:07
> *To:* Rules Users List
> *Subject:* Re: [rules-users] Re: Is this scenario suitable for using
> Drools?
>
> change DBUtils to return a Collection and it should work I think.
>
> On Wed, Apr 23, 2008 at 5:50 PM, Anstis, Michael (M.) <manstis1 at ford.com>
> wrote:
>
> > So, in my usual helpful manner I thought Drools would be a perfect
> > match and put together what I thought would be a simple example:-
> >
> > package com.sample
> >
> > global com.sample.DBUtils dbutils;
> > rule "a1"
> > when
> > $max : Integer() from accumulate( Integer( $v : intValue ) from
> > dbutils.getNumbers(), max($v) )
> > then
> > System.out.println($max);
> > end
> >
> >
> > public class DBUtils {
> >
> > public Integer[] getNumbers() {
> >
> > Integer[] numbers = new Integer[10];
> > for (int i = 0; i < numbers.length; i++) {
> > numbers[i] = (int) (Math.random() * 100);
> > }
> > return numbers;
> > }
> > }
> >
> > However this led to some errors:-
> >
> > org.drools.RuntimeDroolsException: java.lang.ClassCastException:
> > [Ljava.lang.Integer; incompatible with java.lang.Integer
> > at org.drools.rule.Accumulate.accumulate(Accumulate.java:131)
> > at
> > org.drools.reteoo.AccumulateNode.assertTuple(AccumulateNode.java:127)
> > at
> > org.drools.reteoo.CompositeTupleSinkAdapter.createAndPropagateAssertTuple(CompositeTupleSinkAdapter.java:73)
> > at
> > org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:116)
> > at
> > org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:22)
> > at
> > org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:153)
> > at org.drools.reteoo.Rete.assertObject(Rete.java:177)
> > at
> > org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
> > at
> > org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute(ReteooWorkingMemory.java:179)
> > at
> > org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1292)
> > at
> > org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:891)
> > at
> > org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:858)
> > at
> > org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:659)
> > at com.sample.DroolsTest.main(DroolsTest.java:36)
> > Caused by: java.lang.ClassCastException: [Ljava.lang.Integer;
> > incompatible with java.lang.Integer
> > at
> > org.drools.base.java.lang.Integer968047027$intValue.getIntValue(Unknown
> > Source)
> > at
> > org.drools.base.ClassFieldExtractor.getIntValue(ClassFieldExtractor.java:197)
> > at org.drools.rule.Declaration.getIntValue(Declaration.java:230)
> > at
> > com.sample.Rule_a1_0AccumulateExpression0Invoker.evaluate(Rule_a1_0AccumulateExpression0Invoker.java:16)
> > at
> > org.drools.base.accumulators.JavaAccumulatorFunctionExecutor.accumulate(JavaAccumulatorFunctionExecutor.java:74)
> > at org.drools.rule.Accumulate.accumulate(Accumulate.java:123)
> > ... 13 more
> > Have I done something really stupid and is Drools a fit?
> >
> > Cheers,
> >
> > Mike
> >
> > ------------------------------
> > *From:* rules-users-bounces at lists.jboss.org [mailto:
> > rules-users-bounces at lists.jboss.org] *On Behalf Of *Cheng Wei Lee
> > *Sent:* 22 April 2008 17:27
> > *To:* rules-users at lists.jboss.org
> > *Subject:* [rules-users] Re: Is this scenario suitable for using Drools?
> >
> > I've 2 algorithms to calculate the cost of a product. At any one time,
> > there is only 1 algorithm in use. Initially algorithm 1 will be the default.
> > Subsequently, the decision to use which algorithm will depend on customers
> > feedback. The algorithms are:
> >
> > Algorithm 1:
> > Cost = MAX(P1, T1, P2, T2, P3, T3, ...)
> >
> > Algorithm 2:
> > Cost = MIN(P1, P2, P3, ...) + MIN(T1, T2, T3, ...)
> >
> > The values of P1, P2, ... are stored within a database. The number of Ps
> > & Ts are unknown but can be determined by querying the database, Would
> > drools be a good option to use to store the algorithms? If so, how could I
> > be able to retrieve the values of P1, P2, etc from the database from within
> > drools?
> >
> > Thanks!
> >
> >
> > _______________________________________________
> > rules-users mailing list
> > rules-users at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/rules-users
> >
> >
>
>
> --
> Steven Williams
>
> Supervising Consultant
>
> Object Consulting
> Office: 8615 4500 Mob: 0439 898 668 Fax: 8615 4501
> steven.williams at objectconsulting.com.au
> www.objectconsulting.com.au
>
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>
>
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