2:09 a.m.
I am trying to use an external storage for loading and persisting objects.
But when I try a set a temporal reasoning rule it start to fail. The rule,
test code and exception are given below. Please help
// rules file
package foo.externalwm;
global foo.ExternalStorage session;
import foo.externalwm.YUser
import foo.externalwm.Test
declare User
@role(event)
end
declare Contest
@role(event)
end
rule "test"
dialect "java"
when
$c1:Contest() from session.getContestByName("Contest1")
User(this after[0,3m] $c1) from session.getUserByIndex(0)
then
System.out.println("rule fired");
end
// ************ code
public class Test {
public static void main(String[] args) throws Exception {
KnowledgeBaseConfiguration config =
KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
config.setOption( EventProcessingOption.STREAM );
KnowledgeBase k = init(); // read and compile rules done here
final StatefulKnowledgeSession ksession =
k.newStatefulKnowledgeSession();
ExternalStorage session = new ExternalStorage();
ksession.setGlobal("session", session);
ksession.fireAllRules();
}
***********EXCEPTION
Exception in thread "main" org.drools.RuntimeDroolsException: Unexpected
exception executing action
org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction@669a4cb
at
org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:996)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:730)
at
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:699)
at
org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:218)
at foo.externalwm.Test.main(Test.java:55)
Caused by: java.lang.ClassCastException: org.drools.common.DefaultFactHandle
cannot be cast to org.drools.common.EventFactHandle
at
org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedLeft(AfterEvaluatorDefinition.java:332)
at
org.drools.rule.VariableRestriction.isAllowedCachedLeft(VariableRestriction.java:110)
at
org.drools.rule.VariableConstraint.isAllowedCachedLeft(VariableConstraint.java:111)
at
org.drools.common.SingleBetaConstraints.isAllowedCachedLeft(SingleBetaConstraints.java:127)
at
org.drools.reteoo.FromNode.checkConstraintsAndPropagate(FromNode.java:274)
at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:137)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:64)
at
org.drools.reteoo.FromNode.checkConstraintsAndPropagate(FromNode.java:279)
at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:137)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.createAndPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:138)
at
org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:141)
at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59)
at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:185)
at
org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:143)
at org.drools.reteoo.Rete.assertObject(Rete.java:107)
at
org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:260)
at
org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute(ReteooWorkingMemory.java:343)
at
org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:994)
... 4 more
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11:46 a.m.
Could someone please provide an answer?
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12:20 p.m.
Objects produced by a "from" clause that haven't been inserted into Working
Memory previously are not facts, let alone events.
As the presented code shows, the timestamp of event User should be set by
Drools when the fact is inserted. Frist, with "from" it isn't inserted at
all, and second, if it were inserted, what timestamp would it receive - the
time it was taken from session.getUserByIndex(0)?
Not knowing why you do what you do it's difficult to suggest alternatives.
-W
On 12 July 2011 18:46, rp2 <amanteja(a)gmail.com> wrote:
Could someone please provide an answer?
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12:47 p.m.
Thanks.
Basically I am trying to retrieve (and store) events from an external store
like in http://magazine.redhat.com/2008/07/11/jboss-drools-meets-hibernate/
expect that the backing store in not a relational db but a custom key-value
store.
This example also does not show the facts/events being inserted. Is this
incorrect?
All it does is
... ...
workingMemory.setGlobal("hibernateSession", session); // sets a hibernate
session
workingMemory.fireAllRules();
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1:07 p.m.
On 12 July 2011 19:47, rp2 <amanteja(a)gmail.com> wrote:
Thanks.
Basically I am trying to retrieve (and store) events from an external store
like in
http://magazine.redhat.com/2008/07/11/jboss-drools-meets-hibernate/
expect that the backing store in not a relational db but a custom key-value
store.
This example also does not show the facts/events being inserted. Is this
incorrect?
The example does not use events, as in @role(event). You can maintain
a value of type java.util.Date in your hibernated facts, but don't make
them events the way you do.
-W
All it does is
... ...
workingMemory.setGlobal("hibernateSession", session); // sets a hibernate
session
workingMemory.fireAllRules();
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7:13 p.m.
Wolfgang Laun-2 wrote:
The example does not use events, as in @role(event). You can maintain
a value of type java.util.Date in your hibernated facts, but don't make
them events the way you do.
It is important for me to use temporal reasoning and CEP, and hence HAD to
define these as @events.
In addition I wanted to load and persist these events from/in a custom non
JPA compliant key-value store because I will be running multiple instances
of drools as opposed to only one server. Therefore relying on RAM based
working memory is not enough.
What would be your suggestion in that regard?
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11:51 p.m.
First of all, don't use automated time stamping of events; add a field
carrying the (original) event time. I think you could also run the session
in CLOUD mode.
Also, it may not be advisable to pull in facts and reason over them in the
same rule. Perhaps retrieval and proper insertion of facts should even be
coded in Java, kept separate from the rule logic.
Much depends on the required use cases for running those multiple sessions,
and how canned events relate to other data.
-W
On 13 July 2011 02:13, rp2 <amanteja(a)gmail.com> wrote:
Wolfgang Laun-2 wrote:
>
> The example does not use events, as in @role(event). You can maintain
> a value of type java.util.Date in your hibernated facts, but don't make
> them events the way you do.
>
>
It is important for me to use temporal reasoning and CEP, and hence HAD to
define these as @events.
In addition I wanted to load and persist these events from/in a custom non
JPA compliant key-value store because I will be running multiple instances
of drools as opposed to only one server. Therefore relying on RAM based
working memory is not enough.
What would be your suggestion in that regard?
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6 comments
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participants (3)
-
Aman Teja -
rp2
-
Wolfgang Laun