Interfaces without inputs and with multiple operations
by sam.squire＠paretopartners.com
Hello there,
I am using BPMN and trying to call a ServiceTask without any input
messages. Unfortunately the BPMN specification seems to require exactly
one inMessageRef. Is there a way to get it to call a method without
arguments, like doStuff() ?
Is there any way to get around this without having to change the class and
add a nonce parameter? This works but it is not ideal.
Does drools support the <operations> tag in BPMN? It seems to complain If
I try to use it. I can only have a single operation in each interface.
Thanks,
Sam Squire
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15 years, 5 months
Parallel processing of large batches of facts
by Tim Jones
Hello,
I’m working on a project that needs a high performance rules system for
processing batches of objects. Typically I’ll have a dozen or so rules, the
most complex of which will aggregate several objects based on timestamps and
specified data patterns. The objects will come in batches of a few 100ks.
The system is reset back to the starting point after each batch is
processed.
My guess at doing this with Drools is that you load up all the rules and
enter all the objects as “facts”. You then hit fireallrules and sit back and
wait. Doing this, I only get so much performance and I can see that its only
using a single thread. Is there a way to process the whole lot in a
parallel, or multithreaded way? Unfortunately there's no natural way to
partition the objects that would make things easier.
Cheers,
Tim
15 years, 5 months
unexpected ClassCastException when dealing with sliding windows
by will_lauer
I'm playing with Drools Fusion 5.1.1 a bit to try and evaluate whether it is
an appropriate tool for a project I'm working on. As part of that, I'm
playing a bit with its event capabilities, but I'm running into a problem
and I'm not sure whether its a bug or something that I'm doing.
I'm trying to write a rule that looks for a series of two events and I want
to preclude another specific type of event from coming between the two. I've
tried a couple of ways of doing this, and am now trying to use a sliding
window with the following rule:
declare Event
@role(event)
@expires(30ms)
end
rule TestWindow
when
$up : Event (type == "linkup", $inf : extra)
$window : ArrayList () from collect (
Event (extra == $inf) over window:length(2))
$down : Event (type == "linkdown", this before $up) from $window
then
channels["up"].send($up);
end
This is the only rule in my knowledge base. I create a stateful session and
start inserting facts into it. First a "linkdown" event and then a "linkup"
event with the same "extra" value. I get the following exception when
inserting the second event:
Exception in thread "main" java.lang.ClassCastException:
org.drools.common.DefaultFactHandle cannot be cast to
org.drools.common.EventFactHandle
at
org.drools.base.evaluators.BeforeEvaluatorDefinition$BeforeEvaluator.evaluateCachedLeft(BeforeEvaluatorDefinition.java:333)
at
org.drools.rule.VariableRestriction.isAllowedCachedLeft(VariableRestriction.java:110)
at
org.drools.rule.VariableConstraint.isAllowedCachedLeft(VariableConstraint.java:115)
at
org.drools.common.SingleBetaConstraints.isAllowedCachedLeft(SingleBetaConstraints.java:142)
at
org.drools.reteoo.FromNode.checkConstraintsAndPropagate(FromNode.java:274)
at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:138)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:64)
at
org.drools.reteoo.AccumulateNode.evaluateResultConstraints(AccumulateNode.java:662)
at
org.drools.reteoo.AccumulateNode.assertLeftTuple(AccumulateNode.java:181)
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:148)
at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59)
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:145)
at
org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:450)
at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:368)
at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:190)
at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:145)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1174)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1123)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:917)
at
org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:251)
at
net.wlauer.DroolsEngine.NonSpringRulesEngine.main(NonSpringRulesEngine.java:71)
Browsing the mailing list seems to indicate that this means that for some
reason Drools is interpretting one of my facts as of role fact instead of
role event. I'm not sure why this would be event that the only things I'm
inserting are Event objects, which can be seen above to have the role of
event.
Am I doing something wrong here? Is there something wrong with my rule (and
is it going to do what I think its doing)? Or have I encountered a bug with
the sliding window implementation?
Any thoughts or help would be appreciated.
Will
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15 years, 5 months
sliding window problems
by will_lauer
(reposting to a more appropriate list)
I'm starting to expirament with Drools and Drools Fusion and am running into
some problems using sliding windows. I'm using Drools 5.1.1 with a fairly
simple configuration. I have one rule:
package net.wlauer.DroolsEngine
import net.wlauer.DroolsEngine.Event
import java.util.ArrayList
declare Event
@role(event)
@expires(30s)
end
rule TestWindow
when
$up : Event (type == "linkup", $inf : extra)
$window : ArrayList () from collect (
Event (extra == $inf) over window:length(2))
$down : Event (type == "linkdown", this before $up) from
$window
then
channels["up"].send($up);
end
I expect this rule to fire whenever it sees a "linkup" event immediately
after a "linkdown" event for the same value of extra. (If you can suggest a
better way to write this, I would appreciate it). My sample program simply
inserts four Events, calling fireAllRules once all the inserts have been
completed.
What I'm seeing instead of my expected results is the exception:
Exception in thread "main" java.lang.ClassCastException:
org.drools.common.DefaultFactHandle cannot be cast to
org.drools.common.EventFactHandle
at
org.drools.base.evaluators.BeforeEvaluatorDefinition$BeforeEvaluator.evaluateCachedLeft(BeforeEvaluatorDefinition.java:333)
at
org.drools.rule.VariableRestriction.isAllowedCachedLeft(VariableRestriction.java:110)
at
org.drools.rule.VariableConstraint.isAllowedCachedLeft(VariableConstraint.java:115)
at
org.drools.common.SingleBetaConstraints.isAllowedCachedLeft(SingleBetaConstraints.java:142)
at
org.drools.reteoo.FromNode.checkConstraintsAndPropagate(FromNode.java:274)
at org.drools.reteoo.FromNode.assertLeftTuple(FromNode.java:138)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.doPropagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:189)
at
org.drools.reteoo.SingleLeftTupleSinkAdapter.propagateAssertLeftTuple(SingleLeftTupleSinkAdapter.java:64)
at
org.drools.reteoo.AccumulateNode.evaluateResultConstraints(AccumulateNode.java:662)
at
org.drools.reteoo.AccumulateNode.assertLeftTuple(AccumulateNode.java:181)
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:148)
at
org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:59)
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:145)
at
org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:450)
at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:368)
at
org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:190)
at
org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:145)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1174)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:1123)
at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:917)
at
org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:251)
at
net.wlauer.DroolsEngine.NonSpringRulesEngine.main(NonSpringRulesEngine.java:71)
>From scanning the list, it looks like this implies that a non-event fact is
being treated as an event-type fact, but I don't see where that could be
happening. Am I doing something obviously wrong? I've tried marking
ArrayList as an event type, but that didn't change the behavior.
Any insight you can give me would be appreciated.
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15 years, 5 months
Is it possible to use CEP features in Guvnor?
by John Peterson
I was wondering if it was possible to leverage the CEP features in
Guvnor. I am not sure how we'd set the "@role(event)" in Guvnor or
putting the "entry-point" in the rule unless you use DSL (embedding it
in the translation) or doing technical rules.
15 years, 5 months
Task persistence problem
by fuankarion
Hi, I'm not sure if this is the best place to ask this, I'll give it a try.
I'm building an application with drools, one of the features is that it
should keep a “TODO List”, this is given by the human tasks contained in
ruleflows, I've managed to set up drools persistence for workflows
kwnoeledge sessions and humans tasks (tricky but i got it working), however
it seems that I'm still missing something, when I try to start a workflow
with 2 human tasks and a script tasks, arranged like this
start >> human task 1 >> script task >> human tasks 2 >> end
its behavior is irregular.
A first review of this problem got me to the conclusion that the ruleflow
fails to register (with mina) the second human task about half the times
(first one is allways a success), interesting is that if you start the
ruleflow several times it shows a “pattern”, it registers the task once then
it does not, then it registers the task again and so on.
When it is unable to register the second task I don't get any exception
report (on the web interface) however after looking at the server logs I
found that every time the ruleflow fails to register the second task an
exception is thrown, it is
java.lang.IllegalArgumentException: attempt to create merge event
with null entity
followed by a
java.lang.NullPointerException
(I can provide the full stack trace or the log output of drools if you need
them, I'm trying to keep this post as readable as possible)
Digging deeper in this situation I noticed that some weird values are
getting inserted on the column workItemId on table Task (which I guess is
mapped from org.drools.task.Task), and sometimes the value 0 gets inserted
in this column (this colums right now looks looks like 22,0,24,25,0), so my
guess is that the human task is actually getting registered to mina but, it
is not registered in a “proper way” and those 0s are a sign of it.
Has any one any idea of what might be happening (what I might be missing),
any help will be appreciated.
By the way
I'm using drools 5.1
The database is a mysql database.
The persistence of the workflows and tasks is done in the same mysql server
but in different databases.
I'm using mina as task server and task client on the default port.
This whole thing is running inside a jboss 5.1 server on jdk 1.5.
I can provide more implementation details, logs or code if necessary
Thanks in advance
Fuanka
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15 years, 5 months
Re: [rules-users] Upating drl file without restarting the application
by devyani.sapre＠wipro.com
Hi, I am using Drools version 4.x .
Also I am looking for an approach where manual updations to the .drl
file are
reflected in the application without restarting.
Thanks
Devyani
________________________________
From: DEVYANI SAPRE (WT01 - GMT-Global Comm Service Provider)
Sent: Monday, October 11, 2010 7:18 PM
To: 'rules-users(a)lists.jboss.org'
Subject: Upating drl file without restarting the application
Hi
How to achieve dynamic updation of rule file
(rules-added/deleted/modified) without the need for the application to
be restarted so as to load the rule file? Is there any property that can
be set to achieve this or do I need to run a thread to continuously
monitor the rule file for any change?
Thanks
Devyani
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15 years, 5 months
Check if fact is subset of items in the rule
by Kumar Pandey
Posting a new thread for this specific problem that has been a head
scratcher for me for days now.
Here is the problem space.
I have a rule that can have a superset of elements such as say "String1",
"String2", "String3" , "String4". These are known in rule creation time.
Fact can have subset say "String1", "String4"
How can I form a drl to check to verify that fact is a subset of elements in
the rule?
I need to not fire the rule if fact is a subset but I should be able to add
a not if I can first figure out if it is a sub set.
Any help would be greatly appreciated.
Thanks
Kumar
15 years, 5 months
Get rid of redundant conditions in combined rules.
by Dominik Hüttner
Hello everyone,
Ive got a question. Im using drools-guvnor to execute some rule-scenarios.
I have to solve the following problem: I have an amount of objects in my
working memory and cant remove objects from the working memory in the
then-part of the rule. I want to combine two rules, the first rule selects
some objects and the second rule checks only these selected objects for
additional criteria. I have to use two rules, because I want to report the
objects selected in the first rule, too. Now I have implemented this with
two rules and in the second rule, the criterias of the first rule are copied
to the second rule, my question is, is there a way to get rid of this
redundandance?
I have tried this with a rule flow, but the problem is, this always works on
the whole working memory, but I cant remove the not used objects from
working memory for performance reasons. Is there another way to solve this
problem?
Here is an example for what I intend to do:
Rule1:
when
customer:Customer(town=="London")
then
System.out.println(customer.getLname() + " is inhabitant of
London");
Rule2:
when
customer:Customer(town=="London",job=="TEACHER")
then
System.out.println(customer.getLname() + " is a teacher");
This example illustrates, with the first rule I want to get to know, how
many customers are from London and in the second rule I want to know, how
many of the London customers are teachers. I want to create a kind of
statistics. I have quite a lot of conditions for the first rule, so I dont
want to have them redundantly.
Greetings, Dominik
15 years, 5 months
Approach for loading the rules| How to use MultithreadEvaluationOption.YES
by Harshit Bapna
Hi All,
1. Is it a good idea to categorize rules, place each category of rules in a
different drl file and load the different drls in a same knowledge base ?
Approaches to loading of rules in the knowledge base:
1. Load different drl files in a single knowledge builder and add the
package to a single knowledge base.
2. Load each drl file in a new knowlegeBuilder and then add the package to a
single knowledge base.
3. Load different knowledge bases for different drl files.
IMO, 1 is better. (Since none of the examples are using multiple drl files
so I asked this question)
2. My drools usage is for rules that requires stateless sessions
I was thinking of using Sequential Rete. (
http://blog.athico.com/2007/07/sequential-rete.html)
Apart from the below two lines of code is there anything which should be
taken care of ?
KnowledgeBaseConfiguration kbaseConf =
KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
kbaseConf.setOption(SequentialOption.YES);//
http://blog.athico.com/2007/07/sequential-rete.html
// kbaseConf.setOption(MultithreadEvaluationOption.YES);
3. How to achieve Multi Threading in drools for stateless rules? Is there a
way where I can use the inbuilt parallelism (if it supports) ?
I found an option MultithreadEvaluationOption.YES in the knowledge base
configuration.
If any sample code or example for multi threaded usage of drools is
available it would be of good help..
--Harshit
15 years, 5 months
