creating .pkg from .drl
by Amit Kumar
Hi Folks,
I am trying to create a .pkg file (for probably faster loading) from a .drl
file
Does anybody has a code snippet which I can use. Am unable to find it in
javadocs.
Thanks
Amit
16 years
KnowledgeAgent and OSGI
by mmarmol
Hi, I have managed to install Drools-core and Drools-compiler in my Equinox
osgi environment, I can compile rules and execute them just fine, I was just
wandering how to configure a KnowledgeAgent using
KnowledgeBuilderFactoryService and KnowledgeBaseFactoryService. I managed to
configure one but i am not able to reload rules when they change at runtime.
I have started ResourceChangeScannerService and
ResourceChangeNotifierService, changeset related to the rules file gets read
but no change gets implemented. An idea?
Here is the code:
ResourceFactory.getResourceChangeScannerService().start();
ResourceFactory.getResourceChangeNotifierService().start();
ServiceReference serviceRef = bc
.getServiceReference(ServiceRegistry.class.getName());
ServiceRegistry registry = (ServiceRegistry) bc.getService(serviceRef);
KnowledgeBuilderFactoryService knowledgeBuilderFactoryService = registry
.get(KnowledgeBuilderFactoryService.class);
KnowledgeBaseFactoryService knowledgeBaseFactoryService = registry
.get(KnowledgeBaseFactoryService.class);
ResourceFactoryService resourceFactoryService = registry
.get(ResourceFactoryService.class);
KnowledgeBuilderConfiguration kbConf = knowledgeBuilderFactoryService
.newKnowledgeBuilderConfiguration(null, getClass()
.getClassLoader());
KnowledgeBuilder kbuilder = knowledgeBuilderFactoryService
.newKnowledgeBuilder(kbConf);
ResourceFactoryService resource = resourceFactoryService;
kbuilder.add(resource.newFileSystemResource(filePath),
ResourceType.CHANGE_SET);
if (kbuilder.hasErrors()) {
System.out.println(kbuilder.getErrors());
throw new RuntimeException(kbuilder.getErrors().toString());
}
KnowledgeBaseConfiguration kbaseConf = knowledgeBaseFactoryService
.newKnowledgeBaseConfiguration(null, getClass()
.getClassLoader());
KnowledgeBase kbase = knowledgeBaseFactoryService
.newKnowledgeBase(kbaseConf);
kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
KnowledgeAgentConfiguration aconf =
KnowledgeAgentFactory.newKnowledgeAgentConfiguration();
aconf.setProperty("drools.agent.scanDirectories", "true");
aconf.setProperty("drools.agent.scanResources", "true");
aconf.setProperty("drools.agent.newInstance", "false");
kagent = KnowledgeAgentFactory.newKnowledgeAgent( "CoreDroolsAgent",kbase,
aconf);
kagent.applyChangeSet(resource.newFileSystemResource(filePath));
Thanks in advance!
Cheers
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16 years
Failed to read schema document when trying to transform from XML to DRL
by Chang Liu
Hi there,
Error message:
(null: 5, 77): schema_reference.4: Failed to read schema document 'drools.org/drools-5.0.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>.
I ran into this issue when experimenting a project that transforming the rules back and forth from DRL to XML with utility classes as documented in following link:
http://downloads.jboss.com/drools/docs/5.0.1.26597.FINAL/drools-expert/ht...
My code:
...
XmlPackageReader xmlReader = new XmlPackageReader(null);
StringReader sr = new StringReader(rulesInXml);
try {
PackageDescr packageDescr = xmlReader.read(sr);
DrlDumper drlDumper = new DrlDumper();
String drlString = drlDumper.dump(packageDescr);
}
catch (Exception ex) {
System.out.println(ex);
}
...
where string "rulesInXml" is the result xml string transformed from a valid .drl file. It looks like:
<?xml version="1.0" encoding="UTF-8"?>
<package name="com.sample"
xmlns="http://drools.org/drools-5.0"
xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
xs:schemaLocation="http://drools.org/drools-5.0 drools.org/drools-5.0.xsd">
<import name="com.sample.DroolsTest.Message" />
<rule name="Hello World">
<lhs><pattern identifier="m" object-type="Message" >
<field-constraint field-name="status">
<qualified-identifier-restriction evaluator="==">Message.HELLO </qualified-identifier-restriction>
</field-constraint>
<field-binding field-name="message" identifier="myMessage" />
</pattern>
</lhs>
<rhs> System.out.println( myMessage );
m.setMessage( "Goodbye cruel world" );
m.setStatus( Message.GOODBYE );
update( m );
</rhs>
</rule>
<rule name="GoodBye">
<lhs><pattern object-type="Message" >
<field-constraint field-name="status">
<qualified-identifier-restriction evaluator="==">Message.GOODBYE </qualified-identifier-restriction>
</field-constraint>
<field-binding field-name="message" identifier="myMessage" />
</pattern>
</lhs>
<rhs> System.out.println( myMessage );
</rhs>
</rule>
</package>
What did I miss here?
Moreover, the Drools 5.0 API's for XML support are poorly-documented. For example, the constructors of class "XmlPackageReader" has an arg of "SemanticModules" type which is not documented. :(
Any help would be highly appreciated!
Thanks,
Chang
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16 years
Timers' Week :)
by nanic23
Alright... two more:
1. If a process suspends, do timers keep running/firing?
2. Let's say I have workItem_1 --> workItem_2 --> workItem_3 of which
"workItem_1" suspends the flow and "workItem_3" has a timer. After reloading
the StatefulKnowledgeSession and completing "workItem_1" and moving on do I
need to restart the timer for "workItem_3"?
I would like to mention some inconsistent behavior I have experienced:
- ksession.fireUntilHalt() is not starting the timers, instead
ksession.fireAllRules() DOES.
- ksession.halt() does not stop the timers (if that is the way I'm supposed
to stop them)
Any tips or personal experience will be very appreciated.
Thanks,
Nick.
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16 years
Decision Tree input?
by Wilson O Ojwang
All,
Is there something in the works to support Decision Tree Inputs in
addition to Decision Table?
Regards
Wilson
16 years
java.lang.NoSuchMethodError on every Action node
by Ana F Santos
Hi everyone.
I've been trying to use Drools for the past month, and sometimes I have
problems I can't guess anymore how to solve.
This time, every action I try to insert in a ruleflow, I receive a
java.lang.NoSuchMethodError. I'm even trying a really simple ruleflow with
just one simple action - like System.out.println("Test"); - and all I get
is a java.lang.NoSuchMethodError.
[
The stack trace:
java.lang.NoSuchMethodError:
br.com.pst.packages.ruleflows.Process_br_com_pst_packages_ruleflows_0.action0(Lorg/drools/spi/KnowledgeHelper;Lorg/drools/spi/ProcessContext;)V
at
br.com.pst.packages.ruleflows.Process_br_com_pst_packages_ruleflows_0Action0Invoker.execute(
Process_br_com_pst_packages_ruleflows_0Action0Invoker.java:20)
at
org.drools.workflow.instance.node.ActionNodeInstance.internalTrigger(
ActionNodeInstance.java:54)
at org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(
NodeInstanceImpl.java:111)
at
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerConnection(
NodeInstanceImpl.java:142)
at
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(
NodeInstanceImpl.java:128)
at
org.drools.workflow.instance.node.StartNodeInstance.triggerCompleted(
StartNodeInstance.java:49)
at
org.drools.workflow.instance.node.StartNodeInstance.internalTrigger(
StartNodeInstance.java:41)
at org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(
NodeInstanceImpl.java:111)
at
org.drools.ruleflow.instance.RuleFlowProcessInstance.internalStart(
RuleFlowProcessInstance.java:16)
at org.drools.process.instance.impl.ProcessInstanceImpl.start(
ProcessInstanceImpl.java:185)
at
org.drools.workflow.instance.impl.WorkflowProcessInstanceImpl.start(
WorkflowProcessInstanceImpl.java:230)
at org.drools.common.AbstractWorkingMemory.startProcess(
AbstractWorkingMemory.java:1639)
at org.drools.common.AbstractWorkingMemory.startProcess(
AbstractWorkingMemory.java:1604)
at org.drools.impl.StatefulKnowledgeSessionImpl.startProcess(
StatefulKnowledgeSessionImpl.java:267)
at br.com.pst.packages.ServicePackages.main(
ServicePackages.java:99)
]
Actually, the beginning problem was with my project, with a process and
subprocess. The subprocess works fine, but the main process throws a
java.lang.NoSuchMethodError always on any node I put after a specific
RuleFlowGroup node. Everyting used to work before, but when I begin to
enlarge it, nothing seems to work anymore. And, as I told, I can't always
guess the exact problem as the thrown exceptions are very generic.
Hope anyone could help me!
Thanks a lot
ANA FLÁVIA FONSECA DOS SANTOS
Analista de Desenvolvimento de Software
PST Eletrônica S/A
Phone: +55 19 3787 6379
aflavia(a)pst.com.br
www.pst.com.br
www.positron.com.br
16 years
KnowledgeAgent doesn't load dsl files and dslr file from a change-set correctly
by Pritham
I have a folder in classpath:
dsl/global.dsl
rules/section-A.dslr
rules/section-A/page-1.dslr
I create a knowledge base like this:
public KnowledgeBase createKnowledgeBase() throws DroolsParserException,
IOException {
KnowledgeBuilder knowledgeBuilder = KnowledgeBuilderFactory
.newKnowledgeBuilder();
knowledgeBuilder.add(ResourceFactory
.newClassPathResource("dsl/global.dsl"),
ResourceType.DSL);
knowledgeBuilder.add(ResourceFactory
.newClassPathResource("rules/section-A.dslr"),
ResourceType.DSLR);
knowledgeBuilder.add(ResourceFactory
.newClassPathResource("rules/section-A/page-1.dslr"),
ResourceType.DSLR);
if (knowledgeBuilder.hasErrors()) {
throw new RuntimeException(knowledgeBuilder.getErrors().toString());
}
KnowledgeBase knowledgeBase = KnowledgeBaseFactory.newKnowledgeBase();
knowledgeBase.addKnowledgePackages(knowledgeBuilder.getKnowledgePackages());
return knowledgeBase;
}
// code
knowledgeBase = createKnowledgeBase();
session = knowledgeBase.newStatefulKnowledgeSession();
// insert facts
session.fireAllRules();
session.dispose();
The above code works and I can get a unit test to work that processes rules
accordingly. I can see my dslr converting to a drl using the "drl viewer"
correctly (provided I temporarily place the dsl file in the same location
since expander doesn't accept a relative path).
The problem, however is when I use a change-set.xml and a KnowledgeAgent,
things don't work
code for loading via knowledgeAgent
public static KnowledgeBase loadKnowledgeBase() throws
DroolsParserException, IOException {
agent = KnowledgeAgentFactory.newKnowledgeAgent("msll agent");
agent.applyChangeSet(ResourceFactory.newClassPathResource("change-set.xml"));
return agent.getKnowledgeBase();
}
<change-set xmlns='http://drools.org/drools-5.0/change-set'
xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
xs:schemaLocation='http://drools.org/drools-5.0/change-set.xsd'
>
<add>
<resource source='classpath:dsl/' type='DSL' />
<resource source='classpath:rules/' type='DSLR' />
<resource source='classpath:rules/section-A/' type='DSLR' />
</add>
</change-set>
I get the following generic drools errors:
ERR 103] Line 4:0 rule 'rule_key' failed predicate:
{(validateIdentifierKey(DroolsSoftKeywords.RULE))}? in rule[7,0]: [ERR 101]
Line 7:0 no viable alternative at input 'import' in rule Con in rule
attribute
...
...
The rules are same, folder location is the same. I believe that drools has a
problem resolving path (expander global.dsl) from the dslr file when using a
KnowlegeAgent since in the earlier strategy, one could build a dsl into the
knowledgeBuilder directly from the classpath.
Pl suggest.
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16 years
Implementing Timers With Drools Persistence Enabled
by nanic23
Hi All,
I was able to implement some timers and they behave as expected until I
enable persistence. Timers work (get triggered) when creating the
StatefulKnowledgeSession by kbase.newStatefulKnowledgeSession() but they do
NOT work (do not get triggered) when creating the StatefulKnowledgeSession
by JPAKnowledgeService.newStatefulKnowledgeSession(kbase, null, env);
I am calling ksession.fireUntilHalt() from within a new thread and all that.
The problem is not getting timers to work, as I have already accomplished
this, but the problem is rather getting them to work with persistence
enabled.
- Has anyone implemented timers while using (having enabled) persistence?
- Did you experience any problems such as timers not triggering?
- If so, have you found a work around you could share?
The timers are being implemented in ruleflow (DRF) and I'm using drools
5.1.0
Any comments are welcome.
Thanks,
Nick.
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16 years
