Use of KnowledgeAgent in JEE Container
by Dave Macpherson
I was wondering if it's safe to use the KnowledgeAgent inside of a JEE
container. I'm assuming that the KnowledgeAgent implementation spawns a
thread to poll for changed resources (to reinitialize a KnowledgeBase, for
instance, when updated DRL files are detected). Normally, use of unmanaged
threads is considered a no-no inside of a JEE container. Has anyone
encountered any problems with this?
Dave
17 years
Using immutable Globals in the new Command API
by Dan Seaver
In the M5 release, I could use a Boolean global as an Out type parameter and
changes I made to the global would be maintained in the results. In CR1, I
use the CommandFactory to add the global with out set to true, and I get
back the initial value of the Boolean, not the updated value.
Here's a code snippet:
List<Command< ? >> commands = new ArrayList<Command< ? >>();
commands.add(CommandFactory.newInsertElements(sessionFacts));
commands.add(CommandFactory.newSetGlobal("result", null, true));
Command< ? > execution = CommandFactory.newBatchExecution(commands);
BatchExecutionResults results = session.execute(execution);
Here's the rule that fires:
rule 'Initialize'
dialect 'mvel'
when
then
drools.getWorkingMemory().setGlobal("result", new Boolean(false));
logger.debug("Initialized result to false");
end
In M5, result would have a value of false.
In CR1, result has a vaule of null.
Am I doing something wrong with the new command structure?
Is this behavior expected, or is it supposed to work like it did in M5?
Thanks for any assistance.
Dan
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17 years
refreshing rules in 4.0.7, Janino
by Mike Merrill
Hi all,
I'm seeing consistency issues when trying to refresh rules manually. I am
seeing issues with sessions getting different results while I call this
function in a loop. Is there a more proper way of migrating the sessions over
to a rules base that has updated rules?
/**
* Function to compile the drools rules. It reads the rules from the data
access object
* @throws APIException
*/
public static void refreshRules() throws APIException {
if(null == DAO) return;
try {
DAO.getSqlMapClient().flushDataCache();
RULES_BASE.lock();
Package[] packages = RULES_BASE.getPackages();
for(int i = 0; i < packages.length; ++i) {
RULES_BASE.removePackage(packages[i].getName());
}
Properties properties = new Properties();
properties.setProperty( "drools.dialect.java.compiler",
"JANINO" );
PackageBuilderConfiguration cfg = new
PackageBuilderConfiguration( properties );
PackageBuilder builder = new PackageBuilder(cfg);
Collection<DroolsVO> rulesCollection = DAO.getRules();
for(DroolsVO rule : rulesCollection) {
Reader source = new StringReader(rule.getRules());
builder.addPackageFromDrl(source);
}
Package pkg = builder.getPackage();
if(null != pkg) {
RULES_BASE.addPackage(pkg);
}
} catch(... e) {
throw APIExceptionFactory.generateException(e);
} finally {
RULES_BASE.unlock();
}
}
17 years
Sudoku example in Guvnor 5.0.0 CR1
by Ingold, Jonathan
Hello,
I was wondering if anyone has tried using Guvnor with the Sudoku example
in examples for 5.0.0 CR1. We are looking at Guvnor's functionality and
I'm have difficulty running any successful scenario's against the Sudoku
rules in Guvnor. I know this is one of the more complex examples in the
drl package but it seems that there would have to be a lot of work done
to get any benefit from Guvnor without rewriting some of the Java
Classes. Anyone willing to share any experiences with this?
Thanks,
Jon
17 years
how to use Array type in Drools
by Zeke
Hi,
I am using Drools 4.0.7 GA. I want to use Array type in my rule condition.
My drl is like below:
> package org.drools.examples.test;
>
> import org.drools.examples.HelloWorldExample.Message;
>
> rule "check.array"
> dialect "java"
> when
> m:Message( arr[0] == "1" )
> then
> System.out.println( "===check array ok===" );
> end
arr is an int type array. When I run the test case, I meet below
exception:
> Exception in thread "main" org.drools.RuntimeDroolsException: Exception
> executing predicate eval( arr[0] == "1" )
> at
> org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:216)
> at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:137)
> at
> org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:22)
> at
> org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:162)
> at org.drools.reteoo.Rete.assertObject(Rete.java:175)
> at
> org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
> at
> org.drools.reteoo.ReteooWorkingMemory.doInsert(ReteooWorkingMemory.java:71)
> at
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:911)
> at
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:883)
> at
> org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:684)
> at
> org.drools.examples.HelloWorldExample.main(HelloWorldExample.java:69)
> Caused by: org.mvel.CompileException: illegal use of []: unknown type: [I
> at
> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.getCollectionProperty(ReflectiveAccessorOptimizer.java:482)
> at
> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.compileGetChain(ReflectiveAccessorOptimizer.java:274)
> at
> org.mvel.optimizers.impl.refl.ReflectiveAccessorOptimizer.optimizeAccessor(ReflectiveAccessorOptimizer.java:110)
> at org.mvel.ASTNode.getReducedValueAccelerated(ASTNode.java:186)
> at
> org.mvel.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:21)
> at org.mvel.MVELRuntime.execute(MVELRuntime.java:90)
> at org.mvel.CompiledExpression.getValue(CompiledExpression.java:111)
> at org.mvel.MVEL.executeExpression(MVEL.java:234)
> at
> org.drools.base.mvel.MVELPredicateExpression.evaluate(MVELPredicateExpression.java:45)
> at
> org.drools.rule.PredicateConstraint.isAllowed(PredicateConstraint.java:209)
> ... 10 more
>
Can anyone kindly tell me how to use Array type in Drools? Thanks in
advance!
- Zeke
17 years
Bug in binary package generation?
by Dan Seaver
I built a rule package in Guvnor and downloaded the binary. When I use:
builder.add(ResourceFactory.newInputStreamResource(inStream),
ResourceType.PKG);
I get a NullPointerException. But, if I use Guvnor's "view source", copy the
source to a file, and use:
builder.add(ResourceFactory.newInputStreamResource(inStream),
ResourceType.DRL);
the package is added without an exception and behaves as anticipated. It
appears that the exception generated by the binary package is occurring in
PackageBuilder.addKnowledgeResource (line 495).
Am I using a valid technique for loading binary packages?
I don't have drools source code to trace into the details with Eclipse.
What's the standard procedure for getting drools source code?
Any other suggestions for determining the cause of my problem?
Any and all help is appreciated.
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17 years
Rules formulation question
by Armaghan Mahmud
I'm new to the mailing list so I'll start off by saying hello to everyone.
I've recently started using DROOLS and I seem to have hit a dead end. I'm
trying to pass in an enum and a list into the working memory one at a time
but I would like my rule to first see if it the enum matches a hard coded
enum value. Additionally, I would also like the rule to see if the enum
value that is being passed to the working memory happens to fall in the list
or not. First of all, is it possible to do that in one rule? I've been
trying to do that using "&&" and "contains" keywords but I'm not getting
anywhere. I don't have the code in front of me or I would've pasted it but I
hope you can understand my point. Any help that I can get in this matter
will be greatly appreciated.
Thanks,
Armaghan
17 years
