Fire Rule in Stateless Knowledge Session
by snehils
Hi,
I am new in Drools. I am using Drools version 5.1.0
My requirement is kind of request response, where I have to perform some
checks for the request and respond the result. Hence, I decided to go with
stateless knowledge session.
I have prepared .DRL file and it contains set of rules. When some request
receives I have to identify the rule(s) belongs to that request and then
fire the rule(s).
I am not able to figure out how to categories the rules request wise in DRL
file? Also, how to fire only those rules which belongs to the category.
For example, there are three kinds of requests Rq1, Rq2 and Rq3. There are
rules in DRL file: R1, R2, R3, R4 and R5. R1, R2 belongs to Rq1, R3 belongs
to Rq2 and R4, R5 belongs to Rq3.
When some request receives only its belonging rules should be fired. For
example, on receiving of Rq2 only R3 should be fired.
Please provide me some code snipped or link.
Thanks
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13 years
Guvnor: Accessing Bound Variable in "Then" Statement
by Vann_the_Red
Hello. I started with a search and didn't find an answer. I apologize if my
search-fu was lacking today.
I'm a non-developer tasked with rules creation and testing using guvnor. I
have found some scenarios where I can bind a variable to either the whole
input model or a fact in the input model and then later access those in the
output model by selecting "Bound Variable" from the popup box in the Then
statement. In other scenarios, "Bound Variable" is not an option (only
Literal or Formula). What must I do to be able to access the bound
variables from the When statement(s) in the Then statement(s)?
TIA,
Vann
This is a repost because I wasn't on the mailing list yet and I gather most
didn't see it. Apologies again.
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13 years, 1 month
How to write Hibernate query lang(HQL) in .DRL file
by zeeshan
Hi !
According to my requirement I need to fetch and Insert data from database
using Hibernate Query from .DRL file.
I have idea how to execute HQL in Plain Java class but according to my
requirement,I need to fire query to database from .DRL file which I tried
but unable to get output instead I was getting errors.
Can anyone suggest me process to execute Hibernate Query from DRL file
or please provide me some sample code or any link.
Thanks !!
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13 years, 2 months
[Drools Planner] Multi depot CVRP / CVRPTW
by Mats Norén
Hi,
I've been looking at the VRP example in Drools and I'm thinking about using
it for multi depot cvrp and / or capacitated vrp with time windows.
Has anyone else tried planner for these use cases and can maybe shed some
light on their implementation?
Regards,
Mats
13 years, 3 months
"Rule-Id" for a Drools Rule
by harishtejwani
All:
We are using Drools to detect specific events/conditions in our system.
In the 'then' condition of Drools rule, we would like to persist the "Rule
Id" of the rule that created the specific event/condition
This is because all our reporting is based on "rules" as filters, where
users can look at exceptions by specific rules.
Is there a suggestion or sample as how can the "Rule Id" be persisted or
indicated in the then condition that is immutable or can be long-lived. The
current approach of using Rule Name itself as the ID is brittle as this can
be changed and suddenly all reports would break.
If we assign ID's to rules, where do we keep the mapping of RULE ID to
Rules. If we store rules in GUVRNOR is there a way we can get Rule Id's for
Rules?
Best regards
Harish Tejwani
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13 years, 3 months
Implementing Refraction with Drools
by magaram
I believe we can inject in Refraction capabilities into Drools Rule Engine
using a simple Agenda Filter. I have tested this with test cases against
JRules and Drools and get similar results. Without the Refraction Agenda
Filter it loops infinitely as expected.
Please try it out and tell me what you think. I believe refraction is a much
needed feature of a forward chaining rule engine for commercial purposes.
Any feedback is deeply appreciated.
Here is what the code looks like
---------Agenda Filter---------------------------
package test;
import java.util.ArrayList;
import java.util.List;
import org.drools.runtime.rule.Activation;
import org.drools.runtime.rule.AgendaFilter;
/**
* This custom agenda filter injects refraction behavior into the rule engine
* @author Mukundan Agaram
*
*/
public class RefractionAgendaFilter implements AgendaFilter {
private List encounteredActivations = new ArrayList();
@Override
public boolean accept(Activation act)
{
//Check for a Refraction
if (encounteredActivations.contains(act))
{
//Remove from encountered activations for future firing
encounteredActivations.remove(act);
//return false so the rule is not selected as part of the refraction
return false;
}
//Otherwise add the rule to check for potential refractions in the future
encounteredActivations.add(act);
//select the rule to be part of the agenda
return true;
}
}
-----------------DRL------------------------
//created on: Jan 15, 2013
package test
dialect "mvel"
rule testFooBar1
salience 100
when
$foo : Foo()
$bar : Bar(y > 0)
then
$foo.setX(($foo.getX() + $bar.getY()));
System.out.println("Fired "+drools.getRule().getName())
update($foo);
end
rule testFooBar2
salience 150
when
$foo : Foo(x >= 6)
then
System.out.println("Fired "+drools.getRule().getName())
end
rule testFooBar3
salience 50
when
$foo : Foo(x >= 7)
then
System.out.println("Fired "+drools.getRule().getName())
end
----------------Runtime execution code--------------------------
package test;
import org.drools.KnowledgeBase;
import org.drools.KnowledgeBaseFactory;
import org.drools.builder.KnowledgeBuilder;
import org.drools.builder.KnowledgeBuilderFactory;
import org.drools.builder.ResourceType;
import org.drools.io.ResourceFactory;
import org.drools.runtime.StatefulKnowledgeSession;
public class TestFooBarMain {
private static void test()
{
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add( ResourceFactory.newClassPathResource( "TestFooBar.drl",
TestFooBarMain.class ),
ResourceType.DRL );
if ( kbuilder.hasErrors() ) {
System.out.println( kbuilder.getErrors().toString() );
}
else
{
System.out.println("DRL parsing - success!");
}
KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase();
kbase.addKnowledgePackages( kbuilder.getKnowledgePackages() );
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();
Foo foo1 = new Foo();
foo1.setX(6);
Bar bar1 = new Bar();
bar1.setY(3);
ksession.insert(foo1);
ksession.insert(bar1);
ksession.fireAllRules(new RefractionAgendaFilter());
}
/**
* @param args
*/
public static void main(String[] args) {
test();
}
}
----------------Facts-------------------------
package test;
public class Foo {
private int x;
private int y;
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
}
package test;
public class Bar {
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
private int x;
private int y;
}
Thanks,
Mukundan Agaram
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13 years, 4 months
