Drools6.0 Basic Example
This post has been updated to the very latest Drools6.x – the new post can be found here: Drools6.x Basic Example
Creating the Project
- Open Eclipse (Kepler)
- New -> Maven Project
- Simple Project
- Group Id: com.skills421.examples.drools
- Artifact Id: Drools6.0Example
- Finish
pom.xml
[code language=”xml”]
<project xmlns=”http://maven.apache.org/POM/4.0.0″ xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance” xsi:schemaLocation=”http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd”>
<modelVersion>4.0.0</modelVersion>
<groupId>com.skills421.examples.drools</groupId>
<artifactId>Drools6.0Example</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-compiler</artifactId>
<version>6.0.0.CR1</version>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-core</artifactId>
<version>6.0.0.CR1</version>
</dependency>
</dependencies>
</project>
[/code]
Rule Runner
src/main/java
com.skills421.examples.drools.controller.RuleRunner
[code language=”java”]
package com.skills421.examples.drools.controller;
import org.kie.api.KieServices;
import org.kie.api.builder.KieBuilder;
import org.kie.api.builder.KieFileSystem;
import org.kie.api.builder.KieRepository;
import org.kie.api.builder.Message.Level;
import org.kie.api.io.KieResources;
import org.kie.api.io.Resource;
import org.kie.api.runtime.KieContainer;
import org.kie.api.runtime.KieSession;
public class RuleRunner
{
public RuleRunner()
{
}
public void runRules(String[] rules, Object[] facts)
{
KieServices kieServices = KieServices.Factory.get();
KieResources kieResources = kieServices.getResources();
KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
KieRepository kieRepository = kieServices.getRepository();
for(String ruleFile : rules)
{
Resource resource = kieResources.newClassPathResource(ruleFile);
// path has to start with src/main/resources
// append it with the package from the rule
kieFileSystem.write(“src/main/resources/com/skills421/examples/drools6_0/”+ruleFile, resource);
}
KieBuilder kb = kieServices.newKieBuilder(kieFileSystem);
kb.buildAll();
if (kb.getResults().hasMessages(Level.ERROR))
{
throw new RuntimeException(“Build Errors:\n” + kb.getResults().toString());
}
KieContainer kContainer = kieServices.newKieContainer(kieRepository.getDefaultReleaseId());
KieSession kSession = kContainer.newKieSession();
for (Object fact : facts)
{
kSession.insert(fact);
}
kSession.fireAllRules();
}
}
[/code]
Person
src/main/java
com.skills421.examples.drools.model.Person
[code language=”java”]
package com.skills421.examples.drools.model;
public class Person
{
private String name;
private int age;
public Person()
{
}
public Person(String name, int age)
{
this.name = name;
this.age = age;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public int getAge()
{
return age;
}
public void setAge(int age)
{
this.age = age;
}
}
[/code]
Main
src/main/java
com.skills421.examples.drools.Main
[code language=”java”]
package com.skills421.examples.drools;
import com.skills421.examples.drools.controller.RuleRunner;
import com.skills421.examples.drools.model.Person;
public class Main
{
public static void main(String[] args)
{
RuleRunner runner = new RuleRunner();
String[] rules = { “test1.drl” };
Object[] facts = { new Person(“Jon Doe”, 21) };
runner.runRules(rules,facts);
}
}
[/code]
Rules
src/main/resources
test1.drl
[code language=”java”]
package com.skills421.examples.drools6_0
import com.skills421.examples.drools.model.Person
dialect “mvel”
/*
* This rule checks that a person is >= 21
*/
rule “Person is 21”
when
$person : Person(age>=21)
then
System.out.println($person.name);
end
[/code]
Output
[code]
Jon Doe
[/code]
5 Comments
Nice example. But, is there anything more to be done? kSession.fireAllRules return 0 when I run this example
Hi, this is a quick note to acknowledge your comment. I will look into the details of your question over the weekend and come back with a full response.
regards
John
very nicely graphed.. I was searching for drools examples on 6.0 and I stopped here…it’s given me the answer of my query.. 🙂
Short and simple, thanks 🙂
very good guide,,Very very simple..Thanks