Drools integration with Spring Boot

Drools is a versatile business rule engine that can elevate your application by externalizing a lot of decision logic. As the most application servers are now using Spring boot, let's understand how to use Drools with Spring boot.

For a simple example, you can create a KieContainer as shown below.

@Bean
public KieContainer getKieContainer() {
    KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
    kieFileSystem.write( ResourceFactory.newClassPathResource("discount.drl"));
    KieBuilder kb = kieServices.newKieBuilder(kieFileSystem);
    kb.buildAll();
    KieModule kieModule = kb.getKieModule();
    return kieServices.newKieContainer(kieModule.getReleaseId());
}

Once you have a container, You can execute the rules within it by creating a session and firing all rules.

More on this explained at Drools integration with Spring Boot.

Comments

[Roddy]

I've always just leveraged the kmodule.xml and let Drools load the various kbases from memory from files on the classpath. Simplifies things greatly, and your bean becomes just:

@Bean
public KieContainer kieContainer() {
    KieServices kieServices = KieServices.Factory.get();
    return kieServices.getKieClasspathContainer();
}