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Drools scripting Build Status License Maven

Drools made easy to use for scripting or testing purposes.

This library allows you to easily design proof of concepts based on the drools expert system. It greatly simplifies how you can quickly write drools based code examples or small experiments.

Just insert JSON facts into your drools working memory, and use the available engine methods to interact with the expert system and extract data from it. Data extraction can be done through simple accessors or through the JSON format. Check the documented methods in the DroolsEngine class or take a look to the large amount of example I've made available. (Most of them can be run directly by using the great ammonite REPL solution from Li Haoyi)

A selection of my drools shared code examples based on drools-scripting project :

A hello world drools example runnable with ammonite :

import $ivy.`fr.janalyse::drools-scripting:1.0.11`, $ivy.`org.scalatest::scalatest:3.2.2`
import fr.janalyse.droolscripting._, org.scalatest.flatspec._, org.scalatest.matchers._

object HelloTest extends AnyFlatSpec with should.Matchers {
  "Drools" should "say hello" in {
    val drl =
      """package test
        |rule "hello" when
        |then
        |  insert("HELLO WORLD");
        |end
        |""".stripMargin
    val engine = DroolsEngine(drl)
    engine.fireAllRules()
    engine.strings shouldBe List("HELLO WORLD")
  }
}
HelloTest.execute()

or an other one runnable with ammonite :

import $ivy.`fr.janalyse::drools-scripting:1.0.11`, $ivy.`org.scalatest::scalatest:3.2.2`
import fr.janalyse.droolscripting._, org.scalatest._, flatspec._, matchers._, OptionValues._

object HelloTest extends AnyFlatSpec with should.Matchers {
  "Drools" should "say hello" in {
    val drl =
      """package test
        |
        |declare Someone
        |  name:String
        |end
        |
        |declare Message
        |  message:String
        |end
        |
        |rule "hello" when
        |  Someone($name:name)
        |then
        |  insert(new Message("HELLO "+$name));
        |end
        |""".stripMargin
    val engine = DroolsEngine(drl)
    engine.insertJson("""{"name":"John"}""","test.Someone")
    engine.fireAllRules()
    val msgOption = engine.getModelFirstInstanceAttribute("test.Message", "message")
    msgOption.value shouldBe "HELLO John"
  }
}
HelloTest.execute()

Ammonite notes

Ammonite resolves by default both binary and source artifacts, with recent release of drools it generates a runtime error as drools can't deal with several kie.conf file for a given module, so you'll have to change ammonite default start up behavior in order to avoid sources resolutions. Just add those following lines at the beginning of all your drools scripts (@ separates bootstrapping code from regular one, this is required as we change the behavior of the import $ivy. instruction):

interp.resolutionHooks += { fetch =>
  // -- This is mandatory with drools >= 7.0.46 because drools sources artifacts also brings kie.conf
  // -- (it generates resources conflict at KIE init) and because by default ammonite also load sources artifact...
  import scala.jdk.CollectionConverters._
  fetch.withClassifiers(fetch.getClassifiers.asScala.filter(_ != "sources").asJava)
}

@

import $ivy.`fr.janalyse::drools-scripting:1.0.13`

The interp.resolutionHooks instruction can also instead be added into your default ammonite configuration, in the file $HOME/.ammonite/predefShared.sc which is probably a better workaround to add those lines into all your scripts.