Learn to use drools working memory persistence to disk. / published by https://github.com/dacr/code-examples-manager #f54e7d0b-5d98-4243-8526-a80e3116161c/2115f636862183f1a0d5016fa410c8b234823402

drools-persistence.sc

// summary : Learn to use drools working memory persistence to disk.
// keywords : scala, drools, mvel, scalatest, ai, persistence
// publish : gist
// authors : David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : f54e7d0b-5d98-4243-8526-a80e3116161c
// created-on : 2018-09-12T21:11:39+02:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.5.1"
//> using dep "fr.janalyse::drools-scripting:1.2.0"
//> using dep "org.scalatest::scalatest:3.2.19"
// ---------------------

import fr.janalyse.droolscripting.*, org.scalatest.*, flatspec.*, matchers.*, OptionValues.*
import java.util.Date
import scala.jdk.CollectionConverters.*
import DroolsEngineConfig.*
import org.kie.api.*
import org.kie.api.runtime.KieSession
import org.kie.api.builder.*

import reflect.Selectable.reflectiveSelectable

object SimplePersistenceTest extends AnyFlatSpec with should.Matchers {
  override val suiteName = "SimplePersistenceTest"

  def using[T <: { def close():Unit }, R](resource: T)(block: T => R):R = {
    try { block(resource) } finally {
      if (resource != null) resource.close()
    }
  }

  /* Inspired from this OpenNMS project change :
    https://github.com/OpenNMS/opennms/pull/1447/files/493b8008c6b89933219ce0f6b70bb0eac4af4741#diff-808685f08db05ed0726ce0402470c221
  */
  def marshallStateToDisk(filename:String, kieSession:KieSession):Unit = {
    val kMarshallers = KieServices.Factory.get().getMarshallers()
    val kieBase = kieSession.getKieBase()
    val oms = kMarshallers.newSerializeMarshallingStrategy()
    //val oms = kMarshallers.newIdentityMarshallingStrategy()
    val marshaller = kMarshallers.newMarshaller( kieBase, Array(oms) )
    using(new java.io.FileOutputStream(filename)) { fos =>
      kieSession.halt()
      marshaller.marshall(fos, kieSession)
      kieSession.dispose()
      kieSession.destroy()
    }
  }
  def unmarshallStateFromDisk(filename:String, kieSession:KieSession):Unit = {
    val kMarshallers = KieServices.Factory.get().getMarshallers()
    val kieBase = kieSession.getKieBase()
    val oms = kMarshallers.newSerializeMarshallingStrategy()
    //val oms = kMarshallers.newIdentityMarshallingStrategy()
    val marshaller = kMarshallers.newMarshaller( kieBase, Array(oms) )
    using(new java.io.FileInputStream(filename)) { fos =>
      marshaller.unmarshall(fos, kieSession)
    }
  }




  val defaultKModuleContent =
    """<kmodule xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      |         xmlns="http://www.drools.org/xsd/kmodule">
      |  <kbase name="{KBASENAME}" default="true" eventProcessingMode="stream" equalsBehavior="identity">
      |     <ksession name="ksession1" type="stateful" default="true" clockType="pseudo"/>
      |  </kbase>
      |</kmodule>
      |""".stripMargin


  "drools" should "be able to persist its working memory" in {
    val drl =
      """package testdrools
        |
        |global org.slf4j.Logger logger
        |
        |declare Arrived
        |  @role(event)
        |  @expires(2s)
        |end
        |
        |declare Say
        |  that:String
        |end
        |
        |rule "init" when
        |then
        |  insert(new Arrived());
        |end
        |
        |rule "hello" when
        |  Arrived()
        |then
        |  insertLogical(new Say("HELLO John DOE"));
        |end
        |
        |""".stripMargin
    val engine0 = DroolsEngine(drl)
    engine0.fireAllRules()
    engine0.getObjects.size shouldBe(2)
    engine0.getModelFirstInstanceAttribute("testdrools.Say", "that").value.toString should include regex "(?i)hello"

    val filename = "drools-persistence.tmp"
    marshallStateToDisk(filename, engine0.session)

    val engine1 = DroolsEngine(drl)
    unmarshallStateFromDisk(filename, engine1.session)
    engine0.getObjects.size shouldBe(2)
    engine1.getModelFirstInstanceAttribute("testdrools.Say", "that").value.toString should include regex "(?i)hello"
    engine1.timeShiftInSeconds(5)
    engine1.fireAllRules()
    engine1.getObjects.size shouldBe(0)
    engine1.dispose()
  }

}

SimplePersistenceTest.execute()