Drools5 Community Training: Module 1.5 - Drools Expert First Example

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Module 1.5: Drools Expert First Example Drools5 Community Training version: 1.0-SNAPSHOT Release Date: 03/16/2011Under The Creative Common License

Module 1.5: Drools Expert First Example Drools5 Community Training Course by Mauricio "Salaboy" Salatino and Esteban Aliverti is licensed under a Creative Commons Attribution 3.0 Unported License. Based on a work at salaboy.wordpress. com. Permissions beyond the scope of this license may be available at http: //salaboy.wordpress.com/.

AgendaIntroductionBusiness Rule StructureDrools Expert Example ScenarioHands on lab

Drools Expert in 2 slidesThe core of DroolsLets us express our Knowledge -> Business RulesLets us create Sessions -> Our WorldIt will be in charge of making inferences between them andfiring the correspondent actions.Lets see how it works!

Drools Expert in 2 slides

Business Rule Structurerule "My Rule" when <LHS> Person(name == "John") <CEs> then <RHS> System.out.println("Hi John!"); <Actions>end

Example Scenario

Example ModelWe can define that a Pet will have a name, type and a position.For this example a Person will have a Pet which he/she can call. Andthis Person can also call the fire department.The Firefighter will know how to retrieve a Cat from a Tree.

Example Rules Rule "Call Cat when it is in a tree" When my Cat is on a limb in a tree Then I will call my Cat Rule "Call the fire department" When my Cat is on a limb and it doesnt come down when I call Then call the Fire Department Rule "Firefighter gets the cat down" When the Firefighter can reach the Cat Then the Firefighter retrieves the Cat

Technical View of the Model

Technical View of the Rulesrule "Call Cat when it is in a tree" when $p: Person($pet: pet, petCallCount == 0) $cat: Pet(this == $pet, position == "on a limb", type == PetType.CAT) then //$cat.getName() + " come down!" $p.setPetCallCount($p.getPetCallCount()+1); update($p);end Rule "Call Cat when it is in a tree" When my Cat is on a limb in a tree Then I will call my Cat

Technical View of the Rulesrule "Call the fire department" when $p: Person($pet: pet, petCallCount > 0) $cat: Pet(this == $pet, position == "on a limb", type == PetType.CAT) then Firefighter firefighter = new Firefighter("Fred"); insert(firefighter);end Rule "Call the fire department" When my Cat is on a limb and it doesnt come down when I call Then call the Fire Department

Technical View of the Rulesrule "Firefighter gets the cat down" when $f: Firefighter() $p: Person($pet: pet, petCallCount > 0) $cat: Pet(this == $pet, position == "on a limb", type == PetType.CAT) then $cat.setPosition("on the street"); retract($f); update($cat);end Rule "Firefighter gets the cat down" When the Firefighter can reach the Cat Then the Firefighter retrieves the Cat

Active Scenario in JavaFor the previous rules to fire in our Java world we need to have: An instance of a Person that contains a relation to its Pet An instance of a Pet that is on a limb Person person = new Person("Salaboy!"); Pet pet = new Pet("mittens", "on a limb", Pet.PetType.CAT); person.setPet(pet);

APIs Sneak Preview

Hands OnProject Name: drools5/00-Drools5-FirstExampleSources: https://github.com/Salaboy/Drools_jBPM5-Training-ExamplesCharacteristics: Java Project (jar) Uses Maven (pom.xml) Drools Dependencies (core, api, compiler) DRL File (src/test/resources/rules.drl)To do: Run the test (src/test/java/org/plugtree/example/FirstExampleTest.java) Get familiar with the output

Hands OnExercise 1: Create a new rule that inserts a Dog (on the street) when there is Cat on the street too. Create a new rule for the situation when a Cat and a Dog are on the street, the Dog should chase it up to the tree and then the Cat should climb the limb.

Hands On - Solutionrule "Cat on the street" when Pet(position == "on the street", type == PetType.CAT) then Pet dog = new Pet("doggy", "on the street" , PetType.DOG); insert (dog);endrule "Cat on the street and a dog is around" when $cat: Pet(position == "on the street", type == PetType.CAT) $dog: Pet(position == "on the street", type == PetType.DOG) then modify($cat){ setPosition("on the limb"); } modify($dog){ setPosition("under the tree"); }end

Hands On - What Happen?Exercise 1: What happens with the execution? Why? Try to find a solution

Briefing UpCovered Topics: Quick review about Drools Expert Project Dependencies A simple example that shows the key things that we need to have to use Drools

Questions?

Enjoy! Questions and Feedback are alwaysappreciated!Stay Tuned!

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Drools5 Community Training: Module 1.5 - Drools Expert First Example

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