GETTING STARTED WITH DROOLS

MAURICIO SALATINO - ESTEBAN ALIVERTI JBUG DENMARK APRIL - 2016

GETTING STARTED WITH DROOLS

AGENDA

▸ First steps

▸ What is Drools?

▸ DRL language

▸ Execution Cycle

▸ Our First Drools Project

▸ Drools Common Usage

▸ Drools Common Pitfalls

▸ Integrating Drools

▸ Roadmap (7.x version)

GETTING STARTED WITH DROOLS

ABOUT US

▸ Mauricio Salatino (aka Salaboy)

▸ Senior Software Engineer @ Red Hat

▸ Drools & jBPM contributor since 2009

▸ http://salaboy.com

▸ Esteban Aliverti

▸ Senior Software Engineer @ Cognitive

▸ Drools contributor since 2010

▸ http://ilesteban.wordpress.com

GETTING STARTED WITH DROOLS

WHAT IS DROOLS?

▸ Lightweight Rule Engine (a library)

▸ Rule Engine -> Inference Engine

▸ Data Driven -> Forward Chaining Algorithms

▸ Goal Driven -> Backward Chaining Algorithms

▸ Change of paradigm from Imperative (Java) to Declarative

GETTING STARTED WITH DROOLS

RULE STRUCTURE

▸ rule “Large Orders require approval” //<rule attributes>

When // Right Hand Side Order(items.size >= 10 && total >= 100000) Then // Left Hand Side // Trigger approval process end

GETTING STARTED WITH DROOLS

DROOLS ENGINE OVERVIEW (STATIC)

GETTING STARTED WITH DROOLS

DROOLS ENGINE OVERVIEW (RUNTIME)

GETTING STARTED WITH DROOLS

RULE EXECUTION CYCLE

GETTING STARTED WITH DROOLS

DROOLS HISTORY

▸ 2003: Created by Mark Proctor and Bob McWhirter

▸ 2005: Acquired by JBoss

▸ 2007: Drools 3.x introduced the first version of the Rete OO Algorithm

▸ 2009: Drools 4.x focused on performance and production ready

▸ 2012: Drools 5.x focused on integration and unification of Drools, jBPM and CEP (KIE was born)

▸ 2014: Drools 6.x focused on infrastructure, deployment and tooling

GETTING STARTED WITH DROOLS

KIE PLATFORM

▸ Drools

▸ Drools CEP (Fusion)

▸ jBPM

▸ OptaPlanner

▸ KIE Server (Drools, jBPM & CEP unified server)

▸ Uberfire (uberfireframework.com)

▸ KIE Workbench (Drools, jBPM, Optaplanner Authoring, Runtime & monitoring)

▸ KIE Drools Workbench (Drools Authoring)

GETTING STARTED WITH DROOLS

KIE APIS

▸ KieContainer

▸ KieBase

▸ KieSession

▸ insert(Object)

▸ retract(FactHandle)

▸ update(FactHandle, Object)

▸ fireAllRules() / fireAllRules(int)

▸ KieScanner

▸ kmodule.xml

DROOLS SPECIFICS

GETTING STARTED WITH DROOLS

OUR FIRST DROOLS PROJECT

▸ Simple JAR Java Maven Project

▸ Add Maven Dependencies

▸ drools-compiler

▸ drools-core (transitive)

▸ kie-api (transitive)

▸ CDI Enabled

▸ cdi-api

▸ weld-se-core

▸ beans.xml

▸ KIE specific

▸ kmodule.xml

▸ conventions over configurations

GETTING STARTED WITH DROOLS

RULES POWER

▸ Any Java Model (non-intrusive)

▸ Filter Data (Simple Filters)

▸ Correlate Data (Multiple filters between patterns)

▸ Accumulations / Aggregations (accumulate functions)

▸ Inference Chain

▸ Justification Log

▸ Query Data

▸ Truth Maintenance System(TMS)

GETTING STARTED WITH DROOLS

COMMON PITFALLS

▸ Start simple, don’t over complicate things

▸ Compare with if/else statements

▸ Too much logic on the RHS

▸ Infinite Loop

▸ Complex (Nested) Models - Facts VS Non-Facts

▸ Cross Product - DB/SQL analogy

▸ From/Eval executed multiple time in RHS

▸ External Service Calls (Sync calls)

▸ Persistence

GETTING STARTED WITH DROOLS

INTEGRATE DROOLS

▸ Inside your app (Embedded)

▸ Knowledge as a Service

▸ Custom

▸ Kie Server

▸ Others

▸ CDI

▸ Spring

▸ Camel

GETTING STARTED WITH DROOLS

ROADMAP (7.X)

▸ Cloud Deployments

▸ Tooling for the Cloud

▸ Self-service applications (Future)

▸ Different Vertical’s Packages

▸ API refactoring towards

▸ Flexibility

▸ Services

▸ Composition

▸ Drools language improvements

▸ Phreak tuning and fragmentation for distribution

GETTING STARTED WITH DROOLS

COMMUNITY

▸ www.drools.org / www.jbpm.org

▸ Drools & jBPM Mailing lists

▸ Report Bugs & Suggest Features: jira.jboss.org

▸ irc.freenode.net

▸ #drools

▸ #jbpm

▸ Blogs:

▸ blog.athico.com

▸ salaboy.com

▸ ilesteban.wordpress.com

QUESTIONS?

GETTING STARTED WITH DROOLS

GETTING STARTED WITH DROOLS

RETE

GETTING STARTED WITH DROOLS

PHREAK