Getting Started with #Drools 6, for more information visit http://salaboy.com

1. GETTING STARTED
WITH DROOLS
MAURICIO SALATINO - ESTEBAN ALIVERTI
JBUG DENMARK APRIL - 2016

2. 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)

3. 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

4. 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

5. 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

6. GETTING STARTED WITH DROOLS
DROOLS ENGINE OVERVIEW (STATIC)

7. GETTING STARTED WITH DROOLS
DROOLS ENGINE OVERVIEW (RUNTIME)

8. GETTING STARTED WITH DROOLS
RULE EXECUTION CYCLE

9. 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

10. 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)

11. GETTING STARTED WITH DROOLS
KIE APIS
▸ KieContainer
▸ KieBase
▸ KieSession
▸ insert(Object)
▸ retract(FactHandle)
▸ update(FactHandle, Object)
▸ fireAllRules() / fireAllRules(int)
▸ KieScanner
▸ kmodule.xml
DROOLS SPECIFICS

12. 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

13. 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)

14. 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

15. GETTING STARTED WITH DROOLS
INTEGRATE DROOLS
▸ Inside your app (Embedded)
▸ Knowledge as a Service
▸ Custom
▸ Kie Server
▸ Others
▸ CDI
▸ Spring
▸ Camel

16. 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

17. 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

18. QUESTIONS?
GETTING STARTED WITH DROOLS

19. GETTING STARTED WITH DROOLS
RETE

20. GETTING STARTED WITH DROOLS
PHREAK