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Cork JUG - Drools basics & pitfalls

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March 2nd Cork JUG meet up

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Cork JUG - Drools basics & pitfalls

  1. 1. DroolsBasics&Common Pitfalls Mauricio Salatino / JBoss - Red Hat JUG Cork March - 2016
  2. 2. Agenda ● What is Drools? ○ Drools History ○ Rule Engine ○ DRL language ○ Execution Cycle ● KIE - Knowledge is Everything ○ KIE Platform & KIE API ● Our First Drools Project ● Drools Common Usage ● Drools Common Pitfalls ● Roadmap (7.x version)
  3. 3. AboutMe ● Senior Software Engineer @ Red Hat/JBoss ● I joined the Drools & jBPM in 2012 ● Passionate about Drools & jBPM ● Author of 3 books about jBPM ● New book about Drools ○ (1st April 2016)
  4. 4. WhatisDrools? -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
  5. 5. WhatisDrools? ● It depends on what you need ○ Core: lightweight Rule Engine (a library) ○ KIE Server: standalone - as a service provider ● Rule Engine -> Inference Engine ○ Data Driven -> Forward Chaining Algorithms ○ Goal Driven -> Backward Chaining Algorithms ● Change of paradigm from Imperative (Java) to Declarative
  6. 6. WhatisDrools?-RuleStructure rule “Large Orders require approval” //<rule attributes> when Order(items.size >= 10 && total >= 100000) then // Trigger approval process end
  7. 7. WhatisDrools?-RuleENgineOverview
  8. 8. WhatisDrools? -RuleExecutionCycle
  9. 9. KIEPlatform ● 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)
  10. 10. KIEAPIs ● KieContainer ● KieBase ● KieSession ○ insert(Object) ○ retract(FactHandle) ○ update(FactHandle, Object) ○ fireAllRules() / fireAllRules(int) ● KieScanner ● kmodule.xml Drools Specific
  11. 11. OurFirstDroolsProject ● 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
  12. 12. RulesPower ● Any Java Model (non-intrusive) ● Filter Data (Simple Filters) ● Correlate Data (Multiple filters between patterns) ● Accumulations / Aggregations (accumulate functions) ● Inference Chain ○ Detailed Log ○ Query Data ○ Truth Maintenance System(TMS)
  13. 13. CommonPitfalls ● 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
  14. 14. Roadmap(7.xseries) ● Cloud Deployments ● Tooling for the Cloud ● Self-service applications ● Different Vertical’s Packages ● API refactoring towards ○ Flexibility ○ Services ○ Composition ● Drools language improvements ● Phreak tuning and fragmentation for distribution
  15. 15. Community ● www.drools.org / www.jbpm.org ● Drools & jBPM Mailing lists ● irc.freenode.net ○ #drools ○ #jbpm ● Blogs: ○ blog.athico.com ○ salaboy.com
  16. 16. Questions?
  17. 17. RETENetwork
  18. 18. Phreak

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