1. Decision TablesMichael AnstisCore Developer, Red Hat8th March 2012

2. AgendaWhat are they?A little theoryGuvnorDemo2 3. What are they?http://images.wellcome.ac.uk/indexplus/image/V0041734.html3 4. What are they?Simply a table "Decision tables are a precise yet compact way to model complicated logic." wikipediaEasily understood by humansEnable quick and easy analysis4 5. What are they?http://commons.wikimedia.org/wiki/File:Formal_Place_Setting_12_Course_Dinner.jpg5 6. What are they?Sections ConditionsCondition states stubActions Action states stub Rule identifiers6 7. What are they?Layouts - horizontal7 8. What are they?Layouts - vertical8 9. A little theoryExtended Entry9 10. A little theory Limited Entry10 11. A little theory http://www.flickr.com/photos/ctbto/4926598654/in/photostream/11 12. A little theory Expanded form Guarantee of completeness Rule for every combination of conditions The number of columns should equal the product of thenumber of states for every condition.12 13. A little theoryhttp://www.flickr.com/photos/marcovdz/4520986339/in/photostream/13 14. A little theory Contracted form Contraction is the first optimization Stage 1 impossible matches Stage 2 merge condition states14 15. A little theory Contraction impossible conditions15 16. A little theory Contraction merge condition states16 17. A little theory http://www.flickr.com/photos/worldseriesboxing/6334574625/sizes/z/in/photostream/17 18. A little theory Multiple, all hits Given a 35 year old with 15 years service 1. Rule 1 matches, giving 22 days 2. Rule 5 matches, giving an additional 3 days 3. A total of 25 days is assigned Supported by default in Drools18 19. A little theory Multiple, first hit Given a 35 year old with 15 years service 1. Rule 4 matches, giving 25 days 2. Rule 6 would match but Rule 4 was the first hit Can be emulated with Drools using Control Facts19 20. A little theory Single hit Given a 35 year old with 15 years service 1. Rule 3 matches, giving 25 days 2. No other rules match20 21. A little theoryhttp://www.flickr.com/photos/kmakice/4713798045/sizes/m/in/photostream/21 22. A little theory Validation and verification Completeness Redundancy Conflict Deficiency22 23. Guvnor23 24. Guvnor Flexible authoring environment Extend or Limited Entry Automatic expansion V&V Import from Excel24 25. And now for something completely different...25