### BRM 2012 (Decision Tables)

1. Decision Tables Michael Anstis Core Developer, Red Hat 8th March 2012
2. Agenda What are they? A little theory Guvnor Demo 2
3. What are they? http://images.wellcome.ac.uk/indexplus/image/V0041734.html 3
4. What are they? Simply a table "Decision tables are a precise yet compact way to model complicated logic." wikipedia Easily understood by humans Enable quick and easy analysis 4
5. What are they? http://commons.wikimedia.org/wiki/File:Formal_Place_Setting_12_Course_Dinner.jpg 5
6. What are they? Sections Conditions Condition states stub Actions Action states stub Rule identifiers 6
7. What are they? Layouts - horizontal 7
8. What are they? Layouts - vertical 8
9. A little theory Extended Entry 9
10. A little theory Limited Entry 10
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 the number of states for every condition. 12
13. A little theory http://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 states 14
15. A little theory Contraction – impossible conditions 15
16. A little theory Contraction – merge condition states 16
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 Drools 18
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 Facts 19
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 match 20
21. A little theory http://www.flickr.com/photos/kmakice/4713798045/sizes/m/in/photostream/ 21
22. A little theory Validation and verification Completeness Redundancy Conflict Deficiency 22
23. Guvnor 23
24. Guvnor Flexible authoring environment Extend or Limited Entry Automatic expansion V&V Import from Excel 24
25. And now for something completely different... 25