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Mastering JBoss Drools 6

You're reading from   Mastering JBoss Drools 6 Discover the power of Drools 6 and Business Rules for developing complex scenarios in your applications

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Product type Paperback
Published in Mar 2016
Publisher Packt
ISBN-13 9781783288625
Length 330 pages
Edition 1st Edition
Languages
Tools
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Authors (3):
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Mariano De Maio Mariano De Maio
Author Profile Icon Mariano De Maio
Mariano De Maio
 Salatino Salatino
Author Profile Icon Salatino
Salatino
 Aliverti Aliverti
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Aliverti
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Table of Contents (18) Chapters Close

Mastering JBoss Drools 6
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
1. Rules Declarative Nature FREE CHAPTER 2. Writing and Executing Rules 3. Drools Runtime 4. Improving Our Rule Syntax 5. Understanding KIE Sessions 6. Complex Event Processing 7. Human-Readable Rules 8. Rules' Testing and Troubleshooting 9. Introduction to PHREAK 10. Integrating Rules and Processes 11. Integrating Drools with our Apps Index

Rule inheritance


One last important aspect of rule creation is the possibility of having a rule hierarchy. Just like classes, rules allow inheritance between them. If rule B inherits rule A, it will be the same as having all the conditions in rule A at the beginning of the conditions of rule B. The following table shows two rules using inheritance and their equivalent without it:

rule "A"
when
  s: String(this == "A")
then
  System.out.println(s);
end

rule "B" extends "A"
when
  i: Integer(intValue > 2)
then  System.out.println(i);
end

rule "A"
when
  s: String(this == "A")
then
  System.out.println(s);
end

rule "B"
when
  s: String(this == "A")
  i: Integer(intValue > 2)
then
  System.out.println(i);
end

This can be a good strategy to manage rules that have repetitive conditions but still change structure. However, you need to be careful when deciding to use rule inheritance. Inheriting from another rule means that your sub-classed rule will not be independent; people reading...

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