Using Decision Table in JBoss Drools

Rules. We have known this word since childhood. First, parents teach us how to do the right thing, then we come to school, where teachers dictate their own rules. At the university, we are again faced with the rules that teachers and the dean's office set for us. As we grow up, we begin to follow the laws that are developed by the state. What do all these rules have in common? The fact that they have been verified over the years, decades, and some even generations. Imagine what our life would be like if the rules were changed often: every week or every day!

, Mediascope, : , . . -.  , , . 

?

, . ( ) - . BRMS Business Rule Management System. ,

- , -. , - , - .

, , «», . . : , , , , . , !

BRMS . : IBM, Red Hat, Agiloft, SAS Bosch. – , . JBoss Drools. , , , , - DRL, Excel-. UI- . , UI Excel-.

- ?

- , . , , , . .

,   (gender).   (SEX).  ,  gender = male, «»  1.  2. DRL :

rule "Rule 1 Example 1"
      when
         $s: Respondent($s.gender == "male")
      then
         $s.addResult("SEX", "1");
end

 rule "Rule 2 Example 2"
      when
         $s: Respondent($s.gender == "female")
      then
         $s.addResult("SEX", "2");
 end
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, ,  Gherkin. , (  when) , (  then).   Drools   Left Hand Side ( LHS), - Right Hand Side ( RHS). : Respondent.  fact,   Drools, .  gender  result. , , framework  .  $.

 Excel-:

?

, , , , . ,  Drools  ,  Miscrosoft Excel OpenOffice,  CSV.  DRL-.

: .  RuleSet, –  RuleTable. , .

 DRL- . - . . : 

• RuleSet –  DRL.

  
  
  
  
  

• Import – ,  Java-, , , java.lang.Math

  
  
  
  
  

• Functions – ,  RuleSet’.  DRL-.

  
  
  
  
  

,  RuleTable, , ,  Drools   DRL-. .  nameforRuleTable.

:

• NAME – . .

  
  
  
  
  

• DESCRIPTION – . . , . 

  
  
  
  
  

• CONDITION –  Left Hand Side  ,  ACTION. .

  
  
  
  
  

• ACTION – , .  addResult,  Map  . .  ACTION  Java-, . .

  
  
  
  
  

  ,  CONDITION  ACTION  . 

  
  
  
  
  

,  $s  Respondent. , , ,  Import.  CONDITION  , .  CONDITION-: ,  Import.

, ,  CONDITION   ACTION, . , . . (Text-Parameter-Result  ). . /, , Drools . .

?

, , . .

,  Respondent. – , . (, , ). , ,  Drools,  Respondent. ,  Map<String, String> result, . ,  Respondent  :

public class Respondent {

    public int id;
    public String gender;
    public Boolean isActive;
    public Integer age;
    public List<String> pets;
    public String city;
    public List<String> devices;
    public Map<String, String> properties;
    public Car car;
    public MobileBrand mobileBrand;
    public Household household;

    public Map<String, String> result = new HashMap<>();

    public void addResult(String key, String value) {
        result.put(key, value);
    }

//  getters, setters, constructor

}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

, , . , , ?  isActive.  true – , false – .

, : . , , ,  .  Respondent.  DRL:

rule "name_for_RuleTable_20"
	when
		$s: Respondent(isActive == true, gender == "male")
	then
		$s.addResult("SEX", "M");
end

rule "name_for_RuleTable_21"
	when
		$s: Respondent(isActive == true, gender == "female")
	then
		$s.addResult("SEX", "F");
end
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

 $param -  .  isActive == $param   isActive == true. .  Drools , . ,  gender.

. :

, - 17 18 . , .

, – . , . , ,  PHONE_SALES_PER  2019 . ,  $param . ,  MobileBrand   Import  .

, . ,  ACTION   $param, . .  in:

:  SAMSUNG  APPLE,  PREMIUM. ,  HUAWEI  XIAOMI,  NOT_PREMIUM. ( ,    :) ) , . 

, ?  contains.  java.util.Collection.  Respondent   pets.  , . , , . « » – ,  $param .

: forall(<>){<>}.  . , . ,  ,  . . , , ,  param. , – ($s). , ,  Drools , - (city devices),  CONDITION  . 

, – .  size:

- , , . «-». Drools  :

, . . ,  Car c  : , , . , , . , -, .  from:

, . , ,  Car,   Respondent,  Map<String, String> properties .  POWER.  Drools getValue.  Functions :

:

, . : ,  PlayStation. ,  Household  Respondent  TVDevices   PlayStation. :

?

.  ACTION? ,  Java. . , ,  ACTION  .

 Drools, :

• set –  ,  Drools  ;

  
  
  
  
  

• update –  ,  set;

  
  
  
  
  

• modify –  , , ;

  
  
  
  
  

• insert –  .

  
  
  
  
  

 modify.

 RuleTable  , - 99 0. ,  $r,  Respondent’a   false.   RuleTable   isActive   REJECTED   TRUE.

 CONDITION. , . , , . . Drools . , , , . 

 Drools  (https://github.com/sxexesx/drools-decision-table).

Thanks for attention! I hope this article will be useful for those who want to dive into the wonderful world of BRMS!