Introduction to Drools

eBusiness Technologies (ebTech) Introduction to Drools Adrian Giurca, eBusiness Technologies, Craiova, March 2009 Dr. Adrian Giurca Brandenburg University of Technology Cottbus, Germany

Repetition ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Developing Rule-based applications ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Drools Vocabulary is basically POJO package org.btu.it.userv.vocabulary; class YoungDriver extends Driver { // properties //default constructor public YoungDriver(){ } //setters and getters for the properties } Adrian Giurca, eBusiness Technologies, Craiova, March 2009 ,[object Object]

Rules are grouped in rulesets ,[object Object],[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Sample ruleset (package) package org.btu.it.userv.driverPremium #list any import classes here. import org.btu.it.userv.vocabulary.YoungDriver; import java.io.IOException; // ... #declare any global variables here global java.io.BufferedWriter out; global org.btu.it.userv.utils.Output writer; // Rules #write any global function here function void writeLog(String text, BufferedWriter out)throws IOException{ // function code comes here } # or imports such as import function org.btu.it.userv.utils.Logger.writeLog Adrian Giurca, eBusiness Technologies, Craiova, March 2009 Ruleset name Vocabulary Global variables Global functions

Drools Rule structure ,[object Object],[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Rules condition part (LHS) ,[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Actions (the RHS) ,[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Standard Actions in RHS ,[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Slide No. 11 ,[object Object],[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

The basic pattern ,[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 For example: $driver:Driver(age < 25) The $driver variable is bound sequentially to all Driver objects from the working memory for which the age value is less than 25 , something like:  X driver( X ) && age( X ) < 25

Constraints (1) ,[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 For example: $driver:Driver(age < 25) age < 25 is a (field) constraint

Constraints (2) ,[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 ,[object Object],[object Object],[object Object]

Field constraints (1) ,[object Object],[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Field constraints (2) ,[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 ,[object Object],[object Object],[object Object]

The eval pattern and inlineEvalConstraint ,[object Object],[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 For example: eval(isApprovedByManager($client, $vip)) supposing isApprovedByManager() be a Boolean function.

Advanced patterns - from ,[object Object],[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 For example: $item : OrderItem( value > 100 ) from $order.items $item is bounded sequentially to all OrderItem objects with value greater than 100 from the list $order.items

More complex from : using collect ,[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009 $drivers : ArrayList() from collect( Driver( gender == 'F', noOfAccidents > 0 ) from $town.getDrivers() )

More complex from: using accumulate ,[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Accumulate example $total : Number( doubleValue > 100 ) from accumulate( OrderItem( order == $order, $value : value ), init( double total = 0; ), action( total += $value; ), reverse( total -= $value; ), result( total ) ) Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Do you like rule-based applications? ,[object Object],[object Object],Adrian Giurca, eBusiness Technologies, Craiova, March 2009

Introduction to Drools

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Introduction to Drools

Ähnlich wie Introduction to Drools (20)

Mehr von giurca

Mehr von giurca (12)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Introduction to Drools