September 2008 - rules-users - Jboss List Archives

by Mark Proctor

For anyone looking for a good and complex example on how to write rules properly, please look at Conways Game of Life in drools-examples, for extra bonus points compare it to the old version in M1. You'll see nearly all the logic is moved from java to the drl and we have removed the need for nested objects by using objects relaitionally, which also allows us to exploit cross products to drive the application. Mark

2 months

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FW: Implementation of expert system

by Binyala, Krishna Gopal IN BLR SISL

Hello, I am new to drools community... I want to develop an expert system for medical application using drools. can you please let me know how to use history data in drools... Because as far as i know we have to keep all the data in the working memory to access. How should i implement such system? Would be better if you can provide some reference to existing expert system implemented using drools. Thanks in advance. Krishna Gopal In three words I can sum up everything I've learned about life: it goes on... Important notice:This e-mail and any attachment thereto contains corporate proprietary information. If you have received it by mistake, please notify us immediately by reply e-mail and delete this e-mail and its attachments from your system. Thank You.

12 years, 10 months

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enquiry on drools webservice

by Prem Kumar L

13 years, 1 month

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java.lang.OutOfMemoryError: Java heap space

by vdelbart

Hello, In my tests of the 4.0.3, I have some : java.lang.OutOfMemoryError. So, I try a simple test with 10.000 sequential execution of 1 rule with no context and just a workingmemorylogger and I have the error : java.lang.OutOfMemoryError: Java heap space My code is : public class ExecReglesMemotyTest { private static final Reader DRL = new InputStreamReader(ExecReglesMemotyTest.class .getResourceAsStream("/rules/exemple.drl")); private static final String FICHIER_LOG = "session"; /** * @param args */ public static void main(String[] args) { try { PackageBuilder builder = new PackageBuilder(); builder.addPackageFromDrl(DRL); RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage(builder.getPackage()); for (int i = 0; i < 10000; i++) { StatefulSession session = ruleBase.newStatefulSession(); WorkingMemoryFileLogger logger = new WorkingMemoryFileLogger(session); logger.setFileName(FICHIER_LOG); session.fireAllRules(); logger.writeToDisk(); session.dispose(); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } with this rule (doesn't matter): #created on: Fri Nov 09 15:48:45 CET 2007 package initPackage #list any import classes here. rule "ERG9" when then end I try this in 4.0.1, and it's working (no OutOfMemoryError) What's the problem ? thanks for any information, V. -- View this message in context: http://www.nabble.com/java.lang.OutOfMemoryError%3A-Java-heap-space-tf477... Sent from the drools - user mailing list archive at Nabble.com.

13 years, 1 month

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Log4j in the rules?

by granz＠MIT.EDU

Hi, Is it possible to use Log4j inside the rules (RHS)?? (drl file) Thanks, Fabrice

14 years, 2 months

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how to import rules from a drl to another drl file

by raj_drools

hi , i'm using drools 4.7 . i have requirement in Drools . i have some common rules which can be used in many places . so i want to keep them in seperate drl file and impot those rules in another drl file in same package or in other . how can i share rules or functions to other rules which are in other drl files . thanks for the help in advance . regards , sekhar -- View this message in context: http://www.nabble.com/how-to-import-rules-from-a-drl-to-another-drl-file-... Sent from the drools - user mailing list archive at Nabble.com.

14 years, 10 months

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About for and inheritance

by Chris Woodrow

Hi, I recently find out a few issues using for, and I wanted to share it with you. I made a simple exemple to illustrate my purpose. My classes are (I did not represent accessors & constructors): public class Cheese { protected String name; } public class FrenchCheese extends Cheese{ private String smell; } public class Person { private Cheese likes; } Here is my rule set : package rules rule "likes cheese" when $person : Person () Cheese( ) from $person.getLikes() then System.out.println("likes cheese"); end rule "likes french cheese" when $person : Person () FrenchCheese( ) from $person.getLikes() then System.out.println("likes french cheese"); end First test : Cheese cheese = new FrenchCheese("good", "camembert"); Person person = new Person(); person.setLikes(cheese); Output : likes french cheese likes cheese Wich is expected... Second test : Cheese cheese = new Cheese(); Person person = new Person(); person.setLikes(cheese); Output : likes french cheese likes cheese That's the first strange thing. As far as I am concerned, rule "likes french cheese" should not match (since a Cheese is not a FrenchCheese). I made a change to the second rule : rule "likes french cheese" when $person : Person () FrenchCheese( smell == "good" ) from $person.getLikes() then System.out.println("likes french cheese"); end Third test : Cheese cheese = new Cheese(); Person person = new Person(); person.setLikes(cheese); output : It throwed an exception : Exception in thread "main" java.lang.ClassCastException: rules.Cheese I am not saying the ClassCastException is not to expect in such a case but I think I would simply expect it not to match (as far as a Cheese is not a FrenchCheese). Chris

14 years, 10 months

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Drools 4.0, Support for multiple pattern in accumulate source pattern

by Juergen

It appears as if accumulate does support only a single pattern CE as source pattern, e.g.: Number() from accumulate( Cheese( price : price ), sum( price ) ) Is it possible to have more than one pattern in the source pattern, e.g.: Number() from accumulate( Cheese( price : price, type : type ) Person( favouriteCheese == type, age > 30 ), sum( price ) ) The same could be said for collect, but there the problem to specify which item of a matching tuple is to be collected, but this could be handled recreating collect via accumulate, e.g.: Collection() from accumulate( cheese : Cheese( type : type ) Person( favouriteCheese == type, age > 30 ), collect( cheese ) )

14 years, 11 months

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Why is a flat object recommended?

by Christie, Blair

In the documents this is dicussed briefly: "). Object models can often have complex relationships and hierarchies in them - for rules you will want to simplify and flatten the model where possible, and let the rule engine infer relationships (as it provides future flexibility." What does it mean that the rule engine can infer relationships? Are there performance reasons for having a flat model? Cheers, Blair

16 years, 3 months

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Can I check if a collection contains one, and only one item of another collection

by David Cracauer

Hi, I'm getting stuck on this and I'm hoping someone can help.. I need to be able to check that a collection contains one, and only one item from another collection. Ideally, I would do something like this: a:Answer(responses contains one of ("a","b","c")); Is there a way do do this without resorting to evals or predicate expressions? (drools 4.07) Thanks, Dave -- View this message in context: http://www.nabble.com/Can-I-check-if-a-collection-contains-one%2C-and-onl... Sent from the drools - user mailing list archive at Nabble.com.

16 years, 7 months

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rules-users September 2008