July 2008 - rules-users - Jboss List Archives

by Senlin Liang

Hi all, I am trying to insert some object, querying them and the retract them. My question, when I query the inserted objects using defined "query", it return 0 objects. But when I iterate over all objects in WM, the objects are returned. Any information is appreciated! Files: ===================test.drl==================== package tests; query "selectQuery" p : ClassP() end ==================end of test.drl================ ==================Test.java==================== package tests; import java.io.*; import java.io.InputStreamReader; import org.drools.RuleBase; import org.drools.RuleBaseFactory; import org.drools.StatefulSession; import org.drools.compiler.PackageBuilder; import org.drools.QueryResult; import org.drools.QueryResults; import org.drools.FactHandle; import java.util.Iterator; public class Test { public static void main (String args[]) { try { Reader source = new InputStreamReader(Test.class.getResourceAsStream("../test.drl")); final PackageBuilder builder = new PackageBuilder(); builder.addPackageFromDrl(source); if (builder.hasErrors()) { System.out.println(builder.getErrors().toString()); System.exit(0); } final RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage(builder.getPackage()); final StatefulSession session = ruleBase.newStatefulSession(); System.out.println("Inserting objects ..."); for (int i = 0; i < 5; i ++) { session.insert(new ClassP(1, i)); } System.out.println("Querying objects ..."); QueryResults results = session.getQueryResults("selectQuery"); System.out.println("ResultSize = " + results.size()); /*************************************************************************************** Here, it reports results.size() is 0, and there should be 5 objects in WM right now. It is the place I got the question. I have no idea whether I am using the "query" correctly. Anything wrong? ***************************************************************************************/ for (Iterator it = results.iterator(); it.hasNext(); ) { final QueryResult result = (QueryResult) it.next(); ClassP p = (ClassP) result.get("p"); System.out.println("p(" + p.getFirst() + ", " + p.getSecond()+")"); } System.out.println("Deleting ..."); for (Iterator it = session.iterateFactHandles(); it.hasNext(); ) { FactHandle factHandle = (FactHandle) it.next(); ClassP p = (ClassP) session.getObject(factHandle); System.out.println("p(" + p.getFirst() + ", " + p.getSecond()+")"); session.retract(factHandle); } /*************************************************************************************** Here, it prints out: it is deleting p(1, 1), ... p(1, 5). It verifies that there are the 5 objects inserted. ***************************************************************************************/ session.dispose(); } catch (Exception e) { System.out.println(e); System.exit(0); } } public static class ClassP { private int first; private int second; public ClassP() {} public ClassP(int firstIn, int secondIn) { this.first = firstIn; this.second = secondIn; } public int getFirst() { return this.first; } public int getSecond() { return this.second; } } } ========================end of Test.java===================== Thanks a lot, -- Senlin Liang

17 years, 6 months

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asking the best next question to have as many rules fire as possible

by Fred Kwakkel

Hi, We are building with a team an application for matching "green customers" to "green companies" based on rules that match customer (wanting to save energy, money and climate) to green companies that offer "products to save energy, money and climate" We are evaluation if drools would be a good tool for this. Now my question: (how) will drools (or any other rule engine) be able to support the process of "asking the best next question to have as many rules fire as possible"? but without having to code in each rule some relationship with other rules in the rule base explicitely, because that would make the rule base very hard to maintain when we have hundreds or maybe even thousands of rules in the future. Let's take an example: R1 a rule that tells me to visit "www.isoleer.nu" to isolate my house WHEN I own (and don't rent the house) AND the type of house is "house at corner" (fire: savings 8 Euro / month, error margin +/- 10%) R2 a rule that tells me to "buy a new hot-water boiler at www.warmwater.nl" WHEN I own a house AND my current hot-water-boil is-of-type "XX1" "XX2" or "XX3" (fire: saving 7 +/-10% Euro when is-of-type "XX1", savings 12 Euro +/- 8% when is-of-type "XX2" or "XX3") R3 a rule that tells me to go to "www.drive-diesel.nl" WHEN I own a car, AND drive more than 40.000 Km per year (fire: savings per month #Km/year * 1.20, marge 15%) R4 a rule that tells me to go to "www.drive-benzine.nl" WHEN I own a car, AND drive less then 40.000 Km per year (fire: saving per month #Km/year */1.20, marge 20%) R5 a rule that tells me to visit "mercedez-benz.com" WHEN I plan the buy a new car AND my income > 100.000 Euro / year (NO savings per month) R6 a rule that tells me to vist "www.smart-car.nl" WHEN I own a car (savings per month 10 Euro, marge 50%) R7 a rule that tells me to visit "www.smar-car.nl" WHEN I own a car AND use-it-to "Drive to work" (savings per month 15 Euro, marge 25%) I think the best path to answering questions (taking into account rules R1..R7 from previous email) would be something like: 1. Do you own a car? (yes,no) -> because this might lead to R6 to fire immediately 1.1. (If do-you-own-a-car=yes) -> Then R6 will fire 1.1.1 How many Km / year? (0-...) -> because this will lead to R3 or R4 fire 1.1.1.2 (if km-per-year > 40.000) Then R3 will fire 1.1.1.3 (if km-per-year < 40.000) Then R4 will fire 1.2 (If do-you-own-a-car=no) -> Then R6 will NOT fire SO it is USELESS to ask "km-per-year" or "use-car-to" 1.2.1 ... etc. However, this means the order to ask the questions can not be predetermined, but depends on anwers to earlier questions. How can this be done with a rule engine (like drools?) in a way that the rules are still well maintainable and rule base can grow. Thank you for your help and tips! -- Fred Kwakkel (fkwakkel(a)qubiz.eu) -- View this message in context: http://www.nabble.com/asking-the-best-next-question-to-have-as-many-rules... Sent from the drools - user mailing list archive at Nabble.com.

17 years, 6 months

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Calling EntityManager from DRL--DRL Parser attempts to parse sql query instead of passing as string to createNativeQuery method

by David Siefert

Hello, I am trying to use the EntityManager within a rule. I pass the EntityManager instance in from my test (currently just a mock of the interface using EasyMock) using setGlobal("em", entitymanager); so in my drls, I have: <code> global javax.persistence.EntityManager em; </code> And then I use this in my LHS of the rule with a from: <code> rule "query-db" when SampleObject(property from (em.createNativeQuery("select PROP from SAMPLEOBJECT").getResultList())) then System.out.println("Got an object!"); end </code> However, when I run my JUnit test, I get an error saying "unexpected token 'PROP'". So it looks like the Drools parser is trying to interpret what is in my string. Is there a special way to pass a string to the Java operation? Or can I simply not do this? How would I be able to get a result set from the db to use in pattern matching? The rule is dependent upon data from a table to make a decision. Thanks, David Siefert

17 years, 6 months

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Re: [rules-users] Comparing Strings (sort order)

by Charles Binford

17 years, 6 months

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nqueens or puzzle16 problems

by Paul Fodor

Dear Sir, I am new to Drools and I wonder if any of the classic declarative problems, such as, nqueens, puzzle16 were implemented in Drools by anyone. I realize that might be hard because of the bottom-up evaluation. Regards, Paul Fodor

17 years, 6 months

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5.0 M1 is out!!!

by Mark Proctor

5.0 M1 is out. New and Noteworth http://blog.athico.com/2008/07/drools-50-m1-new-and-noteworthy.html Downloads http://www.jboss.org/drools/downloads.html Have Fun The Drools Team.

17 years, 6 months

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Comparing Strings (sort order)

by Charles Binford

I'm trying to figure out how to compare strings in drools. I'd prefer to just be able to say something like: when obj(member > "string") .... This doesn't work because the > or < operations are not allowed (though I saw in a May 6th post Edson gave a pointer to how to add it.) Next I tried using eval(). Based on everything I've read this should work. My problem is getting the syntax correct. My object "ActionArchive" has a member called "mediaPool". I'd like to choose the one with the lowest (alphabetically) mediaPool string. Try one..... rule "testme" when $ar : ActionArchive($mp : mediaPool) not (eval (ActionArchive(getMediaPool().CompareTo($mp)) < 0)) then System.out.println("low mp= " + $ar.getMediaPool()); end ----------- Rule Compilation error : [Rule name=junk, agendaGroup=MAIN, salience=0, no-loop=false] rules/Rule_testme_0.java (8:997) : The method getMediaPool() is undefined for the type Rule_junk_0 Try two...... rule "testme" when $ar : ActionArchive($mp : mediaPool) not (eval (ActionArchive(mediaPool.CompareTo($mp)) < 0)) then System.out.println("low mp= " + $ar.getMediaPool()); end ----------- Rule Compilation error : [Rule name=testme, agendaGroup=MAIN, salience=0, no-loop=false] rules/Rule_testme_0.java (8:999) : mediaPool cannot be resolved Thanks for any pointers. Charles p.s. consider this a vote for adding > < support for Strings....

17 years, 6 months

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transitive closure

by Paul Fodor

Dear Sir, I am new to Drools and I want to ask how can I implement the classical transitive closure in Drools. For instance we have a bunch of facts edge/2 and the transitive closure: reach(X,Y):- edge(X,Y). reach(X,Y):- edge(X,Z),reach(Z,Y). Should I create classes Edge and Reach with attributes source and target? rule "reachDirect" when exists( Edge(X,Y) ) then insertLogical( new Reach(X,Y) ); end rule "reachIndirect" when exists( Edge(X,Z) ) exists( Reach(Z,Y) ) then insertLogical( new Reach(X,Y) ); end Regards, Paul Fodor

17 years, 6 months

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Function Compilation Error when using JANINO

by Garde, Varun (Equity Linked Technology)

Hello, I am trying to use JANINO with drools 4.0.7. In my rule file I have a function definition, which is throwing a compilation error with JANINO but works perfectly with ECLIPSE compiler. The only janino in my classpath is v 2.5.10. Want to make sure I am not doing something stupid here. /* Drool File snippet */ function List getFieldsFromDelimiter(String value, String delimiter) { List fieldList = new ArrayList(); String[] values = value.split(delimiter); for(String val: values){ fieldList.add(new Field(val)); } return fieldList; } /* Exception trace */ org.drools.rule.InvalidRulePackage: [ getFieldsFromDelimiter : Function Compilation error getFieldsFromDelimiter (line:26): File com/elt/saturn/enumerations/GetFieldsFromDelimiter.java, Line 28, Column 18: Operator ";" expected ]com.elt.saturn.enumerations.GetFieldsFromDelimiter.getFieldsFromDelimit er at org.drools.rule.Package.checkValidity(Package.java:424) at org.drools.common.AbstractRuleBase.addPackage(AbstractRuleBase.java:394) at com.ml.elt.saturn.core.functionality.enumerations.DroolsChainComponent.< init>(DroolsChainComponent.java:63) /* Class extract from dump directory */ public class GetFieldsFromDelimiter { private static final long serialVersionUID = 400L; public static List getFieldsFromDelimiter(String value,String delimiter) throws Exception { List fieldList = new ArrayList(); String[] values = value.split(delimiter); for(String val: values){//this is line 28 fieldList.add(new Field(val)); } return fieldList; } } /* /* Configurations supplied to the PackageBuilderConf */ drools.dialect.java.compiler = JANINO drools.dialect.java.compiler.lnglevel= 1.5 Any help would be much appreciated. Thanks, Varun. -------------------------------------------------------- This message w/attachments (message) may be privileged, confidential or proprietary, and if you are not an intended recipient, please notify the sender, do not use or share it and delete it. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Merrill Lynch. Subject to applicable law, Merrill Lynch may monitor, review and retain e-communications (EC) traveling through its networks/systems. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaranteed to be secure or error-free. This message is subject to terms available at the following link: http://www.ml.com/e-communications_terms/. By messaging with Merrill Lynch you consent to the foregoing. --------------------------------------------------------

17 years, 6 months

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insert a collection/ArrayList of facts

by thomas kukofka

Hello, is it possible to insert an Arraylist of facts like this?: ArraList list; wm.insert (list); And if yes how can I iterate over the list in the when-part of the rule? The rule should be applied to all elements of the inserted list. A short drl-example would be perfect. Kind Regards Thomas

17 years, 6 months

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rules-users July 2008