February 2007 - rules-users - Jboss List Archives

[newbie] Using rules to enforce constraints?

by Scott Finnie

Hi, Apologies if this has been covered somewhere, couldn't find it in the archives. I'm wondering about ability / sensibility of above. For example, say I want to model the following rules: 1. A customer must be suspended if they default on a payment 2. A suspended customer may place any orders Now the first one I can readily map to the when/then format of production rules. But I can't see how to elegantly represent the second one - at least not in a transactionally clean manner. I could write: when c: Customer (status == "suspended") o: Order ( customer == c) then o.reject() #etc. But that's not really what I want to achieve. Rather, I'd like the check enforced before the order was created, not after. Or maybe I'm just thinking wrong? Main influence is RDBMS, where I'd write a trigger that would stop the transaction completing if violated. Hope that makes sense, and thanks in advance. - Scoot.

18 years, 2 months

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Shadow Facts don't require default no-arg constructor anymore

by Edson Tirelli

All, As some of you trying out 3.1M1 already noticed, we were requiring all classes of facts asserted into working memory to have a no-arg default public constructor. This was because shadow facts are implemented as lazy proxies internally in the engine, even not being "accessible" from external world. Today I inlined and integrated Objenesis (http://objenesis.googlecode.com/svn/docs/index.html) into drools-core as a way to avoid that. Objenesis team did a pretty good job in their project and I can say I'm really happy with the results. Facts don't need any special constructor anymore. So far, all my tests passed and I found no problem. Although, I would like to ask those of you trying out new drools version in different environments (Application Servers, Security Managers, OSs and JVMs) to checkout and try trunk code. Please let us know if you encounter any odd exception. Work was done under: http://jira.jboss.com/jira/browse/JBRULES-700 Thank you, Edson -- Edson Tirelli Software Engineer - JBoss Rules Core Developer Office: +55 11 3124-6000 Mobile: +55 11 9218-4151 JBoss, a division of Red Hat @ www.jboss.com

18 years, 2 months

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debugging with 3.1M1 IDE?

by Barry Kaplan

I'm ready to get back into drools... whoops, I meant jboss rules. I installed 3.1M1 into eclipse 3.2.1 and added the examples project. I set a breakpoint in all RHS of an example and debugged the corresponding java. I get no breaks hit and I get no updates in any of the views. I couldn't find any help in the docs. Does the IDE still work in 3.1M1? -barry

18 years, 2 months

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Rule definition help

by Rahul Phadnis

I am very new to JBoss rules and I am trying to use it for evaluating alert conditions. I am asserting the AlertDefinition object as a fact into the working memory. The rules file would define a variety of alert condition rules. for example rule "Device not working (condition id = 4)" # the if part when alertDefinition : AlertDefinition (conditionID == 4, eid : entityID) # here i would like to get the last power reading from device # with id == eid eval (dao.getPower(eid).doubleValue() < 1000) # then get temperature from the device eval ((dao.getTemperature(eid) != null && dao.getTemperature(eid) > 50) || (dao.getAmbTemperature(eid) != null && dao.getAmbTemperature(eid) > 40) ) then # what do we do if the rule evaluates to true log("Triggered Device not working alert for " + eid); end Here are my questions: 1. Am using the evals correctly? Can I possibly split this into multiple rules to make it work better? 2. Can assign dao.getTemperature(eid) to a field. The getTemperature call is expensive and doing it twice is not right. Any pointer would be appreciated. -Rahul

18 years, 2 months

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RE: [rules-users] talking about new features...

by Olenin, Vladimir (MOH)

This will just check if MyMapSubClass contains the entry (which I think would not work anyways, since 'entrySet' does not comply to POJO spec). _____ From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Anstis, Michael (M.) Sent: 22 February 2007 12:14 To: Rules Users List Subject: RE: [rules-users] talking about new features... Can this not be achieved by using a Map's entrySet property? $o : MyMapSubClass( entrySet contains 'myName' ); _____ From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Olenin, Vladimir (MOH) Sent: 22 February 2007 16:17 To: Rules Users List Subject: [rules-users] talking about new features... Hi, Talking about new features to be included in the new release, I think the most compelling might be the ability to use Maps as facts (ie, from the point of view of a complete DROOLS newbie). Technically POJO is a Map with some restricted functionality (can't count properties, check for property existence, etc). Is it really a big change? The rule formulation will remain the same from what I understand and the LHS like Map(name == 'myName') Will simply mean any map object which has a key 'name' and value for the key is 'myName'. The 'type matching' feature would be kind of less useful in case Map fact is used, but this can probably solved through introducing some default 'type' key which Map object should have and in a very simplistic implementation just include 'type' as a constraint. Another alternative (which might probably be more 'backward compatible' with existing implementation) is to dynamically generate POJOs from Map definition. 'type' or 'class' key will correspond to a full qualified class name, all other keys found in the map - POJOs properties. Or 'type' can stay 'anonymous' - might be useful in some cases as well.... The 'weakly defined' fact objects might be quite useful in some cases, eg when rules 'cross cut' business domain. Kind of 'dynamic rules' :-). Vlad

18 years, 2 months

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RE: [rules-users] accumulate / collect behaviour question - another stupid question

by Anstis, Michael (M.)

I think you have misunderstood (or at least one of us has!) The "transaction consistency" rule consists of four patterns:- 1 - Transaction ( $id : id) pattern. 2 - The "$credit : Double() from..." pattern 3 - The "$debit : Double() from..." pattern 4 - eval( ! $credits.equals( $debits ) ) The rule will only be activated when all patterns match. IMO, I think of "accumulate" as a nested rule: the "action" will fire when the pattern following the "accumulate (..." matches. Therefore pattern 2 above is matched when the "accumulate" returns - i.e. it is always matched. The same for patterns 1 and 3. Pattern 4 is only matched when the credits and debits don't equal. So for 100 Transaction facts and 10 TransactionEntry facts per each of 10 unique id's the rule will be activated once per pattern 4 match. Pattern 1 always matches; pattern 2 always matches and pattern 3 always matches. Although pattern matches 100 times, pattern 2 matches 10 times per id and pattern 3 matches 10 times per id. I think it is different to consider pattern matches versus rule activations. I hope this helps!??! - or I'm completely wrong ;-) Cheers, Mike -----Original Message----- From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Olenin, Vladimir (MOH) Sent: 22 February 2007 14:52 To: Rules Users List Subject: RE: [rules-users] accumulate / collect behaviour question - another stupid question > So, you are right: action will be executed 10 times for each id and eval > will be executed 1 time for each id. Hmm... So, the 'action' part of the _rule_ (NOT of the accumulate statement) will be called 100 times? How should the rule be modified for the action to be called only 10 times? (once per each unique transaction id). Basically the idea is to do smth if all debit operations are not balanced with credit operations within the same transaction id.... Or have I misunderstood -----Original Message----- From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Edson Tirelli Sent: 21 February 2007 17:19 To: Rules Users List Subject: Re: [rules-users] accumulate / collect behaviour question - another stupid question Vlad, Inside an accumulate CE, the action code will be executed once for each match of the given pattern (TransactionEntry in this case). Eval CEs are executed once for each tuple that matches all previous patterns. So, you are right: action will be executed 10 times for each id and eval will be executed 1 time for each id. To understand better how forward rule engines work, there are some books and articles listed in JBoss Rules project page. I can personally recomend "Expert Systems..." by Gary Riley. And don't worry about asking. Usually people ask a lot in the begining and then when they feel confident, they start to answer more than ask. :) []s Edson Olenin, Vladimir (MOH) wrote: > Hi, > > Edson quoted the following sample rule some time ago: > > rule "transaction consistency" > > when > > Transaction( $id : id ) > > $credits: Double( ) > > from accumulate( TransactionEntry( id == $id, operation == "credit", > $amount : amount ), > > init( double balance = 0 ), > > action( balance += $amount ), > > result( new Double( balance ) ) ); > > $debits: Double( ) > > from accumulate( TransactionEntry( id == $id, operation == "debit", > $amount : amount ), > > init( double balance = 0 ), > > action( balance -= $amount ), > > result( new Double( balance ) ) ); > > eval( ! $credits.equals( $debits ) ) then > > // inconsistency for transaction $id > > End > > If there are 100 transactions overall and only 10 unique transaction > ids (eg, id = 1..10), so that we have on average 10 Transaction facts > per id, > > - how many times will 'eval' be called? > > - how many times will the action be called, assuming 'eval' always > returns 'true'? > > I guess the answer for the above should be '10 times', once per each > id? What if I put another eval statement like "eval($id == 1)" after > existing 'eval'? Would that be evaluated 100 times (for all > Transaction facts) or only 10 times (once per unique id)? > > I think I'm missing quite significant piece on how tuples are selected > in DROOLS and how 'eval' and new 'from accumulate' features work.... Any > pointers would be greatly appreciated! (would some general literature > on rule engines help to clear up this types of questions?...) > > Thanks, > > Vlad > > PS: sorry for posting so many questions and answering so few..... > >----------------------------------------------------------------------- - > >_______________________________________________ >rules-users mailing list >rules-users(a)lists.jboss.org >https://lists.jboss.org/mailman/listinfo/rules-users > > -- Edson Tirelli Software Engineer - JBoss Rules Core Developer Office: +55 11 3124-6000 Mobile: +55 11 9218-4151 JBoss, a division of Red Hat @ www.jboss.com _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

18 years, 2 months

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RE: [rules-users] debugging with 3.1M1 IDE?

by Anstis, Michael (M.)

Just a thought, but any chance of a Rules plugin for NetBeans too? (If my knowledge of NetBean plugin authoring and Drools was sufficient; and I had enough time at home I'd love to volunteer...) -----Original Message----- From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Kris Verlaenen Sent: 22 February 2007 16:25 To: Rules Users List Subject: Re: [rules-users] debugging with 3.1M1 IDE? The 3.1M1 version should definitely work with eclipse 3.2.1. Higher versions of eclipse are probably good as well, just haven't tested any of those yet. It is possible eclipse is not using the new version of the plugin if you installed the new version on the same eclipse as the old one. You should remove the old drools plugin files (jar or directory) and restart eclipse with "eclipse -clean" to notify eclipse that one of its plugins has been updated. The final version of this new version of the IDE will of course be installable from an update site again (a much more user-friendly and fool-proof solution). Because this is just an intermediate milestone release, it has not been put on the update server. Kris ----- Original Message ----- From: "Barry Kaplan" <groups1(a)memelet.com> To: "Rules Users List" <rules-users(a)lists.jboss.org> Sent: Thursday, February 22, 2007 5:06 PM Subject: Re: [rules-users] debugging with 3.1M1 IDE? > Thanks Micheal. I don't get a "Drools Application". I've tried eclipse > 3.2.1, 3.3M4, 3.3M5 using drools 3.1M1 from the downloads and 3.1M1 build > from svn. I am currently downloading a fresh 3.2.2 and will only install > the drools plugin. Maybe there is some plugin conflict with an already > installed plugin. I'll post back... > > -barrry > > Anstis, Michael (M.) wrote: >> Barry, on reading your email I downloaded the current binaries and >> followed the installation instructions for the Eclipse plugin. I simply >> copied org.drools.ide_3.1.0.1.jar to >> <eclipse-install>\sdk-3.2.1\eclipse\plugins and I could put breakpoints >> in the RHS of my rules. I started a new debug configuration in Eclipse >> by clicking on the "Debug..." on the dropdown list beside the "bug" icon >> and choosing a new "Drools Application". >> >> Sorry all appears OK to me :-( >> >> Mike >> >> -----Original Message----- >> From: rules-users-bounces(a)lists.jboss.org >> [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Barry Kaplan >> Sent: 22 February 2007 14:25 >> To: Rules Users List >> Subject: Re: [rules-users] debugging with 3.1M1 IDE? >> >> Well, I just checked out head and rebuilt the IDE with both the feature >> and plugin. But I get no drools launch type.... >> >> (BTW, The ant/maven build seem to run clean. But importing the drools >> projects into eclipse results in lots of projects with errors. Is this >> expected for M1.) >> >> -barry >> _______________________________________________ >> rules-users mailing list >> rules-users(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-users >> >> _______________________________________________ >> rules-users mailing list >> rules-users(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/rules-users >> > > _______________________________________________ > rules-users mailing list > rules-users(a)lists.jboss.org > https://lists.jboss.org/mailman/listinfo/rules-users Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users

18 years, 2 months

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FYI: IDE 3.1M1 does not work with eclipse 3.3M5

by Barry Kaplan

The problems seems to be the jar container created by the plugin in the project. In 3.3M5 it seems to only have the JDT. So for example classes like RuleBase and WorkingMemory are not found. This not really a problem for me since I'm going to add the jars to the project directly (as opposed to using the eclipse plugin.) But I'm not sure yet whether the compiler or debugger will work with 3.3M5.

18 years, 2 months

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RE: [rules-users] talking about new features...

by Anstis, Michael (M.)

Can this not be achieved by using a Map's entrySet property? $o : MyMapSubClass( entrySet contains 'myName' ); ________________________________ From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Olenin, Vladimir (MOH) Sent: 22 February 2007 16:17 To: Rules Users List Subject: [rules-users] talking about new features... Hi, Talking about new features to be included in the new release, I think the most compelling might be the ability to use Maps as facts (ie, from the point of view of a complete DROOLS newbie). Technically POJO is a Map with some restricted functionality (can't count properties, check for property existence, etc). Is it really a big change? The rule formulation will remain the same from what I understand and the LHS like Map(name == 'myName') Will simply mean any map object which has a key 'name' and value for the key is 'myName'. The 'type matching' feature would be kind of less useful in case Map fact is used, but this can probably solved through introducing some default 'type' key which Map object should have and in a very simplistic implementation just include 'type' as a constraint. Another alternative (which might probably be more 'backward compatible' with existing implementation) is to dynamically generate POJOs from Map definition. 'type' or 'class' key will correspond to a full qualified class name, all other keys found in the map - POJOs properties. Or 'type' can stay 'anonymous' - might be useful in some cases as well.... The 'weakly defined' fact objects might be quite useful in some cases, eg when rules 'cross cut' business domain. Kind of 'dynamic rules' :-). Vlad

18 years, 2 months

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talking about new features...

by Olenin, Vladimir (MOH)

Hi, Talking about new features to be included in the new release, I think the most compelling might be the ability to use Maps as facts (ie, from the point of view of a complete DROOLS newbie). Technically POJO is a Map with some restricted functionality (can't count properties, check for property existence, etc). Is it really a big change? The rule formulation will remain the same from what I understand and the LHS like Map(name == 'myName') Will simply mean any map object which has a key 'name' and value for the key is 'myName'. The 'type matching' feature would be kind of less useful in case Map fact is used, but this can probably solved through introducing some default 'type' key which Map object should have and in a very simplistic implementation just include 'type' as a constraint. Another alternative (which might probably be more 'backward compatible' with existing implementation) is to dynamically generate POJOs from Map definition. 'type' or 'class' key will correspond to a full qualified class name, all other keys found in the map - POJOs properties. Or 'type' can stay 'anonymous' - might be useful in some cases as well.... The 'weakly defined' fact objects might be quite useful in some cases, eg when rules 'cross cut' business domain. Kind of 'dynamic rules' :-). Vlad

18 years, 2 months

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rules-users February 2007