May 2007 - rules-dev - Jboss List Archives

by Anirvan Majumdar

Is there any way to circumvent the constraint that only getter methods can be called from the asserted bean object? If the input data is dynamic in nature and instead I capture it in a HashMap, then how can I retrieve specific key-value pairs in the "when" block of a Rule? Basically, I need to utilize a method, in the bean, which would have a definition like: <code> public String getValue(String sKey){ return (String)hmpData.get(sKey); } </code> Can this getValue method be accessed by the "when" block? If no, then can someone let me know which class in the source I might have to tweak to extract a similar behavior from the engine? Thanks a lot! Anirvan

16 years, 11 months

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RE: [rules-users] Using the Rule Flow Builder GUI

by Anstis, Michael (M.)

So I'm increasingly excited with ruleflow.... but I'm afraid I want to understand more... Is the decision stuff for ruleflow set to be in 4.0? Can more information as to the role of IConstraint and IVariable be given? Will IConstraint continue to be Strings (that are evaluated at runtime)? What purpose do IVariables have; are they bound to (WorkingMemory) Global variables? Can IConstraints access Fact properties (so decisions are made on a per-fact basis - probably horredous truth maintenance issues - rather than global to the process). I'd love to try and contribute... ________________________________ From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Kris Verlaenen Sent: 14 May 2007 22:57 To: Rules Users List Subject: Re: [rules-users] Using the Rule Flow Builder GUI > 1) Yes kris is still working on the decision stuff for ruleflow. Some of the stuff is already partially implemented, but an (X)OR split (where you can define which path(s) to follow based on some conditions) is still on the TODO list. > 3) The Eclipse GUI ruleflow builder doesn't seem to allow loops in the flow. It does support the creation of loops: create an XOR split as the starting point of your loop, you can then always create nodes that link back to this starting point, resulting in a loop. Note that looping kind of depends on the (X)OR split as well, as that would allow you to exit the loop in specific conditions (now you will probably create an endless loop). I hope I'll be able to add that piece of functionality pretty soon to trunk. Kris

16 years, 11 months

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Re: [drools-dev] async stuff

by Mark Proctor

Hmm, maybe I meant for this to be a user configurable setting, so that async wouldn't block engine if there was a large queue. Not sure, I'll remove it for now. Mark Greg Barton wrote: > Nah, yield() not necessary. The wait() inside of > LinkedBlockingQueue.take() takes care of that. But > the Thread.sleep(100) limits the CommandExecutor to > only handling, at most, 10 Commands per second. Just > wondering why that is. > > --- Mark Proctor <mproctor(a)codehaus.org> wrote: > > >> heh, habit :) Hadn't put that much thought into it, >> probably for my >> testing purposes, whats better a standard yield() ? >> >> Mark >> Greg Barton wrote: >> >>> Just looked at it. Looks good. >>> >>> Just curious: why the "Thread.sleep(100)" on line >>> >> 39 >> >>> of org.drools.concurrent.CommandExecutor? >>> >>> --- Mark Proctor <mproctor(a)codehaus.org> wrote: >>> >>> >>> >>>> Greg, >>>> >>>> Did you checkout what I did with the async apis >>>> >> in >> >>>> 4.0 MR2, happy I got >>>> the balance and implementation right? >>>> >>>> Mark >>>> >>>> >>>> >>>> >>>> > --------------------------------------------------------------------- > >>> >>> >>>> To unsubscribe from this list please visit: >>>> >>>> http://xircles.codehaus.org/manage_email >>>> >>>> >>>> >>>> >>> >>> >>> >>> > ____________________________________________________________________________________You > >> snooze, you lose. Get messages ASAP with AutoCheck >> >>> in the all-new Yahoo! Mail Beta. >>> >>> > http://advision.webevents.yahoo.com/mailbeta/newmail_html.html > >>> >>> >> > > > > > ____________________________________________________________________________________Luggage? GPS? Comic books? > Check out fitting gifts for grads at Yahoo! Search > http://search.yahoo.com/search?fr=oni_on_mail&p=graduation+gifts&cs=bz > >

16 years, 11 months

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;

by Mark Proctor

thought i couht all of these, but just found this, last time I checked lines ending in ; causing the parser to ignore that line? Can we warn when erroneous ; are used. rule "Collect Test" salience 70 when $person : Person( name == "Bob", $likes : likes ) $cheeseList : ArrayList(size > 2) from collect( Cheese( type == $likes ) ); then //System.out.println($person.getName() +" will buy "+ $cheeseList.size() + " pieces of cheese"); results.add($cheeseList); end -- Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in UK and Wales under Company Registration No. 3798903 Directors: Michael Cunningham (USA), Charlie Peters (USA) and David Owens (Ireland)

16 years, 11 months

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Re: [drools-dev] async stuff

by Mark Proctor

np I took a simplified approach in the end, but I think it should capture the main use cases. Mark Greg Barton wrote: > I haven't gotten the chance to look at it yet, but I > will. Sorry I dropped the ball on that. It's been a > craaaaaazy year. :) > > --- Mark Proctor <mproctor(a)codehaus.org> wrote: > > >> Greg, >> >> Did you checkout what I did with the async apis in >> 4.0 MR2, happy I got >> the balance and implementation right? >> >> Mark >> >> >> >> > --------------------------------------------------------------------- > >> To unsubscribe from this list please visit: >> >> http://xircles.codehaus.org/manage_email >> >> >> > > > > > ____________________________________________________________________________________Get the Yahoo! toolbar and be alerted to new email wherever you're surfing. > http://new.toolbar.yahoo.com/toolbar/features/mail/index.php > > --------------------------------------------------------------------- > To unsubscribe from this list please visit: > > http://xircles.codehaus.org/manage_email > > >

16 years, 11 months

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Designing Service Layer issues

by Arjun Dhar

Hi Mark, I did not want to continue our discussion on "[rules-dev] Bugs/Problems with 3.1.0M1"; because the conversation would become out of context and abuse the thread subject so creating this one. At a microscopic level it may not be still clear why I'm resistant to the idea of not having access to the WorkingMemory of a StatelessSession. So let me take it one level higher; of something that may be interest to you guys. Philosophy ========== According to a domain, it is possible to know from your data what you want from the system. Example 1: {See http://permalink.gmane.org/gmane.comp.java.drools.devel/1984 on conflict resolution options} Point 1 Example 2: {See http://permalink.gmane.org/gmane.comp.java.drools.devel/1984 on conflict resolution options} Point 2 E.g. 2 - Work-Around: ..To be honest I have achieved it 'functionally' with a work around at the rule level itself, which is: Keep a initialization variable. Once the most significant rule fires first, un-initialize the Business Object and modify (Object) {If not in Auto mode}; to prevent other rules from firing. E.g. 2 - Limitation I forsee: The problem with this is the R.E. has already spent time in creating an Agenda and then we are able to limit the engine in firing other rules is only a patch in a way. Also, not sure how well this approach will scale because I assume here that making modifications to objects while run time once agenda was created is possible. (It works in 3.X atleast and I'm greatful for it; please dont remove it!) {Similarly I have solutions and work around for 1} Back to our general discussion... So, there can be a need to have a service layer that extends the default service layer to write smart services which call allow for assumptions about a domain and reduce overhead on 'Rule Developers'. Writing DSL that looks like english is is not the main problem. Where I see people sruggling with Rule Engines is: 1. 'Black Box problem'(How to build a business rules engine - Chapter 6; While it may not be a rule engine I think I share his view 100% from my own experience) 2.Because the logic is abstracted to a higher non-engineering level and is not just propositional logic which makes it hard for engineers to initially understand, so it affects their ability to design good rules with lesser effort (the format helps bt is not your bang for the buck). >From a Code Perspective; Design - To Err is human ==================================================== An out of context example: In a Object/Relational mapping and persistence framework 'Ibatis', I once experienced a problem that because of a bug in the code, it was not possible to persist a CLOB onto Oracle. Now we know in JDBC we can do that, so if we could get access to the connection and then write native JDBC code we would be saved!? Right?! Guess what, it was 'private'. I'm sure he made it private with the intention of not having people abuse it, but hey its Open source and we never know when we can get a fix for it and to modify the code directly is disaster because you dont know if it will find its way in the future... well 'necessity is the mother of Invention' :o), the solution is not in context. Design ======= Comming back to the problem of 'StatelessSession'; Sure I understand why we dont want to make the WorkingMemory visible. Infact a problem I faced with previous WM in 3.X is that after assertion I'd have to retract facts. But If I want to build an intelligent service layer that at runtime wants to decide what sort of a session it requires, I must build a service over common types (polymorphism compared to writing dirty 'if' statements), I have 3 options: 1. Have StatelessSession also extend WorkingMemory --> NO WAY, this defeats the purpose of segragating the two and promotes abuse (I agree). 2. Have a public method that exposes the working memory --> NO, this again promotes abise 3. Have the 'WorkingMemory' as 'protected' in the default implementation. You may ask, why not write ones own implementation of 'StatelessSession', its an interface right?! Please see option 4. 4. Sessions come from 'RuleBase' and the 'RuleBase' (again an interface) come for 'RuleBaseFactory'. I see 'RulebaseConfiguration' but this does not solve my purpose. Theoretically, extend 'RulebaseConfiguration' and do what?! :o) And its crazy going on and on. ... So 3 seems to be reallllllllly easy and practical. But you may want to work a little from on RuleBaseFactory to allow for greater things. Please let me know if you have alternate paths or ideas. I'm very open and still learning. It's not about just re-factoring code, about writing services that can have adapters and be extended for domain specific reasons. Thanks, Arjun

16 years, 11 months

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AW: [rules-dev] Rule-Flow in Rules 4.0 M2 and ruleFlowGroups

by Mahler, Bjoern (EXTERN: LINEAS)

Ah - damn ;) ... I forget to look for the properties-view (should maybe appear automatically after double-click?). That really helps - and now it runs like hell ;) ... Thanks a lot... Björn

16 years, 11 months

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Bugs/Problems with 3.1.0M1

by Wolfgang Betz

Hello to all, i would like to address some problems with 3.1.0M1: I've noticed that: - using eclipse 3.2.2, and JPDL Plugin 3.1.0 alpha3 a program using rules does not stop at breakpoints in rules (RHS) - ok, its alpha, maybe i'm missing something - throws an internal NPE at parsing rules havin NO_LOOP set (even if parse result caching is on) - comparisons like "bpairl : BagsPerAirline(nrOfBusinessBags >= (500 + 333))" throw NPE if field is null - maybe adressed by http://jira.jboss.com/jira/browse/JBRULES-627 - when BagsPerAirline(nrOfBusinessBags >= (500 + 333)) //gives all >= 833 BUT BagsPerAirline(nrOfBusinessBags >= 500 + 333) //all >= 500!!!!! - when c : Flight(flightId == 1 | == (1+1)) // throws java.lang.UnsupportedOperationException: // does not support method call // isAllowed(Object object, InternalWorkingMemory workingMemoiry) // at // org.drools.rule.ReturnValueRestriction. // isAllowed(ReturnValueRestriction.java:137) Thanx a lot for the "from" extension :-)

16 years, 11 months

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Rule-Flow in Rules 4.0 M2 and ruleFlowGroups

by Mahler, Bjoern (EXTERN: LINEAS)

Hello... I don't know whether it's a bug or something else... - i'm currently evaluating the new version m2 and especially the rule-flow feature, which would be the yet missing part for us to use drools. So after creating a testflow.rf with your editor i've put the created .rfm-file in the context as sugested on the blog/release-notes: processBuilder.addProcessFromFile(new InputStreamReader(DroolsTest.class.getResourceAsStream( "/testflow.rfm" ) ) ); After invoking the rules with workingMemory.startProcess("test"); and/or workingMemory.fireAllRules(); nothing happened... A look in the sources and the rfm-xml-file shows, that the element <ruleFlowGroup> is empty! I would have expected the name of the group at this point... After changing this to the desired string, the behaviour looks more expecting ;) The problem is, that the .rfm file is regenerated after editing the rf-file so changes to that will be lost... Is it a bug or did i something wrong? TIA Björn

16 years, 11 months

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Run Rules on Dynamic Input Data (No. of Input Params not Fixed!)

by Anirvan Majumdar

Hi, As of my current understanding of Drools, an instance of a bean class is acted upon when it is asserted onto a DRL file (using: assertObject). However, the limitation in such a scenario is that the bean class cannot accept a dynamic data-set. If say, my input parameters are varying in number then I can't possibly capture the data in a properly defined bean class. On the other hand, I can capture the data in a data structure like HashMap. But my problem arises when I try to use the value for a HashMap key in the DRL file, since in the "when" part I can only use "getter" methods which accept no parameters. I did try to circumvent this problem by setting a key value in a particular getter method before asserting the bean object and then retrieving the value through a getValue method which would return the value from the HashMap for the key value associated with the current instance of the asserted bean class. But this too leads to another problem; at any given instant I can only associate a single key value with a bean instance, thus, if I need a rule to have multiple conditions (AND/OR) based on different key-values stored in the HashMap, I can't access them simultaneously. I was wondering, is there a way by which I can access a method, of the asserted Bean class, from the "when" part of a rule, in the DRL file, which can accept a parameter input? If no, is there any part of the source code where I can make some changes to allow this behaviour (pointers to the class names concerned)? Any and all assistance would be hugely appreciated. Thanks! Anirvan

16 years, 11 months

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rules-dev May 2007