February 2011 - rules-users - Jboss List Archives

by David Jacobsson

Hi, I'm currently working with a system where we have customers with different status flags. This could look something like: customer has bought a car and a bicycle -> "wheel" status customer has bought a tent, a jacket and food -> "camper" status Since these rules can be quite complex and change often using Drools would be a good way so solve the problem. The problem now is that we want to answer the question, what's needed to achieve "camper" status? When it comes to DRL this becomes that we want to know which LHS facts that are missing for the "camper" rule to fire, i.e. so we can tell the customer that in order to achieve "camper" status you also need to buy a tent when he/she already have bought a jacket and food. The solution we have so far is to add a number of "negative" rules in DRL that can identify the missing facts. Our concern though is that this doesn't scale since these extra rules become several more then the base rules that define the statuses. Is it possible to solve this in a general way with Drools, i.e. to find missing facts leading to a specific conclusion? And example of status rule in DRL would look something like: ----- when BoughtCar( $c : customer ) BoughtBicycle( customer == $c ) then insert( new WheelStatus( $c ) ); end ----- The example above is of course just an example and not actual rules from our system. Regards, David

15 years, 4 months

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Can we use Multiple dsl in a dslr

by Bala

Hi, Can we use multiple dsl files in a dslr i.e. expander dsl1.dsl expander dsl2.dsl Since my dsl file is going to be large, I find it difficult to store in database. Is there a way to split the dsl files and store. and combine back to the original dsl for better use? If i am going to keep my dsl file as a binary object and add that to the builder, how can i specify the expander in dslr? ----- Thanks, Bala -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Can-we-use-Multiple-d... Sent from the Drools - User mailing list archive at Nabble.com.

15 years, 4 months

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Simple Disjunction Question

by thomas.polzin＠gmail.com

Hi there Assume we have a rule like this: when $a : A(a==1) or ($b : B(b==1) and $c : C(c==1)) then do($a) do($b) do($c) end Assuming also, that for some reason I do not want to split this rule into two. Then, I get a NullPointer exception because either $a or $b and $c are not defined. Is there a way to catch or check for this. Thanks so much for any help Thomas

15 years, 4 months

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"Rule Engine Development with JBoss Drools" Training in Phoenix, Feb 22-23

by Brian Sam-Bodden

* Integrallis Software (http://www.integrallis.com) is proud to announce our upcoming 2-day Java training class “Rule Engine Development with JBoss Drools” <http://tekspike.com/camp/agenda/11> in Phoenix, Arizona on Tuesday February 22 and Wednesday February 23. Rule Engine Development with JBoss Drools This course is aimed at Java and Java EE developers looking to understand and apply a Rule Engine to solve problems typically (and painfully) addressed with traditional programming techniques. In this course you will learn how to build lean applications using Test-Driven Development Techniques in conjunction with jBoss’ Drools Rule Engine to streamline, simplify and minimize the maintenance burden of a growing application in a rapidly changing business environment This is a hands on course for developers so bring your laptop and be prepared to write a lot of code! Contents at a glance: JBoss Drools Foundations: - Business Rules: Separating Policy from Code - Declarative Programming in Rule Engines - Understanding Rules in the context of a Rule Engine - Expert Systems and Expert Shells - Forward and Backward Chaining Explained - Architecture of a Rule Based System - Introducing Drools 5.0 - Eclipse and the Drools IDE - Drools Expert: Rule Basics and Rule Syntax - Working with the KnowledgeRuntime interface - Working with Facts: Inserting, Updating, Retracting - Self-cleaning facts with InsertLogical - Querying the Engine - Unit Testing with Drools - Using JUnit 4 to Test your Rules - Exploring Drools Architecture - Drools and Maven Problem Solving with Drools: - Reasons to use Rule-based systems / Common Rule Technology Uses - Efficient Pattern Matching: The Magic Behind a Rule Engine - Fact Combinations and Permutations (cross product) - Ordering Conditions - Basic Conflict Resolution: Dealing with Clashing Rules - Salience - Rule Families and Message Passing - Deep into the Rule Language - Using DRL files, organizing into domains and namespaces - Property Change Listeners (when to use them) - Globals - Understanding the Agenda - NoLoop - Operators and Elements - Eval and Inline Eval - Test-Driven Development with Drools - Using JUnit 4 to Test Rules - Developing the Loan Calculator using TDD - Rule Systems Design Considerations - Rules as first class citizens - Domain Object versus Rule Engine Objects - Using Rules in a Web Environment - Synchronous versus Asynchronous Rule Engine Usage - Stateless versus Stateful Knowledge Sessions Advanced Topics: - Human Readable Rules: Domain Specific Languages in Drools - Integrating Processes and Rules using Rule Flows (Drools Flow) - Decision Tables - Storing and Managing your Rules with Drools Guvnor - Technical Rules and Business Rules - Rule Packages and the Global Package - Importing Rules - Creating Test Scenarios and using the QA module - Overview of Drools Deployment in a Java EE Environment - Options and Gotchas on Specific Application Servers and Frameworks (EJB3, Spring, Seam) - Drools Execution Server - Spring Framework Integration - Recipe Finder: A Java EE Web Drools Application (A Guided Lab) - Integrating Rules with EJB 3 Stateless Session Beans - Design Principles for Building Better Rule Systems - When and when not to use a Rule Engine * The course is open to 25 students at cost of $499.99 The course registration <http://tekspike.com/camp/agenda/11> is open at the Integrallis TekSpike http://tekspike.com/camp/agenda/11 site. The course runs from __9am to 6pm__. Audience This course is aimed at Java/Java EE developers with 2/3 years of programming experience looking to learn how to solve complex problems with the use of Rule Engine Technology Training Day Overview The course follows the approach “I do, we do, you do”. Each section starts with a 20/30 minute lecture, followed by either an instructor lead example or a follow-along exercise. After 2 to 3 sections the students are presented with a Lab Exercise to be performed either individually or in small groups based on complexity. Each day includes 2 to 3 follow along exercises and 4 to 5 Labs. Your Instructor Brian Sam-Bodden<http://www.nofluffjuststuff.com/conference/speaker/brian_sam-bodden>is a developer, author, trainer and well-known speaker that has spent over fifteen years working with object technologies. He is the president and chief software architect for Integrallis http://www.integrallis.com, where he focuses on building great applications with Java, Ruby and Groovy. Brian has worked as an architect, developer, mentor, and trainer for several Fortune 500 companies in a myriad of industries. Brian is the author of "Beginning POJOs: Spring, Hibernate, JBoss and Tapestry" and has also co-authored the Apress Java title "Enterprise Java Development on a Budget: Leveraging Java Open Source Technologies" and contributed to O'reilly's "97 Things Every Project Manager Should Know" *

15 years, 4 months

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Questions concerning Java and rules / Flexibility

by Martin Richardsen

I am a complete novice concerning Drools and have some basic questions, which arised after studying the drools documentation and some examples as well. As far as I got it right, you have two possibilities to work with drools 1) You write a java program, rules / actions are hard coded inline or saved in text files / excel sheets / XML files etc. After importing the necessary drools classes you call the drools interface routines, with the following functionalities: load rules, providing working memory, adding facts und finally starting the rule engine (e.g. firing rules). 2) You use the capabilities of the Drools GUI tools (such as Guvnor), which allows entering rules, objects and actions via GUI tools. Here, I don't get the point whether a part of the java code is generated automatically, or whether you have to write your java classes by yourself, as presented in possibility 1 (above), but without coding the rules by yourself in the source code / external input files. I would be very pleased, if anyone could explain me the essential difference between the two approaches and accordingly tell me what the advantage of using method 2) would be in contrast to method 1), particularly concerning the necessary java coding. --- Well and there would be another question, if you write down your rules and the corresponding software, which accesses the rules, is it possible to add some rules later, without rewriting/recompiling your software? Thanks in advance! Cheers, Martin.

15 years, 4 months

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guvnor integration gives 401 error

by tsarkar

Hi, I have my application running in one instance of jboss server and guvnor running in another. When my application code tries to fireAllRules created in guvnor, the following error comes: 16:00:12,131 INFO [STDOUT] java.lang.RuntimeException: KnowledgeAgent exception while trying to deserialize KnowledgeDefinitionsPackage Caused by: java.io.IOException: Server returned HTTP response code: 401 for URL: http://pcbng100:18080/drools-guvnor/org.drools.guvnor.Guvnor/package/com.... When I use same code within a java file with main method & run as java application in eclipse, the rules fire properly.Any suggestions would be appreciated.

15 years, 4 months

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Drools Java and .Net

by Gorantla, Bhaskar (GE Capital)

We are looking for a rules engine that has the following characteristics. 1. Supports both Java and .net 2. Provides a business user friendly UI for creating/editing rules 3. Supports versioning 4. The rues in the rules repository are accessible to both Java and .net applications - Nice to have Do you know whether Drools supports all the above? Thanks

15 years, 4 months

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Who writes your rules? Dev vs. BA

by cclark01

My company is looking to use Guvnor in a new application we're writing. Part of the appeal is the idea that Business Analysts will be able to go and write rules by themselves. However, in doing a small proof-of-concept, it appears that you need intimate knowledge of the object model in order to write any meaningful rules. I've read up on DSL and it looks like that might help things, but it also sounds like DSL is the kind of thing that gets built up over time. So... what's your experience? Do BA's or Developers write the rules in your applications? Does the complexity of the object model play a role in who can write rules, or is it just a matter of training? If you've created a DSL, how easy/quick was it? If not, any particular reason why not? I'm looking for some "real life" experiences so that we can have appropriate expectations going into the project. Thanks, Chris -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Who-writes-your-rules... Sent from the Drools - User mailing list archive at Nabble.com.

15 years, 4 months

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Timer Event Node and Persistence

by jschmied

Hi! Playing around I created a ruleflow with a timer event. When the timer is firing and I try to persist the ruleflow the timer keeps fireing and I get the following exception: org.drools.RuntimeDroolsException: Unexpected exception executing action org.jbpm.process.instance.event.DefaultSignalManager$SignalProcessInstanceAction@82b92b at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1000) at org.drools.impl.StatefulKnowledgeSessionImpl.executeQueuedActions(StatefulKnowledgeSessionImpl.java:832) at org.jbpm.process.instance.event.DefaultSignalManager.signalEvent(DefaultSignalManager.java:89) at org.jbpm.process.instance.timer.TimerManager$ProcessJob.execute(TimerManager.java:164) at org.drools.time.impl.JDKTimerService$JDKCallableJob.call(JDKTimerService.java:147) at org.drools.persistence.jpa.JpaJDKTimerService$JpaJDKCallableJob.internalCall(JpaJDKTimerService.java:81) at org.drools.persistence.jpa.JpaJDKTimerService$JpaJDKCallableJob.access$100(JpaJDKTimerService.java:64) at org.drools.persistence.jpa.JpaJDKTimerService$JDKCallableJobCommand.execute(JpaJDKTimerService.java:97) at org.drools.persistence.jpa.JpaJDKTimerService$JDKCallableJobCommand.execute(JpaJDKTimerService.java:85) at org.drools.persistence.SingleSessionCommandService.execute(SingleSessionCommandService.java:295) at org.drools.persistence.jpa.JpaJDKTimerService$JpaJDKCallableJob.call(JpaJDKTimerService.java:76) at org.drools.persistence.jpa.JpaJDKTimerService$JpaJDKCallableJob.call(JpaJDKTimerService.java:64) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98) at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:207) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:619) Caused by: org.drools.WorkItemHandlerNotFoundException: Could not find work item handler for Log at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.throwWorkItemNotFoundException(JPAWorkItemManager.java:60) at org.drools.persistence.jpa.processinstance.JPAWorkItemManager.internalExecuteWorkItem(JPAWorkItemManager.java:55) at org.jbpm.workflow.instance.node.WorkItemNodeInstance.internalTrigger(WorkItemNodeInstance.java:101) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150) at org.jbpm.workflow.instance.node.ActionNodeInstance.triggerCompleted(ActionNodeInstance.java:55) at org.jbpm.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:51) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150) at org.jbpm.workflow.instance.node.JoinInstance.triggerCompleted(JoinInstance.java:152) at org.jbpm.workflow.instance.node.JoinInstance.internalTrigger(JoinInstance.java:65) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150) at org.jbpm.workflow.instance.node.ActionNodeInstance.triggerCompleted(ActionNodeInstance.java:55) at org.jbpm.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:51) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:122) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:185) at org.jbpm.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:150) at org.jbpm.workflow.instance.impl.ExtendedNodeInstanceImpl.triggerCompleted(ExtendedNodeInstanceImpl.java:47) at org.jbpm.workflow.instance.node.StateBasedNodeInstance.triggerCompleted(StateBasedNodeInstance.java:162) at org.jbpm.workflow.instance.node.TimerNodeInstance.triggerCompleted(TimerNodeInstance.java:135) at org.jbpm.workflow.instance.node.TimerNodeInstance.signalEvent(TimerNodeInstance.java:125) at org.jbpm.workflow.instance.impl.WorkflowProcessInstanceImpl.signalEvent(WorkflowProcessInstanceImpl.java:333) at org.jbpm.process.instance.event.DefaultSignalManager$SignalProcessInstanceAction.execute(DefaultSignalManager.java:117) at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:998) ... 18 more I think the timer calls object in the disposed session? How do I stop the timer event before disposing the session? Should the timer run again after reloading the ruleflow? (Couldn't get so far) Thanks juergen -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/Timer-Event-Node-and-... Sent from the Drools - User mailing list archive at Nabble.com.

15 years, 4 months

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How do I prevent the package registry from being null in my package builder?

by retoy

I just installed Drools and wanted to build a simple RuleFlow. But When I add any process containing constraints or rules to my Knowledgebuilder, I'm always getting a NullPointerException, because the "package registry" seems to be null. ..... java.lang.NullPointerException at org.drools.compiler.ProcessBuilder.buildProcess(ProcessBuilder.java:119) at org.drools.compiler.ProcessBuilder.addProcessFromFile(ProcessBuilder.java:223) at org.drools.compiler.PackageBuilder.addProcessFromXml(PackageBuilder.java:447) at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:503) at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:25) ..... ProcessBuilder.java:118 PackageRegistry pkgRegistry = this.packageBuilder.getPackageRegistry(process.getPackageName()); ProcessBuilder.java:119 org.drools.rule.Package p = pkgRegistry.getPackage(); ..... The ruleflow is successfully validated though when i press that button in eclipse... Can somebody give me a hint what's missing? Thanks! -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/How-do-I-prevent-the-... Sent from the Drools - User mailing list archive at Nabble.com.

15 years, 4 months

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rules-users February 2011