[rules-users] Drools and jBPM integration

[Mark Proctor]

Fabian Weisensee wrote:
> Yes, thanks for your help. I'll try your suggestion for #2.
>
> I resolved the deployment problem by myself. It was just a mistake 
> with the JBoss ESB deploying...
>
> But now I have another problem. The rule file is found, but there seem 
> to be some problems with the parser.
>
> The FireRulesActionHandler class from the jbpm wiki uses the following 
> code:
> RuleBaseImpl ruleBase = new RuleBaseImpl();
> ruleBase.addPackage(pkg);
You should read the Drools docuemtation, heck every example we have 
shows how to do this, and every example will show
RuleBase ruleBase = RuleBaseFactory.newRuleBase()
ruleBase.addPackage( pkg )

Where the pkg is created from the PackageBuilder class, again this is 
all documented with full examples. What you are using, and someone 
wrongly documented, was an internal implementation class, you should be 
using the interface.
>
> But the RuleBaseImpl class doesn't seem to be part of drools anymore. 
> I looked at the javadocs to find a replacement. I've found the 
> RuleBaseLoader class which looked like what I needed. I replaced the 
> two lines with this:
> RuleBaseLoader rbl = RuleBaseLoader.getInstance();
> RuleBase ruleBase = rbl.loadFromReader(reader);
> ruleBase.addPackage(pkg);
>
> but when I run this I get the following error:
>
> ERROR [GraphElement] action threw exception: Unable to parser Reader
> java.lang.RuntimeException: Unable to parser Reader
>     at org.drools.compiler.DrlParser.getParser(DrlParser.java:209)
>     at org.drools.compiler.DrlParser.parse(DrlParser.java:60)
>     at 
> org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:165) 
>
>     at 
> org.drools.compiler.RuleBaseLoader.loadFromReader(RuleBaseLoader.java:38)
>     at 
> rechnung.kontrolle.FireRulesActionHandler.readRule(FireRulesActionHandler.java:92) 
>
>     at 
> rechnung.kontrolle.FireRulesActionHandler.execute(FireRulesActionHandler.java:49) 
>
>
> Of course I thought my rule file would be syntacticaly incorrect, but 
> even this rule file didn't work:
>
> package rechnung.kontrolle
>
> rule "test rule 1"
>     when
>     then        
>         System.out.println("rule fired!");   
> end
>
> What am I doing wrong? Is RulesBaseLoader the right class?
> Are there any other Informations about integrating jBPM and Drools?
>
> --Fabian
>
>
>
> Aziz Boxwala schrieb:
>> Fabian,
>>
>> Response to #1: I believe the rule file needs to reside in the root 
>> directory of the archive/directory of the example application. I have 
>> not tried that out so not sure.
>>
>> With Drools 4.0.x, you have the option of having your rules be 
>> located in the BRMS.
>>
>> Response to #2: You should be able to do so using one decision-node. 
>> Associate the rule action handler with either the Before Signal or 
>> Node Enter event and specify your decision conditions on the 
>> transitions out of that node..
>>
>> --Aziz
>>
>> ----- Original Message ----
>> From: Fabian Weisensee <fabian at weisensee.net>
>> To: rules-users at lists.jboss.org
>> Sent: Monday, November 12, 2007 7:35:02 AM
>> Subject: [rules-users] Drools and jBPM integration
>>
>> Hi there
>>
>> I have some questions concerning Drools and jBPM integration.
>> I know there is this wiki page:
>> http://wiki.jboss.org/wiki/Wiki.jsp?page=JbpmAndDrools
>> but first it's not really detailed and second does it seem to be 
>> outdated.
>>
>> 1) I changed the FireRulesActionHandler from the wiki to reflect the
>> API-changes, that at least it's compileable. In the jBPM process
>> definition the rule file is simply passed as parameter like this:
>> "/Shipper.drl". To which directory does this relative path apply? So
>> where do I have to deploy this rule file? I tried several locations in
>> the application server, but even with an absolute path every time
>> FireRulesActionHandler tries to read the rule it crashes:
>>
>> ERROR [GraphElement] action threw exception: null
>> java.lang.NullPointerException
>>     at java.io <http://java.io.Re>.Reader.<init>(Unknown Source)
>>     at java.io <http://java.io.In>.InputStreamReader.<init>(Unknown 
>> Source)
>>     at
>> rechnung.kontrolle.FireRulesActionHandler.readRule(FireRulesActionHandler.java:83) 
>>
>>     at
>> rechnung.kontrolle.FireRulesActionHandler.execute(FireRulesActionHandler.java:50) 
>>
>>
>> 2) As I understood the example in the wiki you have to create a node
>> which executes the rule and then a decision-node which routes the
>> process flow according to the rule results.
>> Is it possible to do this with just one node?
>> But perhaps I should ask this at the jBPM forums.
>>
>> Every help would be appreciated. Thanks in advance.
>>
>> Fabian Weisensee
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