[rules-users] Process variables in split/action nodes

Fri Oct 2 06:53:52 EDT 2009

Renato,

You stumbled on a bug that was still in Drools 5.0.  There are issues in
using an Integer variable inside constraints (as the constraint will try
to interpret it as a String).  This has been fixed a long time ago in
the snapshot releases:
http://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/

As workaround, you could also change the type of your variable to Object
and then use java.lang.Integer as class.

Kris

Quoting Renato Herebia <renato.herebia at dextra-sw.com>:

> Kris, thanks for your answer...
> 
> I've tried to access the variable in a split constraint (return count
> != 1;)
> with mvel dialect and I got this trace in runtime:
> 
> Uncaught exception on client
> java.lang.RuntimeException: unable to execute ReturnValueEvaluator
>     at
>
org.drools.workflow.instance.impl.ReturnValueConstraintEvaluator.evaluate(ReturnValueConstraintEvaluator.java:124)
>     at
>
org.drools.workflow.instance.node.SplitInstance.internalTrigger(SplitInstance.java:62)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:111)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:141)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:128)
>     at
>
org.drools.workflow.instance.impl.ExtendedNodeInstanceImpl.triggerCompleted(ExtendedNodeInstanceImpl.java:37)
>     at
>
org.drools.workflow.instance.node.EventBasedNodeInstance.triggerCompleted(EventBasedNodeInstance.java:96)
>     at
>
org.drools.workflow.instance.node.EventBasedNodeInstance.triggerCompleted(EventBasedNodeInstance.java:77)
>     at
>
org.drools.workflow.instance.node.WorkItemNodeInstance.triggerCompleted(WorkItemNodeInstance.java:192)
>     at
>
org.drools.workflow.instance.node.HumanTaskNodeInstance.triggerCompleted(HumanTaskNodeInstance.java:74)
>     at
>
org.drools.workflow.instance.node.WorkItemNodeInstance.workItemCompleted(WorkItemNodeInstance.java:246)
>     at
>
org.drools.workflow.instance.node.WorkItemNodeInstance.signalEvent(WorkItemNodeInstance.java:222)
>     at
>
org.drools.workflow.instance.impl.WorkflowProcessInstanceImpl.signalEvent(WorkflowProcessInstanceImpl.java:258)
>     at
>
org.drools.process.instance.impl.DefaultWorkItemManager.completeWorkItem(DefaultWorkItemManager.java:96)
>     at
>
org.drools.process.workitem.wsht.WSHumanTaskHandler$GetCompletedTaskResponseHandler.execute(WSHumanTaskHandler.java:282)
>     at
>
org.drools.task.service.TaskClientHandler.messageReceived(TaskClientHandler.java:67)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.messageReceived(DefaultIoFilterChain.java:752)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:414)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:49)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:832)
>     at
>
org.apache.mina.filter.codec.ProtocolCodecFilter$ProtocolDecoderOutputImpl.flush(ProtocolCodecFilter.java:379)
>     at
>
org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecFilter.java:173)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:414)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:49)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:832)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain$HeadFilter.messageReceived(DefaultIoFilterChain.java:616)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:414)
>     at
>
org.apache.mina.core.filterchain.DefaultIoFilterChain.fireMessageReceived(DefaultIoFilterChain.java:408)
>     at
>
org.apache.mina.core.polling.AbstractPollingIoProcessor.read(AbstractPollingIoProcessor.java:578)
>     at
>
org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:540)
>     at
>
org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:532)
>     at
>
org.apache.mina.core.polling.AbstractPollingIoProcessor.access$400(AbstractPollingIoProcessor.java:58)
>     at
>
org.apache.mina.core.polling.AbstractPollingIoProcessor$Worker.run(AbstractPollingIoProcessor.java:857)
>     at
>
org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:51)
>     at
>
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
>     at
>
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
>     at java.lang.Thread.run(Thread.java:619)
> Caused by: java.lang.ClassCastException: java.lang.Integer cannot be
> cast to
> java.lang.String
>     at
>
org.mvel2.math.MathProcessor.getInternalNumberFromType(MathProcessor.java:555)
>     at
> org.mvel2.math.MathProcessor._doOperations(MathProcessor.java:155)
>     at
> org.mvel2.math.MathProcessor.doOperations(MathProcessor.java:79)
>     at
>
org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:102)
>     at
> org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:37)
>     at
> org.mvel2.ast.ReturnNode.getReducedValueAccelerated(ReturnNode.java:45)
>     at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)
>     at
>
org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:107)
>     at org.mvel2.MVEL.executeExpression(MVEL.java:978)
>     at
>
org.drools.base.mvel.MVELReturnValueEvaluator.evaluate(MVELReturnValueEvaluator.java:110)
>     at
>
org.drools.workflow.instance.impl.ReturnValueConstraintEvaluator.evaluate(ReturnValueConstraintEvaluator.java:121)
>     ... 36 more
> 
> With Java dialect I got a problem when I add the rule flow to the
> KnowledgeBuilderFactory:
> 
> java.lang.RuntimeException: Process Compilation error :
> org.drools.lang.descr.ProcessDescr at 69695f
>     com/sample/Process_com_sample_0.java (9:387) : Incompatible
> operand
> types String and int
> 
>     at com.sample.ProcessTest.readKnowledgeBase(ProcessTest.java:81)
>     at com.sample.ProcessTest.main(ProcessTest.java:30)
> 
> 
> Using action node, I could get the variable process with mvel dialect
> in
> action just calling:
> 
> System.out.println("The counting is: " + count);
> 
> If I use Java dialect with the same System.out, I got this problem
> after add
> the rule flow to the KnowledgeBuilderFactory:
> 
> java.lang.RuntimeException: unable to execute Action
>     at
>
org.drools.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:56)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:111)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:141)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:128)
>     at
>
org.drools.workflow.instance.node.StartNodeInstance.triggerCompleted(StartNodeInstance.java:49)
>     at
>
org.drools.workflow.instance.node.StartNodeInstance.internalTrigger(StartNodeInstance.java:41)
>     at
>
org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:111)
>     at
>
org.drools.ruleflow.instance.RuleFlowProcessInstance.internalStart(RuleFlowProcessInstance.java:16)
>     at
>
org.drools.process.instance.impl.ProcessInstanceImpl.start(ProcessInstanceImpl.java:185)
>     at
>
org.drools.workflow.instance.impl.WorkflowProcessInstanceImpl.start(WorkflowProcessInstanceImpl.java:230)
>     at
>
org.drools.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1639)
>     at
>
org.drools.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:272)
>     at com.sample.ProcessTest.main(ProcessTest.java:42)
> Caused by: java.lang.ClassCastException: java.lang.Integer cannot be
> cast to
> java.lang.String
>     at
>
com.sample.Process_com_sample_0Action0Invoker.execute(Process_com_sample_0Action0Invoker.java:18)
>     at
>
org.drools.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:54)
>     ... 12 more
> 
> 
> In this scenario, my doubts are:
> - It's necessary any configuration for the access in action/split
> nodes to
> process variables?
> - How can I do that?
> 
> 
> Thanks in advance.
> 
> -- 
> Renato Herebia
> 

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