Couple of new features in seam-drools integration

[tsurdilovic]

We added a couple of new features to the seam-drools integration:

1. Support for Decision Tables (JBSEAM-4188):

<drools:rule-base name="ruleBase" rule-files="myDecisionTable.xls"/>

You can now compile rules from your Decision Table (xls) when using the drools:rule-base component in components.xml

2. Support for Drools Custom Consequence Exception Handlers (JBSEAM-4049):

<drools:rule-base name="ruleBase" rule-files="myDecisionTable.xls" consequence-exception-handler="#{myConsequenceExceptionHandler}"/>

You can use the new consequence-exception-handler attribute to add a new exception handler. This exception handler can be a Seam component and can look like:

Scope(ScopeType.APPLICATION)
@Startup
@Name("myConsequenceExceptionHandler")
public class MyConsequenceExceptionHandler implements ConsequenceExceptionHandler, Externalizable {

   public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
   }

   public void writeExternal(ObjectOutput out) throws IOException {
   }

   public void handleException(Activation activation,
                               WorkingMemory workingMemory,
                               Exception exception) {
       throw new ConsequenceException( exception,
                                       activation.getRule() );
   }

}

3. Support for Drools Event Listeners (JBSEAM-4225):

<drools:managed-working-memory name="workingMemory" rule-base="#{ruleBase}">
         <drools:event-listeners>
           <value>org.drools.event.DebugWorkingMemoryEventListener</value>
           <value>org.drools.event.DebugAgendaEventListener</value>
        </drools:event-listeners>
</drools:managed-working-memory>

This allows you to be notified of rule engine events, including rules firing, objects being asserted, etc by simply adding the drools:event-listeners element to your managed-working-memory component in components.xml as shown in the example

These updates will be available in 2.2.0.CR1. We are also working on adding RuleFlow support in the near future.

[gilson.tavares]

I believe this link to thread in the rule-dev mail list gives further information about Seam / Drools integration and offers a way to send comments and suggestions on this subject (JBSEAM-4260):

http://lists.jboss.org/pipermail/rules-dev/2009-August/001414.html

[mas_dayana]

Hi, could you please help me,

i try to inject the working memory in the Seam component

@In

WorkingMemory decisionWM

but when i run the server, i got error.

Please help me. thank you

[tsurdilovic]

Hello Mas,

What is the Seam version used? Post your entire error and your components.xml so we can try to help.

Thanks.

[mas_dayana]

Hi Tihomir,

Sorry for my late reply. Ok, this is my scenario. I am using seam 2.1.2. I create a process in my project, in the first node, the process will call some data from the dB, pass the data to the second node. In the second node, i want to evaluate the data using Drools. This is a part of my processDefinition.xml;

....

        <node name="Collect Data">
                <event type="node-enter">
                        <action expression="#{notifyPatient.notification}"/>
                </event>
                <transition to="Evaluate Data"></transition>
        </node>

        <node name="Evaluate Data">
                <event type="node-enter">
                        <action expression="#{evaluateData.evaluatStatus}"/>
                </event>
                <transition to="Send Email"></transition>
        </node>
.....

I'm having trouble in the EvaluateData, in this seam component, i want to inject the workingMemory like the code below;

@Name("evaluateData")
public class EvaluateData {

@In WorkingMemory evaluationRulesWorkingMemory;
@In Status status;
@In Result result;

public void evaluateStatus() throws FactException
{

    policyPricingWorkingMemory.insert(status);
    policyPricingWorkingMemory.fireAllRules();
}
....


The error is at the @In WorkingMemory..where it will create a null value, and will create error in the JBPM context. The error will also occur if i define the workingmemory directly in processDefinition. I do not have problem injecting the data that i pass from the previous node. And the output from the .drl file is a just strings.

This is my Drools part in the component.xml;

...

     <component name="evaluationRule"
        class="org.jboss.seam.drools.RuleBase">
        <property name="ruleFiles">evaluation.drl</property>
     </component>
    
     <component name="evaluationRulesWorkingMemory"
        class="org.jboss.seam.drools.ManagedWorkingMemory" auto-create="true">
        <property name="ruleBase">"#{evaluationRules}"</property>
      </component>

.........

Another question is, where should i put my .drl file? Currently, i put it in the EAR folder.

Thank you for your time.