BusinessRuleTask // icon + implementation

[skay]

Hi,

This topic is actually for both forums : designer and engine.

I would like to keep the bpm icon semantic of BusinessRuleTask, but we have our own RuleEngine implementation / not a drools 5.5 lib directly in the classpath, but rather a kind of remote executor.

This is currently possible / User Guide / Business Rule Task [Experimental]:

"
As mentioned earlier another option is to hook in the implementation of the BusinessRuleTask yourself:

<businessRuleTask id="businessRuleTask" activiti:class="${MyRuleServiceDelegate}" />
                         
Now the BusinessRuleTask behaves exactly like a ServiceTask, but still keeps the BusinessRuleTask icon to visualize that we do business rule processing here.
"

I'm facing  2 problem

#1 designer
Activiti designer currently does not provide the field "activiti:class";  Curiously, this field is available in Activiti Modeler.
I can edit manually in the XML, but could you add this field in a future release of the designer ? would be great !

#2 engine
Currently, a businessRuleTaskActivityBehaviour is tightly coupled with drools.
See here below :
——
…
import org.activiti.engine.impl.rules.RulesHelper;
import org.drools.KnowledgeBase;
import org.drools.runtime.StatefulKnowledgeSession;


/**
* activity implementation of the BPMN 2.0 business rule task.
*
* @author Tijs Rademakers
*/
public class BusinessRuleTaskActivityBehavior extends TaskActivityBehavior {
 
  protected Set<Expression> variablesInputExpressions = new HashSet<Expression>();
  protected Set<Expression> rulesExpressions = new HashSet<Expression>();
  protected boolean exclude = false;
  protected String resultVariable;

  public BusinessRuleTaskActivityBehavior() {}

——

Conclusion :
I need to put the drools library within my classpath just for having the visual representation of "BusinessRuleTask" BPMN component in my process / better than just "ServiceTask" / the understanding of my bosses

On a technical point of view, you are not providing any param to control if the user re-use a stateful ruleEngine session or if he just need a statelessSession.
Furethermore, the usage of the RulesHelper is a little bit static and not clearly open to any customization.

A purist would say that we should rely on e.g. JSR-94 spec rather than KnowledegeBase Drools impl and custom factories.

So 2 different pieces of solutions.

a)
We could modify the implementation of the current BusinessRuleTaskActivityBehavior into something a little more abstract.
Actually we don't need Drools at this stage / we could delegate this job to a Drooly / Custom specific implementation of the BusinessRuleTask.

b)
A new feature of the designer/modeler would be to let the user link the freedom of bpmn tasks icons (why not custom icon?!).
E.G a new "Custom ActivityTask" / same as "serviceTask" but referencing an ActivityBehavior java class implementation as main parameter ?
, and the BPMN icon as second main parameter.

Do you see other/simpler solutions ?

I'll be glad to contribute to the small change proposed here (a) and stage the current [experimental] feature of BusinessRuleTask to a definive one.

Best Regards

[jbarrez]

> I think that the BusinessRule Task should move to that pattern / should be unified in order to inherit from the delegate expression, etc.

Why? We want to encapsulate the business rule task and only expose what is relevant for it.
If you don't like it, you can swap it out using the approach above with whatever implementation you want. Not many people have the use case of needing to do that.