I create prototype of business rule task for bpmn2 support. I tried to follow spec as much as possible (and as much as I understood it).
In general, it follows the same concept as RulesActivity and uses Drools for rules evaluation. So, you need to to provide facts for the business rule task that will be used to create state full knowledge session and fires all matching rules.
This is how definition of business rule task should look like (there can be many dataInputRefs)
<businessRuleTask id="_3" name="Validation"> <ioSpecification> <inputSet> <dataInputRefs>itemDefinition1</dataInputRefs> </inputSet> </ioSpecification> </businessRuleTask>
In addition, item definitions should be declared
<itemDefinition id="itemDefinition1"> <jbpm:var name="fact" /> </itemDefinition>
I am not sure that referencing item definitions directly from dataInputRef is correct and according to spec?!
Complete example with all code changes can be found in jira