11.3. Using rules from a jBPM process definition
You can even allow a rule base to act as a jBPM action handler, decision handler, or assignment handler—in either a pageflow or business process definition.
<decision name="approval">
<handler class="org.jboss.seam.drools.DroolsDecisionHandler">
<workingMemoryName>orderApprovalRulesWorkingMemory</workingMemoryName>
<assertObjects>
<element>#{customer}</element>
<element>#{order}</element>
<element>#{order.lineItems}</element>
</assertObjects>
</handler>
<transition name="approved" to="ship">
<action class="org.jboss.seam.drools.DroolsActionHandler">
<workingMemoryName>shippingRulesWorkingMemory</workingMemoryName>
<assertObjects>
<element>#{customer}</element>
<element>#{order}</element>
<element>#{order.lineItems}</element>
</assertObjects>
</action>
</transition>
<transition name="rejected" to="cancelled"/>
</decision>
The <assertObjects>
element specifies EL expressions that return an object or collection of objects to be asserted as facts into the WorkingMemory
.
There is also support for using Drools for jBPM task assignments:
<task-node name="review">
<task name="review" description="Review Order">
<assignment handler="org.jboss.seam.drools.DroolsAssignmentHandler">
<workingMemoryName>orderApprovalRulesWorkingMemory</workingMemoryName>
<assertObjects>
<element>#{actor}</element>
<element>#{customer}</element>
<element>#{order}</element>
<element>#{order.lineItems}</element>
</assertObjects>
</assignment>
</task>
<transition name="rejected" to="cancelled"/>
<transition name="approved" to="approved"/>
</task-node>
Certain objects are available to the rules as Drools globals, namely the jBPM Assignable
, as assignable
and a Seam Decision
object, as decision
. Rules which handle decisions should call decision.setOutcome("result")
to determine the result of the decision. Rules which perform assignments should set the actor id using the Assignable
.
package org.jboss.seam.examples.shop
import org.jboss.seam.drools.Decision
global Decision decision
rule "Approve Order For Loyal Customer"
when
Customer( loyaltyStatus == "GOLD" )
Order( totalAmount <= 10000 )
then
decision.setOutcome("approved");
end
package org.jboss.seam.examples.shop
import org.jbpm.taskmgmt.exe.Assignable
global Assignable assignable
rule "Assign Review For Small Order"
when
Order( totalAmount <= 100 )
then
assignable.setPooledActors( new String[] {"reviewers"} );
end