customizing task instances

[jbpm2005]

Hi,
I am looking at implementing jbpm for the workflow related tasks in my application.
The process consists of the followings steps ->create tasks , assign/re-assign tasks and complete tasks.
I have had a look at the task-node and the JBPM_TASKINSTANCE table in which the tasks instances are stored. However i find that we need to store more information regrading the tasks then those that stored in JBPM_TASKINSTANCE.

I need a solution for the problem .
Should i customize the taskinstance , ie subclass it .
If yes, where can i find some examples /more elaborate steps to do the same? because the tutorial ( scetion 9.8 ) does not include any details.

please suggest how i should go about this ?

[icyjamie]

9.8 says exactly what to do:
- create a subclass of TaskInstance
- update the property jbpm.task.instance.class to specify the name of custom class
- create a mapping file for the subclass, for mapping the extra properties you want to save
- add that mapping file to the list of mapping files

What else do you want to know?

[jbpm2005]

Thanks for that reply.

I managed to customize the taskInstance to suit my requirements and persisted the same in the database using task-nodes in my processdefinition. Obviously the extra properties are saved as null as i have not set them.

How do i access the TaskInstances created by the task-node ?
How do i set these properties in the Assignment Handler for my TaskInstances ?

Some sample code will be helpful

[aguizar]

Section 9.3.1 states that assignment handlers are called when a task instance is created. Therefore, you access task instances in assignment handlers.
The signature of the assign method is:

void assign(Assignable assignable, ExecutionContext executionContext)

9.3.1 points out that both TaskInstance and SwimlaneInstance implement this interface. Hence, you can cast the assignable to your custom subclass of TaskInstance:

public class MyAssignmentHandler implements AssignmentHandler {
 void assign(Assignable assignable, ExecutionContext executionContext) {
 MyTaskInstance mti = (MyTaskInstance) assignable;
 mti.setActorId("someone");
 mti.setCustomIntProperty(24);
 }
}

[jbpm2005]

Thanks alex , that was helpful, i guess i missed that bit in the docs
I have some more questions,
This is my process definition,

<process-definition name="test2">
 <start-state name="start">
 <transition name="tr1" to="create action"></transition>
 </start-state>
 <task-node name="create action">
 <task name="task1">
 <assignment class="com.jbay.CreateTaskHandler"></assignment>
 </task>
 <transition name="tr1" to="assign action"></transition>
 </task-node>
 <node name="assign action">
 <event type="node-enter">
 <action name="AssignAction" class="com.jbay.AssignTaskHandler"></action>
 </event>
 <transition name="tr2" to="end1"></transition>
 </node>
 <end-state name="end1"></end-state>
</process-definition>

It consists of 1) creating tasks , 2) the person assigned the task can now reassign the task to someone else.

After each node is executed the processinstance is persisted in the database.
1.At node "assign action" - i need to know how the taskinstance created by the previos task-node can be retrieved from the execution context and assigned to another actor ID in the ActionHandler .
2. Knowing TaskInstanceID can i find out the processinstanceId of the process that created it ? or do i have to maitain this mapping myself in a session?