Hi,
I am not an expert on this but I will share what I know.
Normally when the actor ID is mentioned in the BPMN diagram he is the potential owner of the task
and becomes the actual owner ultimately. You will find the task status as RESERVED in this case.
If you don't assign anybody for the ActorID field and assign a group in the GroupID field in the BPMN diagram
then anybody who belongs to that group can become potential owners of the task. The task will be
in READY state and the moment a person belonging to that group stakes a claim he beocmes the actual
owner of the task.
This is how you claim a particular task. This is a method of the Task Client class. There are
several variants and I am giving you the simplest :
taskClient.claim(taskID, "krisv", taskOperationHandler);
/* In this case krisv is claiming the task */
If you want to know the details of the parameters and usage you can take a look at the examples
that came with the package. I am providing the link below.
When you claim a task you have to pass the userID of the person who is claiming. This information can be
mapped to a process variable and you can access it in the ftl forms using ${userid}
What is not yet clear to me is where the grouping between userID's and groups are done.
You can find details about human tasks and the API in the following docs :
JBPM5.3 API
http://docs.jboss.org/jbpm/v5.3/javadocs/
JBPM Developer Guide
http://docs.jboss.com/jbpm/v4/devguide/html_single/
Human Task Spec ( Version 1.1 )
http://docs.oasis-open.org/bpel4people/ws-humantask-1.1-spec-cs-01.html
JBPM Examples
http://sourceforge.net/projects/jbpm/files/jBPM%205/jbpm-5.2.0.Final/jbpm-5.2.0.Final-examples.zip/download