jemmerling [
https://community.jboss.org/people/jemmerling] created the discussion
"Proposed temporary and limited approach to supporting excluded owners"
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https://community.jboss.org/message/646719#646719
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I have been looking at way to do the following within jBPM:
Have a node in a process definition be associated with a particular group (or groups),
however due to the history of a given process, to exclude some actor(s) who might be
members of that group.
Now the WS-HumanTask specification supports something called excluded owners. Here is a
snippet from one version of this specification (not certain if it is the latest one):
+"Potential owners of a task are persons who receive the task so that they can claim
and complete it. A potential owner becomes the actual owner of a task by explicitly
claiming it. Before the task has been claimed, potential owners can influence the progress
of the task, for example by changing the priority of the task, adding ad-hoc attachments
or comments. All excluded owners are implicitly removed from the set of potential owners.
A WS-HumanTask Definition MAY define assignment for this generic human role.+
+Excluded owners are are people who cannot become an actual or potential owner and thus
they cannot reserve or start the task. A WS-HumanTask Definition MAY define assignment for
this generic human role. "+
Although the jBPM5 schema supports the existence of excluded owners, I have seen no
explicit mechanism to support this when developing an application. If there is something I
am missing, please point this out.
In the meantime, I can see a way that a developer could add this functionality without the
need to directly modify jBPM5, using the following approach. I would like to know whether
it is believed this would work. I am not completely comfortable with this for reasons I
will give (although these reasons should be more or less obvious):
1.) First, define a new work item parameter (or analogous mechanism) that represents users
who will be excluded from the next node. Let's assume we can correctly identify the
next node.
2.) Create a class that extends WSHumanTaskHandler. This class will override the
executeWorkItem method. This method will populate excluded owners in the people
assignments from having inspected the new parameter. It will otherwise be the same as the
method it overrides except for this one additional logic step.
3.) Replace the existing Taskorm.xml with a modified version in which the
TasksAssignedAsPotentialOwnerByGroup named query (and possibly some similar named queries)
is modified so that excluded owners are not able to claim the task.
I believe all the above is feasible because a.) there is nothing to stop the developer
from extending WSHumanTaskHandler in the described manner, and using it in the application
code and b.) the ORM file is specified in persistence.xml which is a
developer-configurable file, so the developer should be at liberty to specify a different
file. So all this could be done without "hacking" jBPM directly.
However I am uncomfortable with this approach because the overridden executeWorkItem
method as well as the replacement ORM file would be created using a copy-and-paste
methodology so that when progressing to a later version of jBPM it would be necessary to
modify these to reflect the original logic.
Nevertheless, if there is some intention to support this type of functionality in a future
release of jBPM (and assuming I am right to conclude it is not currently supported) this
might be a justifiable short-term solution.
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