[jbpm-users] Using Work Items out of a process

[Michael Anstis]

Hi,

I am adding the ability to execute WorkItems as function calls in Actions
defined in Drools Guvnor.

The intent is not to duplicate the invocation of Rules and WorkItems from
within a process using Task nodes, but a simple means for non-jBPM users to
call functions defined as WorkItems from rules.

At present, my prototype adds DRL to the RHS of a rule along these lines:-

...
when
  WorkItemManager wim = drools.getWorkingMemory().getWorkItemManager();
  SessionConfiguration sessionConfiguration = (SessionConfiguration)
kcontext.getKnowledgeRuntime().getSessionConfiguration();
  Map handlers = sessionConfiguration.getWorkItemHandlers();

  WorkItemHandler wihMyStringTask = handlers.get( "MyStringTask" );
  if( wihMyStringTask != null ) {
    WorkItemImpl wiMyStringTask = new WorkItemImpl();
    wiMyStringTask.getParameters().put( "Param1-string", "hello" );
    wihMyStringTask.executeWorkItem( wiMyStringTask, wim );
}

Parameters are defined as literals or bound to facts\fields in the UI.

I'm not convinced of the value of Result parameters for this use-case, as
execution of the Work Item has no context, however it is possible they will
end up in Working Memory and can be re-bound for use in other rules.

My concerns are that the WorkItem does not have an ID, a State or a
ProcessInstanceID and I am concerned WorkItem implementations may break when
signalling back to the ProcessManager (or other internal jBPM plumbing I've
not come to yet). Can anybody with a greater insight of jBPM's internals
comment (or am I heading towards a train wreck of biblical proportions)?

Cheers,

Mike
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