use service task instead of script task. Here is an example of a process that defines java class and method as interface and operation respectively and then that method is invoked by service task. Here is the actual code that does the execution.

HTH

Thanks for providing this example. I have some of questions:

1. Does this service task still for JBPM 6.3 since there is no option to select Service Implementation of type "Other" on JBPM Workbench.
2. Is there a way to pass multiple parameters to this kind of a service task.
3. Should the called method be a part of the same kjar?

Thanks in advance.