Hi Mauricio,
I found answer to my question in “jBPM5 Developer Guide” book on page 143:
“Business users do not commonly use script tasks, but they are really helpful for technical people. By adding script tasks to a process we can easily modify the behavior of our processes without modifying any Java class. We can use this type of task to add logs, messages, or to perform data transformation tasks in our processes. As a rule of thumb, script tasks shouldn’t contain business logic inside them. Abstract tasks, human tasks, and service tasks are better place to implement this kind of logic.”
In our company we usually implement the business logic in plain classes and call methods from the script tasks.
Thanks,
Vladimir