Create a rules engine controller service in NiFi which would allow processors, reporting tasks and/or other controller services to interrogate a centralized engine for actions required given a certain set of data (or facts). The rules engine should leverage a rules file or database to fire rules and either return the list of action or execute required actions.
For a default implementation the EasyRules engine can be used however an interface should be offered to allow other implementations. An internal Rule/Action API can also be created to provide a common representation for rules and actions within NiFi. This would allow Actions to be received and processed by callers or allow Rules to generated and fired dynamically if needed.