A resource that performs the work represented by a workflow activity instance.
This work is normally manifested as one or more work items assigned to the workflow participant via the worklist.
These terms are normally applied to a human resource, but it could conceptually include machine-based resources such as an intelligent agent.
Where an activity requires no human resource and is handled automatically by a computer application, the normal terminology for the machine-based resource is invoked application.
An actor, agent, or role may be identified directly within the business process definition or (more normally) is identified by reference within the process definition to a role, which can then be filled by one or more of the resources available to the workflow system to operate in that role during process enactment.