Who is the primary actor of an automated system?

Question

In an automated black box trading application who should be identified as the primary actor in the use cases? Is it the system itself or the system administrator or the organization who has a vested interested in the system?

Answer 1

An actor is external to the system and interact with it; the organization is not an actor per se it is a stakeholder.

In this case the primary actor would be the stock market which send quotes to the automated trading system.

Answer 2

A system can be identified as such. According to Wikipedia

An actor in the Unified Modeling Language (UML) "specifies a role played by a user or any other system that interacts with the subject."

Answer 3

Your actor will be any system using your black box trading application.