Whether or not inclusion of System as an Actor in Use Case Diagram when it is implicitly doing work

Question

我需要为系统绘制一个UML用例图。在我的系统中，它会为注册者生成一个loginID和密码。我是否应该将该系统作为参与者包括在内？

Answer 1

Of course not. The system under consideration is never an actor (to self). It is THE system that adds value to its actors.

Answer 2

According to UML specification actor is one of the three:

• A person interacting with the system (for computer systems: a user)
• Other systems interacting with the system (eg bank system when our system directly retrieves account history to import payments)
• Hardware interacting with the systems (eg sensors or printers).

This list is closed. Neither the system in consideration not any of its parts are actors to the same system.

As a rule of thumb actors are always external to the system.