问题
So my question is as follows, is it possible to move an actor inside the system boundary of a use case diagram? Can it be a part of the system.
I set a server as an actor, in where a customer interacts with the server in an e-commerce environment. Is it possible or should I move the server inside of the system? Since the server is a part of the system that the customer is interacting with.
This server is most likely then going to be used by an admin role.
回答1:
TL;DR
No, you can't do that, unless you model only a part of the system.
Explanation
By definition an actor is external to the system. It can be a user, other system or a sensor.
If you want to show a system decomposition into smaller parts, use component diagram.
Note, the role of a use case diagram is to show functions of the system as a whole.
On the other hand you may depict just one part of the system (ie. system tier). In such case other parts (tiers) are external to the modeled system part under consideration.
回答2:
I suppose you mean "move an actor inside the system boundary" since in any case the actor appears inside the UC diagram (or you just won't see it).
You can do that. However, it would be rather pointless since actors are meant to interact with the system under consideration (SUC) from outside. The only case where you can do that is, when you create sub-systems (that is you have boundaries of sub-systems within the SUC boundary). I wouldn't do that either from the very beginning. Only in a later design phase you could introduce such a construct. In that case you'd have independent teams working on the different sub-systems and one on the integration for the SUC. For "normally" sized systems you should leave these sub-systems just away and focus on actors and their UCs inside the SUC boundary.
来源：https://stackoverflow.com/questions/55101348/moving-in-an-actor-inside-system-boundary-of-uml-usecase-diagram