hi all
i have some confusion about actors in use case.
im doing my final year project and now i have to write my thesis/documentation.
of course for system design i need a use case.
im developing a web based file encryption application with usage of TPM specification. TPM stand for trusted platform module that has been promoted by trusted computing group. TPM role as RSA private key storage and decryption occurs in it. and the RSA public key stored in database.RSA public key will encrypt AES public key that has been generated for file encryption.so what i wanna know is it possible if i set the database and TPM as actors?i have 6 actors in my use case: user, sender, receiver, database, TPM and application. sender and receiver under the generalization of user.i set application as actor because the application also decide for some action which not controlled by user.so is it okay if i use these actors?

If they perform specific tasks, maybe they are actors.
If they're just storage containers, I'd not call them actors.

Every dbms that we use now-a-dayz, usually are not just a storage containers, but we query them, orelse perform tasks and operations. even if we wanna get some result, we query them from business logic directly or use some stored procedure elseway.

So, I consider it that way, where database can be considered as an actor, as it should be.

From my point of view, actor is entity, which:
1. Initiates actions in the whole system
2. Is outside of any system
In this point of view, you are using too much actors here. So that the *real* actor maybe only web user. The rest - should be system-system interaction part - (aka. system component's interaction).
But you may not agree with this point of view.

Good luck.

I think use cases are more general and not as informative as sequence diagrams, you wouldn't have to give detailed information in a use case about what your DB does so much that it has to be an actor.
Why don't you use a sequence diagram?

The actors are those who will perform some work in the project like Admin is the actor and user is the actor user sends request for registration to the admin and he confirm him the data stored in some place which is not counted as actor.

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