RE: (ROSE) Question About Actors

[Crain, Anthony R.]

A use case can NOT become an actor.

 

By definition:  An actor is something external to the system that interacts with the system.

By definition:  A use case is something the system does.  It is internal.

 

Since a use case is internal and an actor is external, a use case can not be an actor.

 

The original definition looks fine, except that you can act upon an actor in the form of requesting something.  For example if there were a legacy system out there we could ask it to do work for us, or for data from it.  If that can be considered acting upon, then actors can be acted upon.

 

Here's how I define it:

An actor is anything outside of our system, that interacts with our system.

 

I also use primary and secondary actors conceptually too:

Primary actors:  An actor that has a goal on our system.  They start the use case and receive something of value once the use case ends.

 

Secondary actors:  An actor that is needed to accomplish a use case.  It does not have a goal of it's own, but exists to help our system satisfy some other actor's goal.

 

    --anthony

 

 

 -----Original Message-----
From: Flum, Michael [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, February 06, 2001 3:37 AM
To: 'Pankaj Chatterjee'; '[EMAIL PROTECTED]'
Subject: RE: (ROSE) Question About Actors

Hi,

  An actor is a coherent set of roles that users of use cases play when interacting with the use cases.

 

  Your definition is okay, but, you last statement bears scrutiny.  A use case can become an actor and it could have been acted upon by another actor.

-----Original Message-----
From: Pankaj Chatterjee [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, February 06, 2001 2:20 AM
To: 'Rose Forum'
Subject: (ROSE) Question About Actors

Hello,

 

My understanding is that an Actor is an entity that is outside the scope of the system under consideration. They help us to define the scope that is outside the system as well as what is inside. Actors act upon the system but are not acted upon.

 

Is this a correct description or is there some thing untrue? Please also add the missing parts

 

Thanks

 

Pankaj