Beginning C# 2008 Objects: From Concept to Code

9.2. Actors

Actors represent anybody or anything that will interact with the system after it's built; actors' needs are the basis for use cases. Actors generally fall into two broad categories:

• Human users

• Other computer systems

When actors interact with the system, they generally want to achieve some result, but actors can also simply provide/contribute information to the system and/or receive/consume information from the system.

By providing information, we mean whether or not the actor inputs substantive information that adds to the residual data stored by the system; for example, a department chairperson defining a new course offering or a student registering his or her plan of study. This doesn't include the relatively trivial information ...