Actors
A use case defines the interactions between external actors and the system under consideration to accomplish a goal. Actors must be able to make decisions, but need not be human: "An actor might be a person, a company or organization, a computer program, or a computer system — hardware, software, or both." Actors are always stakeholders, but many stakeholders are not actors, since they "never interact directly with the system, even though they have the right to care how the system behaves." For example, "the owners of the system, the company's board of directors, and regulatory bodies such as the Internal Revenue Service and the Department of Insurance" could all be stakeholders but are unlikely to be actors.
Similarly, a person using a system may be represented as different actors because he is playing different roles. For example, user "Joe" could be playing the role of a Customer when using an Automated Teller Machine to withdraw cash from his own account, or playing the role of a Bank Teller when using the system to restock the cash drawer on behalf of the bank.
Actors are often working on behalf of someone else. Cockburn writes that "These days I write 'sales rep for the customer' or 'clerk for the marketing department' to capture that the user of the system is acting for someone else." This tells the project that the "user interface and security clearances" should be designed for the sales rep and clerk, but that the customer and marketing department are the roles concerned about the results.
A stakeholder may play both an active and an inactive role: for example, a Consumer is both a "mass-market purchaser" (not interacting with the system) and a User (an actor, actively interacting with the purchased product). In turn, a User is both a "normal operator" (an actor using the system for its intended purpose) and a "functional beneficiary" (a stakeholder who benefits from the use of the system). For example, when user "Joe" withdraws cash from his account, he is operating the Automated Teller Machine and obtaining a result on his own behalf.
Cockburn advises to look for actors among the stakeholders of a system, the primary and supporting (secondary) actors of a use case, the system under design (SuD) itself, and finally among the "internal actors", namely the components of the system under design.
Read more about this topic: Use Case
Famous quotes containing the word actors:
“To save the theatre, the theatre must be destroyed, the actors and actresses must all die of the plague. They poison the air, they make art impossible. It is not drama that they play, but pieces for the theatre. We should return to the Greeks, play in the open air; the drama dies of stalls and boxes and evening dress, and people who come to digest their dinner.”
—Eleonora Duse (1859–1924)
“The actors today really need the whip hand. They’re so lazy. They haven’t got the sense of pride in their profession that the less socially elevated musical comedy and music hall people or acrobats have. The theater has never been any good since the actors became gentlemen.”
—W.H. (Wystan Hugh)
“Modern tourist guides have helped raised tourist expectations. And they have provided the natives—from Kaiser Wilhelm down to the villagers of Chichacestenango—with a detailed and itemized list of what is expected of them and when. These are the up-to- date scripts for actors on the tourists’ stage.”
—Daniel J. Boorstin (b. 1914)