Explanation

To fully understand the purpose of a business you must know who the business interacts with; that is, who puts demands on it, or is interested in its output. The different types of "interactors" are represented as business actors.

The term actor means the role someone, or something plays while interacting with the business. The following types of business users are examples of potential business actors:

• Customers
• Suppliers
• Partners
• Potential customers (the "market place")
• Local authorities
• Colleagues in parts of the business not modeled.

Hence, an actor normally corresponds to a human user. However, there are situations where, for instance, an information system plays the role of an actor. If your bank's on-line services are so good that your business can manage most of its bank transactions from a PC on your own premises, your use cases interacting with the "money supplier" actor, the bank, will in fact interact with an information system.

An actor represents a particular type of business user rather than a real physical user. Several physical users of a business can play the same role in relation to it; that is, they act as instances of one and the same actor. Also, the same user can act as several different actors. This means that one and the same person can embody instances of different actors.

How to Name Business Actors

A business actor should be given a name that reflects its role towards the business. The name should be applicable to any person-or any information system-playing the role.

Business Actor Characteristics

The characteristics of a business actor should cover the following topics: 

• Prior knowledge and experience.
• Physical characteristics.
• Social and physical environment. 
• Job, tasks, and requirements.
• Cognitive characteristics.

This information is useful to define the business use cases in a way that is meaningful to the business actor. It is only relevant for "human" business actors. 

Checklist for Good Business Actors

• All actors are found. Everything in the business environment interactions-both human and mechanical-is modeled with actors. You cannot be sure of finding every actor until you have found and described every use case.
• Each human actor expresses a role, not a specific person. You should be able to name at least two persons that can play the role of each actor. If you can't, you may have modeled a person, not a role. Of course, there are situations in which you can find only one person who can play a role.
• Each actor models something outside the business.
• Each actor is involved with at least one use case. If an actor does not interact with at least one use case, you should remove it.
• A specific actor does not interact with the business in several completely different ways. If an actor interacts in several completely different ways, you have probably assigned several roles to one actor. In that case, you should split the actor into several actors, each representing a different role.
• Each actor has an explanatory name and description. An actor's name should represent the role it plays in relation to the business. The name must be understandable to people outside the business-modeling team.