Work Product Descriptor (Artifact): Actor
Purpose
This artifact captures details of the actors which are important to understanding the relationship and interaction between a use-case and the system boundary.
Relationships
Container Artifact
Fulfilled Slots
RolesResponsible: Modified By:
Input ToMandatory:
  • None
Optional: External:
  • None
Description
Main Description

Actors represent different types of users. An actor is anyone or anything that exchanges data with the system. An actor can be a user, external hardware, or another system.

The difference between an actor and an individual system user is that an actor represents a particular class of users, rather than an actual user.

Several different individual users can play the same role, which means that they can be represented by the same, single actor. In that case, each individual user constitutes an instance of the actor.

However, in some situations, only one person plays the role modeled by an actor. For example, there may be only one individual in the role of system administrator for a rather small system.

The same user can also act as several actors (that is, the same person can take on different roles).



Brief OutlineFor each actor identified, document the name and a brief description.
NotationUML Representation: Actor

The actor may have the following properties:

  • Name: The name of the actor.
  • Brief Description: A brief description of the actor's sphere of responsibility and what the actor needs the system for. 
  • Characteristics: For human actors: The physical environment of the actor, the number of users the actor represents, the actor's level of domain knowledge, the actor's level of computer experience, other applications the actor is using, and other general characteristics such as gender, age, cultural background, and so on. 
  • Relationships: The relationships, such as actor-generalizations, and communicates-associations in which the actor participates. 
  • Diagrams: Any diagrams local to the actor, such as use-case diagrams depicting the actor's communicates-associations with use cases. 

Decide which properties to use and how to use them. In particular, you need to decide at which level of detail the "Characteristics" property needs to be described.

Properties
Optional
Planned
Illustrations
Templates
Key Considerations

This artifact concentrates on the classes of person and other systems that interact with the system under consideration. Not every role in an organization becomes an actor. However, work products that describe organizational roles may be useful sources for coming up with actors.

Tailoring
Impact of not havingIf you do not use this artifact, you will not develop a comprehensive view of whom and what can interact with the system. Important stakeholder perspectives and interactions of the roles and systems may not be taken into account. This will result in a system where some classes of person who need to interact with it have not been identified or a solution that does not meet all users' interaction needs. It can be very difficult, if not impossible, to assess the completeness of the set of use cases without the context provided by the associated actors. 
Reasons for not needingIf you have chosen a non-use case approach, or you have captured the information elsewhere, or there is no human interaction with the system, or it is possible to capture the interaction with other systems solely through architectural artifacts, then you may not need this artifact on your project.
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