Artifact: Actor |
This artifact represents a set of roles interacting with a system. An instance can be an individual or an external system.
Domain: Requirements Work Product Kinds: Model Element
Purpose
Different stakeholders use this artifact for different purposes: Analysts - use this artifact to define the system boundaries, identify external interfaces, and to describe use cases interaction with actors. Developers - use this artifact to capture characteristics of human actors when creating the user interface and to realize use cases (in terms of objects) and their interaction with actors.
Relationships
Container Artifact | Use Case Model
Roles | Responsible: Analyst | Modified By: Analyst
Tasks | Input To: | Output From: Find and Outline Requirements Detail Requirements
Description
Main Description | To fully understand the system's purpose you must know who the system is for, that is, who will be using the system. Different user types are represented as actors. An actor is anything or anyone 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 user rather than an actual user. Several users can play the same role, which means they can be one and the same actor. In that case, each user constitutes an instance of the actor. Ivar and Mark are operators of a recycling machine. When they are using the machine each is represented by an instance of the actor Operator. However, in some situations, only one person plays the role modeled by an actor. For example, there may be only one individual playing 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). Charlie uses the Depot-Handling System primarily as Depot Manager, but sometimes he also uses the Depot-Handling System as ordinary Depot Staff. For each actor identified, capture the name and brief description. It is also necessary to capture the use cases that this actor initiates and those use cases in which the actor plays a secondary role.
Tailoring
Impact of not having | If this artifact is not used, important stakeholder perspectives may not be taken into account. This will result in a solution that does not meet all user needs. It will be very difficult, if not impossible, to assess the completeness of the set of use cases without the context provided by the associated actors.
Representation Options | If your project is using a use-case model, there is no need for a separate representation for actors other than in the use-case model and in the use-case specification. The simplest option is to capture the actor's name and brief description in a table, along with a list of the use cases that this actor initiates and those use cases in which the actor participates in a secondary role. See the discussion of the Actor-Goal-List in Guideline: Use Case Formats for more information on this representation option.
More Information
Checklists | Actor
Guidelines | Find and Outline Actors and Use Cases Use Case Formats
This program and the accompanying materials are made available under the Eclipse Public License v1.0 which accompanies this distribution. View copyright information here: OpenUP Copyright