Scenario (computing)
Encyclopedia
In computing
, a scenario is a narrative describing foreseeable interactions of types of users (characters) and the system. Scenarios include information about goals, expectations, motivations, actions and reactions. Scenarios are neither predictions nor forecasts, but rather attempts to reflect on or portray the way in which a system is used in the context of daily activity.
Scenarios are frequently used as part of the systems development process. They are typically produced by usability or marketing specialists, often working in concert with end users and developers. Scenarios are written in plain language, with minimal technical details, so that stakeholders (designers, usability specialists, programmers, engineers, managers, marketing specialists, etc.) can have a common example which can focus their discussions.
Increasingly, scenarios are used directly to define the wanted behavior of software: replacing or supplementing traditional Functional requirements
.
style of software development, scenarios are written as brief user stories. In the more deliberate style of software development, scenarios are written as structured use cases.
Negative scenarios or misuse case
s may be written to indicate likely threats which should be countered to ensure that systems have sufficient security
, safety
, and reliability
. These are categories of non-functional requirements
.
's As We May Think
essay is a famous example of a scenario that served as a vision piece. It was the user scenario that presented the idea of hyperlink
s, and illustrated the value of hypertext. It described the (fictitious) Memex
machine that inspired Douglas C. Engelbart to see the potential of the personal computer, and enabled him to secure the funding necessary to design the computer mouse and first graphical user interface
in 1968.
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, a scenario is a narrative describing foreseeable interactions of types of users (characters) and the system. Scenarios include information about goals, expectations, motivations, actions and reactions. Scenarios are neither predictions nor forecasts, but rather attempts to reflect on or portray the way in which a system is used in the context of daily activity.
Scenarios are frequently used as part of the systems development process. They are typically produced by usability or marketing specialists, often working in concert with end users and developers. Scenarios are written in plain language, with minimal technical details, so that stakeholders (designers, usability specialists, programmers, engineers, managers, marketing specialists, etc.) can have a common example which can focus their discussions.
Increasingly, scenarios are used directly to define the wanted behavior of software: replacing or supplementing traditional Functional requirements
Functional requirements
In software engineering, a functional requirement defines a function of a software system or its component. A function is described as a set of inputs, the behavior, and outputs ....
.
Types
In the AgileAgile software development
Agile software development is a group of software development methodologies based on iterative and incremental development, where requirements and solutions evolve through collaboration between self-organizing, cross-functional teams...
style of software development, scenarios are written as brief user stories. In the more deliberate style of software development, scenarios are written as structured use cases.
Negative scenarios or misuse case
Misuse case
Misuse Case is a business process modeling tool used in the software development business. The term "Misuse case" or "mis-use case" has derived from use case, meaning it is the inverse of a use case. The concept was created in the 1990s by Guttorm Sindre of the Norwegian University of Science and...
s may be written to indicate likely threats which should be countered to ensure that systems have sufficient security
Security
Security is the degree of protection against danger, damage, loss, and crime. Security as a form of protection are structures and processes that provide or improve security as a condition. The Institute for Security and Open Methodologies in the OSSTMM 3 defines security as "a form of protection...
, safety
Safety
Safety is the state of being "safe" , the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be...
, and reliability
Reliability engineering
Reliability engineering is an engineering field, that deals with the study, evaluation, and life-cycle management of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. It is often measured as a probability of...
. These are categories of non-functional requirements
Non-functional requirements
In systems engineering and requirements engineering, a non-functional requirement is a requirement that specifies criteria that can be used to judge the operation of a system, rather than specific behaviors. This should be contrasted with functional requirements that define specific behavior or...
.
Uses
Scenarios can also be used in a number of other ways:- As vision pieces. Vision pieces provide a high level picture of an envisioned system or product. One example is Apple's Knowledge NavigatorKnowledge NavigatorThe Knowledge Navigator is a concept described by former Apple Computer CEO John Sculley in his 1987 book, Odyssey. It describes a device that can access a large networked database of hypertext information, and use software agents to assist searching for information.Apple produced several concept...
video. - Scenarios may focus on the value offered by a system, showing how it offers an advantage over the way things are. This type of scenario may be used to 'sell' an idea within the organization that is considering developing the system.
Example
Vannevar BushVannevar Bush
Vannevar Bush was an American engineer and science administrator known for his work on analog computing, his political role in the development of the atomic bomb as a primary organizer of the Manhattan Project, the founding of Raytheon, and the idea of the memex, an adjustable microfilm viewer...
's As We May Think
As We May Think
As We May Think is an essay by Vannevar Bush, first published in The Atlantic Monthly in July 1945, and republished again as an abridged version in September 1945 — before and after the U.S. nuclear attacks on Japan...
essay is a famous example of a scenario that served as a vision piece. It was the user scenario that presented the idea of hyperlink
Hyperlink
In computing, a hyperlink is a reference to data that the reader can directly follow, or that is followed automatically. A hyperlink points to a whole document or to a specific element within a document. Hypertext is text with hyperlinks...
s, and illustrated the value of hypertext. It described the (fictitious) Memex
Memex
The memex is the name given by Vannevar Bush to the hypothetical proto-hypertext system he described in his 1945 The Atlantic Monthly article As We May Think...
machine that inspired Douglas C. Engelbart to see the potential of the personal computer, and enabled him to secure the funding necessary to design the computer mouse and first graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
in 1968.
External links
- Notes on Design Practice: Stories and Prototypes as Catalysts for Communication. by Thomas Erickson, in "Scenario-Based Design: Envisioning Work and Technology in System Development (ed. John M. Carroll)