Artifact:  Use-Case Model

Use-Case Model	The use-case model is a model of the system's intended functions and its environment, and serves as a contract between the customer and the developers. The use-case model is used as an essential input to activities in analysis, design, and test.
UML representation:	Model, stereotyped as «use-case model».
Role:	System Analyst
Sample Reports:	Use-Case Model Survey
Examples:	Use Case Model, from the Course Registration System Use Case Model, from the Collegiate Sports Paging System (e-business)
More information:	Guidelines:Use-Case Model Guidelines:Actor-Generalization Guidelines: Communicate-Association Guidelines:Extend-Relationship Guidelines:Include-Relationship Guidelines:Use-Case-Generalization Guidelines:Use-Case Diagram Checkpoints:Use-Case Model
Purpose Properties Timing Responsibility Tailoring

Input to Activities: Capture a Common Vocabulary Manage Dependencies Review Requirements Detail a Use Case Detail the Software Requirements Identify Targets of Test Identify Test Ideas Identify Test Motivators Prioritize Use Cases Architectural Analysis Assess Viability of Architectural Proof-of-Concept Use-Case Analysis Define Test Approach Structure the Use-Case Model

Output from Activities: Find Actors and Use Cases Elicit Stakeholder Requests Define Automation Requirements Structure the Use-Case Model

Purpose

The following people use the use-case model:

• The customer approves the use-case model. When you have that approval, you know the system is what the customer wants. You can also use the model to discuss the system with the customer during development.
• Potential users use the use-case model to better understand the system.
• The software architect uses the use-case model to identify architecturally significant functionality.
• Designers use the use-case model to get a system overview. When you refine the system, for example, you need documentation on the use-case model to aid that work.
• The manager uses the use-case model to plan and follow up the use-case modeling and also the subsequent design.
• People outside the project but within the organization, executives, and steering committees, use the use-case model to get an insight into what has been done.
• People review the use-case model to give appropriate feedback to developers on a regular basis.
• Designers use the use-case model as a basis for their work.
• Testers use the use-case model to plan testing activities (use-case and integration testing) as early as possible.
• Those who will develop the next version of the system use the use-case model to understand how the existing version works.
• Documentation writers use the use cases as a basis for writing the system's user guides.

Properties

Timing

The use-case model primarily sets the functional requirements on the system, and is used as an essential input to analysis and architectural design. It can be used early in the inception phase to outline the scope of the system, as well as during the elaboration phase. The use-case model is refined by more detailed flows of events during the construction phase. The use-case model is continuously kept consistent with the design model.

Because it is a very powerful planning instrument, the use-case model is generally used in all phases of the development cycle.

Responsibility

A system analyst is responsible for the integrity of the use-case model, and ensures that the use-case model as a whole is correct, consistent, and readable. The use-case model is correct when it describes the system's functionality, and only this functionality.

Note that details of use-case packages, use cases, actors, relationships, and diagrams are the responsibilities of the corresponding requirements specifier. For more information, refer to Role: Requirements Specifier. The use-case view is the responsibility of the software architect. For more information, refer to Role: Software Architect.

Tailoring

Tailor to support project needs.  This may include including only a subset of the sub-artifacts (properties), tailoring the level of formality in which the sub-artifacts are created and managed, and tailoring of the individual sub-artifacts.  Document tailoring decisions in the Artifact: Use Case Modeling Guidelines.

Copyright  © 1987 - 2001 Rational Software Corporation

Rational Unified Process