Use_Case

What is Use-Case 2.0?
Use Case: A use case is all the ways of using a system to achieve a particular goal for a particular user. Taken
together the set of all the use cases gives you all of the useful ways to use the system, and illustrates the value
that it will provide.
Use-Case 2.0: A scalable, agile practice that uses use cases to capture a set of requirements and drive the
incremental development of a system to fulfill them.
Use-Case 2.0 drives the development of a system by first helping you understand how the system will be used
and then helping you evolve an appropriate system to support the users. It can be used alongside your chosen
management and technical practices to support the successful development of software and other forms
of system. As you will see Use-Case 2.0 is:
　　• Lightweight
　　• Scalable
　　• Versatile
　　• Easy to use

First Principles
There are six basic principles at the heart of any successful application of use cases:
　　1. Keep it simple by telling stories
　　2. Understand the big picture
　　3. Focus on value
　　4. B uild the system in slices
　　5. Deliver the system in increments
　　6. Adapt to meet the team’s needs

Use-Case Model
A use-case model is a model of all of the useful ways to use a system, and the value that they will provide. The
purpose of a use-case model is to capture all of the useful ways to use a system in an accessible format that
captures a system’s requirements and can be used to drive its development and testing.
A use-case model:
　　• Allows teams to agree on the required functionality and characteristics of a system.
　　• Clearly establishes the boundary and scope of the system by providing a complete picture of its actors
　　(being outside the system) and use cases (being inside the system).
　　• Enables agile requirements management.
A use-case model is primarily made up of a set of actors and use cases, and diagrams illustrating their relationships.
Use-case models can be captured in many different ways including as part of a Wiki, on a white board or
flip-chart, as a set of PowerPoint slides, in a MS Word document, or in a modeling tool.

Use-Case Narrative
The purpose of a use-case narrative is to tell the story of how the system and its actors work together to
achieve a particular goal.
Use-case narratives:
　　• Outline the stories used to explore the requirements and identify the use-case slices
　　• Describe a sequence of actions, including variants that a system and its actors can perform to achieve
　　a goal.
　　• Are presented as a set of flows that describe how an actor uses a system to achieve a goal, and what
　　the system does for the actor to help achieve that goal.
　　• Capture the requirements information needed to support the other development activities.