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Lesson 2The use case model
ObjectiveDefine the purpose of the use case model.

Purpose of the Use Case Model

Create a dialog

The use case model determines the functionality an application must provide by creating a dialog about the features users need, by asking questions such as:
  1. How will people use the application?
  2. What will they see when they use it?

User dialog
User dialog

Determine functionality

Think about your own experience researching a system. Typically, we ask users something like, How do you post a transaction? How do you verify an account balance? Then the user describes a workflow or process. The need to determine functionality was one of the reasons why structure analysis, a form of functional modeling, was created.

Goal-focused modeling

The key difference between use cases and functional design is the focus. Functional design documents a process, but a use case focuses on the goal of a process. This change in mindset is essential in keeping us from jumping to process solutions without first understanding the intended goal. Remember how rapidly technology changes since a process that works today will likely be obsolete or inadequate by the end of the project. Functional modeling often leads to rewriting existing systems, rather than redesigning them, precisely because it focuses on the current process rather than the goal.
Goal-focused modeling keeps us attuned to a target rather than the means to the target. This keeps us open to a variety of solutions, allowing and possibly encouraging us to take advantage of technological advances.
In the next lesson, the use case diagram will be discussed.

Use Case Model - Exercise

Click the Exercise link below to practice targeting goals rather than processes.
Use Case Model - Exercise

Writing Effective Use Cases