Lesson 12

In this module, we covered the use case view, comprising the use case diagram, use case narrative, and use case scenarios. The use case narrative is not part of the UML standard, but you will find it pretty much everywhere use cases are used.

The use case diagram emphasizes goals of the system, not processes. This is one of the most common mistakes people make in applying use cases. The difference is sometimes subtle, so watch out. Use cases are the goals; actors are the users who want to achieve those goals. Actors are roles or relationships between users and the system. These roles may be played by systems, people, or devices. Associations are the visual means identifying interactions between actors and use cases or between use cases.
Stereotypes help to qualify the meaning of a model element without specifying an implementation. In this module, we applied only two of the many predefined stereotypes in the UML documentation, <<Uses>> and <<Extends>>. <<Uses>> indicates delegation, whereas <<Extends>> indicates specialization or variation on a use case.

A void analysis paralysis by not trying to be right the first time through. It just is not possible. Allow for a number of passes through the problem. Move on to other models and revisit the use cases after digging a little deeper. Let the models reveal information and inconsistencies, or more positively, prove you right. Above all, allow time for practice. Trial and error can be excellent teachers.

The Eclipse Process Framework (EPF) is an open source project that is managed by the Eclipse Foundation. It lies under the top-level Eclipse Technology Project. It has two goals: To provide an extensible framework and exemplary tools for software process engineering, method and process authoring, library management, configuring and publishing a process. To provide exemplary and extensible process content for a range of software development and management processes supporting iterative, agile, and incremental development, and applicable to a broad set of development platforms and applications. For instance, EPF provides the OpenUP/Basic, an agile software development process optimized for small projects.

Scenarios provide a closer examination of the use cases. Visual evaluation of the use case narrative can be very helpful by using 1) flowcharts or 2) activity diagrams (we will show these later in the course). The scenarios become the basis for your acceptance testing for the system as well as the testing of your models in the logical view.

This module introduced you to the following terms:

1. Scenario: In computing, a scenario is a narrative of foreseeable interactions of user roles (known in the Unified Modeling Language as 'actors') and the technical system, which usually includes computer hardware and software. A scenario has a goal, which is usually functional.
2. Use case view: A view dedicated to the description of user requirements.

Click the Quiz links below to check your knowledge with 2 multiple-choice quizzes addressing the lessons worked through in this module.

1. Use Case Quiz One
2. Use Case Quiz Two