Chapter 2. Top-Down Design with Use Case Diagrams, Activity Diagrams, and Sequence Diagrams


  • How to create and use use case diagrams

  • How to create and use activity diagrams

  • How to create and use sequence diagrams

Chapter 1 introduced you to architecture and modeling in the software space, and hinted at all the new architectural goodness available in Visual Studio 2010 Ultimate. This chapter dives deeper into three aspects of that, by looking at use case, activity, and sequence diagrams.

One of the strengths with modeling tools is that they enable you to design how the architecture of the application should be. Part of that is defining common terms around the problem domain, and then ensuring that everyone on the team understands those concepts. Using the use case, activity, and sequence diagrams, you can model your application, while ensuring that everyone on the team understands exactly what is being built.

This chapter is divided into three main sections:

  • Use Case Diagrams

  • Activity Diagrams

  • Sequence Diagrams

Each section begins by examining a completed diagram and explaining the different components of it. Next, the discussion looks at all the objects that are available when building a particular diagram. And, finally, you will see a step-by-step walkthrough of how to build the diagram shown at the beginning of the section.


A use case diagram provides a graphical overview of the functionality of a system. It shows who is using the system and what they ...

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