Beginning C# 2008 Objects: From Concept to Code

9.5. To Diagram or Not to Diagram?

The use case concept is fairly straightforward, and hence simple narrative text as we've seen thus far in the chapter is often sufficient for expressing use cases. The UML does, however, provide a formal means for diagramming use cases and their interactions with actors. As mentioned earlier:

• Actors who are people are represented as stick figures;

• The core system and all actors that are external systems are represented with rectangles.

Now we'll add the following:

• Use cases are represented as ovals labeled underneath with a brief phrase describing the use case

• The boxes surrounding the oval(s) represent the system boundaries.

Figure 9-4 shows a sample UML use case diagram; here, we depict three actors—Student, ...