This chapter focuses on activity diagrams, which depict the activities and responsibilities of elements that make up a system. First, I introduce activity diagrams and how they are used. Next, I discuss action states and their details. Finally, I go over flows and their details. Many details of activity diagrams that were not fleshed out in Chapter 2 are more fully elaborated here, and throughout the chapter, I include suggestions relating to activity diagrams.
Activity modeling is a specialized type of behavioral modeling concerned with modeling the activities and responsibilities of elements. You usually apply activity modeling in conjunction with sequence and collaboration modeling (Chapter 6) to explore the activities and responsibilities of interacting and collaborating elements.