Where to Find Out More

Although activity diagrams have always been rather complicated and are even more so with UML 2, there hasn't been a good book that describes them in depth. I hope this gap will get filled someday.

Various flow-oriented techniques are similar in style to activity diagrams. One of the better known—but hardly well known—is Petri Nets, for which http://www.daimi.au.dk/PetriNets/ is a good Web site.