When to Use Communication Diagrams

The main question with communication diagrams is when to use them rather than the more common sequence diagrams. A strong part of the decision is personal preference: Some people like one over the other. Often, that drives the choice more than anything else. On the whole, most people seem to prefer sequence diagrams, and for once, I'm with the majority.

A more rational approach says that sequence diagrams are better when you want to emphasize the sequence of calls and that communication diagrams are better when you want to emphasize the links. Many people find that communication diagrams are easier to alter on a whiteboard, so they are a good approach for exploring alternatives, although in those cases, I often prefer CRC cards.