19.1. When to Create DCDs

Although this presentation of DCDs follows the creation of interaction diagrams, in practice they are usually created in parallel. Many classes, method names and relationships may be sketched out very early in design by applying responsibility assignment patterns, prior to the drawing of interaction diagrams. It is possible and desirable to do a little interaction diagramming, then update the DCDs, then extend the interaction diagrams some more, and so on.

These class diagrams may be used as an alternative, more graphical notation over CRC cards in order to record responsibilities and collaborators.