Executable UML: A Foundation for Model-Driven Architecture

17.3. Implicit Bridging with Join Points

The explicit bridges—asynchronous signals to and from external entities and bridge operations—represent the absolutely required coupling between the bookstore domain and the rest of the system. Collectively, the explicit bridges represent the requirements made by the bookstore on other domains in the system.

Explicit bridges, however, represent only some of the interfaces between the bookstore domain and the rest of the system. Most of the bridging in the system is implicit. There is no explicit mention, not even anonymously, of how one domain links to another to be seen anywhere in the models.

17.3.1. Rationale for Join Points

Consider, for example, how the user interface connects to the bookstore domain. ...