And-dependencies

4.4 And-dependencies

An and-dependency is a logical conjunction of dependencies. It is represented by a line with a connection point on one side that represents the conjunction, and connection points on the other side that represent the parts of the conjunction, called the conjuncts (figure 4.4). This is a purely logical construction and represents no time ordering. So in figure 4.4, a = (b and c and d). By this we mean that

a occurs in the contract period of the model if and only if b, c and d occur in the contract period of the model.

Figure 4.4:An and-dependency.

A dependency path may contain and-dependencies.

For example, in figure 4.5, the traveler need occurs in the contract period if and only if both traveler interfaces are triggered in the contract period.

Figure 4.5:An and-dependency: both a train trip and food are needed to satisfy the consumer need.

In figure 4.6, the Luxury rail transporting activity has outsourced the Catering and Ticketing activities in order to be able to concentrate on its core competency, providing luxury rail transport.

Figure 4.6:An and-dependency that represents outsourcing of two activities.