The PIM for Rosa's Breakfast System is depicted in Figure 4-2. The PIM is the only model that must be created by humans in a creative process. To find out how to build such a model you can read a large number of books on UML and modeling. Here we assume that the creative process has been successfully completed with the PIM in Figure 4-2 as the result.
Figure 4-2. PIM of Rosa's Breakfast Service
In the PIM every standard breakfast contains a number of parts ; each part indicates the amount in which a certain comestible is present in the breakfast. Every order consists of a number of breakfasts. The price of each breakfast is determined based on the chosen style and the price of the chosen standard breakfast. The price of the order is simply the addition of the prices of all breakfasts plus a small delivery fee.
The model in Figure 4-2 defines the breakfast services independently from any specific technology, so indeed, it is a PIM. But Rosa does not want a model, she wants a running system. Therefore, we need to transform the PIM into a number of PSMs, taking into account the relationships between these PSMs.