The following table shows the definition of the different types.

Definition element of Producer type Store:

Note that in our example each of the stores’ output terminals is wired to a separate channel. We have chosen to use separate channels for each event type, with the exception of the Assignment channel which is used for both Manual and Automatic assignments.

Definition element of Producer type GPS Sensor:

Definition element of Producer type Vehicle:

This producer belongs to the category of GPS sensor, which has been defined as an abstract producer type in the previous definition element.   

Definition element of Producer type Driver:

Delivery confirmation is produced by the Driver's handheld device, but requires signature of the delivery recipient.

We have three concrete types of producer in this application: the participating stores, the vehicles and the drivers themselves (represented by their hand-held devices). We represent each of these using class-style definition elements. We can do this because, for each of the three types, all the producers of that type are treated similarly – for example each store has two output terminals and these terminals are connected to the same targets, regardless of which store it is.  There is one abstract type definition (GPS Sensor) and the Vehicle producer class is a specialization of that type, reflecting the fact that there is a physical GPS sensor in each vehicle, and the event types are actually being produced by that sensor.