Specification of Reactive Hardware/Software Systems - Electronic ...

12.3 The Essential Specification 383
first wakeUp message. If the first wakeUp message arrives, the Product Output Handler
retrieves the PI from the appropriate Product Info Keeper and starts offering the accept(PI)
message to its right neighbour station. If this station still has not accepted this message
at the point of arrival of the second wakeUp message, the Product Output Handler sends a
message stop to the Transporter Image. At the moment the right neighbour station accepts
the accept(PI) message again, the Transporter Image is sent the message start.
12.3.4 Feeding Scenario of Feeder Station
The scenario of the previous section describes the objects and message flows required
to transport mailing products and to keep track of these products. This generic scenario
does not focus on the specific services that have to be performed on the mailing products.
In case of a feeder station the services are the addition of particular items to packets in the
station. The behaviour necessary to perform this service is depicted in the Message Flow
Diagram of Figure 12.5. The Message Flow Diagram shows the Feeding Scenario of the
Product_
Input_
Handler
Transporter_
Image
schedule
(PIKeeperId,
InitialPosition)
Service_
Scheduler
wakeAt(Position,Id)/
wakeup(Id)
serviceRequired
(PIKeeperId,
Service)/
required,
notRequired
Product_
Info_
Keeper
feed(PIKeeperId,InitialPosition)
giveStatus/
notMounted,
mounted(Service)
Feeding_Unit_
Image
mounted, feed
notMounted
misFed,
doubleFed
Feeding_
Unit
servicePerformed
(PIKeeperId,Service)
feedReady
(ProductInfoKeeperId,
Service)
Service_
Administrator
Figure 12.5: Feeding Scenario of Feeder Station
Feeder_Station
Feeder_Controller
feeder station. Next to a number of objects introduced in the Product Flow Scenario, the
diagram shows a Service Administrator, a Feeding Unit terminator and a corresponding