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

46 Concepts for Analysis, Specification and Design
accept(PI)
i
productArrived
Product_
Input_
Handler
piti
currentPosition
(Position)
wake
wakeAt(Position,Id)
wakeup(Id)
free(PIKeeperID
)
pihp
store(PIKeeperId,PI)
pihs
schedule
(PIKeeperId,
InitialPosition)
Figure 3.10: Product Input Handler Message Interface
Channels are visualised in Instance Structure Diagrams. We do not show such diagram
in this very brief overview of the method.
Below we present an example of a behaviour description in POOSL for a
Product Input Handler object class. Behaviour is always described of classes and
not of individual objects. All stations in a mailing machine contain at least one
Product Input Handler object. Therefore it is convenient to describe the behaviour only
once for the whole class of Product Input Handler objects. An explanation of the meaning
follows immediately after the next example:
process class "Announces the behaviour description of a process class."
Product Input Handler myId,productDistance ¡
instance variables "Declaration of the variables."
myId
productDistance
productInfo
initialPosition
piKeeperId
: ProductInputHandlerId
: PositionDelta
: PI
: InitialPosition
: PIKeeperId
communication channels "Definitions of the communication channel names."
i piti wake pihs pihp
message interface "Definition of messages to be sent (!) or received (?) on channels."
i?accept(PI)
piti?productArrived
piti?currentPosition(Position)
wake!wakeAt(Position,ProductInputHandlerId)