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

10.5 Example: The Elevator Problem 319
Transformation 15
e
envs¥ p BSpec ¥ Sys
¥ Sys
e BSpec ¡ ¥ envs¥ p Sys ¡ ¥ Sys
¢
¡
if BSpece and ¡ Sysp are derived from ¡ BSpece respectively Sysp by replacing every occurrence of
some class name Cpc by some different class name which is not used in Sysp ¨ .
According to 15 it is allowed to replace the name of any process or cluster class by a
new and fresh name. Replacing the name of a class involves the replacement of every
occurrence of this class name.
10.5 Example: The Elevator Problem
In [Voe] we have applied the 15 basic behaviour-preserving transformations to a POOSL
specification of the Elevator Problem as defined in [You89]. In this section we will show
the result of this transformation exercise.
Figure 10.1 presents an Instance Structure Diagram of the elevator specification. It
visualises an elevator control system (instance) as well as the collaborating instances
from which this system is constituted. These instances are represented by rounded
rectangles. The environment of the elevator control system consists of a number of
terminator instances which are represented by hexagons. All instances communicate by
exchanging messages over static logical channels. The structure of the Instance Structure
Diagram basically follows the problem description as stated in [You89].