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

76 Abstraction of a Problem Domain
a single POOSL communication primitive, which models one way synchronous message
passing. Details are described in Subsection 6.3.4.
Process objects cannot be understood without a more in depth explanation of various
concepts such as of identity, state, method and of message. All these subjects are covered
in dedicated sections in this chapter.
4.4.4 Multiple process objects
Multiple X
Figure 4.13: Multiple Process Object Symbol
Besides a graphical symbol for single instances we offer a symbol for a collection of objects
of the same class, called a multiple process object. This symbol can simplify diagrams
by denoting a collection of instances of the same class. Figure 4.13 shows the symbol
for a multiple process object, as it can be used in a Message Flow Diagram. Examples of
multiples are collections of identical resources, such as collections of mailboxes, buffers,
or sensors. Figure 4.14 shows that all objects of a multiple share the same channels. In
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Multiple X
Figure 4.14: Common Channels on Multiple Process Objects
this figure each of the channels is shown n-fold. It is also allowed to draw only one
representative for each channel.
A message to a multiple arrives at all individual objects simultaneously. Only one entity,
however, can accept the message. A more detailed description of communication with
multiples is described in Subsection 6.3.8.
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