7 Realizing Use Cases
It is usually a good idea NOT to show model elements of different layers in
one diagram to prevent aspects from being confused. I recommend to use the
callout notation shown in Figure 2.78 rather than the direct representation shown
in Figure 2.77 .
Similar to the system/actor interactions, we can derive the interfaces from the
interaction between the blocks. The messages become operations and signals,
which are meaningfully grouped into interfaces ( Figure 2.79 ). Each of these interfaces
is then either a providing interface or a requesting interface and allocated to
the respective port of the block.
FIGURE 2-77
Using a structural allocation.
ibd [block] On-board computer
[structural allocation]
:Card reader :Customer card
e:Energy
ICustomerCard
ICustomerCard
?«allocate?»
FIGURE 2-78
Using the callout notation for structural allocation.
:Card reader :Customer card
e:Energy
ibd [block] On-board computer [structural allocation on
application layer]
ibd [block] On-board computer [structural allocation on
transport layer]
:Card reader :Customer card
allocatedTo
?«port?» energyPort
allocatedTo
?«port?» energyPort
allocatedFrom
?«port?» readerPort
allocatedFrom
?«port?» cardPort
ICustomerCard ICustomerCard
122 CHAPTER 2 The Pragmatic SYSMOD Approach
The sequence of fl ows shown in Figure 2.
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