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One Model, Many Interests, Many Views
If a service function supports the transition, the name of the function is shown after the trigging event
and call information.
In addition, the nodes representing states optionally display entry (what functions occur when
transitioning into the state), exit (what functions occur when transitioning out of the state), and do
functions (the behavior that elaborates this state).
The ability to effectively read a state transition diagram corresponds more to an individual’s mental
model than their role or background. That said, systems and software engineers are classically trained
to understand state transition diagrams. For that reason, the view is an effective representation when
taking a higher-level, orthogonal look at the behavior of the system.
Representing the System Implementation
Much as Jim Long noted that the various systems engineering diagrams of behavior could be plotted
along a spectrum representing the degree of data and structural content, diagrams representing the
physical architecture can be plotted in two dimensions. The first dimension (the X axis) parallels Jim’s
concepts of a behavioral spectrum in the physical architecture domain. The spectrum reflects the two
key physical characteristics of composition (the parts tree of a system) and connectivity (how those
parts are interconnected externally and internally). The second dimension is the level of detail moving
from representations best suited for system architecting and diverse audiences at level 0 and level 1 of
the system architecture to representations better suited for design and technical audiences at level N
of the architecture.