Sommerville-Software-Engineering-10ed

Chapter 19 ■ Systems engineering 555
Architecture
Electrical
engineering
Electronic
engineering
Civil
engineering
Systems
engineering
Software
engineering
Figure 19.2 Professional
disciplines involved in
ATC systems engineering
Mechanical
engineering
Ergonomics
User interface
design
design the controller workstations and software engineers, and user interface designers
are responsible for the software in the system.
The involvement of a range of professional disciplines is essential because of the
different types of components in complex systems. However, differences and misunderstandings
between disciplines can lead to inappropriate design decisions.
These poor decisions can delay the system’s development or make it less suitable for
its intended purpose. There are three reasons why there may be misunderstandings
or other differences between engineers with different backgrounds:
1. Different professional disciplines often use the same words, but these words
do not always mean the same thing. Consequently, misunderstandings are
common in discussions between engineers from different backgrounds. If
these are not discovered and resolved during system development, they can
lead to errors in delivered systems. For example, an electronic engineer may
know a bit about C programming but may not understand that a method in
Java is like a function in C.
2. Each discipline makes assumptions about what other disciplines can or cannot
do. These assumptions are often based on an inadequate understanding of what
is possible. For example, an electronic engineer may decide that all signal processing
(a computationally intensive task) should be done by software to simplify
the hardware design. However, this may mean significantly greater
software effort to ensure that the system processor can cope with the amount of
computation that is resolved.
3. Disciplines try to protect their professional boundaries and may argue for certain
design decisions because these decisions will call for their professional expertise.
Therefore, a software engineer may argue for a software-based door locking system
in a building, although a mechanical, key-based system may be more reliable.
My experience is that interdisciplinary working can be successful only if enough
time is available for these issues to be discussed and resolved. This requires regular
face-to-face discussions and a flexible approach from everyone involved in the systems
engineering process.