Sommerville-Software-Engineering-10ed

608 Chapter 20 ■ Systems of systems
20.3. The classification of SoS presented in Section 20.2 suggests a governance-based classification
scheme. Giving reasons for your answer, identify the classifications for the following
systems of systems:
(a) A health care system that provides unified access to all patient health records from hospitals,
clinics, and primary care.
(b) The World Wide Web
(c) A government system that provides access to a range of welfare services such as pensions,
disability benefits, and unemployment benefits.
Are there any problems with the suggested classification for any of these systems?
20.4. Explain what is meant by reductionism and why it is effective as a basis for many kinds of
engineering.
20.5. Define systems of systems engineering. List the problems of software SoS engineering that
are also common to problems of integrating large-scale application systems.
20.6. How beneficial is a unified user interface in the interface design of SoS? What are the factors on
which the cost-effectiveness of a unified user interface is dependent?
20.7. Sillitto suggests that communications between nodes in a SoS are not just technical but
should also include informal sociotechnical communications between the people involved in
the system. Using the iLearn SoS as an example, suggest where these informal communications
may be important to improve the effectiveness of the system.
20.8. Suggest the closest-fit architectural pattern for the systems of systems introduced in Exercise
20.3.
20.9. The trading system pattern assumes that there is no central authority involved. However, in
areas such as equity trading, trading systems must follow regulatory rules. Suggest how this
pattern might be modified to allow a regulator to check that these rules have been followed.
This should not involve all trades going through a central node.
20.10. You work for a software company that has developed a system that provides information
about consumers and that is used within a SoS by a number of other retail businesses. They
pay you for the services used. Discuss the ethics of changing the system interfaces without
notice to coerce users into paying higher charges. Consider this question from the point of
view of the company’s employees, customers, and shareholders.
References
Boehm, B., and C. Abts. 1999. “COTS Integration: Plug and Pray?” Computer 32 (1): 135–138.
doi:10.1109/2.738311.
Hitchins, D. 2009. “System of Systems—The Ultimate Tautology.” http://www.hitchins.net/profsstuff/profs-blog/system-of-systems---the.html