A system of systems (SoS) is defined as a system composed of multiple independent systems that are integrated. Key characteristics of a SoS include that each system can operate independently, each has its own manager and policies, and the overall SoS is developed evolutonarily rather than being fully pre-specified. Examples given include a cloud management system integrating private and public cloud systems, an online banking system integrating with credit agencies, and an emergency response system integrating information from different emergency services.

1. Systems of systems
Software Engineering 10

2. More and more systems are being
constructed by integrated existing,
independent systems.

3. A system of systems is a system that
contains two or more independently
managed elements that are systems
in their own right.

4. There is no single manager for all of
the parts of the system of systems
and different parts of a system are
subject to different management and
control policies and rules.

5. A cloud management system that
integrates local private cloud
management systems and
management systems for servers on
public clouds.

6. An online banking system that
handles loan requests which
integrates with credit reference
systems provided by credit reference
agencies.

7. An emergency information system
that integrates information from
police, ambulance, fire and
coastguard services about the
assets available to deal with civil
emergencies, such as flooding and
large-scale accidents.

8. Systems of systems have seven
essential characteristics

9. Each system can operate
independently of other systems

10. Each system has its own manager
and management policies

11. The SoS as a whole is not pre-
specified completely but is
developed in an evolutionary way

12. Some SoS characteristics (such as
compliance, reliability, etc.) are
emergent so that they only become
understandable when the SoS is
integrated

13. The systems in the SoS are not co-
located but may be widely
distributed with consequent
problems of human interaction,
sometimes across time zones

14. Typically, the size of the databases in
a SoS exceeds the code size by one
or more orders of magnitude

15. The different systems in a SoS are
likely to be built using different
hardware and software technologies

16. These seven characteristics mean
that SoS are incredibly complex.
No individual or small group can
understand an SoS in its entirety