System of Systems

A System of Systems (SoS) is an integration of a finite number of constituent systems which are independent and operatable, and which are networked together for a period of time to achieve a certain higher goal.[1]

Another approach of definition resulted in SoS being a metasystem that consists of multiple autonomous embedded complex systems that can be diverse in technology, context, operation, geography and conceptual frame.[2]

Designing, developing and deploying Systems of Systems is a multidisciplinary process summarised under the term System of systems engineering (SoSE).

Among the biggest challenges of SoS and SoSE are the characterisation of governance structures, implementing the evolutionary aspect of SoS in a prototype and ensuring safety and security within the SoS.


Maier's characterisation becomes more and more recognised according to which an SoS generally matches a majority of the following five characteristics.[3]

  • Operational independence includes that each constituent system has a purpose of its own and can be operated independently over time

  • Managerial independence of the constituent systems means that they are controlled by different authorities

  • SoS can be expected to show emergent behavior that cannot be achieved by any of the constituent systems operating independently


Boardman and Sauser characterised an SoS very similar, namely that it can be distinguished by the terms autonomy, belonging, connectivity, diversity and emergence.[4] 


Different classes of SoS

In general, Systems of Systems can be divided in four different types depending on the hierarchy of the costituent systems, the organisations behind them or the purpose they are fulfilling.[5]

  1. A directed SoS has a specific, predefined purpose. The constituent systems operate independently but are subordinated to this purpose.

  2. An acknowledged SoS has own objectives, management and resources but the constituent systems maintain their independence in these areas.

  3. In a collaborative SoS, the constituent systems interact voluntarily and central players collectively decide about the provision of services.

  4. A virtual SoS lacks a central management and agreed purpose. An often used example is the WWW.

Related Terms

See also



  1. Jamshidi, 2009.
  2. Keating et al., “System of Systems Engineering,” Engineering Management Journal, 2003.
  3. Maier, Architecting principles for systems-of-systems", Systems Engineering, 1998.
  4. Boardman, and Sauser, "System of Systems - the meaning of of", 2006.
  5. Dahmann, J. and K. Baldwin (2008), Understanding the Current State of US Defense Systems of Systems and the Implications for Systems Engineering, 2nd Annual IEEE Systems Conference, Montreal.