Difference between revisions of "Types of Systems"

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System Classification

A taxonomy is "a classification into ordered categories" (Dictionary.com 2011). Taxonomies are useful ways of organizing large numbers of individual items so their similarities and differences are apparent. Classification methods for systems have been proposed over the past forty years, yet no standard classification system exists. A brief discussion of classification approaches is given below.

The early developers of general system theory developed systems classification which has been the starting point for much of the subsequent work. Bertalanffy (Bertalanffy 1968) divided systems into 9 types, including control mechanisms, socio-cultural systems, open systems, and static structures. These classification approaches tend to focus on making sense of the natural and social world around us.

As System Science moved away from the theory of systems and began to consider how this theory might be used to provide practical approaches and tools classification approaches began to separate human-designed from non-human-designed systems or natural from man-made systems (Magee and de Weck 2004),. While they provide some methods for classifying natural systems, their primary emphasis and value to the practice of systems engineer is in their classification method for human-designed or manmade systems.

A discussion of and guide to the various classification methods proposed by systems scientists is included in History of Systems Science.

Types of Systems

The modern world has numerous kinds of systems that influence daily life. Some examples include transport systems, solar systems, telephone systems, the Dewey Decimal System, weapons systems, ecological systems, space systems, and so on; indeed it seems there is almost no end to the use of the word “system” in today’s society.

The classification methods above tend to classify systems either by the types of elements they contain or by their purpose. A simple classification of system elements , is into:

Natural Elements, objects or concepts which exist outside of any human control. Examples: the real number system, the solar system, planetary atmosphere circulation systems.
Human Elements, either abstract human types or social constructs; or concrete individuals or social groups.
Technological Elements, man made artefacts or constructs; including physical hardware, software and information.

Peter Checkland (Checkland 1999) proposed a classification of systems into five classes: natural systems, designed physical systems, designed abstract systems, human activity systems and transcendental systems.

Using the basic systems science definition of a system , we can relate systems to the real world through three related system domains as follows and shown in Figure 1:

A natural system is one whose elements are wholly natural.

A social system includes only humans as elements.

An engineered system is a man-made aggregation which may contain physical, informational, human, natural and social elements; normally created for the benefit of people.

These three types overlap to cover the full scope of real-world systems.

Figure 1.System Boundaries of Engineered Systems, Social Systems, and Natural Systems (Figure Developed for BKCASE)

natural systems are real world phenomena to which we apply systems thinking to help us better understand what they do and how they do it. A truly natural system would be a system we can observe and reason about, but over which we cannot exercise control, such as the solar system.

social systems are purely human in nature, such as legislatures, conservation foundations, and the United Nations (UN) Security Council, are exclusively in the SS domain. These systems are human artifacts created to help us gain some kind of control over, or protection from, the natural world.

Note: from the definitions above Natural and Social Systems can contain only natural and human elements respectively. In reality, while it is possible to describe and reason about Social System, many of them rely on some interaction or relationship with Engineered Systems to fully realise their purpose and thus will form part of one or more Engineered Systems Contexts.

engineered systems may be purely technical systems, such as bridges, electric autos, and power generation. Engineered Systems which contain technical and either human or natural elements, such as water and power management, safety governance systems, dams and flood control systems, and water and power safety assurance systems, are often called sociotechnical systems . The behavior of such systems is determined both by the nature of the engineered elements, and by their ability to integrate with or deal with the variability of the natural and social systems in which they sit. The ultimate success of any engineered system is thus measured by its ability to contribute to the success of relevant sociotechnical system context.

Wherever system elements are combined into an Engineered System the complexity of the resulting system will be increased. It is this increase in complexity that creates the need for a systems approach .

Groups of Systems

Systems can be grouped together to create more complex systems. In some cases systems become elements in a higher level system. However, there are cases where the groupings of system produce an entity that must be treated differently from a single integrated system. The most common groupings of systems that have characteristics beyond a single integrated system are systems of systems (sos) and federations of systems (fos) .

Maier examined the meaning of System of Systems (glossary) in detail and used a characterization approach which emphasises the independent nature of the system element, rather than “the commonly cited characteristics of systems-of-systems (complexity of the component systems and geographic distribution) are not the appropriate taxonomic classifiers” (Maier 1998, 268).

Wherever independent systems are combined into groups the interaction between the systems adds a further complexity in particular by constraining how the resulting system can be changed or controlled. This dimension of complexity leads to the management and control aspects of the systems approach .

Engineered Systems Classifications

Engineered systems:

Are created, used and sustained to achieve a purpose, goal or mission that is of interest to an enterprise , team , or an individual.
Require a commitment of resources for development and support.
Are driven by stakeholders with multiple views on the use or creation of the system, or with some other stake in the system, its properties or existence.
Contain engineered hardware, software, people, services or a combination of these.
Exist within an environment that impacts the characteristics, use, sustainment and creation of the system.

Engineered systems typically:

Are defined by their purpose, goal or mission.
Have a life cycle and evolution dynamics.
May include human operators (interacting with the systems via processes) and other natural components that must be considered in the design and development of the system.
Are part of a system-of-interest hierarchy.

The systems approach includes models and activities useful in the understanding, creation, use and sustainment of Engineered Systems. Disciplines which use a systems approach (such as Systems Engineering) deal with the apparent System Context. This is done by creating a system context focused on a selected Engineered system of interest (soi) .

Historically, “Economists divide all economic activity into two broad categories, goods and services. Goods-producing industries are agriculture, mining, manufacturing, and construction; each of them creates some kind of tangible object. Service industries include everything else: banking, communications, wholesale and retail trade, all professional services such as engineering, computer software development, and medicine, nonprofit economic activity, all consumer services, and all government services, including defense and administration of justice....” (Encyclopedia Britannica 2011). A product or service is developed and supported by an individual, team, or enterprise. For example, express package delivery is a service offered worldwide by many enterprises, both public and private, both small and large.

The nature of engineered systems has changed dramatically over the past several decades from systems dominated by hardware (mechanical and electrical) to systems dominated by software. In addition systems that provide services, without delivering hardware or software, have become common as the need to obtain and use information has become greater. Recently organizations have become sufficiently complex that the techniques that were demonstrated to work on hardware and software have been applied to the engineering of enterprises.

Three specific types of engineered system context are generally recognized in systems engineering: product system , service system and enterprise system .

Products and Product Systems

The word product is define as "a thing produced by labour or effort; or anything produced" (Oxford English Dictionary). In a commercial sense a product is anything which is acquired, owned and used by an enterprise (hardware, software, information, personnel, an agreement or contract to provide something, etc.)

product systems are systems in which products are developed and delivered to the acquirer for the use of internal or external user. For product systems the ability to provide the necessary capability must be defined in the specifications for the hardware and software, or the integrated system that will be provided to the acquiring enterprise .

Services and Service Systems

A service can be simply defined as an act of help or assistance, or as any outcome required by one or more users which can be defined in terms of outcomes and quality of service without detail to how it is provided. e.g. transport, communications, protection, data processing, etc. Services are processes, performances, or experiences that one person or organization does for the benefit of another – such as custom tailoring a suit, cooking a dinner to order, driving a limousine, mounting a legal defense, setting a broken bone, teaching a class, or running a business’ information technology infrastructure and applications. In all cases, service involves deployment of knowledge and skills (competences) that one person or organization has for the benefit of another (Lusch and Vargo 2006), often done as a single, customized job. In all cases, service requires substantial input from the customer or client (Sampson 2001) – for example, how can a steak be customized unless the customer tells the waiter how the customer wants the steak prepared? (business/marketing science definition)

A service systems is a system that provide outcomes for a user without necessarily delivering hardware or software products to the service supplier. The hardware and software systems may be owned by a third party who is not responsible for the service. The use of service systems reduces or eliminates the need for acquirers to obtain capital equipment and software in order to obtain the capabilities needed to satisfy users.

Enterprises and Enterprise Systems

An enterprise system defines one or more organizations or individuals sharing a definite mission, goals, and objectives to offer an output such as a product or service

An enterprise system consists of a purposeful combination (e.g., network) of interdependent resources (e.g., people, processes, organizations, supporting technologies, and funding) that interact with 1) each other (e.g., to coordinate functions, share information, allocate funding, create workflows, and make decisions), and 2) their environment(s), to achieve (e.g., business and operational) goals through a complex web of interactions distributed across geography and time (Rebovich and White 2011, 4, 10, 34-35).

Both product and service systems require an Enterprise System (glossary) to create them and an enterprise to use the product system to deliver services either internally to the enterprise or externally to a broader community.

According to Maier’s definition, an enterprise would not necessarily be called a system of systems (sos) since the systems within the enterprise do not usually meet the criteria of operational and managerial independence. In fact, the whole purpose of an enterprise is to explicitly establish operational dependence between systems that the enterprise owns and/or operates in order to maximize the efficiency and effectiveness of the enterprise as a whole. Therefore, it is more proper to treat an enterprise system and an SoS as different types of things, with different properties and characteristics (DeRosa 2005).

Enterprise systems are unique, compared to product and service systems, in that they are constantly evolving, they rarely have detailed configuration controlled requirements, they typically have the goal of providing shareholder value and customer satisfaction, which are constantly changing and are difficult to verify, and they exist in a context (or environment) that is ill-defined and constantly changing.

Links to other areas of the SEBoK

SEBoK Part 4 Applications of Systems Engineering explores how systems engineering is applied differently in product, service, and enterprise systems. The notion of enterprises and enterprise systems permeates Part 5 Enabling Systems Engineering.

References

Works Cited

Aslaksen, E.W. 1996. The Changing Nature of Engineering. New York, NY, USA: McGraw-Hill.

Blanchard, B.S., and W.J. Fabrycky. 2005. Systems Engineering and Analysis, 4th ed. Prentice-Hall International Series in Industrial and Systems Engineering. Englewood Cliffs, NJ, USA: Prentice-Hall.

Checkland, P.B. 1999. Systems Thinking, Systems Practice. Chichester, UK: John Wiley & Sons Ltd.

Hitchins, D. 2007. Systems Engineering: A 21st Century Systems Methodology. Hoboken, NJ, USA: Wiley.

Giachetti, R.E. 2009. Design of Enterprise Systems: Theory, Architectures, and Methods. Boca Raton, FL, USA: CRC Press.

Magee, C. L., O.L. de Weck. 2004. "Complex System Classification." Proceedings of the 14th Annual International Council on Systems Engineering International Symposium, 20-24 June 2004, Toulouse, France.

Maier, M., and E. Rechtin. 2009. The Art of Systems Architecting, 3rd Ed.. Boca Raton, FL, USA: CRC Press.

Paul, A. S. 1998. "Classifying Systems." Proceedings of The Eighth Annual International Council on Systems Engineering International Symposium, 26-30 July, 1998, Vancouver, BC, Canada.

Wasson, C. S. 2006. System Analysis, Design and Development. Hoboken, NJ, USA: John Wiley and Sons.

AFSAB. 2005. Report on Domain Integration. Washington, D.C.: U.S. Air Force Scientific Advisory Board/U.S. Air Force. SAB-TR-05-03.

Brill, J. H. 1998. "Systems Engineering – A Retrospective View." Systems Engineering. 1(4): 258-266.

Clark, J. 2008. "System of Systems Engineering and Family of Systems Engineering From a Standards, V-Model, and Dual-V Model Perspective." Proceedings of the 18th Annual International Council on Systems Engineering International Symposium 15-19 June, 2008, Utrecht, The Netherlands.

Dahmann, J.S., J.A. Lane, and G. Rebovich. 2008. "Systems Engineering for Capabilities." CROSSTALK: The Journal of Defense Software Engineering. (November 2008): 4-9.

DAU. February 19, 2010. Defense acquisition guidebook (DAG). Ft. Belvoir, VA, USA: Defense Acquisition University (DAU)/U.S. Department of Defense.

DUS(AT). 2008. Systems Engineering Guide for Systems of Systems," version 1.0. Washington, DC, USA: Deputy Under Secretary of Defense for Acquisition and Technology (DUS(AT))/U.S. Department of Defense (DoD).

Gorod, A., B. Sauser, and J. Boardman. 2008. "System-of-Systems Engineering Management: A Review of Modern History and a Path Forward". IEEE Systems Journal, 2(4): 484-499.

Handy, C. 1995. "How Do You Manage People Whom You Do Not See? Trust and the Virtual Organization." Harvard Business Review.' 73(3) (May-June): 40-50.

Handy, C. 1992. "Balancing Corporate Power: A New Federalist Paper". Harvard Business Review. 70(6) (November/December): 59-72.

Jain, P. and Dickerson, C. 2005. "Family-of-Systems Architecture Analysis Technologies." Proceedings of the 15th Annual International Council on Systems Engineering International Symposium, 10-15, July 2005, Rochester, NY, USA.

Jamshidi, M. "Theme of the IEEE SMC 2005" in IEEE SMC 2005 - International Conference on Systems, Man, and Cybernetics. Accessed 11 September 2011. Available at: http://ieeesmc2005.unm.edu.

Jamshidi, M. (ed.). 2009. Systems of Systems Engineering – Innovations for the 21st Century. Hoboken, NJ, USA: John Wiley and Sons.

Jamshidi, M. 2008. "System of Systems Engineering – New Challenges for the 21st Century". IEEE Aerospace and Electronic Systems Magazine. 23(5) (May 2008): 4-19.

Krygiel, A. J. 1999. Behind the Wizard's Curtain: An Integration Environment for a System of Systems. Arlington, VA, USA: C4ISR Cooperative Research Program (CCRP).

Maier, M. W. 1998. "Architecting Principles for Systems-of-Systems". Systems Engineering, 1(4): 267-84.

Sage, A., and C. Cuppan. 2001. "On the Systems Engineering and Management of Systems of Systems and Federations of Systems". Information-Knowledge-Systems Management Journal. 2(4) (December 2001): 325-45.

Bertalanffy, L. von. 1968. General System Theory. New York, NY, USA: Brazillier.

Dictionary.com, s.v. "Taxonomy," accessed September 7, 2011. Available at http://dictionary.reference.com/browse/taxonomy.

Encyclopedia Britannica, s.v. "Service Industry," accessed September 7, 2011. Available at http://www.britannica.com/EBchecked/topic/535980/service-industry.

INCOSE. 2011. INCOSE Systems Engineering Handbook, version 3.2.1. San Diego, CA, USA: International Council on Systems Engineering. INCOSE-TP-2003-002-03.2.1.

Magee, C.L. and O.L. de Weck. 2004. "Complex System Classification". Proceedings of the Fourteenth Annual International Symposium of the International Council on Systems Engineering. June 20-24, 2004, Toulouse, France.

Miller, J.G. 1986. "Can Systems Theory Generate Testable Hypothesis?: From Talcott Parsons to Living Systems Theory." Systems Research. 3: 73-84.

Primary References

Checkland, P. B. 1999. Systems Thinking, Systems Practice. Chichester, UK: John Wiley & Sons.

Magee, C. L., O.L. de Weck. 2004. "Complex System Classification." Proceedings of the 14th Annual International Council on Systems Engineering International Symposium, 20-24 June 2004, Toulouse, France.

Paul, A. S. 1998. "Classifying Systems." Proceedings of the Eighth Annual International Council on Systems Engineering International Symposium, 26-30 July 1998, Vancouver, BC, Canada.

Gorod, A., B. Sauser, and J. Boardman. 2008. "System-of-Systems Engineering Management: A Review of Modern History and a Path Forward." IEEE Systems Journal. 2(4): 484-499.

Jamshidi, M. editor. 2009. Systems of Systems Engineering – Innovations for the 21st Century. Hoboken, NJ: Wiley and Sons.

Jamshidi, M. 2008. "System of Systems Engineering – New Challenges for the 21st Century". IEEE Aerospace and Electronic Systems Magazine. 23(5) (May 2008): 4-19.

Maier, M. W. 1998. "Architecting Principles for Systems-of-Systems". Systems Engineering. 1(4): 267-84.

Sage, A. and C. Cuppan. 2001. "On the Systems Engineering and Management of Systems of Systems and Federations of Systems". Information-Knowledge-Systems Management Journal. 2(4) (December 2001): 325-45.

Additional References

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@@ Line 1: / Line 1: @@
-==Introduction==
+==System Classification==
-A taxonomy is "a classification into ordered categories" (Dictionary.com 2011).  Taxonomies are useful ways of organizing large numbers of individual items so their similarities and differences are apparent.  (Magee and de Weck 2004) provided a taxonomy for complex systems, and in doing so, did a short review of other classification approaches for systems. They identified the pioneering work of (Bertalanffy 1968) and the later work of (Miller 1986).  Bertalanffy divided systems into 9 types, including control mechanisms, socio-cultural systems, open systems, and static structures.  Miller offered cells, organization, and society among his 7 system types. [[Classifications of Systems]] offers a more detailed look into system classification approaches.
+A taxonomy is "a classification into ordered categories" (Dictionary.com 2011).  Taxonomies are useful ways of organizing large numbers of individual items so their similarities and differences are apparent.  Classification methods for [[System (glossary)|Systems (glossary)]] have been proposed over the past forty years, yet no standard classification system exists.  A brief discussion of classification approaches is given below.
-One simple categorization of systems is to divide it into: natural, social, and engineered.  The SEBoK focuses on [[Engineered System (glossary)|Engineered Systems (glossary)]].
+The early developers of [[General System Theory (glossary)]] developed systems classification which has been the starting point for much of the subsequent work. Bertalanffy (Bertalanffy 1968) divided systems into 9 types, including control mechanisms, socio-cultural systems, open systems, and static structures.  These classification approaches tend to focus on making sense of the natural and social world around us.
-*A [[Natural System (glossary)]] is one whose [[Element (glossary)|Elements (glossary)]], boundary, and relationships exist independently of human control. Examples: the real number system, the solar system, planetary atmosphere circulation systems.
+As System Science moved away from the theory of systems and began to consider how this theory might be used to provide practical approaches and tools classification approaches began to separate human-designed from non-human-designed systems or natural from man-made systems (Magee and de Weck 2004),.  While they provide some methods for classifying natural systems, their primary emphasis and value to the practice of systems engineer is in their classification method for human-designed or manmade systems.
-*A [[Social System (glossary)]] includes humans as elements.
+A discussion of and guide to the various classification methods proposed by systems scientists is included in [[History of Systems Science]].
+==Types of Systems==
+The modern world has numerous kinds of systems that influence daily life. Some examples include transport systems, solar systems, telephone systems, the Dewey Decimal System, weapons systems, ecological systems, space systems, and so on; indeed it seems there is almost no end to the use of the word “system” in today’s society.
+The classification methods above tend to classify systems either by the types of elements they contain or by their purpose.  A simple classification of [[Element (glossary)| System Elements (glossary)]], is into:
+*Natural Elements, objects or concepts which exist outside of any human control. Examples: the real number system, the solar system, planetary atmosphere circulation systems.
+*Human Elements, either abstract human types or social constructs; or concrete individuals or social groups.
+*Technological Elements, man made artefacts or constructs; including physical hardware, software and information.
+Peter Checkland (Checkland 1999) proposed a classification of systems into five classes: natural systems, designed physical systems, designed abstract systems, human activity systems and transcendental systems.
+Using the basic systems science definition of a [[System (glossary)|System (glossary)]], we can relate systems to the real world through three related system domains as follows and shown in Figure 1:
+*A [[Natural System (glossary)]] is one whose elements are wholly natural.
+*A [[Social System (glossary)]] includes only humans as elements.
 *An [[Engineered System (glossary)]] is a man-made aggregation which may contain physical, informational, human, natural and social elements; normally created for the benefit of people.
-As discussed in [[What is a System?]] these three types overlap to cover the full scope of real-world systems.
+These three types overlap to cover the full scope of real-world systems.
+[[File:Scope_SystemBoundaries.png|frame|400px|center|Figure 1.System Boundaries of Engineered Systems, Social Systems, and Natural Systems (Figure Developed for BKCASE)]]
-[[Systems Science (glossary)]] offers a number of ways of further classifying systems, related to a range of perspectives and attributes.  There are also a number of system grouping approaches, which specify ways to define combinations of similar systems, including [[System of Systems (SoS) (glossary)]].
+[[Natural System (glossary)|Natural Systems (glossary)]] are real world phenomena to which we apply systems thinking to help us better understand what they do and how they do it. A truly natural system would be a system we can observe and reason about, but over which we cannot exercise control, such as the solar system.
-Classification methods for [[System (glossary)|Systems (glossary)]] have been proposed over the past forty years, yet no standard classification system exists.  Various methods that have been proposed are summarized in this article.
+[[Social System (glossary)|Social Systems (glossary)]] are purely human in nature, such as legislatures, conservation foundations, and the United Nations (UN) Security Council, are exclusively in the SS domain. These systems are human artifacts created to help us gain some kind of control over, or protection from, the natural world.
-== Classification Methods ==
+Note: from the definitions above Natural and Social Systems can contain only natural and human elements respectively. In reality, while it is possible to describe and reason about Social System, many of them rely on some interaction or relationship with Engineered Systems to fully realise their purpose and thus will form part of one or more Engineered Systems Contexts.
-Kenneth Boulding, one of the founding fathers of [[General System Theory (glossary)]], developed a systems classification which has been the starting point for much of the subsequent work. (Boulding 1956).  He classifies systems into 9 types: 1. Structures (Bridges); 2. Clock works (Solar system); Controls (Thermostat); 4. Open (Biological cells); 5. Lower organisms (Plants); 6. Animals (Birds); 7. Man (Humans); 8. Social (Families); and 9. Transcendental (God).  This approach also highlights some of the subsequent issues of classification.  Boulding implies that physical structures are closed and natural or social ones are open. He also separates humans from animals. (Hitchins 2007).
-Peter Checkland proposed a classification system described below.  (Checkland 1999) Arthur Paul surveyed the work to date and proposed methods for classifying systems. (Paul 1998) One of the most recent work was performed by Magee and de Weck, who developed a classification approach for complex systems and focused on engineered systems.  (Magee and de Weck 2004)  All of these classification approaches separate human-designed from non-human-designed systems or natural from man-made systems.  While they provide some methods for classifying natural systems, their primary emphasis and value to the practicing systems engineer is in their classification method for human-designed or manmade systems.  Peter Checkland divided systems into five classes: natural systems, designed physical systems, designed abstract systems, human activity systems and transcendental systems.  The first two classes are self explanatory.
+[[Engineered System (glossary)|Engineered Systems (glossary)]] may be purely technical systems, such as bridges, electric autos, and power generation.  Engineered Systems which contain technical and either human or natural elements, such as water and power management, safety governance systems, dams and flood control systems, and water and power safety assurance systems, are often called [[Sociotechnical System (glossary)|Sociotechnical Systems (glossary)]].  The behavior of such systems is determined both by the nature of the engineered elements, and by their ability to integrate with or deal with the variability of the natural and social systems in which they sit. The ultimate success of any engineered system is thus measured by its ability to contribute to the success of relevant sociotechnical system context.
-*Designed abstract systems – These systems do not contain any physical artifacts but are designed by humans to serve some explanatory purpose.
+Wherever system elements are combined into an Engineered System the [[Complexity (glossary)]] of the resulting system will be increased.  It is this increase in complexity that creates the need for a [[Systems Approach (glossary)]].
-*[[Human Activity System (glossary)|Human activity systems (glossary)]] – These systems are observable in the world of innumerable sets of human activities that are more or less consciously ordered in wholes as a result of some underlying purpose or mission.  At one extreme is a system consisting of a human wielding a hammer.  At the other extreme lies international political systems.
-*Transcendental systems – These systems that go beyond the aforementioned four systems classes, systems beyond knowledge.
-Checkland refers to these five systems as comprising a “systems map of the universe”. (Checkland 1999, p.111)
-Checkland, himself starting from a systems engineering perspective, successively observed the problems in applying a systems engineering approach to the more fuzzy, ill-defined problems found in the social and political arenas.  (Checkland 1999, p. A9) Thus he introduced a distinction between hard systems and soft systems:
+==Groups of Systems==
-*[[Hard System (glossary)|Hard systems (glossary)]] of the world are characterized by the ability to define purpose, goals, and missions that can be addressed via engineering methodologies in attempting to, in some sense, “optimize” a solution.
+Systems can be grouped together to create more complex systems.  In some cases systems become elements in a higher level system.  However, there are cases where the groupings of system produce an entity that must be treated differently from a single integrated system.  The most common groupings of systems that have characteristics beyond a single integrated system are [[System of Systems (SoS) (glossary)|Systems of Systems (SoS) (glossary)]] and [[Federation of Systems (FoS) (glossary)|Federations of Systems (FoS) (glossary)]].
-*[[Soft System (glossary)|Soft systems (glossary)]] of the world are characterized by extremely complex, problematical, and often mysterious phenomena for which concrete goals cannot be established and which require learning in order to make improvement. Such systems are not limited to the social and political arenas and also exist within and amongst enterprises where complex, often ill-defined patterns of behavior are observed that are limiting the enterprise's ability to improve. Historically, the systems engineering discipline was primarily aimed at developing, modifying or supporting hard systems. More recently, the systems engineering discipline has expanded to address software systems as well.
+Maier examined the meaning of [[System of Systems (glossary)]] in detail and used a characterization approach which emphasises the independent nature of the system element, rather than “the commonly cited characteristics of systems-of-systems (complexity of the component systems and geographic distribution) are not the appropriate taxonomic classifiers” (Maier 1998, 268).
-Arthur Paul surveys previously defined classification methods and arrives at five definitions of system types based on function and usage of the systems. (Paul 1998) He defines: personal/household, military, civil, industrial and infrastructure systems as the five types of operating systems.
-Magee and de Weck examine many possible methods that include: degree of complexity, branch of the economy that produced the system, realm of existence (physical or in thought), boundary, origin, time dependence, system states, human involvement / system control, human wants, ownership and functional type.  They conclude by proposing a functional classification method that sorts systems by their process: transform, transport, store, exchange, or control and by the entity that they operate on: matter, energy, information and value.
+Wherever independent systems are combined into groups the interaction between the systems adds a further [[Complexity (glossary)]] in particular by constraining how the resulting system can be changed or controlled.  This dimension of complexity leads to the management and control aspects of the [[Systems Approach (glossary)]].
-Other categorizations of system types can be found throughout the literature. The varieties of suggested types that relate to specific presentations of various authors include:
+== Engineered Systems Classifications ==
-*Eric Aslaksen describes three main classes of systems, according to the actions they perform:  transport systems (translations in space), storage systems (translations in time), and production systems (time and space independent transformations). (Aslaksen 1996)
+Engineered systems:
-*Ben Blanchard describes several types including human-made systems, physical systems, conceptual systems, static systems, closed systems and open systems. (Blanchard 2005)
+#Are created, used and sustained to achieve a purpose, goal or mission that is of interest to an [[Enterprise (glossary)]], [[Team (glossary)]], or an individual.
-*Ronald Giachetti describes enterprise systems. (Giachetti 2009)
+#Require a commitment of resources for development and support.
-*Scott Jackson describes technological (or product) systems, product-centered infrastructure systems, technological system with human interface, human-intensive systems, process systems, socio-ecological systems, complex adaptive systems and infrastructure systems. (Jackson 2010)
+#Are driven by [[Stakeholder (glossary)|stakeholders (glossary)]] with multiple views on the use or creation of the system, or with some other stake in the system, its properties or existence.
-*Mark Maier describes builder-architected systems, form-first systems, politico-technical systems and socio-technical systems. (Maier 2009)
+#Contain engineered hardware, software, people, services or a combination of these.
-*Charles Wasson describes cultural systems, business systems, educational systems, financial systems, government systems, medical systems and transportation systems. (Wasson 2006)
+#Exist within an environment that impacts the characteristics, use, sustainment and creation of the system.
-==Groupings of Systems==
+Engineered systems typically:
-Systems can be grouped together to create more complex systems.  In some cases systems become subsystems in a higher level system.  However, there are cases where the groupings of system produce an entity that must be treated differently from a single integrated system.  The most common groupings of systems that have characteristics beyond a single integrated system are [[System of Systems (SoS) (glossary)|Systems of Systems (SoS) (glossary)]] and [[Federation of Systems (FoS) (glossary)|Federations of Systems (FoS) (glossary)]].    Wherever systems are combined into groups and interaction between the systems is present the complexity will be increased.  It is this increase in complexity that creates the greatest challenge to the systems engineer. This article provides a definition of and fundamental information about the various groupings of systems.  Other articles within the Systems Engineering Body of Knowledge ([[Acronyms|SEBoK]]) provide methods for dealing with the additional complexity that grouping systems produces.
+#Are defined by their purpose, goal or mission.
+#Have a [[Life Cycle (glossary)]] and evolution dynamics.
+#May include human operators (interacting with the systems via processes) and other natural components that must be considered in the design and development of the system.
+#Are part of a system-of-interest hierarchy.
-===System of Systems (SoS)===
+The [[Systems Approach (glossary)]] includes models and activities useful in the understanding, creation, use and sustainment of Engineered Systems.  Disciplines which use a systems approach (such as Systems Engineering) deal with the apparent [[System Context]].  This is done by creating a system context focused on a selected Engineered [[System of Interest (SoI) (glossary)]].
-The phrase “system of systems” is commonly used, but there is no widespread agreement on its exact meaning, or on how it can be distinguished from a conventional system. An extensive history of SoS is provided in “System-of-Systems Engineering Management: A Review of Modern History and a Path Forward” (Gorod, et. al. 2008).  This paper provides a historical perspective for systems engineering from (Brill 1998).  The authors then provide a chronological history for System-of-Systems (SoS) engineering from 1990 to 2008.  Their history provides an extensive set of references to all of the significant papers and textbooks on SoS.  Gorod et. al. cite Maier as one of the most influencial contributors to the study of SoS.
+Historically, “Economists divide all economic activity into two broad categories, goods and services. Goods-producing industries are agriculture, mining, manufacturing, and construction; each of them creates some kind of tangible object. Service industries include everything else: banking, communications, wholesale and retail trade, all professional services such as engineering, computer software development, and medicine, nonprofit economic activity, all consumer services, and all government services, including defense and administration of justice....” (Encyclopedia Britannica 2011).  A product or service is developed and supported by an individual, team, or enterprise. For example, express package delivery is a service offered worldwide by many enterprises, both public and private, both small and large.
-Maier examined the meaning of SoS in detail and used a characterization approach to create a definition (Maier 1998, 267-284). His definition has been adopted by many working in the field (AFSAB 2005). Maier provides this definition:
+The nature of engineered systems has changed dramatically over the past several decades from systems dominated by hardware (mechanical and electrical) to systems dominated by software.  In addition systems that provide services, without delivering hardware or software, have become common as the need to obtain and use information has become greater.  Recently organizations have become sufficiently complex that the techniques that were demonstrated to work on hardware and software have been applied to the engineering of enterprises.
-<blockquote>''A system-of-systems is an assemblage of components which individually may be regarded as systems, and which possess two additional properties:''
-#''Operational Independence of the Components: If the system-of-systems is disassembled into its component systems the component systems must be able to usefully operate independently. That is, the components fulfill customer-operator purposes on their own.''
-#''Managerial Independence of the Components: The component systems not only can operate independently, they do operate independently. The component systems are separately acquired and integrated but maintain a continuing operational existence independent of the system-of-systems.'' (Maier 1998, 271)</blockquote>
-Maier goes on further saying that “the commonly cited characteristics of systems-of-systems (complexity of the component systems and geographic distribution) are not the appropriate taxonomic classifiers” (Maier 1998, 268). According to the Defense Acquisition Guide: "A SoS is defined as a set or arrangement of systems that results from independent systems integrated into a larger system that delivers unique capabilities" (DAU 2010, 4.1.4. System of Systems (SoS) Engineering). For further details on SoS, see the ''Systems Engineering Guide for SoS'' developed by the US Department of Defense (DoD) (DUS(AT) 2008).
+Three specific types of engineered system context are generally recognized in systems engineering: [[Product System (glossary)]], [[Service System (glossary)]] and [[Enterprise System (glossary)]].
-Four kinds of SoS have been defined (Maier 1998; Dahmann and Baldwin 2008; DUS(AT) 2008; Dahmann, Lane, and Rebovich 2008):
+===Products and Product Systems===
-<blockquote>
+The word [[Product (glossary)]] is define as "a thing produced by labour or effort; or anything produced" (Oxford English Dictionary).  In a commercial sense a product is anything which is acquired, owned and used by an enterprise (hardware, software, information, personnel, an agreement or contract to provide something, etc.)
-*'''''Virtual'''. Virtual SoS lack a central management authority and a centrally agreed upon purpose for the system-of-systems. Large-scale behavior emerges—and may be desirable—but this type of SoS must rely upon relatively invisible mechanisms to maintain it.''
-*'''''Collaborative'''. In collaborative SoS the component systems interact more or less voluntarily to fulfill agreed upon central purposes. The Internet is a collaborative system. The Internet Engineering Task Force works out standards but has no power to enforce them. The central players collectively decide how to provide or deny service, thereby providing some means of enforcing and maintaining standards.''
-*'''''Acknowledged'''. Acknowledged SoS have recognized objectives, a designated manager, and resources for the SoS; however, the constituent systems retain their independent ownership, objectives, funding, and development and sustainment approaches. Changes in the systems are based on collaboration between the SoS and the system.''
-*'''''Directed'''. Directed SoS are those in which the integrated system-of-systems is built and managed to fulfill specific purposes. It is centrally managed during long-term operation to continue to fulfill those purposes as well as any new ones the system owners might wish to address. The component systems maintain an ability to operate independently, but their normal operational mode is subordinated to the central managed purpose.''(DUS(AT) 2008, 4-5; and, Dahmann, Lane, and Rebovich 2008, 4; in reference to (Maier 1998; Dahmann and Baldwin 2008))</blockquote>
-The terms [[Emergence (glossary)|Emergence (glossary)]] and emergent behavior are increasingly being used in SoS contexts. While the concept of emergence and its derivative terms has a long history in science and technology, to this day there is no single, universal definition of emergence.
+[[Product System (glossary)|Product Systems (glossary)]] are systems in which products are developed and delivered to the acquirer for the use of internal or external user.  For product systems the ability to provide the necessary [[Capability (glossary)]] must be defined in the specifications for the hardware and software, or the integrated system that will be provided to the acquiring [[Enterprise (glossary)]].
-In SoS contexts, the recent interest in emergence has been fueled, in part, by the movement to apply systems science and complexity theory to problems of large-scale, heterogeneous information technology based systems. In this context, a working definition of emergent behavior of a system is behavior which is unexpected or cannot be predicted by knowledge of the system’s constituent parts.
+===Services and Service Systems===
+A [[Service (glossary)]] can be simply defined as an act of help or assistance, or as any outcome required by one or more users which can be defined in terms of outcomes and quality of service without detail to how it is provided. e.g. transport, communications, protection, data processing, etc.  Services are processes, performances, or experiences that one person or organization does for the benefit of another – such as custom tailoring a suit, cooking a dinner to order, driving a limousine, mounting a legal defense, setting a broken bone, teaching a class, or running a business’ information technology infrastructure and applications. In all cases, service involves deployment of knowledge and skills (competences) that one person or organization has for the benefit of another (Lusch and Vargo 2006), often done as a single, customized job. In all cases, service requires substantial input from the customer or client (Sampson 2001) – for example, how can a steak be customized unless the customer tells the waiter how the customer wants the steak prepared? (business/marketing science definition)
-One of the leading authors in the area of SoS is Mo Jamshidi who is the editor of a leading textbook (Jamshidi 2009) and articles, such as “System of Systems Engineering – New Challenges for the 21st Century” (Jamshidi 2008).  His article, that addresses the challenges, also provides numerous references to papers that have examined the definition of SoS.  The author selects six of the many potential definitions.  His lead definition is <blockquote>''Systems of systems exist when there is a presence of a majority of the following five characteristics: operational and managerial independence, geographic distribution, emergent behavior, and evolutionary development'' (Jamshidi 2008, 5; adapted from Sage and Cuppan 2001, 326).</blockquote>
+A [[Service System (glossary)|Service Systems (glossary)]] is a system that provide outcomes for a user without necessarily delivering hardware or software products to the service supplier.  The hardware and software systems may be owned by a third party who is not responsible for the service.  The use of service systems reduces or eliminates the need for acquirers to obtain capital equipment and software in order to obtain the capabilities needed to satisfy users.
-===Federation of Systems (FOS)===
+===Enterprises and Enterprise Systems===
+An [[Enterprise System (glossary)]] defines one or more organizations or individuals sharing a definite mission, goals, and objectives to offer an output such as a product or service
-Different from the SoS concept, but related to it in several ways, is the concept called “federation of systems” or FOS. This concept might apply when there is a very limited amount of centralized control and authority (Sage and Cuppan 2001).  Each system in an FOS is very strongly in control of its own destiny, but “chooses” to participate in the FOS for its own good and the good of the “country,” so to speak. It is a coalition of the willing. An FOS is generally characterized by significant autonomy, heterogeneity, and geographic distribution or dispersion (Krygiel 1999). Krygiel  (1999) defined a taxonomy of systems showing the relationships among conventional systems, SoSs, and FOSs. This taxonomy has three dimensions: autonomy, heterogeneity, and dispersion. An FOS would have a larger value on each of these three dimensions than a non-federated SoS. An [[Enterprise System (glossary)]] as described in [[The Enterprise View of Engineered Systems]], could be considered to be an FOS if it rates highly on these three dimensions. However, it is possible for an enterprise to have components that are not highly autonomous, that are relatively homogenous, and are geographically close together. Therefore, it would be a mistake to say that an enterprise is necessarily the same as an FOS.
+An [[Enterprise System (glossary)]] consists of a purposeful combination (e.g., network) of interdependent resources (e.g., people, processes, organizations, supporting technologies, and funding) that interact with 1) each other (e.g., to coordinate functions, share information, allocate funding, create workflows, and make decisions), and 2) their environment(s), to achieve (e.g., business and operational) goals through a complex web of interactions distributed across geography and time (Rebovich and White 2011, 4, 10, 34-35).
-(Handy 1992) describes a federalist approach called “New Federalism” which identifies the need for structuring of loosely coupled organizations to help them adapt to the rapid changes inherent in the Information Age. This leads to the need for virtual organizations where alliances can be quickly formed to handle the challenges of newly identified threats and a rapidly changing marketplace (Handy 1995).  Handy sets out to define a number of federalist political principles that could be applicable to an FOS. Handy’s principles have been tailored to the domain of systems engineering and management by (Sage and Cuppan 2001).
+Both product and service systems require an Enterprise System (glossary) to create them and an enterprise to use the product system to deliver services either internally to the enterprise or externally to a broader community.
-===Families of Systems===
+According to Maier’s definition, an enterprise would not necessarily be called a [[System of Systems (SoS) (glossary)]] since the systems within the enterprise do not usually meet the criteria of operational and managerial independence. In fact, the whole purpose of an enterprise is to explicitly establish operational dependence between systems that the enterprise owns and/or operates in order to maximize the efficiency and effectiveness of the enterprise as a whole. Therefore, it is more proper to treat an enterprise system and an SoS as different types of things, with different properties and characteristics (DeRosa 2005).
-The Defense Acquisition University (DAU 2010, 4.1.4. System of Systems (SoS) Engineering) defines families of systems as:
+Enterprise systems are unique, compared to product and service systems, in that they are constantly evolving, they rarely have detailed configuration controlled requirements, they typically have the goal of providing shareholder value and customer satisfaction, which are constantly changing and are difficult to verify, and they exist in a context (or environment) that is ill-defined and constantly changing.
-<blockquote>''A family of systems is a grouping of systems having some common characteristic(s). For example, each system in a family of systems may belong to a domain or product line (e.g., a family of missiles, aircraft, or situation awareness systems). In general, a family of systems is not considered to be a system per se because it does not necessarily create capability beyond the additive sum of the individual capabilities of its member systems. A family of systems lacks the synergy of a SoS. The family of systems does not acquire qualitatively new properties as a result of the grouping. In fact, the member systems may not be connected into a whole.'' (DAU 2010)</blockquote>
-Very few papers have been written that address families of systems or compare them to systems of systems.
-James Clark (2008) provides a view that a family of systems is equivalent to a product line:
+==Links to other areas of the SEBoK==
-<blockquote>''By family, we mean a product-line or domain, wherein some assets are re-used un-modified; some assets are modified, used, and re-used later; and some assets are developed new, used, and re-used later. Product-lines are the result.'' (Clark 2008)</blockquote>
+SEBoK Part 4 [[Applications of Systems Engineering]] explores how systems engineering is applied differently in product, service, and enterprise systems.  The notion of enterprises and enterprise systems permeates Part 5 [[Enabling Systems Engineering]].
-== Engineered Systems Classifications ==
-There is no agree terminology for classifying the types of [[Engineered System (glossary)|Engineered Systems (glossary)]] to which a [[Systems Approach (glossary)]]
-can be applied.
-In the SEBoK we classify Engineered systems into [[Product System (glossary)|Product Systems (glossary)]], [[Service System (glossary)|Service Systems (glossary)]], and [[Enterprise System (glossary)|Enterprise Systems (glossary)]].
 ==References==