Ultra-Large-Scale Systems
Encyclopedia
Ultra-large-scale system (ULSS) is a term used in fields including Computer Science
, Software Engineering
and Systems Engineering
to refer to software intensive systems with unprecedented amounts of hardware, lines of source code, numbers of users, and volumes of data. The scale of these systems gives rise to many problems: they will be developed and used by many stakeholders across multiple organizations, often with conflicting purposes and needs; they will be constructed from heterogeneous parts with complex dependencies and emergent properties; they will be continuously evolving; and software, hardware and human failures will be the norm, not the exception. The term 'ultra-large-scale system' was introduced by Northrop and others to describe challenges facing the United States Department of Defense
. The term has subsequently been used to discuss challenges in many areas, including the computerization of financial markets. The term 'ultra-large-scale system' (ULSS) is sometimes used interchangeably with the term 'large-scale complex IT system' (LSCITS). These two terms were introduced at similar times to describe similar problems, the former being coined in the USA and the latter in the UK.
at Carnegie Mellon University
authored by Linda Northrop and colleagues. The report explained that software intensive systems are reaching unprecedented scales (by measures including lines of code; numbers of users and stakeholders; purposes the system is put to; amounts of data stored, accessed, manipulated, and refined; numbers of connections and interdependencies among components; and numbers of hardware elements). When systems become ultra-large-scale, traditional approaches to engineering and management will no longer be adequate. The report argues that the problem is no longer of engineering systems
or system of systems
, but of engineering "socio-technical ecosystems".
At a similar time to the publication of the report by Northrop and others, a research and training initiative was being initiated in the UK on Large-scale Complex IT Systems
. Many of the challenges recognized in this initiative were the same as, or were similar to those recognized as the challenges of ultra-large-scale systems. Greg Goth quotes Dave Cliff, director of the UK initiative as saying "The ULSS proposal and the LSCITS proposal were written entirely independently, yet we came to very similar conclusions about what needs to be done and about how to do it". A difference pointed out by Ian Sommerville
is that the UK initiative began with a 5 to 10 year vision, while that of Northrop and her co-authors was much longer term. This seems to have led to there being two slightly different perspectives on ultra-large-scale systems. For example, Richard Gabriel's perspective is that ultra-large-scale systems are desirable but currently impossible to build due to limitations in the fields of software design and systems engineering. On the other hand, Ian Sommerville
's perspective is that ultra-large-scale systems are already emerging (for example in air traffic control), the key problem being not how to achieve them but how to ensure they are adequately engineered.
(systems that have: operationally independent sub-systems; managerially independent components and sub-systems; evolutionary development; emergent behavior; and geographic distribution). But in addition to these, the Northrop report argues that a ULSS will:
The Northrop report states that "the sheer scale of ULS systems will change everything. ULS systems will necessarily be decentralized in a variety of ways, developed and used by a wide variety of stakeholders with conflicting needs, evolving continuously, and constructed from heterogeneous parts. People will not just be users of a ULS system; they will be elements of the system. The realities of software and hardware failures will be fundamentally integrated into the design and operation of ULS systems. The acquisition of a ULS system will be simultaneous with its operation and will require new methods for control. In ULS systems, these characteristics will dominate. Consequently, ULS systems will place unprecedented demands on software acquisition, production, deployment, management, documentation, usage, and evolution practices."
in engineering software intensive systems. In 2008 Greg Goth wrote that although Northrop’s report focused on the US military’s future requirements, "its description of how the fundamental principles of software design will change in a global economy … is finding wide appeal". The term is now used to discuss problems in several domains.
Human interaction – People are key participants in ULS systems. Many problems in complex systems today stem from failures at the individual and organizational level. Understanding ULS system behavior will depend on the view that humans are elements of a socially constituted computational process. This research involves anthropologists, sociologists, and social scientists conducting detailed socio-technical analyses of user interactions in the field, with the goal of understanding how to construct and evolve such socio-technical systems effectively.
Computational emergence – ULS systems must satisfy the needs of participants at multiple levels of an organization. These participants will often behave opportunistically to meet their own objectives. Some aspects of ULS systems will be "programmed" by properly incentivizing and constraining behavior rather than by explicitly prescribing. This research area explores the use of methods and tools based on economics and game theory (e.g., mechanism design) to ensure globally optimal ULS system behavior by exploiting the strategic self-interests of the system’s constituencies. This research area also includes exploring metaheuristics and digital evolution to augment the cognitive limits of human designers, so they can manage ongoing ULS system adaptation more effectively.
Design – Current design theory, methods, notations, tools, and practices and the acquisition methods that support them are inadequate to design ULS systems effectively. This research area broadens the traditional technology-centric definition of design to include people and organizations; social, cognitive, and economic considerations; and design structures such as design rules and government policies. It involves research in support of designing ULS systems from all of these points of view and at many levels of abstraction, from the hardware to the software to the people and organizations in which they work.
Computational engineering – New approaches will be required to enable intellectual control at an entirely new level of scope and scale for system analysis, design, and operation.ULS systems will be defined in many languages, each with its own abstractions and semantic structures. This research area focuses on evolving the expressiveness of representations to accommodate this semantic diversity. Because the complexity of ULS systems will challenge human comprehension, this area also focuses on providing automated support for computing the behavior of components and their compositions in systems and for maintaining desired properties as ULS systems evolve.
Adaptive system infrastructure – ULS systems require an infrastructure that permits organizations in distributed locations to work in parallel to develop, select, deploy, and evolve system components. This research area investigates integrated development environments and runtime platforms that support the decentralized nature of ULS systems. This research also focuses on technologies, methods, and theories that will enable ULS systems to be developed in their deployment environments.
Adaptable and predictable system quality – ULS systems will be long-running and must operate robustly in environments fraught with failures, overloads, and attacks. These systems must maintain robustness in the presence of adaptations that are not centrally controlled or authorized.
Managing traditional qualities such as security, performance, reliability, and usability is necessary but not sufficient to meet the challenges of ULS systems. This research area focuses on how to maintain quality in a ULS system in the face of continuous change, ongoing failures, and attacks. It also includes identifying, predicting, and controlling new indicators of system health (akin to the U. S. gross domestic product) that are needed because of the scale of ULS systems.
Policy, acquisition, and management – Policy and management frameworks for ULS systems must address organizational, technical, and operational policies at all levels. Rules and policies must be developed and automated to enable fast and effective local action while preserving global capabilities. This research area focuses on transforming acquisition policies and processes to accommodate the rapid and continuous evolution of ULS systems by treating suppliers and supply chains as intrinsic and essential components of a ULS system.
The proposed research does not supplant current, important software research but rather significantly expands its horizons. Moreover, because it is focused on systems of the future, the SEI team purposely avoided couching descriptions in terms of today’s technology. The envisioned outcome of the proposed research is a spectrum of technologies and methods for developing these systems of the future, with national-security, economic, and societal benefits that extend far beyond ULS systems themselves.
has been concerned with issues around ULSS development and considers that an LSCITS (Large-scale complex IT system) shares many of the characteristics of a ULSS.
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
, Software Engineering
Software engineering
Software Engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, and the study of these approaches; that is, the application of engineering to software...
and Systems Engineering
Systems engineering
Systems engineering is an interdisciplinary field of engineering that focuses on how complex engineering projects should be designed and managed over the life cycle of the project. Issues such as logistics, the coordination of different teams, and automatic control of machinery become more...
to refer to software intensive systems with unprecedented amounts of hardware, lines of source code, numbers of users, and volumes of data. The scale of these systems gives rise to many problems: they will be developed and used by many stakeholders across multiple organizations, often with conflicting purposes and needs; they will be constructed from heterogeneous parts with complex dependencies and emergent properties; they will be continuously evolving; and software, hardware and human failures will be the norm, not the exception. The term 'ultra-large-scale system' was introduced by Northrop and others to describe challenges facing the United States Department of Defense
United States Department of Defense
The United States Department of Defense is the U.S...
. The term has subsequently been used to discuss challenges in many areas, including the computerization of financial markets. The term 'ultra-large-scale system' (ULSS) is sometimes used interchangeably with the term 'large-scale complex IT system' (LSCITS). These two terms were introduced at similar times to describe similar problems, the former being coined in the USA and the latter in the UK.
Background
The term ultra-large-scale system was introduced in a 2006 report from the Software Engineering InstituteSoftware Engineering Institute
The Carnegie Mellon Software Engineering Institute is a federally funded research and development center headquartered on the campus of Carnegie Mellon University in Pittsburgh, Pennsylvania, United States. SEI also has offices in Arlington, Virginia, and Frankfurt, Germany. The SEI operates...
at Carnegie Mellon University
Carnegie Mellon University
Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....
authored by Linda Northrop and colleagues. The report explained that software intensive systems are reaching unprecedented scales (by measures including lines of code; numbers of users and stakeholders; purposes the system is put to; amounts of data stored, accessed, manipulated, and refined; numbers of connections and interdependencies among components; and numbers of hardware elements). When systems become ultra-large-scale, traditional approaches to engineering and management will no longer be adequate. The report argues that the problem is no longer of engineering systems
Systems engineering
Systems engineering is an interdisciplinary field of engineering that focuses on how complex engineering projects should be designed and managed over the life cycle of the project. Issues such as logistics, the coordination of different teams, and automatic control of machinery become more...
or system of systems
System of systems
System of systems is a collection of task-oriented or dedicated systems that pool their resources and capabilities together to create a new, more complex system which offers more functionality and performance than simply the sum of the constituent systems...
, but of engineering "socio-technical ecosystems".
At a similar time to the publication of the report by Northrop and others, a research and training initiative was being initiated in the UK on Large-scale Complex IT Systems
Large-scale Complex IT Systems
The UK Large-Scale Complex IT Systems Initiative is a research and graduate education program focusing on the problems of developing large-scale, complex IT systems...
. Many of the challenges recognized in this initiative were the same as, or were similar to those recognized as the challenges of ultra-large-scale systems. Greg Goth quotes Dave Cliff, director of the UK initiative as saying "The ULSS proposal and the LSCITS proposal were written entirely independently, yet we came to very similar conclusions about what needs to be done and about how to do it". A difference pointed out by Ian Sommerville
Ian Sommerville
Ian F. Sommerville, is a British academic. He is currently a full professor of software engineering at the University of St Andrews in Scotland and is the author of a popular student textbook on software engineering, as well as a number of other books and papers...
is that the UK initiative began with a 5 to 10 year vision, while that of Northrop and her co-authors was much longer term. This seems to have led to there being two slightly different perspectives on ultra-large-scale systems. For example, Richard Gabriel's perspective is that ultra-large-scale systems are desirable but currently impossible to build due to limitations in the fields of software design and systems engineering. On the other hand, Ian Sommerville
Ian Sommerville
Ian F. Sommerville, is a British academic. He is currently a full professor of software engineering at the University of St Andrews in Scotland and is the author of a popular student textbook on software engineering, as well as a number of other books and papers...
's perspective is that ultra-large-scale systems are already emerging (for example in air traffic control), the key problem being not how to achieve them but how to ensure they are adequately engineered.
Characteristics of an ultra-large-scale system
Ultra-large-scale systems hold the characteristics of systems of systemsSystem of systems
System of systems is a collection of task-oriented or dedicated systems that pool their resources and capabilities together to create a new, more complex system which offers more functionality and performance than simply the sum of the constituent systems...
(systems that have: operationally independent sub-systems; managerially independent components and sub-systems; evolutionary development; emergent behavior; and geographic distribution). But in addition to these, the Northrop report argues that a ULSS will:
- Have decentralized data, development, evolution and operational control
- Address inherently conflicting, unknowable, and diverse requirements
- Evolve continuously while it is operating, with different capabilities being deployed and removed
- Contain heterogeneous, inconsistent and changing elements
- Erode the people system boundary. People will not just be users, but elements of the system and affecting its overall emergent behavior.
- Encounter failure as the norm, rather than the exception, with it being extremely unlikely that all components are functioning at any one time
- Require new paradigms for acquisition and policy, and new methods for control
The Northrop report states that "the sheer scale of ULS systems will change everything. ULS systems will necessarily be decentralized in a variety of ways, developed and used by a wide variety of stakeholders with conflicting needs, evolving continuously, and constructed from heterogeneous parts. People will not just be users of a ULS system; they will be elements of the system. The realities of software and hardware failures will be fundamentally integrated into the design and operation of ULS systems. The acquisition of a ULS system will be simultaneous with its operation and will require new methods for control. In ULS systems, these characteristics will dominate. Consequently, ULS systems will place unprecedented demands on software acquisition, production, deployment, management, documentation, usage, and evolution practices."
Domains in which ultra-large-scale systems are emerging
The term ultra-large-scale system was introduced by Northrop and others to discuss challenges faced by the United States Department of DefenseUnited States Department of Defense
The United States Department of Defense is the U.S...
in engineering software intensive systems. In 2008 Greg Goth wrote that although Northrop’s report focused on the US military’s future requirements, "its description of how the fundamental principles of software design will change in a global economy … is finding wide appeal". The term is now used to discuss problems in several domains.
Defense
The Northrop report argued that "the U.S. Department of Defense (DoD) has a goal of information dominance … this goal depends on increasingly complex systems characterized by thousands of platforms, sensors, decision nodes, weapons, and warfighters connected through heterogeneous wired and wireless networks. … These systems will push far beyond the size of today's systems by every measure … They will be ultra-large-scale systems."Financial trading
Following the flash crash, Cliff and Northrop have argued "The very high degree of interconnectedness in the global markets means that entire trading systems, implemented and managed separately by independent organizations, can rightfully be considered as significant constituent entities in the larger global super-system. … The sheer number of human agents and computer systems connected within the global financial-markets system-of-systems is so large that it is an instance of an ultra-large-scale system, and that largeness-of-scale has significant effects on the nature of the system".Healthcare
Kevin Sullivan has stated that the US healthcare system is "clearly an ultra-large-scale system" and that building national scale cyber-infrastructure for healthcare "demands not just a rigorous, modern software and systems engineering effort, but an approach at the cutting edge of our understanding of information processing systems and their development and deployment in complex socio-technical environments".Others
Other domains said to be seeing the rise of ultra-large-scale systems include government, transport systems (for example air traffic control systems), energy distribution systems (for example smart grids) and large enterprises.Research
Fundamental gaps in our current understanding of software and software development at the scale of ULS systems present profound impediments to the technically and economically effective achievement of significant gains in core system functionality. These gaps are strategic, not tactical. They are unlikely to be addressed adequately by incremental research within established categories. Rather, we require a broad new conception of both the nature of such systems and new ideas for how to develop them. We will need to look at them differently, not just as systems or systems of systems, but as socio-technical ecosystems. We will face fundamental challenges in the design and evolution, orchestration and control, and monitoring and assessment of ULS systems. These challenges require breakthrough research.ULSS research in the USA
The Northrop report proposed a ULS systems research agenda for an interdisciplinary portfolio of research in at least the following areas:Human interaction – People are key participants in ULS systems. Many problems in complex systems today stem from failures at the individual and organizational level. Understanding ULS system behavior will depend on the view that humans are elements of a socially constituted computational process. This research involves anthropologists, sociologists, and social scientists conducting detailed socio-technical analyses of user interactions in the field, with the goal of understanding how to construct and evolve such socio-technical systems effectively.
Computational emergence – ULS systems must satisfy the needs of participants at multiple levels of an organization. These participants will often behave opportunistically to meet their own objectives. Some aspects of ULS systems will be "programmed" by properly incentivizing and constraining behavior rather than by explicitly prescribing. This research area explores the use of methods and tools based on economics and game theory (e.g., mechanism design) to ensure globally optimal ULS system behavior by exploiting the strategic self-interests of the system’s constituencies. This research area also includes exploring metaheuristics and digital evolution to augment the cognitive limits of human designers, so they can manage ongoing ULS system adaptation more effectively.
Design – Current design theory, methods, notations, tools, and practices and the acquisition methods that support them are inadequate to design ULS systems effectively. This research area broadens the traditional technology-centric definition of design to include people and organizations; social, cognitive, and economic considerations; and design structures such as design rules and government policies. It involves research in support of designing ULS systems from all of these points of view and at many levels of abstraction, from the hardware to the software to the people and organizations in which they work.
Computational engineering – New approaches will be required to enable intellectual control at an entirely new level of scope and scale for system analysis, design, and operation.ULS systems will be defined in many languages, each with its own abstractions and semantic structures. This research area focuses on evolving the expressiveness of representations to accommodate this semantic diversity. Because the complexity of ULS systems will challenge human comprehension, this area also focuses on providing automated support for computing the behavior of components and their compositions in systems and for maintaining desired properties as ULS systems evolve.
Adaptive system infrastructure – ULS systems require an infrastructure that permits organizations in distributed locations to work in parallel to develop, select, deploy, and evolve system components. This research area investigates integrated development environments and runtime platforms that support the decentralized nature of ULS systems. This research also focuses on technologies, methods, and theories that will enable ULS systems to be developed in their deployment environments.
Adaptable and predictable system quality – ULS systems will be long-running and must operate robustly in environments fraught with failures, overloads, and attacks. These systems must maintain robustness in the presence of adaptations that are not centrally controlled or authorized.
Managing traditional qualities such as security, performance, reliability, and usability is necessary but not sufficient to meet the challenges of ULS systems. This research area focuses on how to maintain quality in a ULS system in the face of continuous change, ongoing failures, and attacks. It also includes identifying, predicting, and controlling new indicators of system health (akin to the U. S. gross domestic product) that are needed because of the scale of ULS systems.
Policy, acquisition, and management – Policy and management frameworks for ULS systems must address organizational, technical, and operational policies at all levels. Rules and policies must be developed and automated to enable fast and effective local action while preserving global capabilities. This research area focuses on transforming acquisition policies and processes to accommodate the rapid and continuous evolution of ULS systems by treating suppliers and supply chains as intrinsic and essential components of a ULS system.
The proposed research does not supplant current, important software research but rather significantly expands its horizons. Moreover, because it is focused on systems of the future, the SEI team purposely avoided couching descriptions in terms of today’s technology. The envisioned outcome of the proposed research is a spectrum of technologies and methods for developing these systems of the future, with national-security, economic, and societal benefits that extend far beyond ULS systems themselves.
ULSS research in the UK
The UK’s research programme in Large-scale Complex IT SystemsLarge-scale Complex IT Systems
The UK Large-Scale Complex IT Systems Initiative is a research and graduate education program focusing on the problems of developing large-scale, complex IT systems...
has been concerned with issues around ULSS development and considers that an LSCITS (Large-scale complex IT system) shares many of the characteristics of a ULSS.
See also
- System of systemsSystem of systemsSystem of systems is a collection of task-oriented or dedicated systems that pool their resources and capabilities together to create a new, more complex system which offers more functionality and performance than simply the sum of the constituent systems...
- Complex adaptive systemComplex adaptive systemComplex adaptive systems are special cases of complex systems. They are complex in that they are dynamic networks of interactions and relationships not aggregations of static entities...
- Systems theorySystems theorySystems theory is the transdisciplinary study of systems in general, with the goal of elucidating principles that can be applied to all types of systems at all nesting levels in all fields of research...
- Systems designSystems designSystems design is the process of defining the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements. One could see it as the application of systems theory to product development...
- Software architectureSoftware architectureThe software architecture of a system is the set of structures needed to reason about the system, which comprise software elements, relations among them, and properties of both...
- EmergenceEmergenceIn philosophy, systems theory, science, and art, emergence is the way complex systems and patterns arise out of a multiplicity of relatively simple interactions. Emergence is central to the theories of integrative levels and of complex systems....
- Self-organizationSelf-organizationSelf-organization is the process where a structure or pattern appears in a system without a central authority or external element imposing it through planning...
- Sociotechnical systemsSociotechnical systemsSociotechnical systems in organizational development is an approach to complex organizational work design that recognizes the interaction between people and technology in workplaces. The term also refers to the interaction between society's complex infrastructures and human behaviour...
External links
- ULS Systems – Carnegie Mellon Software Engineering Institute's program for Ultra Large Scale Systems
- ULSSIS – The Center for Ultra-Large Scale Software-Intensive Systems; the acronym is pronounced like "Ulysses"
- Ultra-Large-Scale Systems: The Software Challenge of the Future – The 2006 report for a 12-month study of ultra-large-scale systems software, sponsored by the United States Department of DefenseUnited States Department of DefenseThe United States Department of Defense is the U.S...
- ULS Systems Glossary
- Stepping Up to Long-Term Research – IEEE Distributed Systems Online article on Ultra-Large Systems research
- Why Multi-Core is Easy and Internet is Hard – a paper (and discussion) that touches on topics important in ULS research
- The Agoric Papers archived copies of http://www.agorics.com/Library/agoricpapers.html – Three papers on capability-based market-oriented computing (concepts that are the subject of some ULS Systems research), written by Mark S. MillerMark S. MillerMark S. Miller is an American computer scientist. He is known for his work as one of the participants in the 1979 hypertext project known as Project Xanadu; for inventing Miller Columns; as the co-creator of the Agoric Paradigm of market-based distributed secure computing; and the open-source...
and K. Eric DrexlerK. Eric DrexlerDr. Kim Eric Drexler is an American engineer best known for popularizing the potential of molecular nanotechnology , from the 1970s and 1980s.His 1991 doctoral thesis at MIT was revised and published as...