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 in a 2006 report from the Software Engineering Institute at Carnegie Mellon University authored by Linda Northrop and colleagues.
In summary, the talk concluded that (a) ULS systems are in the midst of society and the changes to current social fabric and institutions are significant; (b) The 2006 original research team was probably too conservative in their report; (c) Recent technologies have exacerbated the pace of scale growth; and (d) There are great opportunities.
A difference pointed out by Ian Sommerville[4] is that the UK initiative began with a five to ten year vision, while that of Northrop and her co-authors was much longer term.
[6] On the other hand, 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.
Consequently, ULS systems will place unprecedented demands on software acquisition, production, deployment, management, documentation, usage, and evolution practices."
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".
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.
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.
[10] 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.
This research area investigates integrated development environments and runtime platforms that support the decentralized nature of ULS systems.
[13] 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.
Rules and policies must be developed and automated to enable fast and effective local action while preserving global capabilities.
The National Natural Science Foundation of China has outlined a five-year project for researchers to study the assembly of ultra-large spacecraft.