Software Engineering Institute

Ultra-large-scale systems are interdependent webs of software-intensive systems, people, policies, cultures, and economics.

The sheer scale of ULS systems changes 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. Software and hardware failures will be the norm rather than the exception. The acquisition of a ULS system will be simultaneous with its operation and will require new methods for control.

These characteristics may appear in today’s systems and systems of systems, but in ULS systems, they will dominate. Consequently, ULS systems will place unprecedented demands on software acquisition, production, deployment, management, documentation, usage, and evolution practices.