Ongoing software development without classical requirements

Many prominent open source software (OSS) development projects produce systems without overt requirements artifacts or processes, contrary to expectations resulting from classical software development experience and research, and a growing number of critical software systems are evolved and sustained in this way yet provide quality and rich functional capabilities to users and integrators that accept them without question. We examine data from several OSS projects to investigate this conundrum, and discuss the results of research into OSS outcomes that sheds light on the consequences of this approach to software requirements in terms of risk of development failure and quality of the resulting system.