< programming > A software life-cycle or product life-cycle model, described by W. W. Royce in 1970, in which development is supposed to proceed linearly through the phases of requirements analysis , design, implementation, testing (validation), integration and maintenance. The Waterfall Model is considered old-fashioned or simplistic by proponents of object-oriented design which often uses the spiral model instead.
Earlier phases are sometimes called "upstream" and later ones "downstream".
Compare: iterative model .
[W. W. Royce, "Managing the Development of Large Software Systems", Proceedings of IEEE WESCON, August 1970].
(1997-11-23)