RUP
Rational Unified Process
RUP — Rational Unified Process is an iterative software development method, released as a commercial product by Rational Software in 1998. Based on the prior contributions of the Three Amigos (in particular Booch and Jacobson), it is the heavyweight enterprise process that accompanied UML adoption through the 1990s and 2000s.
How it works #
RUP organises a project into four sequential phases, each composed of one or more internal iterations:
- Inception — vision, business case, general scope
- Elaboration — architecture, detailed requirements, technical risk mitigation
- Construction — iterative software implementation
- Transition — production deploy, beta, rollout, training
Unlike the classic waterfall, RUP is iterative (you go back and forth between phases multiple times). Unlike Scrum, it’s document-intensive — a typical enterprise Elaboration lasts months, with traced artefacts and documented milestones.
When it makes sense today #
RUP’s space in new projects has been eroded by Agile starting in 2001. But it survives alive and well in sectors where documentary rigour is mandatory by law or by audit: aviation (DO-178C), medical (IEC 62304), critical banking, pharmaceutical R&D. In these contexts a pure Agile method doesn’t pass the audit, and RUP — or one of its descendants — is still the standard.
How it differs from Agile #
Agile puts people and short iterations at the centre; RUP puts processes and traceable artefacts at the centre. They are not superior to each other — they suit different contexts. Many Agile ideas (user story, sprint, “Three Amigos meeting” in BDD) have conceptual origin in the UML/RUP world — just stripped of the process weight.