The Unified Process (UP), currently supported by IBM, aims to provide a disciplined approach to assigning tasks and responsibilities within a software development organization. The software lifecycle is broken in four consecutive phases: inception, elaboration, construction and transition [11]; similarly to the CMMI, the Unified Process doesn’t address specifically software acquisition and supply activities.
The Extreme Programming (XP) is an agile software development process, developed specifically for small to medium teams building software in the face of vague and / or rapidly changing requirements. The process is intended to be highly dynamic, where development teams deals with requirements changes throughout an iterative life-cycle with short loops [4]. Specifically about the relationship between software users and developers, XP claims that customers should be completely involved in development activities, participating in all decisions that are made during the iterative development.