The vision of the PIMA application model is described in this Mobicom 2000 Challenges paper:

An Application Model for Pervasive Computing

The way mobile computing devices and applications are developed, deployed and used today does not meet the expectations of the user community and falls far short of the potential for pervasive computing. This paper challenges the mobile computing community by questioning the roles of devices, applications, and a user's environment. A vision of pervasive computing is described, along with attributes of a new application model that supports this vision, and a set of challenges that must be met in order to bring the vision to reality.