Perimorph: run-time composition and state management for adaptive systems

We address a key issue that arises in run-time recomposition of software: the transfer of nontransient state between old components and their replacements. We focus on the concept of collateral change, which refers to the set of recomposition actions that must be applied atomically for continued correct execution of the system. We describe Perimorph, a system that supports compositional adaptation of both functional and nonfunctional concerns by explicitly addressing collateral change. The operation of Perimorph is demonstrated through the implementation and testing of a 2D/3D digital elevation mapping application that supports recomposition and handoff among networked devices with varying capabilities.