The most complete description of PeerWare is available in:
Gianpaolo Cugola and Gian Pietro Picco, "PeerWare: Core Middleware Support for Peer-To-Peer and Mobile Systems". Technical report.
Although the API and design of µCode have changed since then, the motivating criteria and approach are still those described in the aforementioned documents. Other papers, which describe PeerWare and how it has been applied in the MOTION project are:
Gianpaolo Cugola and Gian Pietro Picco, "Peer-to-peer for Collaborative Applications". In Proceedings of the International Workshop on Mobile Teamwork Support, co-located with the 22nd International Conference on Distributed Computing Systems, Vienna (Austria), H. Gall and G.P. Picco eds., IEEE press, pp. 359-364, July 2002.
Gerald Reif, Engin Kirda, Harald Gall, Gian Pietro Picco, Gianpaolo Cugola, and Pascal Fenkam, "A Web-based peer-to-peer architecture for collaborative nomadic working". In Proceedings of the 3rd International Workshop on Web-based Infrastructures and Coordination Architectures for Collaborative Enterprises, co-located with the 10th International Workshops on Enabling Technologies: Infrastructure for Collaborative Enterprises (WETICE 2001). MIT, Cambridge (MA, USA), June 2001.