This work presents a novel peer-to-peer system that is particularly well suited to support context-aware computing. The system, called GeoPeer, aims to combine the advantages of peer-to-peer systems that implement distributed hash tables with the suitability of geographical routing for supporting location-constrained queries and information dissemination. GeoPeer is comprised of two fundamental components: a Delaunay triangulation used to build a connected lattice of nodes and a mechanism to manage long range contacts that allows good routing performance, despite unbalanced distribution of nodes.

This paper proposes a distributed and scalable publish-subscribe broker with support for QoS. The broker, called IndiQoS, leverages on existing mechanisms to reserve resources in the underlying network and on an overlay network of peer-to-peer rendezvous nodes, to automatically select QoS-capable paths. By avoiding flooding of either QoS reservations or link-state information, IndiQoS is able to scale with respect to network size and number of reservations. Experimental results show the validity of our approach