While the rapidly increasing number of users and applications running on Desktop Grid (DG) systems does demonstrate its inherent potential, current DG implementations follow the traditional master-worker paradigm and DG middlewares do not cooperate. To extend the DG architecture, we propose a novel system, called BonjourGrid, capable of 1) creating, for each user, a specific execution environment in a decentralized fashion and 2) contrarily to classical DG, of orchestrating multiple and various instances of Desktop Grid middlewares. This will enable us to construct, on demand, specific execution environments (combinations of XtremWeb, Condor, Boinc middlewares). BonjourGrid is a software which aims to link a discovery service based on publish/subscribe protocol with the upper layer of a Desktop Grid middleware bridging the gap to meta-grid. Our experimental evaluation proves that BonjourGrid is robust and able to orchestrate more than 400 instances of XtremWeb middleware in a concurrent fashion on a 1000 host cluster. This experiment demonstrates the concept of BonjourGrid as well as its potential and shows that, comparing to a classical Desktop Grid with one central master, BonjourGrid suffers from an acceptable overhead that can be explained.
