Partage De Données En Mode Pair A Pair Sur Réseaux Mobiles Ad Hoc. (Peer To Peer Data Sharing Over Mobile Ad Hoc Networks)

Designing collaborative software for mobile ad hoc networks presents news challenges : in a MANEt, devices are mobile, resources are scarce and because of an absence of infrastructure, everything is decentralized. Therefore, algorithms for collaborative application on wired networks cannot be used as is, and new algorithms, adapted to MANet, have to be defined. This thesis proposes a set of algorithms for developing a distributed data sharing system for MANets. First of all we propose a clustering algorithm to create groups of terminals stable over time. This algorithm’s main advantage is that it does not create any network load since it uses cross-layering information from the routing layer to know which terminals are reachable. We also propose a proactive replication algorithm, which, for each data, creates and maintains a number of replica proportional to the number of terminals. It uses semantic information about data and users to try and place these replica on the devices where they are most likely to be used. This algorithm enhances data availability (accesses are faster) and data sharing reliability (if a terminal disappears, or if the network splits, the probability of losing a data is lowered). Finally, we propose a cache management algorithm. This algorithm tries to regulate the best number of replica so as to optimize the use of the network, while maintaining data availability. First of all, when a cache replacement is needed, the algorithm eliminates data less recently used, and for which the number of replica is high enough to maintain data sharing availability. It also reduces the network load by removing useless replica which generate network traffic and are not used by their host. As it is hard to make reproducible experiments on top of a MANet, our proposition was validated by simulation and we have demonstrated a positive influence on data availability, the data sharing service overall reliability and an efficient use of resources. We also present, as a demonstrator, a peer to peer wiki engine, design toward mobile ad hoc networks, which we have used to provide a functional validation of our algorithms. It uses Treedoc to maintain data coherency and is designed to be integrated in the Transhumance middleware. Keyword : MANet, Data sharing, Distributed, Peer to Peer