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In this article we address the problem of counting the number of peers in a peer-to-peer system, and more generally of aggregating statistics of individual peers over the whole system. This functionality is useful in many applications, but hard to achieve when each node has only a limited, local knowledge of the whole system. We propose two generic(More)
As the size of distributed systems keeps growing, the peer to peer communication paradigm has been identified as the key to scalability. Peer to peer overlay networks are characterized by their self-organizing capabilities, resilience to failure and fully decentralized control. In a peer to peer overlay, no entity has a global knowledge of the system. As(More)
A complex network can be modeled as a graph representing the ''who knows who " relationship. In the context of graph theory for social networks, the notion of centrality is used to assess the relative importance of nodes in a given network topology. For example, in a network composed of large dense clusters connected through only a few links, the nodes(More)
In this article, we address the problem of counting the number of peers in a peer-to-peer system. This functionality has proven useful in the design of several peer-to-peer applications. However, it is delicate to achieve when nodes are organised in an overlay network, and each node has only a limited, local knowledge of the whole system. In this paper, we(More)
In recent years the labels "gossip" and "gossip-based" have been applied to an increasingly general class of algorithms, including approaches to information aggregation, overlay network management and clock synchronization. These algorithms are intuitively similar, irrespective of their purpose. Their distinctive features include relying on local(More)
The increase of interest in the analysis of contemporary social networks, for both academic and economic reasons, has highlighted the inherent difficulties in handling large and complex structures. Among the tools provided by researchers for network analysis, the centrality notion, capturing the importance of individuals in a graph, is of particular(More)
The availability of end devices of peer-to-peer storage and backup systems has been shown critical for usability and for system reliability in practice. This has led to the adoption of hybrid architectures composed of both peers and servers. Such architectures mask the instability of peers thus approaching the performances of client-server systems while(More)
It is now common for IPTV systems attracting millions of users to be based on a peer-to-peer (P2P) architecture. In such systems, each channel is typically associated with one P2P overlay network connecting the users. This significantly enhances the user experience by relieving the source from dealing with all connections. Yet, the joining process resulting(More)
Modern storage systems now typically combine plain replication and erasure codes to reliably store large amount of data in datacenters. Plain replication allows a fast access to popular data, while erasure codes, <i>e.g</i>., Reed-Solomon codes, provide a storage-efficient alternative for archiving less popular data. Although erasure codes are now(More)