Peer-to-peer information retrieval

Almer S. Tigelaar
2012 SIGIR Forum  
Peer-to-peer technology is widely used for file sharing. In the past decade a number of prototype peer-to-peer information retrieval systems have been developed. Unfortunately, none of these has seen widespread realworld adoption and thus, in contrast with file sharing, information retrieval is still dominated by centralised solutions. In this article we provide an overview of the key challenges for peer-to-peer information retrieval and the work done so far. We want to stimulate and inspire
more » ... ther research to overcome these challenges. This will open the door to the development and large-scale deployment of real-world peer-to-peer information retrieval systems that rival existing centralised client-server solutions in terms of scalability, performance, user satisfaction and freedom. server farms, but computers in people's homes [Kurose and Ross 2003 ]. Because of this, a peer-to-peer network typically consists of thousands of low-cost machines all with different processing and storage capacities as well as different link speeds. Such a network can provide many interesting applications, like: file sharing, streaming media and distributed search. Peer-to-peer networks have several properties that make them attractive for these tasks. They usually have no centralised directory or control point and thus also no central point of failure. This makes them self-organizing, meaning that they automatically adapt when peers join the network, depart from it or fail. The communication between peers uses a common language and is symmetric as is the provision of services. This symmetry makes a peer-to-peer network self-scaling: each peer that joins the network adds to the available total capacity [Bawa et al. 2003; Risson and Moors 2006] . In the following sections we will first discuss some common applications of peer-topeer networks and the challenges for such networks, followed by an in-depth overview of commonly used peer-to-peer network architectures. Applications Many applications use peer-to-peer technology. There are many important challenges specific to peer-to-peer networks [Daswani et al. 2003; Triantafillou et al. 2003 ]: -How to make efficient use of resources? Resources are bandwidth, processing power and storage. The higher the efficiency the more requests a system can handle and the lower the costs for handling each request. Peers may vary wildly in their available resources. This heterogeneity raises unique challenges. -How to provide acceptable quality of service? Measurable important aspects are: low latency, and sufficient, high-quality results. -How to guarantee robustness? Provide a stable service to peers and the ability to recover from data corruption and communication errors whatever the cause. -How to ensure data remains available? When a peer leaves the network its content is, temporarily, not accessible. Hence, a peer-to-peer network should engage in quick distribution of popular data to ensure it remains available for as long as there is demand for it. -How to provide anonymity? The owners and users of peers in the network should have at least some level of anonymity depending on the application. This enables censorship resistance, freedom of speech without the fear of persecution and privacy protection.
doi:10.1145/2422256.2422276 fatcat:u5n62556ezbrllenb7frlatiri