Search and browse services for heterogeneous collections with the peer-to-peer network Pepper

Peer-to-peer networks have recently gained importance as environments for digital libraries. In this paper, we describe Pepper, a peer-to-peer network for supporting two important access modes, searching and browsing. Pepper seamlessly combines hierarchical networks with service-oriented architectures. Hierarchical networks improve efficiency by partitioning peers into high-end hubs which are responsible for routing the query, and leaf peers (typically running on desktop PCs or laptops) which host documents. Service-oriented architectures allow for loosely coupled systems, improve extensibility and reusability, and enable integration of the two access paradigms by combination of multiple services. For example, distributed searching and browsing both use the same statistical metadata, and thus the same storage service, for solving their tasks.