Peer-to-peer, grid, and service-orientation in digital library architectures : 6th Thematic Workshop of the EU Network of Excellence DELOS Cagliari, Italy, June 24-25, 2004 : revised selected papers - Thermatic Workshop of the EU Network of Excellence DELOS; Türker, Can; Agosti, Maristella; Schek, Hans-Jörg (Lecture notes in computer science, 2005)