“…Email addresses: zoi@di.uoa.gr (Zoi Kaoudi), koubarak@di.uoa.gr (Manolis Koubarakis), kkyzir@di.uoa.gr (Kostis Kyzirakos), iris@di.uoa.gr (Iris Miliaraki ,$$ ), matoula@di.uoa.gr (Matoula Magiridou), apapadak@di.uoa.gr (Antonios Papadakis-Pesaresi) 1 Although RDF is the chosen metadata model for resource annotation only in [7,9], we can easily see how it could have been used in [8,10,11,12]. See also Section 4. lacking the reliability properties typically associated with large distributed systems [13] (e.g., fault-tolerance, load balancing, availability etc.…”